source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-2344 | fossils, drilling
Title: What would people drilling through Mount Everest find? I am interested in knowing what kind of fossils we would find if we were to drill horizontally through the mountain and what we would find if we were to drill vertically. Would we find anything interesting other than the fossils? Looks like some basic hints are necessary (as a complement to @AndyM's answer):
stratigraphy usually goes from younger to older when going down.
there'll be little chance to find any macrofossils in rocks that formed before sufficiently complex life was around.
there'll be little chance to find fossils in rocks that underwent metamorphism, that is have been in pressure/temperature regimes that aren't conducive for their preservation, even if they initially were present in the pre existing rocks.
'trace fossils' are not small remains of fossils but fossilized traces ('footprints'). Very rare thing.
it may be possible to find fossils in overlaying, younger sediments that formed during or after the uplift or were trapped or transported in depressions, but that's not the point of the question I think.
So, below the uppermost formations around the summit you'll likely find nothing of interest in the sense of the question when drilling down.
Will provide sources on specificically focussed request, but this isn't top notch geoscience.
The following is multiple choice question (with options) to answer.
Fossils provide a window into the past. they are evidence for what? | [
"generation",
"intelligent design",
"emergence",
"evolution"
] | D | Fossils provide a window into the past. They are evidence for evolution. |
SciQ | SciQ-2345 | genetics, human-genetics, allele
But some illnesses are carried by dominant alleles (from the same article):
Other disorders, such as Huntington disease, occur when an individual inherits only one dominant allele.
My questions are:
How does harm from alleles correlate with their recessiveness? Generally speaking, do harmful alleles tend to be more recessive?
How does benefits from alleles correlate with their dominance? Generally speaking, do "beneficial" alleles tend to be more dominant? Instead of dividing mutations into two classes, dominant vs. recessive, consider categorizing them into classes based on how the mutation affects the gene--or the gene product. This yields loss-of-function (lf) alleles, that reduce the activity of the gene, or its product, and gain-of-function (gf) alleles that act as if they somehow increase the activity of the gene, or its product.
The logic underlying this classification was described in this classic reference: Muller, H. J. 1932. Further studies on the nature and causes of gene mutations. Proceedings of the 6th International Congress of Genetics, pp. 213–255. Since this was before DNA had been shown to be the genetic material his arguments are based solely on the phenotype of animals carrying various combinations of chromosomes. In particular he relies on genetic duplications and deficiencies (or deletions). In this nomenclature + indicates a chromosome carrying a wild-type (wt) allele of the gene, and m indicates a chromosome carrying a mutant allele of the gene. So if an +/m animal appears Wild-Type then that allele is recessive. Similarly, if an +/m animal has a Mutant phenotype then the allele is dominant.
There are two types of lf alleles:
The following is multiple choice question (with options) to answer.
Dominant alleles rarely cause what type of disorders, since the mutant allele is likely to die out of the population? | [
"sex-linked disorders",
"cancers",
"genetic disorders",
"mutations"
] | C | Few genetic disorders are controlled by dominant alleles. A mutant dominant allele is expressed in every individual who inherits even one copy of it. If it causes a serious disorder, affected people may die young and fail to reproduce. Therefore, the mutant dominant allele is likely to die out of the population. |
SciQ | SciQ-2346 | solar-system, amateur-observing, asteroids, near-earth-object
Is there a distinction between NEOs and near-Earth asteroids? Is there a difference?
What (actually) defines an Aten-class near-earth asteroid?
Has Hubble ever been used to try to image a near Earth asteroid?
Is the passage of three asteroids near Earth today just coincidental?
https://space.meta.stackexchange.com/q/1459/12102 The Near-Earth close approches website shows close approaches to the Earth by near-Earth objects (NEOs). The table showing all close encounters indicates the absolute magnitude.
The data can be exported to a CSV file to estimate the apparent magnitude for each object, using the following equation.
$$
m = H + 5 \log_{10} \bigg( \frac{d_{BS}d_{BO}}{d_0^2} \bigg) - q(\alpha)
$$
where $H$ is the absolute magnitude, $m$ is the apparent magnitude, d_{*} are the distances between the objects and $a(\alpha)$ is the reflected light. $q(\alpha)$ is a number between 0 and 1.
I only want to know what happens when the object is closest to the Earth, so I use the approximation that the distance from the Sun to the NEO is 1AU.
$q(\alpha)$ is complicated to compute, so I just compute $m$ using $q=0$ and $q=1$. This leads to
min value $ = H + 5 \log (d_{BO}) - 1 < m < H + 5 \log (d_{BO}) = $ max value
with $d_{BO}$ the distance between the Earth and the NEO expressed in astronomical units (AU).
The server is unhappy when I try to get the entire database, so I limited my export to the objects that come reasonably close to Earth (d<0.05 AU), with no time limit.
Among these 24588 objects, 4 have a maximal magnitude less than 6, and 16 have a minimal magnitude less than 6. So between 1900 and 2200, no more than 16 NEOs are visible by the naked eye.
The following is multiple choice question (with options) to answer.
Near-earth asteroids cross paths with earth, meaning they could collide; what are the paths called? | [
"curves",
"orbits",
"galaxies",
"trajectory"
] | B | Near-Earth asteroids have orbits that cross Earth’s orbit. This means that they can collide with Earth. There are over 4,500 known near-Earth asteroids. Small asteroids do sometimes collide with Earth. An asteroid about 5–10 m in diameter hits about once per year. Five hundred to a thousand of the known near-Earth asteroids are much bigger. They are over 1 kilometer in diameter. When large asteroids hit Earth in the past, many organisms died. At times, many species became extinct in a mass extinction. Astronomers keep looking for near-Earth asteroids. They hope to predict a possible collision early so they can to try to stop it. |
SciQ | SciQ-2347 | human-anatomy, vision, eyes
Fig. 1. Macaque. Source: Fine Art America
Personally, from these data I think the brain in humans and primates like the macaques adapted to process the information available from the eyes. It can be true, however, that brain circuits and eye structures developed/evolved in parallel to ultimately result in a large white scleral surface and a dedicated neural circuit to process its information.
References
- Frischen et al., Psychol Bull (2007); 133(4): 694–724
- Schulze et al., Front Hum Neurosci (2013); 7: 872
- Tomasello et al., J Human Evol (2007); 52 314-20
Further reading
- Frans de Waal
The following is multiple choice question (with options) to answer.
Reflected in their relatively high level of intelligence and their ability to learn new behaviors, what organs tend to be relatively large in primates? | [
"brains",
"kidneys",
"lungs",
"hearts"
] | A | Primates tend to have bigger brains for their body size than other mammals. This is reflected in their relatively high level of intelligence and their ability to learn new behaviors. |
SciQ | SciQ-2348 | inorganic-chemistry, equilibrium, solubility
Once you find $[\ce{I-}]$ in water and in $\ce{Pb(NO3)2}$ solution, respectively, you would be able to see which solution makes $\ce{PbI2}$ more soluble.
The following is multiple choice question (with options) to answer.
This inverse relationship between solubility and temperature can be understood by looking at a what? | [
"a slide",
"nutrient model",
"molecular model",
"potassium model"
] | C | This inverse relationship between solubility and temperature can be understood by looking at a molecular model. Recall that higher temperatures are associated with faster particles. Gas particles are held in solution by attractive interactions with the solvent molecules. If the particles are moving slowly, these attractive forces will pull back any particles that try to escape the surface of the solution and re-enter the gas phase. However, if the gas particles are moving fast enough, these interactions will not be sufficiently strong to prevent this process from occurring. As a result, more particles are able to escape, and the amount of dissolved solute is less than it would be at a lower temperature. |
SciQ | SciQ-2349 | botany, ecology, energy
Title: Why do plants create enough energy for the entire ecosystem? In my environmental class, we were recently learning about the $10\%$ law that basically says only $10\%$ of the energy goes from one trophic level to the next.
This got me thinking about why energy flows from one level to the next. Specifically, why do plants create enough energy for the entire ecosystem? Wouldn't they do fine without us, and wouldn't that save them the work of creating all that excess energy? Plants collect energy for themselves via photosynthesis, not for others.
It is used for it's own growth and survival.
It's energy is then redistributed to other organisms when either the plant dies and decomposes or when it is consumed. Many organism cannot collect their energy like plants do, and thus must feed on organisms (like plants) that are able to collect and store energy. This is in many cases detrimental to the plant (it should be intuitive why being eaten might be bad), and many, many plants do have traits to discourage other organisms from eating them (plants with toxins, thorns, etc.).
The following is multiple choice question (with options) to answer.
Energy from sunlight enters many ecosystems through what process? | [
"reproduction",
"multiplication",
"photosynthesis",
"isolation"
] | C | Ecosystems need energy. Many ecosystems get their energy in the form of sunlight, which enters the ecosystem through photosynthesis . This energy then flows through the ecosystem, passed from producers to consumers . Plants are producers in many ecosystems. Energy flows from plants to the herbivores that eat the plants, and then to carnivores that eat the herbivores. The flow of energy depicts interactions of organisms within an ecosystem. |
SciQ | SciQ-2350 | climate-change, geography, rivers, rainfall, agriculture
Today Climate change and its consequences are some of the biggest challenges facing Humanity, with water scarcity being the big factor in Sub-Sahara Africa.
By Ultimately raising the Rainfall in the entire Southern Africa, through the managed and controlled filling and utilization of the Natural 30 000 - 60 000 square km of evaporation pans more regularly, will this not lower the extreme temperatures (day and night temperatures due to water absorbing much of the daytime heat and releasing it during the night) and drought patterns Southern Africa has experienced, and by all predictions are bound to worsen and could become more extreme?
In effect, creating a second Okavango Delta, but considerably bigger - large parts of Chobe.
A study of such a magnitude will need large amounts of research in multidisciplinary sciences, from Archaeology to Agriculture to Economics, and a much broader field of expertise - the biggest being Politics!
Could such a mammoth project not be but one small answer to a much bigger Climate Change challenge facing the Earth? (and ultimately send a bit of rain to my little piece of land in the Waterberg in the long dry winter months when we receive those dry West Winds - and fires become a serious hazard - simply by adding a bit of moisture from the vast pans Botswana are so blessed with!)
My mind has been going in circles as to the feasibility of such a mammoth, yet so cheap and easily implementable idea?
Any ideas? We agree that additional evaporation enhances energy transport from the surface to the atmosphere and intensifies the hydrological cycle and cloud formation, and that some of the most serious climate change issues such as:
The following is multiple choice question (with options) to answer.
What is the world’s most serious resource problem? | [
"citrus blight",
"gas shortage",
"deforestation",
"water scarcity"
] | D | Most Americans have plenty of fresh, clean water. But many people around the world do not. In fact, water scarcity is the world’s most serious resource problem. How can that be? Water is almost everywhere. But much of it is unusable. What is usable is not always where it is needed. |
SciQ | SciQ-2351 | quantum-field-theory, particle-physics, electrons, standard-model, quarks
The charges of leptons and quarks differ "slightly" (by a $\frac 23$ difference).
Regarding the weak interaction (see the "weak isospin" column
in the tables aboves) there is no essential difference
between leptons ($\nu$ and $e$) and quarks ($u$ and $d$).
The main difference between leptons and quarks is that quarks have
an additional property named "color".
Every quark comes in three different colors (red, green or blue).
So instead of just $u$ quarks there are actually three different kinds
of them ($u_r$, $u_g$, $u_b$). And similarly for $d$ quarks.
Much like charged particles interact via the electromagnetic interaction,
colored particles interact via the strong interaction.
That is why several quarks combine to form composite particles
(like protons, neutrons, pions, ...).
Leptons don't do this because they are colorless.
The following is multiple choice question (with options) to answer.
Quarks also have a different type of charge, called what? | [
"spontaneous charge",
"pure charge",
"color charge",
"contrast charge"
] | C | There are six types of quarks . In ordinary matter, virtually all quarks are of the types called up and down quarks. All quarks have mass, and they have an electric charge of either +2/3 or -1/3. For example, up quarks have a charge of +2/3, and down quarks have a charge of -1/3. Quarks also have a different type of charge, called color charge, although it has nothing to do with the colors that we see. Quarks are never found alone but instead always occur in groups of two or three quarks. |
SciQ | SciQ-2352 | photosynthesis, chloroplasts
Title: Chloroplasts in an animal cell What would happen if we inject a chloroplast organelle into an animal cell?
Will the animal cell destroy it? Or is it possible that the chloroplast will somehow survive, and even replicate? Could there be photosynthesis in such a cell, or will some of the necessary mechanisms be missing? To answer your bigger question:
Yes, most of this is possible - under some conditions -, and animals and animal cells can acquire chloroplasts, and use them.
E.g.: see Elysia chlorotica whose cells actively take up chloroplasts and use them, and keep them alive (though not replicating). - Though some genes of algae are also contained in the Elysia chlorotica genome - which may be considered as partial replication.
Also there are salamanders that have replicating algae within them (since embryogenesis) - even algae (with chloroplasts) within animal cells - though here the algae might be rather understood as symbionts or "cell types", and the animal cells don't have the chloroplasts by themselves.
The following is multiple choice question (with options) to answer.
Thylakoids in a chloroplast contain what plant pigment? | [
"ultramarine",
"dye",
"melanin",
"chlorophyll"
] | D | The structure of a chloroplast is shown in Figure below . The chloroplast is surrounded by two membranes. Inside the chloroplast are stacks of flattened sacs of membrane, called thylakoids . The thylakoids contain chlorophyll. Surrounding the thylakoids is a space called the stroma . The stroma is filled with watery ("aqueous") fluid. |
SciQ | SciQ-2353 | pregnancy, children
Title: What happens to the umblical cord inside the mother? After giving birth to a child, the umblical cord is cut (and stored if they want). The end connected to the child's navel will fell off eventually but what happens to the end inside the mother?
Will it be removed right after birth by doctors or what happens? Labor is typically divided into 3 stages:
Stage 1: From the onset of contractions (true labor pains) to full dilatation of the cervix (which is about 10 cm) - this takes about 12 to 18 hours
Stage 2: From full dilatation of cervix to expulsion of fetus - This takes about ~ 30 minutes
Stage 3. From expulsion of fetus to expulsion of placenta - this takes about ~ 15 minutes. During the third stage, the umblical cord which is attached to placenta is expelled along with the placenta. This would be the answer to your question.
Source:Hympath.com
The following is multiple choice question (with options) to answer.
The expulsion stage begins when the fetal head enters what? | [
"uterus",
"head is outside vagina",
"birth canal",
"you can see the umbilical cord"
] | C | Expulsion Stage The expulsion stage begins when the fetal head enters the birth canal and ends with birth of the newborn. It typically takes up to 2 hours, but it can last longer or be completed in minutes, depending in part on the orientation of the fetus. The vertex presentation known as the occiput anterior vertex is the most common presentation and is associated with the greatest ease of vaginal birth. The fetus faces the maternal spinal cord and the smallest part of the head (the posterior aspect called the occiput) exits the birth canal first. In fewer than 5 percent of births, the infant is oriented in the breech presentation, or buttocks down. In a complete breech, both legs are crossed and oriented downward. In a frank breech presentation, the legs are oriented upward. Before the 1960s, it was common for breech presentations to be delivered vaginally. Today, most breech births are accomplished by Caesarian section. Vaginal birth is associated with significant stretching of the vaginal canal, the cervix, and the perineum. Until recent decades, it was routine procedure for an obstetrician to numb the perineum and perform an episiotomy, an incision in the posterior vaginal wall and perineum. The perineum is now more commonly allowed to tear on its own during birth. Both an episiotomy and a perineal tear need to be sutured shortly after birth to ensure optimal healing. Although suturing the jagged edges of a perineal tear may be more difficult than suturing an episiotomy, tears heal more quickly, are less painful, and are associated with less damage to the muscles around the vagina and rectum. Upon birth of the newborn’s head, an obstetrician will aspirate mucus from the mouth and nose before the newborn’s first breath. Once the head is birthed, the rest of the body usually follows quickly. The umbilical cord is then double-clamped, and a cut is made between the clamps. This completes the second stage of childbirth. |
SciQ | SciQ-2354 | explosions
Title: What will happen to you if you're standing near exploding TNT bomb near 20meter away in Vaccum? What I think here could be ,that we'll feel less powerful shock wave as there is no medium of air through which gases can travel . If their is any other possibilities than please suggest ! You'll want to add some numbers to your question if you want someone else to do some calculations.
For a simple answer:
In a vacuum
Sound does not travel so you wouldn't suffer overpressure damage to the same extent, though depending on the size of the explosion it could fill the vacuum and increase the pressure enough to kill or injure you.
Any shrapnel will travel faster in a vacuum, doing more damage.
" ... Outer space explosions tend to manifest a spherical 'cloud', reminiscent of other space-based explosions ...".
Underwater (opposite situation)
Sound travels far, and pressure a short distance, resulting in a bubble pulse.
Shrapnel won't travel very far.
Direct contact of an exploding device enhances the explosion because the pressure of the water helps direct the explosion towards the most forgiving direction (you, or a sub).
In your case the combination of air and vacuum is closer to the 'all vacuum' example rather than the opposite 'underwater' example. It depends upon what numbers we are talking about whether 20 meters makes a difference, as does the extent of the vacuum and composition of the container.
A huge explosion will create plenty of vacuum. Small explosions are used to protect against explosions in the Iron Curtain or explosive reactive armor methods of tank protection.
The following is multiple choice question (with options) to answer.
What type of waste is likely to explode? | [
"explosive waste",
"solid waste",
"mesh waste",
"liquid waste"
] | A | Explosive waste is likely to explode. The risk of explosion may be greater if the waste is mixed with other substances. |
SciQ | SciQ-2355 | quantum-mechanics, fusion
Title: Nuclear fusion in Chadwick’s experiment I got confused when I was researching about “neutron’s discovery in Chadwick’s experiment”. There was a nuclear equation said that when we bombard the alpha particles into beryllium, it will emits neutron particles as shown in this equation
$$\rm {^9Be} + \alpha(^4He) \to {^{12}C} + {^1n}$$
What I am confused about is, isn’t the equation above a nuclear fusion reaction? As far as I know, nuclear fusion reactions require really high energy like on the Sun, but this experiment happens in a laboratory. So I wonder if nuclear fusion reactions can happen in laboratory, why can’t we use it to produce clean energy? It is not difficult to achieve fusion reactions in a laboratory. To this end, one can use, for example, accelerators or fusors. What is extremely difficult is achieving net energy gain.
The following is multiple choice question (with options) to answer.
Named after the dutch physicist, the van de graaff is a type of what device used for nuclear research? | [
"radiation detector",
"barometer",
"accelerator",
"electromagnetic"
] | C | Early Accelerators An early accelerator is a relatively simple, large-scale version of the electron gun. The Van de Graaff (named after the Dutch physicist), which you have likely seen in physics demonstrations, is a small version of the ones used for nuclear research since their invention for that purpose in 1932. For more, see Figure 33.7. These machines are electrostatic, creating potentials as great as 50 MV, and are used to accelerate a variety of nuclei for a range of experiments. Energies produced by Van de Graaffs are insufficient to produce new particles, but they have been instrumental in exploring several aspects of the nucleus. Another, equally famous, early accelerator is the cyclotron, invented in 1930 by the American physicist, E. Lawrence (1901–1958). For a visual representation with more detail, see Figure 33.8. Cyclotrons use fixed-frequency alternating electric fields to accelerate particles. The particles spiral outward in a magnetic field, making increasingly larger radius orbits during acceleration. This clever arrangement allows the successive addition of electric potential energy and so greater particle energies are possible than in a Van de Graaff. Lawrence was involved in many early discoveries and in the promotion of physics programs in American. |
SciQ | SciQ-2356 | titration
Title: Strong Acid/Strong Base Titration Bromothymol Blue is an indicator that turns yellow in acid, blue in base.
If I were to titrate NaOH with HCl, what color should I look for at the equivalence point? Should I titrate until the solution turns from blue to yellow or will there be an intermediate colour of green?
I know the salt produced (NaCl) has a pH of 7. http://antoine.frostburg.edu/chem/senese/101/acidbase/indicators.shtml
This is a link to a webpage that talks all about pH indicators and the different pH ranges if you're looking for more info.
When it comes to your question, the color should go from yellow to green because in your breaker is where you add the indicator fluid and HCl acid and you titrate that with the NaOH base. If you titrate further than your green color you have now made your solution more basic.
The following is multiple choice question (with options) to answer.
A substance that displays different colors when in the presence of an acid or a base is called what? | [
"reactor",
"litmus test",
"pH scale",
"an acid-base indicator"
] | D | An acid-base indicator is a substance that displays different colors when in the presence of an acid or a base. How does that work? An indicator is a weak acid that ionizes within a known pH range, usually about 2 pH units. We can represent the protonated form of the indicator molecule as HIn and the deprotonated form as In − . The following equilibrium exists for the indicator. |
SciQ | SciQ-2357 | botany, terminology, nomenclature
Regnum Animale: the animals;
Regnum Vegetabile: the plants;
Regnum Lapideum: the minerals (you read it right).
Note that, in this classification, "animals" correspond to what nowadays we call animals and protozoans, and "plants" correspond to what nowadays we call plants, algae, fungi and bacteria.
You have to keep in mind that this book was first published in 1735, well before the evolutionary biology being proposed in the XIX century and established in the XX century. Therefore, it is a book published when fixism was the current paradigm, full of mentions to the scala naturae.
So, the plants (as well as the animals) showed a continuum of species, going to the lower plants (the bacteria) to the higher plants (the flowering ones). It's worth mentioning again that, by that time, bacteria were plants: Phylum Schyzophyta, to be more precise.
Thus, we have "lower plants" and "higher plants", "lower animals" and "higher animals", as well as "lower minerals" and "higher minerals"!
Unfortunately, this terminology is so embedded in the biological sciences that even today, as I mentioned, we struggle to get rid of it.
Just drop "higher plants", whatever it means
As your Wikipedia link says, "higher plants" is a synonym of vascular plants. However, there are a lot of problems here:
First, this is a remnant of the scala naturae and, just because of that, should be avoided. Think of it as a meaningless term, just like "more evolved organism".
Second, there is no clear and indisputable definition of what is a "higher" plant. Some authors used to define the "higher plants" as the Angiosperms only, or the seed plants (Angiosperms + Gymnosperms), or the vascular plants (Angiosperms, Gymnosperms and Pteridophyta).
For instance, in lusophone biology books, it was very common a division in three groups:
lower plants: bacteria and algae;
intermediate plants: bryophytes and pteridophytes;
higher plants: gymnosperms and angiosperms.
The following is multiple choice question (with options) to answer.
What is the name for the study of the plants and animals that live in fresh water bodies ? | [
"oceanography",
"limnology",
"nematology",
"hydrology"
] | B | Limnology is the study of the plants and animals that live in fresh water bodies. A lake has zones just like the ocean. The ecosystem of a lake is divided into three distinct zones ( Figure below ):. |
SciQ | SciQ-2358 | evolution, mammals
Title: Why haven't land animals evolved beyond urination? It occurred to me (while urinating) that this would seem to be selected against because water is a scarce resource. Why are we constantly losing water we don't need to through urination? What is it about the chemistry of urine and the waste products eliminated that make urination necessary as opposed to eliminating them through defecation and recovering the water on the way out? It is probably true that toilets and other resting-ish area are always a great place to think about biology, I agree $\ddot \smile$.
Why do we urinate?
In short, urine contains the waste from our blood while defecation is just the stuff that we haven't digested. Kidneys are the organs responsible for draining wastes (mostly nitrogen-containing, or nitrogenous, wastes) from our blood.
Trade-off: energy cost vs. water loss
You're correct that the loss of water through urination is a considerable cost for an organism (especially those living in dry environments). But the amount of water used to excrete nitrogenous wastes is negatively correlated with the energy it costs to perform this excretion. In other words, there is a trade-off between water and energy loss during nitrogen excretion. Also, the question of toxicity is important.
Three ways to excrete nitrogenous wastes
Animals basically have three choices to excrete nitrogenous wastes:
Uric acid (excreted by uricotelic organisms)
Solid (crystal) with low water solubility
Low toxicity
Little water is needed
Lots of energy is needed
Ammonia (excreted by aminotelic organisms)
Highly soluble in water
High toxicity
Lots of water is needed to dilute it because of the toxicity
Not much energy is needed
Urea (excreted by ureotelic organisms)
Solid but highly soluble in water
"medium" amount of water is needed
"medium" toxicity
"medium" amount of energy is needed
The following is multiple choice question (with options) to answer.
What does urine leave the body through? | [
"uterus",
"colon",
"urethra",
"vagina"
] | C | Urine leaves the body through the urethra . |
SciQ | SciQ-2359 | cell-biology, organelle
Title: Univocal identifying of a plant cell We yesterday got our biology-exams back and there's one exercise where I don't agree with my teacher. However, since he is the expert and not me, I need the support of external sources, i.e. experts in order to justify my statement.
Now in the exercise, we first had to identify the parts of a cell (which was shown in form of an image) and then in part b) reason whether it was an animal or plant cell.
I had identified a chloroplast and a vacuole and stated that the only cell with this organelles was the plant cell. My teacher answered that I had missed the fact, that the cell had also a cell wall (which is indeed a difference between plant and animal cells).
My question is
Is the fact that the cell had a cell wall necessary in my argumentation, i.e. are there other cells having chloroplasts and a vacuole without being a plant cell?
Could you provide a source which supports, or doesn't support my statement so that I can show it to my teacher?
Thanks in advance Your teacher is right, chloroplasts and vacuoles are not sufficient to define a plant cell.
Amoeba have both chloroplasts (McFadden et al, PNAS, 1994) and vacuoles (Day, J. Morphology, 1927) but they are not plants - and they do not have a cell wall.
Sea slugs eat algae and can "steal" their plastids and keep them working for weeks/months, effectively becoming photosynthetic animals for a while. This is called kleptoplastidy (Pillet, Mob. Genet. Elements, 2013).
The following is multiple choice question (with options) to answer.
What type of plant is the dominant group of land plants? | [
"grass plants",
"oxygen plants",
"vascular plants",
"thermal plants"
] | C | Vascular Plants The vascular plants are the dominant and most conspicuous group of land plants. There are about 275,000 species of vascular plants, which represent more than 90 percent of Earth’s vegetation. Several evolutionary innovations explain their success and their spread to so many habitats. Vascular Tissue: Xylem and Phloem The first fossils that show the presence of vascular tissue are dated to the Silurian period, about 430 million years ago. The simplest arrangement of conductive cells shows a pattern of xylem at the center surrounded by phloem. Xylem is the tissue responsible for long-distance transport of water and minerals, the transfer of water-soluble growth factors from the organs of synthesis to the target organs, and storage of water and nutrients. A second type of vascular tissue is phloem, which transports sugars, proteins, and other solutes through the plant. Phloem cells are divided into sieve elements, or conducting cells, and supportive tissue. Together, xylem and phloem tissues form the vascular system of plants. |
SciQ | SciQ-2360 | diffusion
The reverse process is also happening with molecules diffusing from right to left at a rate proportional to their concentration in the right side solution. As the concentration on the right side increases to be equal to the concentration on the left, so the diffusion rates become equal and there is zero nett diffusion and the system approaches equilibrium.
Note that this assumes a "perfect" system where there is no chemical reaction occurring between the solutes or between the solutes and the membrane. In practice this means that either the interaction between solutes A and B is the same as the interaction between the solutes and the solvent or that the solute molecules are so greatly outnumbered by the solvent molecules that the solute-solute interactions are not significant.
The rate of diffusion of solute A may be different from B (i.e. the proportionality constant between rate and concentration may be different). This means that before reaching equilibrium the relative concentrations of A and B may change but at equilibrium, the relative concentration will be the same as initially.
If we define "reaching equilibrium" as having some fraction (say 99.99%) of the final concentration then increasing the initial global concentration will increase the lag for both solutes equally and will not change their relative concentrations.
The following is multiple choice question (with options) to answer.
What term is used to describe a process in which material travels from regions of high concentration to low concentration until equilibrium is reached? | [
"diffusion",
"Osmosis",
"fission",
"active transport"
] | A | The folded surfaces of the gills provide a large surface area to ensure that the fish gets sufficient oxygen. Diffusion is a process in which material travels from regions of high concentration to low concentration until equilibrium is reached. In this case, blood with a low concentration of oxygen molecules circulates through the gills. The concentration of oxygen molecules in water is higher than the concentration of oxygen molecules in gills. As a result, oxygen molecules diffuse from water (high concentration) to blood (low concentration), as shown in Figure 39.5. Similarly, carbon dioxide molecules in the blood diffuse from the blood (high concentration) to water (low concentration). |
SciQ | SciQ-2361 | climate-change, sea-level
Title: "Five of the Solomon Islands disappeared" due to sea level rise, how is this possible so quickly? The text of the introduction to the BBC Podcast Sea Levels Rise; The Compass, Living on the Edge Episode 1 of 4 says:
Five of the Solomon Islands have disappeared, many more are becoming uninhabitable. For Kerry and Sally, climate change is not a theory - it is what has made them abandon their island and the graves of their ancestors. They see themselves as lucky - they had family land to move to and the skills to build new homes on stilts - but they are resigned to moving again.
Award-winning journalist Didi Akinyelure visits her home city of Lagos to find out the latest solution to sea level rise in West Africa. The glass towers of the new financial district of Eko Atlantic are protected from the waves by state of the art sea defences. The residents of the luxury apartments should keep their feet dry whatever the climate throws at them. That may be small comfort for their unprotected neighbours in the shanty town on the lagoon, Makoko, but they’re experts in survival against the odds.
Certainly sea level is rising, on the order of perhaps 15 centimeters in the last century judging from this plot, and the New Scientist article Five Pacific islands vanish from sight as sea levels rise certainly adds credence to this. Answers to the question Sea Level Rise due to Climate Change shed some light on human-induced climate change.
Between about 04:00 and 06:00 in the podcast, Simon Albert, a climate change scientist from University of Queensland describes the situation in the Solomons.
Here is my best attempt at a transcription of a small part of the podcast:
The following is multiple choice question (with options) to answer.
Poetically speaking, nature reserves are islands of what, in a sea of habitat degraded by human activity? | [
"refuge",
"biodiversity",
"habitats",
"ecosystem"
] | B | |
SciQ | SciQ-2362 | javascript, jquery, html, form
return this;
};
$.fn.reactor = function(options) {
var settings = $.extend({}, $.fn.reactor.defaults, options);
this.each(function() {
// var opts = $.meta ? $.extend({}, settings, $this.data()) : settings;
var $element = $(this);
if (!$element.hasClass('reactor')) { $element.data('conditions.reactor', []).addClass('reactor'); }
var is_reactionary = function() {
var conditionalArray = $(this).data('conditions.reactor');
var r = true;
$.each(conditionalArray, function() {
r = (r && this.call());
});
return r;
}
var reaction = function(evt) {
evt.stopPropagation();
if (is_reactionary.apply(this)) {
settings.compliant.apply($element);
} else {
settings.uncompliant.apply($element);
}
}
$element.bind('change.reactor', reaction);
});
return this;
};
$.fn.reactor.defaults = {
compliant: function() {
$(this).show();
},
uncompliant: function() {
$(this).hide();
}
};
$.fn.reactor.helpers = {
NotBlank: function() {
return( $(this).val().toString() != "" )
},
Blank: function() {
return( $(this).val().toString() == "" )
},
EqualTo: function(matchStr) {
var _func = function() {
var v = $(this).val();
if (v) { return( v.toString() == matchStr ); }
else { return false; }
}
return _func;
},
The following is multiple choice question (with options) to answer.
Reactive elements are able to combine more what with other elements? | [
"quickly",
"symmetrically",
"easily",
"slowly"
] | C | Reactive elements combine easily with other elements. This explains why they usually exist in nature in compounds rather than in pure form. |
SciQ | SciQ-2363 | ocean, ocean-currents, tides
Physical effects, then, are likely to include direct effects on current speed, sediment, and stratification.
The obvious possible biological effect is from collisions. This is not my field, but as I understand it no effect is likely on small fish populations from collisions, although individuals may be affected. Collision risk for large animals (e.g. sharks and marine mammals) and for diving birds is a topic of active research, and is likely (especially for mammals) to depend on their behaviour around the devices. No large animal collisions have been reported on any of the prototypes undergoing testing so far.
A good review of possible effects on benthic organisms is provided by Shields et al (2011). These may include,
The following is multiple choice question (with options) to answer.
What do scientists attach to aquatic animals to collect information? | [
"satellite tags",
"ultraviolet tags",
"radio tags",
"fluorescent tags"
] | A | Beginning in 2000, scientists from the National Oceanic and Atmospheric Administration, Stanford University, and the University of California, Santa Cruz combined to form TOPP. As part of TOPP, researchers attach satellite tags to elephant seals, white sharks, giant leatherback turtles, bluefin tuna, swordfish, and other marine animals. The tags collect information, such as how deep each animal dives, the levels of ambient light (to help determine an animal’s location), and interior and exterior body temperature. Some tags also collect information about the temperature, salinity, and depth of the water surrounding an animal to help scientists identify ocean currents. The tags send the data to a satellite, which in turn sends the data the scientists. They use this information to create maps of migration patterns and discover new information about different marine ecosystems. The information collected by TOPP offers rare insights into the lives of marine animals. Without TOPP, that information would otherwise remain unknown. With TOPP, scientists are developing a working knowledge of the particular migration routes animals take, as well as the locations of popular breeding grounds and the environmental dangers faced by different species. TOPP has shed light on how we can better protect the leatherback turtle and other endangered species. |
SciQ | SciQ-2364 | reproduction
Excerpts from the references that lead to the short answer above:
In the developing female fetus, oogonia become primary oocytes that begin the first division of meiosis. However, this division is not completed and the primary oocytes remain “frozen” in the prophase stage of the first meiotic division.
At birth, oogonia are no longer present. Each primary oocyte is surrounded by a single layer of squamous epithelial cells called follicular cells. The primary oocyte together with its follicular cells is called a primordial follicle. There are about two million primordial follicles with their primary oocytes in the ovaries at birth suspended in the first division of meiosis.
As the female grows, primary oocytes begin to die and disappear with their follicular cells. This process continues until puberty when there are only about 400,000 primordial follicles left in the ovaries. The primary oocytes continue the process of oogenesis after puberty begins.[Source]
The total number of primary oocytes at birth is estimated to vary from 700,000 to2 million. During childhood most oocytes become atretic; only approximately400,000 are present by the beginning of puberty, and fewer than 500 will be ovulated.[Source]
Primary oocytes reach their maximum development at ~20[6] weeks of gestational age, when approximately seven million primary oocytes have been created; however, at birth, this number has already been reduced to approximately 1-2 million.Recently, however, two publications have challenged the belief that a finite number of oocytes are set around the time of birth.[Source]
In the human embryo, the thousand or so oogonia divide rapidly from the second to the seventh month of gestation to form roughly 7 million germ cells.[Source]
REFERENCES:
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0008772
The following is multiple choice question (with options) to answer.
Upon ovulation, the oocyte released by the ovary is swept into where? | [
"placental barrier",
"umbilical cord",
"vas deferens",
"uterine tube"
] | D | Contact Between Sperm and Oocyte Upon ovulation, the oocyte released by the ovary is swept into—and along—the uterine tube. Fertilization must occur in the distal uterine tube because an unfertilized oocyte cannot survive the 72-hour journey to the uterus. As you will recall from your study of the oogenesis, this oocyte (specifically a secondary oocyte) is surrounded by two protective layers. The corona radiata is an outer layer of follicular (granulosa) cells that form around a developing oocyte in the ovary and remain with it upon ovulation. The underlying zona pellucida (pellucid = “transparent”) is a transparent, but thick, glycoprotein membrane that surrounds the cell’s plasma membrane. As it is swept along the distal uterine tube, the oocyte encounters the surviving capacitated sperm, which stream toward it in response to chemical attractants released by the cells of the corona radiata. To reach the oocyte itself, the sperm must penetrate the two protective layers. The sperm first burrow through the cells of the corona radiata. Then, upon contact with the zona pellucida, the sperm bind to receptors in the zona pellucida. This initiates a process called the acrosomal reaction in which the enzyme-filled “cap” of the sperm, called the acrosome, releases its stored digestive enzymes. These enzymes clear a path through the zona pellucida that allows sperm to reach the oocyte. Finally, a single sperm makes contact with sperm-binding receptors on the oocyte’s plasma membrane (Figure 28.2). The plasma membrane of that sperm then fuses with the oocyte’s plasma membrane, and the head and mid-piece of the “winning” sperm enter the oocyte interior. How do sperm penetrate the corona radiata? Some sperm undergo a spontaneous acrosomal reaction, which is an acrosomal reaction not triggered by contact with the zona pellucida. The digestive enzymes released by this reaction digest the extracellular matrix of the corona radiata. As you can see, the first sperm to reach the oocyte is never the one to fertilize it. Rather, hundreds of sperm cells must undergo the acrosomal reaction, each helping to degrade the corona radiata and. |
SciQ | SciQ-2365 | parasitology
Title: Giardia lamblia cases of infections I am wondering if anyone has seen a data of Giardiasis (Giardia Lamblia) cases in different countries on the world? I have found for different diseases and also for 'diarrhoea diseases' in general, but I need especially for Giardia Lamblia.
Any suggestion where I can try to look for this data will be useful.
Thank you very much! If you have or can get access to it, you might try looking in the Incidence and Prevalence database: http://thomsonreuters.com/incidence-and-prevalence-database/
Another possibility is the GIDEON database: http://www.gideononline.com/. It is possible to sign up for a 15-day trial.
For Europe, statistics are available from the WHO CISID at http://data.euro.who.int/cisid/ (select "all infectious diseases", then "Giardiasis").
The WHO does not have any global statistics available on their website, so otherwise you might have to piece together data from individual publications. Some examples:
Thailand, 2005: http://www.ncbi.nlm.nih.gov/pubmed/16438174
Germany, 2006: http://www.ncbi.nlm.nih.gov/pubmed?term=19404678
United States, 2006-2008: http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5906a2.htm
Portugal, 2002-2008: http://www.parasitesandvectors.com/content/5/1/22
Quatar, 2008: http://www.parasitesandvectors.com/content/4/1/211
Tajikistan, 2009: http://www.parasitesandvectors.com/content/4/1/195
Ivory Coast, 2009: http://www.parasitesandvectors.com/content/4/1/96
Tanzania, 2011: http://www.parasitesandvectors.com/content/6/1/3
Ghana, 2006-2009: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170632/?report=classic
The following is multiple choice question (with options) to answer.
Giardiasis and malaria are diseases caused by what organism? | [
"protozoa",
"larvae",
"worms",
"bacteria"
] | A | Many human diseases are caused by protists. Most of them are caused by protozoa. They are parasites that invade and live in the human body. The parasites get a place to live and nutrients from the human host. In return, they make the host sick. Examples of human diseases caused by protozoa include giardiasis and malaria. |
SciQ | SciQ-2366 | quantum-mechanics, schroedinger-equation
Title: Applying the Schroedinger equation I hope this isn't a dumb question, but...
If we have two fixed sine waves, both of which have a frequency range of +1 to -1, with a ratio between the waves of wave(1):3 to wave(2): 1, what does the Schrodinger equation tell us (if anything) about the relationship between the waves?
Equally, if the waves are no longer fixed (ie, time dependent) and wave(1) has complete nine oscillations, what does Schrodinger predict about the relationship between the waves for oscillation number 10? The Schroedinger equation is a dynamical equation that predicts the time evolution of a quantum system. Since it sounds like the time evolution of your system is externally imposed, the schroedinger equation doesn't make any predictions about it.
Your question is analogous to saying, "I define a particle trajectory in 1D, $x(t)$ for $0<t<T_{\mathrm{max}}$. What does $F=ma$ tell us about the trajectory? What does the trajectory do for $T_{\mathrm{max}} < t < T_{\mathrm{max}} + \Delta T$?"
The following is multiple choice question (with options) to answer.
The number of waves that pass a fixed point in a given amount of time is referred to as what? | [
"wave harmonics",
"tendency frequency",
"wave frequency",
"wave speed"
] | C | Wave frequency is the number of waves that pass a fixed point in a given amount of time. |
SciQ | SciQ-2367 | homework-and-exercises, atomic-physics, quantum-chemistry
$[C]=[He]2s^22p^2$ = $[He]2s^22p_x^12p_y^1$.
The first excited state of carbon $C^*$, and the one that explains the existence of $C(+4)$ chemical compounds, is $[He]2s^12p_x^12p_y^12p_z^1$ where all three lone 2p electrons have the same $m_s$ value.
The following is multiple choice question (with options) to answer.
The name carbon tetrachloride implies one carbon atom and four of which other atoms? | [
"chlorine",
"nitrogen",
"calcium",
"iodine"
] | A | The name carbon tetrachloride implies one carbon atom and four chlorine atoms, so the formula is CCl4. Saylor URL: http://www. saylor. org/books. |
SciQ | SciQ-2368 | species-identification, mycology
Title: Mushroom Identificaton(USA) I need help identifying a perculiar species of mushroom found in my yard today. Color is orange-yellow, around 3-4 inches total radius, its a cluster of tiny to medium mushrooms. They were found near an oak tree. Location is southern Georgia, USa. These could be specimens of Omphalotus Illudens based on the orange/yellow color, the time of the year, their association with decaying wood (an oak in this case) and your location (eastern North America)
You can read more about these species in this reference: Messiah College
The following is multiple choice question (with options) to answer.
Most of a mushroom's surface area is actually where? | [
"air",
"hidden",
"underwater",
"underground"
] | D | Fungi can grow fast because they are such good eaters. Fungi have lots of surface area, and this large surface area “eats” or absorbs. Surface area is how much exposed area an organism has, compared to their overall volume. Most of a mushroom's surface area is actually underground. If you see a mushroom in your yard, that is just a small part of a larger fungus growing underground. |
SciQ | SciQ-2369 | neuroscience, neuroanatomy
Likewise, the spinal chord is structured into sensory and motor regions. In summary, the spinal chord consists of: 1) cell bodies (motor, sensory, inter; grey in the picture), 2) ascending axons (blue), 3) descending axons (red). Similar to nerves, axons going up or down the spinal chord are bundled into "tracts". Sensory axons are never bundled with motor axons, making it possible to create a map of the spinal chord in cross-section.
The tracts' names might be a bit confusing at first, but on second look are actually pretty self-explanatory. They usually contain where the axons come from and where they are going in order to synapse with other neurons. E.g. the spinocerebellar tract is formed of axons coming from the spine and going to the cerebellum. Given that the cerebellum is near the brain and the spine is further down, this is obviously an ascending tract - and ascending tracts are always sensory (because sensory information never needs to be carried downwards due to the brain being at the top).
Where it gets blurry
The sensory/motor separation isn't always as clear as I've described above. In fact, nerves (bundles of axons anywhere in the body outside of the CNS) will usually contain both sensory and motor pipelines. In particular, the cranial nerves (12 of the most important nerves) all include sensory and motor components for the respective part of the body that they manage. E.g. the facial nerve contains both the sensory connections for parts of the tongue and the motor connections that control facial muscles.
Another more complex example is pain sensation, where interneurons in the spinal chord can feed back onto sensory neurons and inhibit their signals, or axons can inhibit those packed in the same nerve bundle simply due to electrical effects.
The following is multiple choice question (with options) to answer.
Interneurons carry what back and forth between sensory and motor neurons? | [
"nerve impulses",
"electricity",
"sciatica",
"flux impulses"
] | A | Interneurons carry nerve impulses back and forth between sensory and motor neurons. |
SciQ | SciQ-2370 | geology, mineralogy
Title: Online resources for geographical distribution of minerals I'm trying to find the geographical distribution and availability of mineral Brannerite. Is there a resource online to know or query where a certain mineral is found?
On the link page, they mention certain types of geophysical deposits where this mineral is usually found:
"In granite pegmatites and in granitic gneisses; in silicified pebble conglomerates; in hydrothermal quartz and calcite veins; detrital in placers"
If the answer to the former question is negative; Would there be online information about geographical distribution of these geological features? You did not mention why you are interested in brannerite, so I am assuming you want it as a collector's specimen and not a microscopic crystal.
Unfortunately, there is no definite source. However, there are some possibilities:
Try the Handbook of Mineralogy: http://handbookofmineralogy.org and more specifically the brannerite page. You will fine there a more detailed list of localities for that mineral.
Another option is to run a Google Scholar search for brannerite. You can find scholarly papers dealing with brannerite, and occasionally they also mention where they found the mineral or how they obtained it. Notice that in the specific case of brannerite, there are many articles dealing with brannerite structure. This may not be what you're looking for. There is also the problem of accessibility - unless you have an institutional or personal subscription to these journals, you may not be able to access the full article. However, sometimes this information can be found in the freely available abstract.
Go to Rocks & Minerals magazine and run a search there for brannerite. They may have some articles dealing with localities.
The following is multiple choice question (with options) to answer.
What are the mineral deposits that fill in underground cracks called? | [
"veins",
"currents",
"cores",
"motherlode"
] | A | Underground water can be heated by magma. The hot water moves through cracks below Earth’s surface. Hot water can hold more dissolved particles than cold water. The hot, salty solution has chemical reactions with the rocks around it. The water picks up more dissolved particles. As it flows through open spaces in rocks, the water deposits solid minerals. When a mineral fills cracks in rocks, the deposits are called “veins. ” Figure below shows a white quartz vein. When the minerals are deposited in open spaces, large crystals grow. These rocks are called geodes. Figure below shows a “geode” that was formed when amethyst crystals grew in an open space in a rock. |
SciQ | SciQ-2371 | observational-astronomy, jupiter, saturn, conjunction
Title: If we stood on the surface of a Jovian moon, Saturn would appear as a dot. Why doesn't Saturn appear like this in a telescope? Images from the conjunction like these show Saturn just a bit smaller than Jupiter. However, if you were in the vicinity of Jupiter, Saturn would still appear as a dot to the naked eye, wouldn't it? If so, why is Saturn recognizable as a planet through a telescope in which Jupiter is also seen as a planet? As if they were actually very close to each other, at about the same distance from the Sun. I mean, if you recognize Jupiter in a telescope, shouldn't Saturn behind it look like a dot, unless you have a much, much larger zoom in which Jupiter would appear too close to match into the whole image while being too unsharp anyway? Telescopes magnify, they don't bring you closer.
So if from Earth Jupiter has an apparent radius of 0.01 degrees (measured as an angle because it is the apparent size)
And if Saturn has an apparent angle of 0.005 degrees, then if you magnify 100x then Jupiter will have an apparent size of 1 degree, and Saturn would have a size of 0.5 degrees. Magnification just increases the angular size in proportion
But if You go to Jupiter you have travelled less than half the distance to Saturn.
So saturn is still small. Travelling closer does not make everything increase in size in proportion.
You can see this simply: Stand where you can see something 20 metres of so away, and where you can see into the hills (etc) in the background. Walk towards the thing. Note that the thing appears to get bigger as you approach, but the distant hills don't change size. Travelling closer does not magnify everything in proportion.
Telescopes don't "bring things closer" they "magnify".
The following is multiple choice question (with options) to answer.
Some of the small moons of saturn are found within what features distinctive to the planet? | [
"interior of saturn",
"craters of saturn",
"rings of saturn",
"crest of saturn"
] | C | As of 2011, over 60 moons have been identified around Saturn. Only seven of Saturn’s moons are round. All but one is smaller than Earth’s Moon. Some of the very small moons are found within the rings. All the particles in the rings are like little moons, because they orbit around Saturn. Someone must decide which ones are large enough to call moons. |
SciQ | SciQ-2372 | image-processing, filters, filter-design, sampling, computer-vision
the $2$nd $1/2$ part of the image enlarged by a factor of $2^{-n}$ with mixing weight $1/2$,
the $2$nd $1/4$ part of the image enlarged by a factor of $2^{1-n}$ with mixing weight $1/4$,
the $2$nd $1/8$ part of the image enlarged by a factor of $2^{2-n}$ with mixing weight $1/8$,
the $2$nd $1/16$ part of the image enlarged by a factor of $2^{3-n}$ with mixing weight $1/16$,
... (until the part size goes to zero).
Here, enlarged by a factor of $2^x$ means that if $x < 1$ then the image part in question is reduced in size by factor $2^{-x}$ and replicated (tiled), and if $x > 1$, then the image part is enlarged by factor $2^x$ and the $2^x$ enlarged $1/2^x$ sub-parts are additively mixed with equal weight $1/2^x$.
The small-scale detail ignored in this analysis is the interlacing, which from a large distance looks like additive mixing. Also some unexplained details that don't seem to scale with the data size are ignored.
Here is a Python script (sorry, I don't know Ruby) that reproduces most of the aesthetic qualities of the picture, not by using the above analysis but by mimicking the interlacing in the plot above:
from PIL import Image
import requests
from io import BytesIO
response = requests.get("https://i.stack.imgur.com/T520A.jpg")
img = Image.open(BytesIO(response.content))
pix = img.load()
w, h = img.size
pix_flat = []
for y in range(h):
for x in range(w):
pix_flat.append(pix[x, y])
The following is multiple choice question (with options) to answer.
An image that is double the size of the object would have what? | [
"configuration",
"magnification",
"stimulation",
"illumination"
] | B | The size of an object’s image is larger (or smaller) than the object itself by its magnification, . The level of magnification is proportional to the ratio of and . An image that is double the size of the object would have magnification . |
SciQ | SciQ-2373 | cell-biology, proteins, transcription, cell-signaling, intracellular-transport
Time is in minutes, and zeroed at first contact between the two cells. I've put a red dot on the T-cell and a blue one on the APC in the DIC images (left panes); hopefully that proves more informative than annoying. The right panes show GFP fluorescence and thus CD3 localization. As time progresses, CD3 is re-localized from one part of the membrane to another (the synapse). There is supposedly a video of this is in the supplementary information of the article, though I was unable to open it.
The rate and directionality of the movement implies that an active process is occurring, rather than simple diffusion. However, they did not find the actual mechanism for movement and I haven't found any follow-up papers in a brief search (though many subsequent papers implicate the cytoskeleton in this movement). Just to show that movement of transmembrane proteins can, in fact, be actively directed by the cytoskeleton, I refer you to this paper:
Grabham PW, Foley M, Umeojiako A, Goldberg DJ. 2000. Nerve growth factor stimulates coupling of beta1 integrin to distinct transport mechanisms in the filopodia of growth cones. J Cell Sci 113:3003-3012.
They show that membrane-spanning integrins are moved along actin filaments of the cytoskeleton by myosin motor proteins. Expectedly, the abstract does a good job of summarizing the paper:
The cycling of membrane receptors for substrate-bound proteins via their interaction with the actin cytoskeleton at the leading edge of growth cones and other motile cells is important for neurite outgrowth and cell migration. Receptor delivered to the leading edge binds to its ligand, which induces coupling of the receptor to a rearward flowing network of actin filaments. This coupling is thought to facilitate advance... [T]ransport was dependent on an intact actin cytoskeleton and myosin ATPase...
The following is multiple choice question (with options) to answer.
What is made up of bands of cells that contract for movement? | [
"vascular tissue",
"cartilage",
"collagen",
"muscle tissue"
] | D | Muscle tissue is made up of bands of cells that contract and allow movement. |
SciQ | SciQ-2374 | terminology, human-physiology, organs
Title: Medical term for "holding urine for a long time" Sometimes I get/feel pain in my stomach because of holding urine for long time. Is there any medical terminology describing: "holding urine for a long time", or pain associated with this activity? A swollen organ may be described as distended if the swelling is symptomatic of a medical disfunction.
The purpose of most bladders is to collect and retain a fluid; if that fluid needs to be discharged periodically, and is not able to do so, then there is usually pain as a result of the distension.
Inability to urinate is known as ischuria or urinary retention, and could be the result of obstruction to the urethra, could be a failure of the bladder to fully contract during urination, or could many other possible causes.
The following is multiple choice question (with options) to answer.
What is the name of the muscular tube that carries urine out of the body? | [
"uterus",
"rectum",
"urethra",
"bladder"
] | C | From the collecting ducts of the kidneys, urine enters the ureters , two muscular tubes that move the urine by peristalsis to the bladder (see Figure above ). The bladder is a hollow, sac-like organ that stores urine. When the bladder is about half full, it sends a nerve impulse to a sphincter to relax and let urine flow out of the bladder and into the urethra. The urethra is a muscular tube that carries urine out of the body. Urine leaves the body through another sphincter in the process of urination . This sphincter and the process of urination are normally under conscious control. |
SciQ | SciQ-2375 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
Tissues are organized by what? | [
"structures",
"branches",
"lipids",
"cells"
] | D | Cells are organized into tissues, and tissues form organs. |
SciQ | SciQ-2376 | meteorology, atmosphere, carbon, co2, rain
Bear in mind that this assumes an enormous rainfall intensity, 100% CO2 saturation of the water and equilibrium chemical dynamics. After the raindrops hit the ground at least half of it will immediately re-evaporate back into the air, leaving, at absolute most, about 3% of the atmospheric CO2 leached out of the atmosphere that will be available to react with the soil, rock or biosphere. Also consider that this is but one of several important processes affecting CO2 transience, such as photosynthesis, respiration, volcanism, industrial pollution, etc. So the CO2 estimates that you read about are average values. Advection and turbulent air mixing should ensure that the CO2 regains approximately normal concentration within an hour or two after rainfall.
The following is multiple choice question (with options) to answer.
Carbon released by burning fossil fuels contributes to what effect in the atmosphere? | [
"cloud effect",
"greenhouse effect",
"shielding effect",
"smog effect"
] | B | Burning of fossil fuels, such as oil, releases carbon into the atmosphere. This carbon must be cycled - removed from the atmosphere - back into living organisms, or it stays in the atmosphere. Increased carbon in the atmosphere contributes to the greenhouse effect on Earth. |
SciQ | SciQ-2377 | biochemistry, plant-physiology, plant-anatomy
Title: Why do plants store energy as carbohydrates and not as fats? In my introductory biology class, we are learning about biomolecules. The textbook says fats are a more efficient energy store than carbohydrates.
So my question is - why would plants store their energy as carbohydrates and not as fats, if fats are a more efficient energy store? There are quite some reasons for why plants prefer carbohydrates for energy storage rather than fats. I will reach some of them one at a time.
The following is multiple choice question (with options) to answer.
What are a class of biochemical compounds that living things use to store energy? | [
"hydrocarbons",
"proteins",
"lipids",
"calories"
] | C | Lipids are a class of biochemical compounds that living things use to store energy. Types of lipids include fats and oils. |
SciQ | SciQ-2378 | particle-physics, elements
Title: Is it possible to create a new element that doesn't exist in the universe? When I say something new I do not refer to something already made like H,O etc and when I mean something new I do not refer to a transformation like tritium to helium and gold.
If so how ?(I mean is there a specific way to do that ?) Yes, so far, 20 synthetic elements have been created, with atomic numbers 99 (Einsteinium) to 118 (Ununoctium). All these elements are unstable, with half-lives ranging from a year to a few milliseconds.
You can find a list on wikipedia. These elements are produced in specialized nuclear reactors, by bombarding heavy elements like Uranium and Plutonium with neutrons or other elements.
The following is multiple choice question (with options) to answer.
Which element has an atomic number of 16? | [
"sulfur",
"acid",
"oxygen",
"methane"
] | A | The atomic number of sulfur is 16. Therefore, in a neutral atom of sulfur, there are 16 electrons. Saylor URL: http://www. saylor. org/books. |
SciQ | SciQ-2379 | human-evolution
Title: How do we know the human species arose in Africa? I have heard (from multiple sources) that the current scientific opinion is that the human species arose in Africa. What are the reasons for this opinion? If possible, simple and non-technical explanations (as far as possible) would be appreciated. There are two big prongs of the out of Africa theory or whichever name you wish to call it.
Prong the first: fossil evidence. There are lots of different kinds of protohuman fossils. Homo erectus/ergaster are found all across Europe, Asia, and into Indonesia from about 1.5 million years or so until about 70 thousand years ago, where they stop showing up. Up until 125 thousand years ago anatomically modern humans were only found in Africa. About 70 thousand years ago they start showing up in the Middle East, and then they spread out roughly following these paths. The fossil record shows not-humans or almost-humans (Homo erectus mostly) for millions of years, then humans show up at a certain point and then there's loads of human fossils. This point gets more recent as you get further from East Africa.
Prong the second: genetic diversity. Starting with this paper (not sure if this is behind a paywall but the details are not important anyway) human mitochondrial DNA was compared using restriction enzyme mapping. This kind of mapping is super crude (roughly analogous to grinding pottery into a fine dust and grouping the dusts by color) and the original study was pretty limited by the computers available at the time. Nonetheless, they showed that the most genetically diverse geographical group was Africa, and furthermore that any two people from outside Africa are likely more closely related to each other than any two people inside Africa. Genetic diversity goes down the further away from East Africa you get, matching what you'd expect if humans hadn't been living there long. There have only been (very roughly) 60 generations since humans colonized New Zealand. All Maori people, therefore, are at most 58th cousins. All indigenous Australians are at most 1998th cousins. All Africans are at most 8000th cousins.
The following is multiple choice question (with options) to answer.
Fossil evidence indicates that the ancestors of humans originated on which continent? | [
"south america",
"north america",
"africa",
"australia"
] | C | |
SciQ | SciQ-2380 | mycology
Title: How do fairy rings propagate? It was somewhat new to me that mushrooms usually aren't individual organisms, but are merely the visible bodies of a bunch of fungi living in the soil. I know that mushrooms emit spores to reproduce, but what has been bizarre to me is how fairy rings form. Why do the fruiting bodies arrange themselves in a more or less circular shape, as opposed to the random scattering one would expect from wind-borne spores? When a fungal spore germinates in a suitable location, the growing mycelium will spread underground in all directions. In the ideal situation, the result is that the mycelium will become circular. Over time, the center of the mycelium will die out whereas the newly formed mycelium (underground) will develop the familiar mushrooms above ground and this will result in a fairy ring.
The following is multiple choice question (with options) to answer.
What will spores that eventually germinate develop into? | [
"yeast cells",
"gametes",
"new hyphae",
"hydra"
] | C | This phylogenetic tree is based on comparisons of ribosomal RNA base sequences among living organisms. The tree divides all organisms into three domains: Bacteria, Archaea, and Eukarya. Humans and other animals belong to the Eukarya domain. From this tree, organisms that make up the domain Eukarya appear to have shared a more recent common ancestor with Archaea than Bacteria. |
SciQ | SciQ-2381 | inorganic-chemistry, molecular-orbital-theory, hybridization
MO 4 (occ.=2.00, E=-0.485050)
N2 (S on atom N1) [0.435], N16 (S on atom N2) [-0.435],
N3 (S on atom N1) [0.427], N17 (S on atom N2) [-0.427],
N15 (S on atom N2) [-0.201], N1 (S on atom N1) [0.201],
N5 (Px on atom N1) [0.200], N19 (Px on atom N2) [0.200],
N8 (Px on atom N1) [-0.066], N22 (Px on atom N2) [-0.066],
N13 (D+2 on atom N1) [-0.015], N27 (D+2 on atom N2) [0.015],
N10 (D 0 on atom N1) [0.009], N24 (D 0 on atom N2) [-0.009]
MO 5 (occ.=2.00, E=-0.421640)
N4 (Pz on atom N1) [-0.422], N18 (Pz on atom N2) [-0.422],
N7 (Pz on atom N1) [0.225], N21 (Pz on atom N2) [0.225],
N6 (Py on atom N1) [-0.164], N20 (Py on atom N2) [-0.164],
N9 (Py on atom N1) [0.087], N23 (Py on atom N2) [0.087],
N11 (D+1 on atom N1) [0.033], N25 (D+1 on atom N2) [-0.033],
N14 (D-2 on atom N1) [0.013], N28 (D-2 on atom N2) [-0.013]
The following is multiple choice question (with options) to answer.
A binary molecular compound is made up of two of what? | [
"cells",
"elements",
"wafers",
"compounds"
] | B | A binary molecular compound is a molecular compound that is composed of two elements. The elements that combine to form binary molecular compounds are both nonmetal atoms. This contrasts with ionic compounds, which were formed from a metal ion and a nonmetal ion. Therefore, binary molecular compounds are different because ionic charges cannot be used to name them or to write their formulas. Another difference is that two nonmetal atoms will frequently combine with one another in a variety of ratios. Consider the elements nitrogen and oxygen. They combine to make several compounds including NO, NO 2 , and N 2 O. They all can’t be called nitrogen oxide. How would someone know which one you were talking about? Each of the three compounds has very different properties and reactivity. A system to distinguish between compounds such as these is necessary. |
SciQ | SciQ-2382 | acoustics
Title: Besides the speed of sound, what else changes when the transmitting medium changes? Besides the speed of sound, what else changes when the transmitting medium changes? Say from Oxygen to Hydrogen. I'm pretty sure the loudness does not change, but I think you would HEAR a change in pitch, because I think the wavelength changes when the transmitting medium changes. I don't think speed changes anything you hear. The main question is.... Can you hear a difference if you change the transmitting medium? The short answer is yes. Sound waves are greatly affected by the medium in which they travel, not just in terms of speed, but also in terms of loudness and tonal quality. Just think of the variation in loudness and sound quality of different acoustic guitars which may use the same strings, but the sound is greatly affected by the different media in which it travels, including the wood, sound cavities, even the varnish on the instrument.
By considering 'sound' as the result of the propagation of pressure waves through a mechanical medium such as any solid, liquid or gas, the 'speed of sound' can be shown to be a function of the elastic and inertial properties of the medium, such that:
$v=\sqrt{\frac{elastic~property}{inertial~property}}$
For example, the speed of sound through a gas with Bulk Modulus (elastic property) $B$ and volume density (inertial property) $\rho$, is given by:
$v=\sqrt{\frac{B}{\rho}}$
The speed of sound also depends on the temperature of the medium.
Now, the 'loudness' and 'pitch' of a sound are psychological phenomena which generally correlate to the physical phenomena of intensity and frequency, however there are some subtle differences, some of which relate to physiology of the ear drum.
The wavelength of sound changes with the medium, because it is proportional to the wave speed.
$v=f\lambda$
The frequency however is generally independent of the medium, although it can vary with the relative velocity of the sound source with respect to the observer, due to the Doppler Effect.
The following is multiple choice question (with options) to answer.
Sound, like all waves, travels at a certain speed and has the properties of frequency and this? | [
"energy",
"gravity",
"momentum",
"wavelength"
] | D | Sound, like all waves, travels at a certain speed and has the properties of frequency and wavelength. You can observe direct evidence of the speed of sound while watching a fireworks display. The flash of an explosion is seen well before its sound is heard, implying both that sound travels at a finite speed and that it is much slower than light. You can also directly sense the frequency of a sound. Perception of frequency is called pitch. The wavelength of sound is not directly sensed, but indirect evidence is found in the correlation of the size of musical instruments with their pitch. Small instruments, such as a piccolo, typically make high-pitch sounds, while large instruments, such as a tuba, typically make low-pitch sounds. High pitch means small wavelength, and the size of a musical instrument is directly related to the wavelengths of sound it produces. So a small instrument creates short-wavelength sounds. Similar arguments hold that a large instrument creates long-wavelength sounds. The relationship of the speed of sound, its frequency, and wavelength is the same as for all waves:. |
SciQ | SciQ-2383 | evolution, theoretical-biology, sexual-selection, palaeontology, extinction
to stochastic processes.
The only strictly experimental evidence for evolutionary
suicide comes from microbiology. In the social
bacterium Myxococcus xanthus individuals can develop
cooperatively into complex fruiting structures (Fiegna
and Velicer 2003 - [STUDY #7]). Individuals in the fruiting body are
then released as spores to form new colonies. Artificially
selected cheater strains produce a higher number of
spores than wild types. These cheaters were found to
invade wild-type strains, eventually causing extinction of
the entire population (Fiegna and Velicer 2003). The
cheaters invade the wild-type population because they
have a higher relative fitness, but as they spread through
the population, they decrease the overall density, thus
driving themselves and the population in which they
reside, to extinction.
The following is multiple choice question (with options) to answer.
Do bacteria sexually reproduce? | [
"sometimes",
"yes",
"they don't reproduce",
"no"
] | D | Are there male and female bacteria? Of course the answer is no. So, sexual reproduction does not occur in bacteria. But not all new bacteria are clones. This is because bacteria can acquire new DNA. This process occurs in three different ways:. |
SciQ | SciQ-2384 | photosynthesis, cellular-respiration, energy, sugar
Basically, points 4-7 convey that Calvin-Benson cycle not only produces sugar but what it actually does is fix inorganic carbon (as CO2) to organic form (in the form of sugar). So, most (practically all) of the carbon that a photosynthetic plant has, comes from this carbon fixation process and that's how plants are photoautotrophic.
The following is multiple choice question (with options) to answer.
What is type of sugar is produced through photosynthesis? | [
"carbohydrates",
"glutamate",
"insulin",
"glucose"
] | D | The energy of the sun is first captured by producers ( Figure below ), organisms that can make their own food. Many producers make their own food through the process of photosynthesis . The "food" the producers make is the sugar, glucose . Producers make food for the rest of the ecosystem. As energy is not recycled, energy must consistently be captured by producers. This energy is then passed on to the organisms that eat the producers, and then to the organisms that eat those organisms, and so on. |
SciQ | SciQ-2385 | photons, vision
Title: Dark room lights When I lay down in my room at night it's pretty much completely dark but I observe this strange phenomenon going on.
When I lay down and look at my ceiling I can see my white fluorescent white bulbs and white fan blades but when it's dark I can't. But, as soon as I avert my eyes from the fan and lightbulbs about 1 foot I can see them in the dark but why? If it helps there is a very slight illumination from the street lights. And, also I can't see anything not white on the ceiling.
Why can I see the objects only when I avert my eyes? This is really a biology topic, rather than a physics one.
The light sensing cells in your eyes come in two (or four depending on how you count) types. The cones are color sensitive. The rods are sensitive over almost the whole visible spectrum and offer no color discrimination, but they are considerably more sensitive than the cones.
The rods and cones are not evenly distributed in the eye. Cones are concentrated in the central part of the retina and rods are more common in your peripheral visual region. Which makes your peripheral vision more sensitive to very dim sources than your central vision.
In fact, naked-eye star-gazers learn to look near-but-not-at very dim observing target exactly to take advantage of this effect. But it take a lot of will-power to do at first. You'll find your self having a "Ah-ha!" reaction and then looking right at the target every time you make the trick work. At which point you have to go around again.
The following is multiple choice question (with options) to answer.
The light-sensing cells in the retina are called rods and what else? | [
"light cells",
"sensor cells",
"cones",
"stents"
] | C | The back of the eye is covered by a thin layer called the retina. This is where the image of the object normally forms. The retina consists of special light-sensing cells called rods and cones. Rods sense dim light. Cones sense different colors of light. |
SciQ | SciQ-2386 | species-identification, entomology
Title: I found these in my bathroom and WC Are they somehow dangerous? What are they and how can I get rid of them? These are silver fish (Lepisma saccharina) and harmless. Wikipedia says (image taken from the article):
Silverfish are nocturnal insects typically 13–25 mm (0.5–1.0 in)
long. Their abdomens taper at the end, giving them a fish-like
appearance. The newly hatched are whitish, but develop a greyish
hue and metallic shine as they get older. They have two long cerci
and one terminal filament at the tips of their abdomens; the filament
projects directly off of the end of their body, between the left and
right cerci. They also have two small compound eyes, despite other
members of Zygentoma being completely eyeless, such as the family
Nicoletiidae.
Like other species in Apterygota, silverfish are completely
wingless. They have long antennae, and move in a wiggling motion
that resembles the movement of a fish. This, coupled with their
appearance and silvery scales, inspires their common name. Silverfish
typically live for two to eight years. Silverfish are agile runners
and can outrun most of their predators (including wandering spiders
and centipedes). However, such running is possible only on horizontal
surfaces, as they lack any additional appendages, and therefore are
not fast enough to climb walls at the same speed.[citation needed]
They also avoid light.
The following is multiple choice question (with options) to answer.
Lampreys possess a large round sucker, lined with teeth, that surrounds the mouth and is used to feed on what? | [
"marrow",
"blood",
"herbivores",
"parasites"
] | B | Like hagfish, lampreys also lack scales, but they have fins and a partial backbone. The most striking feature of lampreys is a large round sucker, lined with teeth, that surrounds the mouth (see Figure below ). Lampreys use their sucker to feed on the blood of other fish species. |
SciQ | SciQ-2387 | species-identification, botany, ecology
Title: Algae or Lichen identification. Coastal BC, Canada I have tried all books and internet resources I know of, but I still have no idea what this might be — a lichen or something else.
At first glimpse, I thought it was something man-made and unnatural, but then I looked closer and saw how it appears to be attached and growing. It grows on exposed rocks well above the high tide. The photo is taken in late March, on northern Vancouver Island. It's loosely attached to the rock.
It was somewhat abundant around the general area (within of a few km), but I haven't seen it elsewhere - although I'm not from BC so there might be a lot of this around.
The water droplet in the lower right corner give a rough sense of scale.
Edit:
Adding another photo in which I just noticed a streak of white, which I included in original resolution. I want to propose you expand your search to a broader taxonomic scope. Specifically, I think you might be looking at a species of "red" green algae (family: Trentepohliaceae).
From Nelson et al. (2011):
All Trentepohliaceae have filamentous growth forms and often contain large amounts of carotenoid pigments (ß-carotene and hematochrome), causing the algae to appear yellow orange in color (Thompson and Wujek 1997, Lo´pez-Bautista et al. 2002).
The Trentepohliaceae contains five genera: (Trentepohlia, Printzina, Phycopeltis, Cephaleuros and Stomatochroon) and 70+ species worldwide.
For example, the following algae (picture from England) looks fairly similar to your specimen:
Trentepohlia aurea
Source: David Fenwick
If your specimen is a species in this family of algae, it is most likely in the Trentepohlia genus (or possibly Printzina genus).
Trentepohlia is a genus of filamentous chlorophyte green algae in the family Trentepohliaceae.
Typically orange or yellow in color.
Live on tree trunks and wet rocks or symbiotically in lichens.
Here's a picture of a free-living Trentepohlia species from coastal Oregon, USA:
Source: Richard C. Hoyer (2015)
The following is multiple choice question (with options) to answer.
What is the type of plant that has a single cotelydon in the seedling? | [
"moss",
"dicot",
"monocot",
"conifer"
] | C | Monocots Plants in the monocot group are primarily identified as such by the presence of a single cotyledon in the seedling. Other anatomical features shared by monocots include veins that run parallel to the length of the leaves, and flower parts that are arranged in a three- or six-fold symmetry. True woody tissue is rarely found in monocots. In palm trees, vascular and parenchyma tissues produced by the primary and secondary thickening meristems form the trunk. The pollen from the first angiosperms was monosulcate, containing a single furrow or pore through the outer layer. This feature is still seen in the modern monocots. Vascular tissue of the stem is not arranged in any particular pattern. The root system is mostly adventitious and unusually positioned, with no major tap root. The monocots include familiar plants such as the true lilies (which are at the origin of their alternate name of Liliopsida), orchids, grasses, and palms. Many important crops are monocots, such as rice and other cereals, corn, sugar cane, and tropical fruits like bananas and pineapples (Figure 26.17). |
SciQ | SciQ-2388 | biochemistry, proteins, nutrition, amino-acids, biosynthesis
Title: Essential amino acids Humans and the majority of animal species cannot synthesize essential amino acids (Info: Campbell biology 9th edition). However, meat, eggs, et cetera provide all required essential amino acids. And meat comes from animals.
Main question: So how do these animals we eat get their essential amino acids if they cannot synthesize them either?
My hypothesis: I know they can get it from their diet, but wouldn't it become a never-ending cycle of passing on essential amino acids?
Subquestion if hypothesis is proven: If that is the case, where did these essential amino acids come from? Bacteria and plants are able to synthesize all amino acids, as they are capable of nitrogen fixation. If animals eat plants, they get the essential amino acids needed for their proteins. Humans get the essential amino acids by eating these animals or directly by consuming plants. So yes, it is a never-ending cycle of passing.
The following is multiple choice question (with options) to answer.
What element is essential for amino acid and nucleic acid production? | [
"carbon",
"hydrogen",
"oxygen",
"nitrogen"
] | D | |
SciQ | SciQ-2389 | biochemistry, botany, plant-physiology, photosynthesis
What are typical characteristics of different plants in this regard? I.e., how do common species of plants manage their C consumption before (and after) the development of leaves? There are quite a few questions and thoughts in there, I'll try to cover them all:
First, to correct your initial word equation: During photosynthesis, a plant translates CO2 and water into O2 and carbon compounds using energy from light (photons).
You are correct to assume the C is further used for the growing process; it is used to make sugars which store energy in their bonds. That energy is then released when required to power other reactions, which is how a plant lives and grows. C is also incorporated into all the organic molecules in the plant.
Plants require several things to live: CO2, light, water and minerals. If any of those things is missing for a sustained period, growth will suffer. Most molecules in a plant require some carbon, which comes originally from CO2, and also an assortment of other elements which come from the mineral nutrients in the soil. So the plant is completely reliant on minerals.
Most plants, before a leaf is established or roots develop, grow using energy and nutrients stored in the endosperm and cotyledons of the seed. I whipped up a rough diagram below. Cotyledons are primitive leaves inside the seed. The endosperm is a starchy tissue used only for storage of nutrients and energy. The radicle is the juvenile root. The embryo is the baby plant.
The following is multiple choice question (with options) to answer.
In plants and algae where does photosynthesis takes place in? | [
"cytoplasm",
"nucleus",
"cell wall",
"chloroplasts"
] | D | In plants and algae, photosynthesis takes place in chloroplasts. (Photosynthetic bacteria have other structures for this purpose. ) A chloroplast is a type of plastid, or plant organelle. It contains the green pigment known as chlorophyll . The presence of chloroplasts in plant cells is one of the major ways they differ from animal cells. You can see chloroplasts in plant cells Figure below . |
SciQ | SciQ-2390 | organic-chemistry, everyday-chemistry, experimental-chemistry, biochemistry, food-chemistry
Title: How Bread is made with yeast, sugar and luke warm milk? Materials and Apparatus:
wheat flour
sugar
dry yeast
glass bowl
covering plate
milk
Procedure:
Lukewarm milk is taken in the glass bowl and sugar is added to it. Then, yeast is added to the same.
The mixture is left undisturbed for 10-12 minutes to activate the yeast
3 cups of wheat flour are added to the bowl containing the milk mixture.
The mixture is mixed thoroughly with 100ml of added water and the dough is kneaded well
The dough is placed in a bowl, covered with a plate and left undisturbed for 2 hours.
My query/confusion:
Why is milk needed?
"activated yeast"- what's the difference?
Can yeast work without sugar or milk.
Detail out the stages of the anaerobic oxidative process which takes place as a common first step in both aerobic and anaerobic respiration.
Finally, feel free to share anything I may be missing which should be here.
If you have any confusion regarding what I want to ask, please ask in the comments. Please upvote if you are curious about it too
milk is not needed, 'pure' bread is without milk
yeast is a fungus, therefore, it is alive. Its best to work with fresh yeast, which you find as small cubes in the refrigerated section. This one does not have to be activated. non-fresh yeast is dried, so in order for it to work properly, it has to be undried by adding water, which is called activation.
and 4. As said before, milk is not needed. Sugar however is the food for the yeast, without it, it does nothing. In aerobic breathing, the yeast metabolizes the sugar as we would: sugar + oxygen -> water + CO2. Without oxygen, the yeast resorts to ethanol fermentation: sugar -> alcohol + CO2 (this is, why it is used to make beer or wine). For making bread, we have a mixture of both respirations, which does not really matter, since we are only interested in the CO2, which makes the dough fluffy =) But without sugar, there is no CO2.
The following is multiple choice question (with options) to answer.
What is crucial for the fermentation progress in making bread? | [
"larvae",
"yeast",
"fruit",
"cold"
] | B | Yeasts are crucial for the fermentation process that makes beer, wine, and bread. Fermentation occurs in the absence of oxygen and allows the first step of cellular respiration, glycolysis, to continue. |
SciQ | SciQ-2391 | endocrinology, glucose, homeostasis, insulin, hypothalamus
Title: Role of the Hypothalmus in the control of Blood Sugar In homeostatic regulation of blood glucose, the receptor and effector is the Pancreas, but how does the control centre — the Hypothalamus — connect and link into this process? Your question doesn’t make it clear whether you think that the pancreas must be under the control of the hypothalmus, or whether you are asking whether it has an influence on the pancreas in relation to the secretion of insulin and glucagon, which control the concentration of blood glucose.
First, it has been long known that secretion of insulin can be influenced by the concentration of glucose in isolated pancreatic islets in vitro, so it can not be true that the effects must involve the hypothalmus. This is implicit in most book or general information articles you might find on the web, but for an original reference a review by W.J. Malaisse in Diabetologia 9, 167–173 (1973) seems highly cited.
I know almost nothing about physiology, but on searching the web for the role of the hypothalmus in glucose homeostasis, found a most readable prize-winning postgraduate essay on the topic by Syed Hussein of Imperial College London. I trust that it is in order to append an edited extract of this:
The following is multiple choice question (with options) to answer.
What hormone does the endocrine system secrete to help cells absorb blood sugar? | [
"glucose",
"testosterone",
"insulin",
"Cortisol"
] | C | After you eat and digest a sugary snack, the level of sugar in your blood quickly rises. In response, the endocrine system secretes the hormone insulin. Insulin helps cells absorb sugar from the blood. This causes the level of sugar in the blood to fall back to its normal level. |
SciQ | SciQ-2392 | botany, plant-physiology, plant-anatomy
Title: Sporophyte and gametophyte
My textbook says that in both groups of seedless plants (vascular plants, non-vascular plants) the gametophyte is a free-living plant, independent of the sporophyte.
I don't understand this statement and am now wondering if the sporophyte and gametophyte are stages in a plant's lifecycle, or are they individual parts of the plant, or are the sporophyte and the gametophyte different plants altogether? Secondly, does this differ depending on the organism?
Different plants or different structures that make up the same organism? The sporophtye is the diploid stage in the life cycle. In comparison, with humans, you and I would be sporophytes.
The Gametophyte is the haploid stage in the life cycle. In comparison, with humans, spermatozoids and ovules are gametophytes.
The following is multiple choice question (with options) to answer.
What part of the sporophyte produces microspores that form male gametophytes and megaspores that form female gametophytes? | [
"flower",
"pollen",
"leaves",
"chloroplasts"
] | A | |
SciQ | SciQ-2393 | biochemistry, pathology, teeth, decay, minerals
Crystal growth of fluorapatite from a supersaturated solution:
$\ce{10~Ca^{2+ }~+~6~PO4^{3-}~+~2~F- -> Ca_{10}(PO4)6F2}$
Apatite dissolution with $\ce{CaF2}$ formation:
$\ce{Ca_{10}(PO4)6(OH)2~+~20~F- -> 10~CaF2~+~6~PO4^{3-}~+~2~OH-}$
Instead of preventing cavities, fluoride just controls the rate of formation of cavities (i.e. it repairs, not prevents, tooth decay), due to which its repeated exposure on enamel throughout the day is important (Cate et al, 2013). However, the effects of fluoride are minimal once it gets swallowed (Ismail et al, 2008).
Talking about fluorosis, the cause behind it is dissolution of hydroxyapatite due to higher concentration of fluoride (see the 3rd point in mechanisms, it requires higher level of fluoride to occur). Apart from this, formation of fluorohydroxyapatite is also a cause of fluorosis, the reaction being:
$\ce{Ca_{10}(PO4)6(OH)2~+~F- ~+~H+ -> Ca_{10}(PO4)6(OH)F + H2O}$
Dissolution of fluoroapatite causes depletion of enamel layer, causing fluorosis.
References:
M. Staines, W. H. Robinson and J. A. A. Hood (1981). "Spherical indentation of tooth enamel". Journal of Materials Science. 16 (9): 2551–2556. doi:10.1007/bf01113595.
Wikipedia contributors. "Tooth enamel." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 25 Apr. 2017. Web. 1 May. 2017.
The following is multiple choice question (with options) to answer.
This calcification prevents diffusion of nutrients into the matrix, resulting in what dying and the opening up of cavities in the diaphysis cartilage? | [
"nanoparticles",
"phytocytes",
"keratinocytes",
"chondrocytes"
] | D | matrix and deposit calcium, which hardens the matrix. The non-mineralized portion of the bone or osteoid continues to form around blood vessels, forming spongy bone. Connective tissue in the matrix differentiates into red bone marrow in the fetus. The spongy bone is remodeled into a thin layer of compact bone on the surface of the spongy bone. Endochondral Ossification Endochondral ossification is the process of bone development from hyaline cartilage. All of the bones of the body, except for the flat bones of the skull, mandible, and clavicles, are formed through endochondral ossification. In long bones, chondrocytes form a template of the hyaline cartilage diaphysis. Responding to complex developmental signals, the matrix begins to calcify. This calcification prevents diffusion of nutrients into the matrix, resulting in chondrocytes dying and the opening up of cavities in the diaphysis cartilage. Blood vessels invade the cavities, and osteoblasts and osteoclasts modify the calcified cartilage matrix into spongy bone. Osteoclasts then break down some of the spongy bone to create a marrow, or medullary, cavity in the center of the diaphysis. Dense, irregular connective tissue forms a sheath (periosteum) around the bones. The periosteum assists in attaching the bone to surrounding tissues, tendons, and ligaments. The bone continues to grow and elongate as the cartilage cells at the epiphyses divide. In the last stage of prenatal bone development, the centers of the epiphyses begin to calcify. Secondary ossification centers form in the epiphyses as blood vessels and osteoblasts enter these areas and convert hyaline cartilage into spongy bone. Until adolescence, hyaline cartilage persists at the epiphyseal plate (growth plate), which is the region between the diaphysis and epiphysis that is responsible for the lengthwise growth of long bones (Figure 38.21). |
SciQ | SciQ-2394 | python, beginner, parsing, csv
Full text: On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains
On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains
The following is multiple choice question (with options) to answer.
What is the greek word meaning "to help make things easier"? | [
"machine",
"battery",
"mode",
"toy"
] | A | 9.5 Simple Machines Simple machines are devices that can be used to multiply or augment a force that we apply – often at the expense of a distance through which we apply the force. The word for “machine” comes from the Greek word meaning “to help make things easier. ” Levers, gears, pulleys, wedges, and screws are some examples of machines. Energy is still conserved for these devices because a machine cannot do more work than the energy put into it. However, machines can reduce the input force that is needed to perform the job. The ratio of output to input force magnitudes for any simple machine is called its mechanical advantage (MA). |
SciQ | SciQ-2395 | dna, radiation
Title: How do electrons destroy DNA bonds in radiation? Malignant tumors can be treated by radiation therapy. Most commonly it's radiotherapy with photons, or protons and so on. The common denominator for both types is that the radiation creates electrons inside the body via different effects.
What I haven't quite understood is how these electrons destroy the DNA bonds in the tumor and how this aids in killing off the cancer cells? Is it due to the generation of heat, or otherwise? I think you have a fundamental misunderstanding of the chemical reactions involved in radiation therapy. Neither photon based or proton based therapies "create electrons", but they do cause ionization by adding enough energy to existing electrons around atoms so that the electron is ejected from the atom, creating an ion or free radical, which can then undergo chemical reaction.
Photons, typically gamma rays, X-rays, and high energy UV, typically interact with water molecules and produce free radicals, including the dangerous hydroxyl radical. The hydroxyl radical can interact with proteins and DNA and damage those molecules, but has a very short half-life. Molecular oxygen can help increase the damage by reacting with the hydroxyl radical to produce Reactive Oxygen Species, ROS, which can also damage DNA or protein. However, many tumors have low oxygen concentration that reduces the effectiveness of photon based radiation therapy.
To overcome this, many patients receive proton based radiation therapy. Protons are much heavier than photons (I guess infinitely heavier than a photon, since photons have no mass) and therefore scatter to a much smaller extent. They just sort of plow through tissue and knock electrons out of orbitals as they collide with molecules such as DNA or protein. They don't rely so much on free radical generation or ROS, so low oxygen levels don't reduce their effectiveness.
The goal is damage the DNA to induce double strand breaks which are hard to repair in fast growing cancer cells. Because they grow so quickly, they are already stressed and their DNA repair machinery is less effective than in healthy cells. If their DNA can be sufficiently damaged, the cell will die.
For more information about these processes, please see these wikipedia articles on Radiation Therapy, Radiolysis, Linear Energy Transfer, and Free Radical Damage to DNA.
The following is multiple choice question (with options) to answer.
High levels of radiation can remove electrons from? | [
"humans",
"metals",
"water",
"acids"
] | B | Nonliving things can also be damaged by radiation. For example, high levels of radiation can remove electrons from metals. This may weaken metals in nuclear power plants and space vehicles, both of which are exposed to very high levels of radiation. |
SciQ | SciQ-2396 | exoplanet
It's probably possible to have volcanic eruptions even though dozens or maybe even hundreds of miles of exotic ice because the heat has to go somewhere, eventually, assing it's likely to build up over time, so either by circulation of eruption, the heat has push through at some point. This even happens on so called "dead" planets like Mars or even the Moon. Mars still has the occasional volcanic eruption, just not very often.
But water worlds certainly can have plate tectonics. There's nothing in the water that would prevent it from happening. Plate Tectonics is, as I understand it, primarily a factor of the size of the planet. Gas planets - different story, but planets with a hard surface, Earth sized, a tiny bit smaller to a fair bit but not much bigger are good candidates for plate tectonics (I think). There's some debate on how large, I think, still going on. But I remember reading that ocean/water worlds might even be more likely to have plate tectonics. Plate tectonics is definitely something we'd look for if we ever get a close enough look at other planets in different solar-systems (exoplanets).
Just my thoughts on this. Not meant to be complete or definitive.
The following is multiple choice question (with options) to answer.
What is the only planet we know that has plate techtonics? | [
"Saturn",
"earth",
"Jupiter",
"Mars"
] | B | The Earth is divided into many plates. These plates move around on the surface. The plates collide or slide past each other. One may even plunge beneath another. Plate motions cause most geological activity. This activity includes earthquakes, volcanoes, and the buildup of mountains. The reason for plate movement is convection in the mantle. Earth is the only planet that we know has plate tectonics. |
SciQ | SciQ-2397 | evolution, biochemistry, mitochondria
Title: Is there any advantage of having mitochondria for aerobic respiration? If we consider the pathway of breakdown of glucose which includes glycolysis, the citric acid cycle and the electron transport chain, all these processes takes place in some prokaryotes and eukaryotes. In prokaryotes all these processes take place in cytoplasm while in eukaryotes the last two processes take place in mitochondria.
So is there any advantage of performing the last two processes in the mitochondria? Does it yield more energy? If there is no advantage, what is the point of having a mitochondria (at least for this process)? From the evolutionary point of view, the eukaryotes acquired these metabolisms (except glycolysis) from their prokaryotic endosymbionts. Not all prokaryotes have the ETC. The free living ancestor of mitohondria is supposed to be the alpha-proteobacterium.
Now, glycolysis is a common pathway in lot of lifeforms perhaps because of abundance of glucose. TCA cycle is coupled with ETC at certain steps which makes it essentially a part of aerobic metabolism.
The reason for having a dedicated organelle for respiration
ATP synthesis is a membrane process. Imagine a large prokaryotic cell- as big as an animal cell. Such a cell cannot take care of its energetic demands which primarily consists of protein synthesis with the given area of membrane i.e it needs much more ATP-synthases than it can have to cope up with the energy demands of maintaining such a huge cell (this index is approximated based on surface to volume ratio). Therefore it is wise to harbor multiple efficient organelles i.e. mitochondria which themselves have just a small essential genome and proteome to maintain.
For a better understanding, please read this article. I just loved it.
There is also a book by the same author about mitochondria called Power, Sex, Suicide.
The following is multiple choice question (with options) to answer.
Variation in muscle cells gives further insight into some benefits of what type of respiration? | [
"anaerobic",
"natural",
"aerobic",
"enzymatic"
] | A | Variation in muscle cells gives further insight into some benefits of anaerobic respiration. In vertebrate muscles, lactic acid fermentation allows muscles to produce ATP quickly during short bursts of strenuous activity. Muscle cells specialized for this type of activity show differences in structure as well as chemistry. Red muscle fibers are “dark” because they have a rich blood supply for a steady supply of oxygen, and a protein, myoglobin, which holds extra oxygen. They also contain more mitochondria, the organelle in which the Krebs cycle and electron transport chain conclude aerobic respiration. This is endurance muscle. White muscle cells are “light” because they lack the rich blood supply, have fewer mitochondria, and store the carbohydrate glycogen rather than oxygen. This is muscle built for sprinting. |
SciQ | SciQ-2398 | visible-light, electromagnetic-radiation
Realistically, All wavelengths should differ in shades considering the red hue increases in every colour as wavelength increases. Then how come we say that only Seven colours form White light?
The important thing here is that this spectrum is a $\textbf{continuum}$, which results in no clearly defined limit or frontier between colours because of the smooth color gradient that exists. Looking at this spectrum the first thing that we can tell is that there are seven big categories that result in a range (continuum) of wavelenghts that we can very easily distinguish: purple, blue, cyan, green, yellow, orange and red. Looking for example at 550 nm and 600 nm in the previous figure, we can say that both wavelenghts correspond to the same "bag" of wavelenghts which we name $\textbf{green}$, but if we carefully observe
those colours we note that we can actually tell that they are $\textit{different}$ hues of green because of the shading.
Do all wavelengths between A to B correspond to Yellow light? So, (A+1) nm, (B-1) nm, along with A nm & B nm are all exactly of the same colour ? Is there any difference even in their shades?
The following is multiple choice question (with options) to answer.
Violet and red are two types of what kind of light? | [
"visible",
"ultraviolet",
"radioactive",
"infrared"
] | A | Figure 8.12 The colors of visible light do not carry the same amount of energy. Violet has the shortest wavelength and therefore carries the most energy, whereas red has the longest wavelength and carries the least amount of energy. (credit: modification of work by NASA). |
SciQ | SciQ-2399 | human-anatomy
Title: Difference between Appendix and the Cecum? What's the difference between an appendix and a cecum, and what are their functions? In herbivores the Cecum is an area that stores plant matter and helps digest it via symbiotic bacteria. Carnivores have smaller Cecums because meat is easier to digest than plant matter. In humans the Cecum is also an anatomical landmark that delineates the change from small intestine (a digesting organ) to the large intestine (mostly a capacity/storage organ).
The Appendix is a small, previously thought "superfluous" fleshy worm-shaped organ at the junction between the small and large intestines. Recent research posits that the appendix is sort of a harbor for a person's gut flora that can re-populate the intestines should the existing bacteria die or get removed (diarrhea being the most common cause). It can also become infected, inflamed, and require surgery to remove (Appendicitis).
The following is multiple choice question (with options) to answer.
The duodenum is a part of which part of the gi tract? | [
"small intestine",
"pharynx",
"ulna",
"large intense"
] | A | The duodenum is the first and shortest part of the small intestine. Most chemical digestion takes place here, and many digestive enzymes are active in the duodenum (see Table below ). Some are produced by the duodenum itself. Others are produced by the pancreas and secreted into the duodenum. |
SciQ | SciQ-2400 | aqueous-solution, concentration, terminology
Title: What is a complete reaction? For a lab assignment, I combined $\pu{10 mL}$ of $\pu{1 M}$ sodium sulfate solution with $\pu{10 mL}$ of $\pu{1 M}$ calcium chloride solution. The ionic equation I came up with is:
$$\begin{multline}
\ce{2Na^+ (aq) + SO4^2- (aq) + Ca^2+ (aq) + 2Cl^- (aq) ->}\\
\ce{CaSO4(s) + 2Na^+ (aq) + 2Cl^- (aq)}
\end{multline}$$
I was then asked, in a lab question, the following:
If the reaction called for $\pu{1 M}$ chloride ion with $\pu{1 M}$ calcium ion, would you still use $\pu{10 mL}$ of each solution for a complete reaction? Explain your reasoning.
To my understanding, I initially had $\pu{2 M}$ chloride ion and $\pu{1 M}$ calcium ion. With only $\pu{1 M}$ chloride ion instead, the ionic equation would change to this, or so I'm led to believe:
$$\begin{multline}
\ce{2Na^+ (aq) + SO4^2- (aq) + Ca^2+ (aq) + Cl^- (aq) ->}\\
\ce{CaSO4(s) + 2Na^+ (aq) + Cl^- (aq)}
\end{multline}$$
As a (balanced) molecular equation, to my understanding, this would be:
$$\begin{multline}
\ce{Na2SO4 (aq) + Ca (aq) + Cl (aq) ->}\\
\ce{CaSO4(s) + NaCl (aq) + Na (aq)}
\end{multline}$$
Is this a complete reaction? I have seen conflicting definitions of a complete reaction online:
The following is multiple choice question (with options) to answer.
A complete ionic equation is a chemical equation in which the dissolved ionic compounds are written as what? | [
"charged ions",
"joined ions",
"separated ions",
"realized ions"
] | C | When chemicals in solution react, the proper way of writing the chemical formulas of the dissolved ionic compounds is in terms of the dissociated ions, not the complete ionic formula. A complete ionic equation is a chemical equation in which the dissolved ionic compounds are written as separated ions. Solubility rules are very useful in determining which ionic compounds are dissolved and which are not. For example, when NaCl(aq) reacts with AgNO3(aq) in a double-replacement reaction to precipitate AgCl(s) and form NaNO3(aq), the complete ionic equation includes NaCl, AgNO3, and NaNO3 written as separated ions:. |
SciQ | SciQ-2401 | human-biology, digestive-system, immune-system, microbiome
The next level of defense comes from the cells of the innate immune system (14). In innate immunity, specialized cells monitor the area they are in for Pathogen-Associated Molecular Patterns (PAMPs). PAMPs can be sugars that make up the cell walls of the microbe or proteins that get expressed on the surface of the organism, such as Flagellin, a protein only found in the flagella of certain pathogen. The innate immune cells have pattern recognition receptors (PRR) that have a general specificity for recognizing and responding to the PAMPs. Our cells even have PRRs for DNA and Double Stranded RNA's, however those are usually found in vesicles on the inside of the cell. These interactions are very general, however once PRRs bind to the PAMP, they are able to signal into the cytoplasm, which can lead to the production of proteins, among other possible responses.
Here you can think of PRRs like a motion detector in a security system; the dog, or your two year old, or an intruder are going to set off the alarm just the same. It is not specific. The motion sensor "knows" that something that it is supposed to recognize, i.e. a moving object larger than a mouse passed by and it triggered the response, but it cannot tell you which moving object triggered it, only that it was triggered.
The innate immune cells are also able to respond by "eating" the pathogen in a process called phagocytosis. Here, they break up the bacteria, yeast, or the remnants of other dead host cells or large pathogens, things like worms, and put the broken up pieces on protein molecules on their surface.
When innate immune cells do this, they are presenting molecules to specialized immune cells (adaptive immune cells (14)), B-Cells and T-Cells, that are highly specific as to what they will react to. These cells can also cause a lot of damage to the host, so they are tightly regulated. Think of the interactions as keys and locks. A protein from a bacteria should turn a few of these cells on, but a protein from the host should not fit the lock.
The following is multiple choice question (with options) to answer.
The barrier defenses are not a response to infections, but they are continuously working to protect against a broad range of what? | [
"mates",
"pathogens",
"ecosystems",
"nutrients"
] | B | environment of the body’s soft tissues. Barrier defenses are part of the body’s most basic defense mechanisms. The barrier defenses are not a response to infections, but they are continuously working to protect against a broad range of pathogens. The different modes of barrier defenses are associated with the external surfaces of the body, where pathogens may try to enter (Table 21.2). The primary barrier to the entrance of microorganisms into the body is the skin. Not only is the skin covered with a layer of dead, keratinized epithelium that is too dry for bacteria in which to grow, but as these cells are continuously sloughed off from the skin, they carry bacteria and other pathogens with them. Additionally, sweat and other skin secretions may lower pH, contain toxic lipids, and physically wash microbes away. |
SciQ | SciQ-2402 | atmosphere, ocean, hydrology, climate-change
Comment: I strongly endorse the use of wind and hydropower as sources of energy over the further use of fossil fuels. However, I still think it is important to do research into the actual renewability of presumed-renewable energy sources, as we don't want to end up with another fossil fuel-type situation, in which we become aware of dependency on these energy sources and their malignant environmental side-effects long after widespread enthusiastic adoption. Electricity from waves, from hydro (both run-of-river and storage) and from wind, are all indirect forms of solar power. Electricity from tides is different, and we can deal with that in a separate question. Global tidal electricity generation is not yet at the scale of gigawatts, so it's tiny for now.
Winds come about from the sun heating different parts of the planet at different rates, due to insolation angles, varying cloud cover, varying surface reflectivity, and varying specific heat of surface materials. Temperature differentials create wind currents.
Waves come about from wind, so they're a twice-indirect form of solar power.
Sunlight on water speeds up evaporation, lifting the water vapour into clouds, giving them lots of gravitational potential. That rain then falls, sometimes onto high land, from where it can be gathered into storage reservoirs that are tapped for electricity, or where it flows into rivers that are then harnessed in run-of-river hydro.
How much power is there? Well, the insolation from the sun is, at the outer boundary of the Earth's atmosphere, at an intensity of about 1400 Watts per square metre. The Earth's albedo is roughly about 30% - i.e. on average about 400 Watts are reflected back into space, giving an average irradiation into the Earth of about 1000 Watts per square metre. Picture the Earth's surface as seen from the Sun: wherever the Earth is in its orbit on its own axis, and around the Sun, the Sun sees a disc that has the Earth's diameter, so the surface area exposed to the Sun is just $\pi$ times the square of Earth's radius, which is about 6 300 kilometres.
So the incoming solar radiation is $1000 \times 6,300,000^2 \times \pi \approx 125 \times 10^{15} \rm \ W$
The following is multiple choice question (with options) to answer.
A minority of people on earth use up most of the planet's what, including energy? | [
"sand",
"resources",
"air",
"water"
] | B | Of course not. A minority of people use most of the world’s energy and other resources. Not only are their needs met, but they have many luxuries. Many other people lack resources. Many don’t have enough to eat or live, with the threat of hunger. Many also do not have safe, clean water. Some people live in crowded, run-down housing. Some people live in mansions. |
SciQ | SciQ-2403 | electrochemistry, redox, electrolysis
Title: Why does the copper anode dissolve?
In such a setup, the copper anode is known to dissolve. My question is, why? Does it not receive electrons from the $ \ce{OH^-}$ ions. And if you say that those electrons just flow to the battery, let me provide the counterargument: the electrons flowing to the cathode do not prevent the copper cathode from dissolving because copper ions in solution accept the ions, so there is actually nothing stopping the cathode from dissolving as well. So, very simply, my question is this: Why does the copper anode dissolve? The anode is where oxidations happen (the cathode is where reduction takes place).
In the vicinity of your anode, you have the following compounds: $\ce{H2O}$, $\ce{Cu}$, $\ce{Cu^2+}$, $\ce{SO4^2-}$. If you check oxidation states, you will realise that oxygen is always $\mathrm{-II}$, hydrogen is $\mathrm{+I}$, sulphur is $\mathrm{+VI}$ and copper is present in both $\mathrm{\pm 0}$ and $\mathrm{+II}$. Thus, the only species available for oxidation are copper($0$) and oxygen($\mathrm{-II}$).
Checking standard potentials:
\begin{align}
\ce{O2 + 4 H+ + 4 e- &<=> 2 H2O} \qquad &E^\circ = \pu{+1.23 V}\tag{1}\\
\ce{Cu^2+ + 2 e- &<=> Cu} \qquad &E^\circ = \pu{+0.35 V}\tag{2}
\end{align}
It should be clear why copper is oxidised.
On the reduction side, hydrogen, copper and sulphate all could accept electrons. Copper is again the happiest of the three to accept electrons.
The following is multiple choice question (with options) to answer.
Groundwater dissolves minerals and carries the ions in a what? | [
"mixture",
"transition",
"jet stream",
"solution"
] | D | Groundwater dissolves minerals and carries the ions in solution. |
SciQ | SciQ-2404 | universe, naming, cosmological-horizon
Title: What's the name of outside the cosmic horizon? The word we use to refer to what's inside the cosmic horizon is the 'universe', so what would you call the empty space outside of the horizon? The outside is also the universe, the inside is just the observable universe.
The following is multiple choice question (with options) to answer.
What is the area of our universe that isn't stars and galaxies called? | [
"dark matter",
"nebula",
"solar systems",
"galaxies"
] | A | We see many objects out in space that emit light. We see other objects that emit other types of electromagnetic radiation. The matter we can see is contained in stars. The stars are contained in galaxies. Scientists think that stars and galaxies make up only a small part of the matter in the Universe. The rest of the matter is called dark matter . |
SciQ | SciQ-2405 | eyes
To directly answer your question - yes, I believe this is primarily the "fault" of the eye, rather than the brain. The brain has a role in identifying the flicker at a subconscious level, in terms of fight or flight response, but the eye is responsible for providing the elevated sensitivity at the peripheral.
The following is multiple choice question (with options) to answer.
What neurotransmitter is associated with the fight-or-flight response? | [
"stomach acid",
"endorphins",
"adrenaline",
"bile"
] | C | Adrenaline, or epinephrine, is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages, and participates in the fight-or-flight response of the sympathetic nervous system. Adrenaline is produced in the adrenal medulla of the adrenal gland. So how does it effect processes all over the body?. |
SciQ | SciQ-2406 | microbiology, population-biology
Title: How many eukaryotes are there on Earth? I have been reading:
William B. Whitman, David C. Coleman, and William J. Wiebe, "Prokaryotes: The unseen majority", Proc. Natl. Acad. Sci. USA 95, pp. 6578–6583, June 1998. [Full Text] [PDF]
wherein they estimate the number of prokaryote cells on Earth to be of the order of $10^{31}$.
I can't seem to find any equivalent data for eukaryote one-celled life. Are there any estimates for the number of one-celled eukaryotic living things on Earth? Do any other estimates confirm or tell against the reference I have cited above? Could not fit in a comment....
To make sure we all understand your question...
Is your question how many (eukaryote) species are currently living? or How many (eukaryote) cells are currently living??
Just a hint to answer the question
Micheal Lynch, in his book (On the Origin of Genome Architecture) at page 3, Box 1.1 tries to answer the question How much DNA is there on earth?. He ends up with an estimation of a total length of DNA on earth of $10^{24}$ km for procaryotes, $10^{25}$ km for eukaryote (of which $\frac{1}{1000}$% is accounted to humans). This sums up to a total DNA length of $10^{12}$ light-years, or 10 times the diameter of the known universe!
In his calculations, he estimates that the total number of procaryote cells at $10^{30}$ (citing Whitman et al. 1998 as you did). He estimates the total number of eukaryote species to $10^7$, i.e. 6 times the number of known eukaryote species. However, he doesn't directly give any reference for this estimate but he refers to different chapters in the book that contain lots of references.
...I hope that helps...
The following is multiple choice question (with options) to answer.
What do scientists think are the oldest eukaryotes? | [
"protists",
"prokaryotes",
"arthropods",
"fungi"
] | A | Scientists think that protists are the oldest eukaryotes. |
SciQ | SciQ-2407 | fossils, drilling
Title: What would people drilling through Mount Everest find? I am interested in knowing what kind of fossils we would find if we were to drill horizontally through the mountain and what we would find if we were to drill vertically. Would we find anything interesting other than the fossils? Looks like some basic hints are necessary (as a complement to @AndyM's answer):
stratigraphy usually goes from younger to older when going down.
there'll be little chance to find any macrofossils in rocks that formed before sufficiently complex life was around.
there'll be little chance to find fossils in rocks that underwent metamorphism, that is have been in pressure/temperature regimes that aren't conducive for their preservation, even if they initially were present in the pre existing rocks.
'trace fossils' are not small remains of fossils but fossilized traces ('footprints'). Very rare thing.
it may be possible to find fossils in overlaying, younger sediments that formed during or after the uplift or were trapped or transported in depressions, but that's not the point of the question I think.
So, below the uppermost formations around the summit you'll likely find nothing of interest in the sense of the question when drilling down.
Will provide sources on specificically focussed request, but this isn't top notch geoscience.
The following is multiple choice question (with options) to answer.
Geologists found that the youngest rocks on the seafloor were where? | [
"mid - ocean ridges",
"late - ocean ridges",
"seabed floor",
"early - ocean ridges"
] | A | Different seafloor magnetic stripes equal different ages. By using geologic dating techniques, scientists could figure out what these ages are. They found that the youngest rocks on the seafloor were at the mid-ocean ridges. The rocks get older with distance from the ridge crest. Scientists were surprised to find that the oldest seafloor is less than 180 million years old. This may seem old, but the oldest continental crust is around 4 billion years old. |
SciQ | SciQ-2408 | bacteriology
Title: Why is it that bacteria and fungi cannot develop resistance against essential oils? I wonder why bacteria and fungi cannot develop resistance and mutate agains essential oils?
For example, some fungi get killed by oregano oil.
Being not a biologist, I hope my question is not so stupid..
Thank you! Here are my thoughts on this, taking your example, oregano oil.
The active anti-microbial ingredient in this essential oil is carvacrol. The WP article states that it probably acts by disruption of the membrane.
There appear to be no examples of carvacrol resistance, as suggested by your question. In mammals the compound is detoxified in the liver via esterification to increase solubilty, thus promoting excretion.
Assuming that we can create a situation with a strong selective pressure for the development of resistance in a microbe, what would that resistance look like? If the carvacrol does indeed disrupt the membrane, then it is probably useless to develop intracellular degradation - what is needed is the secretion of an enzyme that is able to inactivate the compound, analogous to the β-lactamases that inactivate antibiotics like penicillin (which also has an extracellular mode of activity).
Furthermore, unlike β-lactams, carvacrol is insoluble in water. This suggests to me that most of the time, in the natural environment, free-living bacteria will not experience significant levels of the compound.
In summary - it may be difficult to evolve a system for the degradation of a lipophilic compound, and because it is lipophilic it may be that it is rarely a problem for bacteria unless they are being subjected to laboratory tests for antimicrobial activity.
The following is multiple choice question (with options) to answer.
The stability of an ecosystem depends on the actions of what, exemplified by mushrooms on a decaying log and bacteria in soil? | [
"whitefly",
"fluxes",
"aphids",
"decomposers"
] | D | The stability of an ecosystem depends on the actions of the decomposers. Examples of decomposers include mushrooms on a decaying log. Bacteria in the soil are also decomposers. Imagine what would happen if there were no decomposers. Wastes and the remains of dead organisms would pile up and the nutrients within the waste and dead organisms would not be released back into the ecosystem. Producers would not have enough nutrients. The carbon and nitrogen necessary to build organic compounds, and then cells, allowing an organism to grow, would be insufficient. Other nutrients necessary for an organism to function properly would also not be sufficient. Essentially, many organisms could not exist. |
SciQ | SciQ-2409 | endocrinology, sexuality
Title: why a testosterone pill can't be effective? Why estrogen, progesterone etc. in the contraceptive pills survive the acid environment of the stomach and all the digestive enzymes, while testosterone needs to be injected or spread with a gel on skin?
I have no idea of why this difference in assumption, because I know testosterone and "feminine" hormones have the same steroid based structure...so I can't pick up why testosterone differently from "feminine" hormones can't resist the digestion. As stated in the comments by Eliane B., testosterone can actually be administered orally when an undecanoate ester is attached. The reason regular testosterone cannot be adminstered orally is because it undergoes extensive first pass metabolism (oxidation of the 17b-hydroxyl group to a 17-keto group, catalyzed by 17b-hydroxysteroid dehydrogenase enzymes, which are active in the liver). The undecanoate ester makes the substance lipophilic enough to be transported by the lymphatic system to the circulation after absorption by the intestines. Without the ester it will first reach the liver via the portal vein, thus exposing it to first pass metabolism. Nevertheless, bioavailability of oral testosterone undecanoate is estimated to be less than 10% [1].
Besides that, there are also derivates of testosterone which have a high oral bioavailability. These derivates have an alpha-oriented alkyl group, usually methyl, at position C-17, which retards hepatic metabolism. However, this can lead to hepatotoxicity [2].
https://www.ncbi.nlm.nih.gov/pubmed/3770015 (note, the subjects were women, but in the literature it is assumed that similiar bioavailability is obtained in men)
https://www.ncbi.nlm.nih.gov/pubmed/27372877
The following is multiple choice question (with options) to answer.
Anabolic steroids, a form of the male sex hormone testosterone, are one of the most widely known performance-enhancing drugs. steroids are used to help build what? | [
"muscle mass",
"brain tissue",
"nervous tissue",
"bone mass"
] | A | Some athletes attempt to boost their performance by using artificial hormones that enhance muscle performance. Anabolic steroids, a form of the male sex hormone testosterone, are one of the most widely known performance-enhancing drugs. Steroids are used to help build muscle mass. Other hormones that are used to enhance athletic performance include erythropoietin, which triggers the production of red blood cells, and human growth hormone, which can help in building muscle mass. Most performance enhancing drugs are illegal for non-medical purposes. They are also banned by national and international governing bodies including the International Olympic Committee, the U. Olympic Committee, the National Collegiate Athletic Association, the Major League Baseball, and the National Football League. The side effects of synthetic hormones are often significant and non-reversible, and in some cases, fatal. Androgens produce several complications such as liver dysfunctions and liver tumors, prostate gland enlargement, difficulty urinating, premature closure of epiphyseal cartilages, testicular atrophy, infertility, and immune system depression. The physiological strain caused by these substances is often greater than what the body can handle, leading to unpredictable and dangerous effects and linking their use to heart attacks, strokes, and impaired cardiac function. Regulation of the Female Reproductive System In females, FSH stimulates development of egg cells, called ova, which develop in structures called follicles. Follicle cells produce the hormone inhibin, which inhibits FSH production. LH also plays a role in the development of ova, induction of ovulation, and stimulation of estradiol and progesterone production by the ovaries, as illustrated in Figure 37.9. Estradiol and progesterone are steroid hormones that prepare the body for pregnancy. Estradiol produces secondary sex characteristics in females, while both estradiol and progesterone regulate the menstrual cycle. |
SciQ | SciQ-2410 | habitable-zone
Title: Better than Earth habitability Earth undoubtly has very good conditions for supporting life. Although it is expected that many other planets on the outer space have conditions at least as good as Earth, the vast majority doesn't, making them unhospitable to life or probably being able to support only very simple lifeforms. Earth itself for some billions of years until the Ediacaran or Cambrian could only support very simple lifeforms.
There are many parameters that may influence the habitability of a planet and its ability to support complex life: Star type; star temperature; star luminosity; stellar activity; stellar stability; star age; planet age; planet composition; planet size; orbital excentricity; orbital length; rotation axis inclination; planet tectonics; planet magnetosphere; presence and influence of satellites; abundance of water; planet atmosphere; interactions with other planets; presence or absence of asteroids, comets and minor planets planets belts and their position, distribution and composition; galactic orbit; galactic neighborhood; mass-extinction events rate, probability and intensity; and hundred of other possible variables including some based on pure luck and random chance.
Many of the parameters are modeled after Earth itself, since Earth is the only place so far that we know that life exists, and even if we found some alien life somewhere, it will probably be limited only to very simple forms of life.
But, what combinations of those parameters could lead to a planet with better life support than Earth itself?
Ok, you may argue that the question is too broad, so by "good life support" we could say something that allows the planet to evolve plenty biodiverse multicellular life ranging from simple microscopic creatures to complex dozens-meters long creatures with many body-differentiated parts and organs in a short timespan. So, a planet that has an environment which allows the development of richly-diverse and complex plant-like and animal-like creatures in a billion years after formation and stay like this for another 10 billion years is expected to be more life-friendly than Earth.
Further, lets restrict the biochemistry to what we know: water-based and carbon-based life, but not necessarily oxygen-breathing.
By the way, I am not asking anything about intelligent life or humans, just complex multicellular and biodiverse life.
The following is multiple choice question (with options) to answer.
What is the only planet that is known to support life? | [
"earth",
"Saturn",
"Mars",
"Venus"
] | A | Mars is a lot like Earth. Mars is rocky and has an atmosphere. Mars even has water! But Mars (and Mercury, Venus, the Moon, Jupiter, Saturn, Uranus and Neptune) does not have any evidence of life. Life is what makes Earth unique. It is also part of Earth's dynamic nature. Life is part of many Earth processes. Life is also dynamic in itself. Constantly adapting and evolving, life forms are always changing. Except those that are so well adapted to their environment, they haven't changed in hundreds of millions of years. |
SciQ | SciQ-2411 | thermodynamics
Title: How would you store heat? Um .. naive question perhaps but if somebody wanted to store heat, how would they go about it? Can heat be stored?
I'm told that decomposing kitchen waste in a closed vessel results in a rise in temperature on the body of the vessel. I'm just wondering whether it could be stored for later use. Building off of the comments to the question.
It might be instructive to think carefully about what is being stored when you store "electricity" in a capacitor or battery.
Note that it is not electrons as I can charge a capacitor either positive or negative relative to a floating ground. The "what" in that case is energy in the form of electric fields (capacitor) or chemical potential (battery).
Heat is also energy, in the form of excitation of microscopic degrees of freedom, and the way you store it is by exciting the microscopic degree of freedom in some material and then don't allow it to transmit that energy to other forms---which you do by insulating the hot stuff. Or you can convert the heat to some more tractable form (as in Dan's answer or Georg's comment) and store that.
The following is multiple choice question (with options) to answer.
Where is food stored? | [
"The gall bladder",
"the stomach",
"The esophagus",
"The liver"
] | B | |
SciQ | SciQ-2412 | human-biology, human-anatomy
Title: Difference between the spinal cord and vertebrae column What is the difference between the spinal cord and the vertebrae column, they both run through from the head to the abdomen. Does any one have any idea. The vertebral column is a bony, segmented structure that supports the torso/head and thorax. The spinal cord is a bundle of nerves that runs inside the structure of the vertebral column. So - they run together, but are completely separate.
The following is multiple choice question (with options) to answer.
The vertebrae are divided into the cervical region, the thoracic region, and which other region? | [
"lumbar region",
"pelvic region",
"cylindrical region",
"central region"
] | A | 7.3 The Vertebral Column The vertebral column forms the neck and back. The vertebral column originally develops as 33 vertebrae, but is eventually reduced to 24 vertebrae, plus the sacrum and coccyx. The vertebrae are divided into the cervical region (C1–C7 vertebrae), the thoracic region (T1–T12 vertebrae), and the lumbar region (L1–L5 vertebrae). The sacrum arises from the fusion of five sacral vertebrae and the coccyx from the fusion of four small coccygeal vertebrae. The vertebral column has four curvatures, the cervical, thoracic, lumbar, and sacrococcygeal curves. The thoracic and sacrococcygeal curves are primary curves retained from the original fetal curvature. The cervical and lumbar curves develop after birth and thus are secondary curves. The cervical curve develops as the infant begins to hold up the head, and the lumbar curve appears with standing and walking. A typical vertebra consists of an enlarged anterior portion called the body, which provides weight-bearing support. Attached posteriorly to the body is a vertebral arch, which surrounds and defines the vertebral foramen for passage of the spinal cord. The vertebral arch consists of the pedicles, which attach to the vertebral body, and the laminae, which come together to form the roof of the arch. Arising from the vertebral arch are the laterally projecting transverse processes and the posteriorly oriented spinous process. The superior articular processes project upward, where they articulate with the downward projecting inferior articular processes of the next higher vertebrae. A typical cervical vertebra has a small body, a bifid (Y-shaped) spinous process, and U-shaped transverse processes with a transverse foramen. In addition to these characteristics, the axis (C2 vertebra) also has the dens projecting upward from. |
SciQ | SciQ-2413 | astronomy, experimental-technique, distance
Title: How do astronomers measure the distance to a star or other celestial object? How do scientists measure the distance between objects in space? For example, Alpha Centauri is 4.3 light years away. There are a variety of methods used to measure distance, each one building on the one before and forming a cosmic distance ladder.
The first, which is actually only usable inside the solar system, is basic Radar and LIDAR. LIDAR is really only used to measure distance to the moon. This is done by flashing a bright laser through a big telescope (such as the 3.5 m on Apache Point in New Mexico (USA), see the Apollo Project) and then measuring the faint return pulse with that telescope from the various corner reflectors placed there by the Apollo moon missions.
This allows us to measure the distance to the Moon very accurately (down to centimeters I believe). Radar has been used at least out to Saturn by using the 305 m Arecibo
radio dish as both a transmitter and receiver to bounce radio waves off of Saturn's moons. Round trip radio time is on the order of almost 3 hours.
If you want to get distances to things beyond our solar system, the first rung on the distance ladder is, as Wedge described in his answer, triangulation, or as it is called in astronomy, parallax. To measure distance in this manner, you take two images of a star field, one on each side of the Earth's orbit so you effectively have a baseline of 300 million kilometers. The closer stars will shift relative to the more distant background stars and by measuring the size of the shift, you can determine the distance to the stars. This method only works for the closest stars for which you can measure the shift. However, given today's technology, that is actually quite a few stars. The current best parallax catalog is the Tycho-2 catalog made from data observed by the ESA Hipparcos satellite in the late 1980s and early 1990s.
Parallax is the only direct distance measurement we have on astronomical scales. (There is another method, the moving cluster method, but it has very limited applicability.) Beyond that everything else is based on data calibrated using stars for which we can determine parallax. And they all rely on some application of the distance-luminosity relationship
The following is multiple choice question (with options) to answer.
What was used to measure the distance between the earth and the moon? | [
"yardstick",
"laser beam",
"ultrasound",
"telescope"
] | B | The development of modern lasers has opened many doors to both research and applications. A laser beam was used to measure the distance from the Earth to the moon. Lasers are important components of CD players. As the image above illustrates, lasers can provide precise focusing of beams to selectively destroy cancer cells in patients. The ability of a laser to focus precisely is due to high-quality crystals that help give rise to the laser beam. A variety of techniques are used to manufacture pure crystals for use in lasers. |
SciQ | SciQ-2414 | fluid-dynamics, acoustics
Title: Whistle Physics I'm looking for a simple explanation of how a whistle operates. I know that forcing air over a sharp lip can set up a wave in a resonating cavity, but how? "Most whistles operate due to a feedback mechanism between flow instability and acoustics"--yes, but what does that feedback mechanism look like?
I was surprised to be unable to find a basic diagram online demonstrating how a whistle operates. I did find lots of images like this:
. . . but such images are unhelpful since they don't show exactly what's producing the oscillation! Let's consider the specific type whistle shown in the question.
When we blow the whistle, air is forced to rush out through the narrow opening. The flow of air at the center of the stream is significantly faster than the neighboring air close to the main stream. If the air stream is easily deflected(unstable), vortexes are generated. If the same thing happens repeatedly, many more vortexes with similar properties will be generated. These vortexes cause air pressure to vary in a periodic way, so sound wave is produced. The frequency of this sound wave is related to the rate at which the vortexes are shed. Since the process is rather chaotic, many different rates or frequencies are produced at a time.
As you can see in the picture, the stream is divided into two parts. One part coming out of the opening and the other part stays inside. Sound wave trapped inside will interfere with each others. If the frequency of sound doesn't match any of the resonant frequencies of the chamber, the waves will interfere destructively and vanish quickly. However if the frequency matches the resonant frequency of the cavity, the wave's amplitude will increase overtime. The rate of increasing will decreases as the amplitude builds up. Eventually it will reach a steady state. At this point the amplitude of sound wave is strong enough that the sound becomes very audible. The sound wave come out of the hole, get dispersed strongly, and finally reaches our ears.
Some whistles have a small ball bounces around inside the cavity. The ball changes the shape of the cavity and at the same time the resonant frequencies. Thus it allows us to hear wider range of sound frequency.
The following is multiple choice question (with options) to answer.
Upon entering the vestibular canal, the pressure waves push down on what duct? | [
"the regrowth",
"the bile",
"the cochlear",
"the implant"
] | C | |
SciQ | SciQ-2415 | water, elements
Title: Chemical composition of seawater Is it true that the sea water is composed of about $86\%$ oxygen, $11\%$ hydrogen and $3\%$ of minerals? The chemical formula of water is $\ce{H2O}$ (two hydrogen and one oxgen) that shows that the number of hydrogen is greater than that of oxygen.
If the number of hydrogen is greater, then why does the sea water consist of $11\%$ hydrogen and $86\%$ oxygen, which is lesser than the oxygen?
The book which I am reading says which is confusing me:
... Seawater is composed of about $86\%$ oxygen, $11\%$ hydrogen and $3\%$ of minerals, consisting mainly of sodium and chlorine. The book that you're reading is measuring by mass.
If you have pure water then you would expect oxygen to make up $\frac{16}{16 + 2}\times 100\% \approx 89 \% $ by mass. Likewise, hydrogen would make up $\frac{2}{16 + 2}\times 100\% \approx 11 \% $ by mass.
The following is multiple choice question (with options) to answer.
Water is formed from oxygen and what other element? | [
"helium",
"lead",
"hydrogen",
"calcium"
] | C | When hydrogen gas is reacted with oxygen gas, water is formed as the product. |
SciQ | SciQ-2416 | geophysics, earth-history, geomagnetism, paleomagnetism
Title: How did the intensity of Earth's magnetic field change through geological time? Looking at the wikipedia article on the Earth's magnetic field, I see that its strength varies through time. How did Earth's magnetic field change throughout its history, from the beginning of the Archean period (~4 billions years ago) to today?
My current attempt
All I found so far is this graph from wikipedia (which is on a too short time scale) and this kind of text (not a science paper) reporting an estimate for a given time point (3.2 billions years ago) reporting a field of about 25 microTeslas. The Earth's initial accretion was about 4.5 billion years ago, and there is good Hf-W isotopic evidence that an iron core started to form within about 10 M years, and may have been largely complete within 30 M years. However, the Earth's dynamo, which is driven by isotopic heating and core rotation/convection, didn't switch on strait away. It must have built up over hundreds of millions of years, possibly kick-started by a the magnetic field of a stronger solar wind at that time. The evidence from 3.5 Bn year old dacites suggest that the magnetic field at that time was only 30 to 50% of the current value. There is no magnetic data for 4.4 to 3.5 Bn years, (the time period you are interested in), but current models lean towards lower rather than higher values. There appears to be no mechanism for strong magnetism in the early Earth. Geomagnetic evidence from about 2.5 Bn years ago seems to indicate that the Earths magnetism was more stable then than now, with few if any peaks of high or low magnetism. Probably the Earth's early magnetic field will always be imprecisely known because nearly all the early rocks have been 'cooked' in such a way as to extinguish the early magnetic evidence.
The following is multiple choice question (with options) to answer.
What is the period from earth's origin to the beginning of the phanerozoic eon? | [
"Cenozoic",
"Paleolithic",
"anatolian",
"precambrian"
] | D | For the first 4 billion years of Earth history there is only a little evidence of life. Organisms were tiny and soft and did not fossilize well. But scientists use a variety of ways to figure out what this early life was like. Note that the period from Earth's origin to the beginning of the Phanerozoic is called the Precambrian. |
SciQ | SciQ-2417 | The slope (gradient) function would be g(x)=dy/dx ... tells you the gradient at position x.
3. Mar 27, 2014
### dilloncyh
I'm still a bit confused.
average slope = detla y / delta x seems very legit, but take y=x^2 and y=x as example.
If I want to calculate the average slope between x=0 and x=1, then by calculating the difference in height and horizontal displacement of the two end points, then both should give the same result (slope=1), but the length of the curve of y=x^2 is obviously longer than y=x (which is just sq root of 2), so by calculating the the sine of the 'triangle' if I straighten the curve section of y=x^2, I will get difference result.
4. Mar 27, 2014
### haruspex
It's a matter of how you choose to define the average. The usual would be to define it as average over horizontal distance, but as you note you could instead chose to define it as average over path distance.
5. Mar 28, 2014
### Simon Bridge
I'm with haruspex - there is no reason that two different averaging methods should produce the same value.
They are just producing a different kind of average.
The following is multiple choice question (with options) to answer.
In a displacement graph, the slope of the line is the average what? | [
"speed",
"velocity",
"direction",
"time"
] | B | Example 2.17 Determining Average Velocity from a Graph of Displacement versus Time: Jet Car Find the average velocity of the car whose position is graphed in Figure 2.47. Strategy The slope of a graph of x vs. t is average velocity, since slope equals rise over run. In this case, rise = change in displacement and run = change in time, so that. |
SciQ | SciQ-2418 | photons, everyday-life, renewable-energy, solar-cells, dissipation
Title: Why not use our own light production to produce new energy instead of wasting it? Why don't we use our own light production at night (I mean home, buildings, streets,..., lighting) to charge photovoltaic panels instead of wasting it? Solar panels work with sunlight. The energy per square meter of light from the sun , depending on the geographic area etc is of order of
8 hour summer day, 40 degree latitude 600 Watts per sq. meter
In one hour a photovoltaic cell of one square meter will provide energy of 600 watthours
Take a light bulb of 100 Watthour . To gather all that irradiance one would need to cover all the walls of the room with photovoltaics, which typically are 30% efficient. So one would gather 30 watthour of that "wasted energy" for an enormous cost in photovoltaics. ( disregarding that photovoltaics should be specially developed for low intensity conditions and as pointed out in the comments that a lot of that energy is in the infrared spectrum ).
In analogy will be the economics for other situations, Take a stadium with its large light sources, the power falls as $1/r^2$, where r is the distance between the light source and the panels.
The following is multiple choice question (with options) to answer.
What is the process by which producers use the energy in sunlight to make food? | [
"Embryogenesis",
"photosynthesis",
"Leukemogenesis",
"glycolysis"
] | B | By far the most common producers use the energy in sunlight to make food. This is called photosynthesis . Producers that photosynthesize include plants and algae. These organisms must live where there is plenty of sunlight. |
SciQ | SciQ-2419 | cell-division
Title: Why doesn't cellular, replicative senescence (or the hayflick limit) constrain the normal development of an organism? The wikipedia article on cellular senescence states:
Cellular senescence is the phenomenon by which normal diploid cells cease to divide. In culture, fibroblasts can reach a maximum of 50 cell divisions before becoming senescent. This phenomenon is known as "replicative senescence", or the Hayflick limit.
The following is multiple choice question (with options) to answer.
What is the term for something that limits the growth or development of an organism, population, or process? | [
"controlling factor",
"variable",
"stumbling block",
"limiting factor"
] | D | In the predator-prey example, one factor limits the growth of the other factor. As the prey population deceases, the predator population is begins to decrease as well. The prey population is a limiting factor. A limiting factor limits the growth or development of an organism, population, or process. |
SciQ | SciQ-2420 | human-biology, biochemistry, metabolism, food
Absorption in the gut is different for glucose and fructose, as is transport into cells.
Both glucose and fructose are (or can be) metabolised to pyruvate. However fructose is first metabolised to fructose 1-phosphate, and only enters glycolysis at the triose phosphate stage. A consequence of this is that it by-passes any regulation that occurs for the metabolism of glucose after conversion to glucose 6-phosphate. (In addition, glucose 6-phosphate has alternative metabolic possibilities not shown).
Postscript
This provides the framework for considerations of the consequences of dietary intake of sucrose, which are not part of the question and off-topic here, as already mentioned. Despite that, this topic has been addressed in questions in SE Biology, as well as elsewhere on the internet. I try not to offer advice to others (nor to take it from strangers). However my wife, whose advice I am sometimes obliged to take, professes the following:
“All things in moderation, and moderation in all things.”
The following is multiple choice question (with options) to answer.
Where is glucose carried in the human body? | [
"the heart",
"the blood",
"the brain",
"the liver"
] | B | Chemical energy that organisms need comes from food. The nearly universal food for life is the sugar glucose. Glucose is a simple carbohydrate with the chemical formula C 6 H 12 O 6 . The glucose molecule stores chemical energy in a concentrated, stable form. In your body, glucose is the form of energy that is carried in your blood and taken up by each of your trillions of cells. |
SciQ | SciQ-2421 | glaciology, glacier, ice
What would be a good average to take? This is a non-trivial issue. When you look at volume change of a glacier, you typically subtract two digital elevation models to obtain the difference between the two. First, you must differentiate between ice sheets where ice berg calving reduces volume and more ordinary glaciers with melt processes. There are of course calving glaciers as well so it is possible to get into great detail for any one specific glacier, so here I will just discuss the most common case which is a smaller glacier with melt-freeze conditions.
The change in elevation differs in magnitude across the glacier surface due to the movement of the glacier and accumulation-melt processes. The surface material can be (1) glacier ice, (2) snow, (3) firn snow that has survived a melt season) or (4) super imposed ice all with more or less differing densities, you need to assess what sort of material has been removed.
Ice can be approximated by a density of 900 kg/m3, firn has a density of about 600 kg/m3 but it must be remembered that the firn is converted to glacier ice by metamorphic processes so that the density changes with depth from 600 to 900 kg/m3. the transition to ice occurs at depths of about 30 m in temperate glaciers although few studies exist on the actual processes that occur. Snow have very differing densities but considering averages, I would say that it would vary between 350 to maybe 500 kg/m3 for winter (cold) conditions and around 550 kg/m3 for a melting snow pack. Super-imposed ice is closer to ice and probably varies in the upper range of 800--900 kg/m3.
To make matters worse, snow superimposes firn which in turn superimposes ice. This means that in the accumulation area, volume change can result from both a reduction in a snow cover and the firn layer. In the zone near the equilibrium line there can be a loss of both firn and ice. this is also where the superimposed ice will play a role.
So there is no simple density to use since the loss you try to estimate will involve varying types of densities spatially as well as vertically. For annual changes, you can largely ignore the vertical distribution, but with volume changes covering larger periods where climate change influences the longer term location of the equilibrium line and the size of the accumulation area, vertical layering also has to be included.
The following is multiple choice question (with options) to answer.
What are large glaciers that cover a larger area than just a valley? | [
"icebergs",
"ice floes",
"ice caps",
"glacial continents"
] | C | Ice caps are large glaciers that cover a larger area than just a valley. An ice cap can bury an entire mountain range or region ( Figure below ). Glaciers come off of ice caps into valleys. |
SciQ | SciQ-2422 | mycology
Title: How do fairy rings propagate? It was somewhat new to me that mushrooms usually aren't individual organisms, but are merely the visible bodies of a bunch of fungi living in the soil. I know that mushrooms emit spores to reproduce, but what has been bizarre to me is how fairy rings form. Why do the fruiting bodies arrange themselves in a more or less circular shape, as opposed to the random scattering one would expect from wind-borne spores? When a fungal spore germinates in a suitable location, the growing mycelium will spread underground in all directions. In the ideal situation, the result is that the mycelium will become circular. Over time, the center of the mycelium will die out whereas the newly formed mycelium (underground) will develop the familiar mushrooms above ground and this will result in a fairy ring.
The following is multiple choice question (with options) to answer.
What type of reproduction do fungi engage in? | [
"microscopic",
"sexual",
"asexual",
"ephemeral"
] | C | Through asexual reproduction , new organisms are produced that are genetically identical to the parent. That is, they have exactly the same DNA. Fungi reproduce asexually through three methods:. |
SciQ | SciQ-2423 | plant-physiology
Title: Would a plant survive if it was watered using hard-water? Hard water is water with high mineral/salt content. I'm told that a potted plant watered with a salt solution dries out sooner or later. Is this true?
If so, would a plant survive if watered using hard-water? It would depend on the content of the hard-water. If the water contained heavier metals like lead or radioactive elements like tritium (Hydrogen-3), the plant would most likely die. Most land plants cannot survive when watered with massive amounts of salt water as the salt would absorb the water from the leaves.
The following is multiple choice question (with options) to answer.
What system transports minerals and water in a plant? | [
"flowers",
"leaves",
"stamen",
"roots"
] | D | Roots absorb water and minerals and transport them to stems. They also anchor and support a plant, and store food. A root system consists of primary and secondary roots. Each root is made of dermal, ground, and vascular tissues. Roots grow in length and width from primary and secondary meristem. |
SciQ | SciQ-2424 | special-relativity, energy, mass, mass-energy, matter
As for cosmology, it's just like in the sun. Different forms of energy can move differently. And that's the only things that makes the situation change when mass is created or destroyed. The energy can move around differently when it converts to different forms.
The following is multiple choice question (with options) to answer.
What is the exchange of energy from one part of the universe to another called? | [
"temperature",
"cold",
"heat",
"humidity"
] | C | Heat is the exchange of energy from one part of the universe to another. Heat and energy have the same units. |
SciQ | SciQ-2425 | genetics, immunology, ecology, biodiversity, fitness
Title: What does genetic diversity in one species have to do with survival rate when an epidemic spreads? I was studying about genes, and soon remembered that the more diverse the genetics of one species, the less the chance of the species to go extinct from natural disaster.
One instance was an epidemic spreads.I don't fully understand why that happens, so I searched for it in Google and books, but all of them only told me that it is true, not why or how.
So my question is : why and how genetic diversity in one species affects the chance of the species's extinction?
I mean, for example, does it relate to antibodies or something else? Genetic diversity could be understood as a variation in alleles (gene variants) and their frequencies in a population. Due to these allelic variations, we would expect an inherent variability in individual genotypes (or genetic codes). Phenotypes (or traits) can and do vary with changes in underlying genotype. (In simple terms: if you change the underlying genetic code, it could result in changes to an individual's traits).
Changes in traits (e.g., color, size, speed, temperature regulation, mobility, etc.) could lead to a variation in energy conservation, survival, reproductive success, and ultimately fitness.
If any member of a population is more fit given a set of environmental circumstances, it is morel likely that they will survive and pass on their genes to subsequent generations.
You would benefit from reviewing evolution and natural selection. (Sexual selection and genetic drift are relevant, too, of course).
However, the environment and resulting ecologies are always changing, and so there is never an "endpoint" of this process. I.e., there's never a perfectly fit individual that will survive all future environmental changes better than all other variants. In fact, all organisms can only tolerate stressful environmental conditions to a point. (See, e.g., principle of allocation).
As a result, any given individual is limited in its ability to survive various environmental conditions, and no individual organism can survive all possible environmental conditions.
The following is multiple choice question (with options) to answer.
If environmental conditions deteriorate, many species can form protective what? | [
"cysts",
"proteins",
"fibers",
"shells"
] | A | |
SciQ | SciQ-2426 | zoology, species-identification, entomology
Title: Identification of a segmented black insect in France
Found in the Lot department of southern France. I think this is some sort of soldier fly larva (family Stratiomyidae). That would explain lack of legs. There are thousands of species world wide, with both aquatic and terrestrial larvae, so it might be possible to narrow it down a bit more.
Image from bugguide.net for comparison:
Thanks to @bli for reminding me of dipteran larvae!
The following is multiple choice question (with options) to answer.
In what subgroup are oligochaetes classified? | [
"polychaetes",
"mammals",
"reptiles",
"insects"
] | A | |
SciQ | SciQ-2427 | taxonomy, phylogenetics
Title: Usage of the taxonomic classification "Pinnipedia" According to ITIS the classification Pinnipedia is invalid, and it is proposed to rather use Caniformia. The later group however includes a range of terrestrial animals as opposed to the pinnipeds (the seals), which only include marine mammals.
Is the term Pinnipedia nevertheless still accepted and used in scientific media? Is there any debate whether to use one and not the other? The Comments section of that page has the explanation:
Wilson & Reeder (eds., 1993) note that "the pinnipeds (otariids,
odobenids, and phocids) are included within the suborder Caniformia;
placing them in a separate Order would make the Carnivora
paraphyletic." This arrangement continues to be followed in Wilson &
Reeder (eds., 2005)
If both Carnivora (Bowdich, 1821) and Pinnipedia (Illiger, 1811) are orders in the traditional Linnean taxonomic sense, then one cannot be nested within the other. If this were to happen, then Carnivora would be paraphyletic because it would exclude some of its members. The same argument is made when discussion birds as dinosaurs (you can't talk about Dinosauria that doesn't include Aves).
The problem arises when phylogenetic systematics (clade names) meets traditional Linnean systematics (orders, suborders, etc.). Phylogenetic systematics does not distinguish these higher taxonomic groups. Clades are just nested groups of monophyletic taxa.
So then to answer your last question, Pinnipedia does appear to be in common usage (Google Scholar reports several hundred citations in the past few years). The key is to distinguish Pinnipedia as a traditional Linnean order (not valid) and Pinnipedia as a monophyletic clade that includes seals, walrus, and sea lions (perfectly fine). Seals, walrus, and sea lions are all more closely related to each other than to other Carnivora, so they are monophyletic, and the name for that grouping is Pinnipedia.
Here's the Tree of Life page that has all the clade names.
The following is multiple choice question (with options) to answer.
The crocodilia order, which includes crocodiles, alligators, caimans, and gharils, is part of what class of animals? | [
"aquatic",
"parasites",
"mammals",
"reptiles"
] | D | Crocodilia Reptiles in the Crocodilia Order are called crocodilians. They include crocodiles, alligators, caimans, and gharils. They have four sprawling legs that allow them to run surprisingly fast. They have strong jaws and replace their teeth throughout life. Crocodilians have relatively complex brains and greater intelligence than other reptiles. crocodile. |
SciQ | SciQ-2428 | pathology
Title: Why are some bodily fluids more of an infection risk than others? Whilst on a recent refresher course it was highlighted that when considering risk of exposure to infection from bodily fluids we should be aware of two distinct risk levels:
High Risk:
Blood
Semen
Vaginal Secretions
Diarrhea
Low Risk:
Saliva
Vomit
Urine
CSF (Cerebrospinal fluid)
Why is it that some bodily fluids are a greater infection risk than others? Is it related to the fluids themselves or the species of pathogen that are located within them? This is just about where the pathogens can be found that are dangerous to people.
Vomit is highly acidic and less accommodating to microbe growth. Similarly saliva has many immune components in it as well as digestive enzymes that keep most microorganisms down.
Urine and CSF are actually quite sterile as they come from environments that are highly filtered - the kidney is an osmotic processor that essentially is a molecular filter and does not allow cells to pass, the spine is highly insulated from the blood and other direct exposure to microorganisms.
Compare that with the 'dangerous' list and you have organs that are open to human pathogens. Venerial disease like HPV is so common that what - about 1 in 5 people under a certain age carry it. That is a pretty high expectation of a biohazard. most infections and viruses are blood bourne - influenza, cold, as well as any bacterial infections.
Feces is always a dangerous thing to handle as the digestive tract is rich in nutrients and essentially directly open to external bacteria and fungi. (and its not acidified like the stomach). Also parasites like tape worms and other multicelled animals! yum!
Diarrhea is often caused by an infection of some sort, so its just more likely a hazard, but feces is always a place where you might find a pathogen.
This is not to say that the 'safe' list is totally safe. Its just less likely to bear disease causing agents.
The following is multiple choice question (with options) to answer.
What fluid is most prevalent in your body? | [
"cold",
"water",
"Coolant",
"liquid"
] | B | Reporting Scientific Work Whether scientific research is basic science or applied science, scientists must share their findings for other researchers to expand and build upon their discoveries. Communication and collaboration within and between sub disciplines of science are key to the advancement of knowledge in science. For this reason, an important aspect of a scientist’s work is disseminating results and communicating with peers. Scientists can share results by presenting them at a scientific meeting or conference, but this approach can reach only the limited few who are present. Instead, most scientists present their results in peer-reviewed articles that are published in scientific journals. Peer-reviewed articles are scientific papers that are reviewed, usually anonymously by a scientist’s colleagues, or peers. These colleagues are qualified individuals, often experts in the same research area, who judge whether or not the scientist’s work is suitable for publication. The process of peer review helps to ensure that the research described in a scientific paper or grant proposal is original, significant, logical, and thorough. Grant proposals, which are requests for research funding, are also subject to peer review. Scientists publish their work so other scientists can reproduce their experiments under similar or different conditions to expand on the findings. The experimental results must be consistent with the findings of other scientists. There are many journals and the popular press that do not use a peer-review system. A large number of online openaccess journals, journals with articles available without cost, are now available many of which use rigorous peer-review systems, but some of which do not. Results of any studies published in these forums without peer review are not reliable and should not form the basis for other scientific work. In one exception, journals may allow a researcher to cite a personal communication from another researcher about unpublished results with the cited author’s permission. |
SciQ | SciQ-2429 | periodic-trends
electron-electron repulsion (negative charges repulse each other)
electron-nucleus attraction (negative charges are attracted towards positive ones)
electron shielding (electrons in shells closer to nucleus 'shield' outer electrons from some charge of the nucleus.
While electrons repulse each other, increasing nuclear charge more then compensates it; so if not for shell organisation of electrons, atoms would monotonically decrease in size toward the end of the periodic table, as it is observable in each period 1—3.
However, inner electronic shells effectively shield the outer electrons from the nucleus, so they 'see' a nucleus that is a) larger in size and b) has charge equal to nuclear charge minus number of electrons in inner shells. Given that, outer electrons 'see' a nucleus with low charge density, so outer shells progressively increase in size within the same column.
In addition to that, electrons still repulse each other, so positive ions are smaller than neutral atoms, and neutral atoms are smaller than negative ions.
Now, consider $\ce{Li+}$ and $\ce{Al^{3+}}$. For the former, 2 outer electrons feel the charge of three protons. For the latter, 8 outer electrons feel the charge of 11 protons in the nucleus. Such great charge easily beats all other factors, so the latter cation is much smaller than the former.
The following is multiple choice question (with options) to answer.
What are negative electrons attracted to? | [
"hormones",
"ions",
"neutral electrons",
"positive protons"
] | D | Negative electrons are attracted to positive protons, and this electric force keeps electrons moving about the nucleus. The force of attraction between protons and neutrons, called the strong force, holds the nucleus together. |
SciQ | SciQ-2430 | sequence-alignment, phylogenetics, genome, phylogeny
Title: What is the most appropriate way to find the most recent common ancestor between two distantly related species I want to specifically find the common ancestor between a lobster and a humans. I suspect it was an aquatic worm of some description. But I want to know about the nervous system of this common ancestor. Because I've now posted several comments, I'll just roll them all up.
For background on the approaches used to identify most recent common ancestors and a high-level look at how animal taxonomy has been inferred, I suggest Lynch 1999.
I think that there are 2 interpretations of this question. If you are interested in just looking up a single MRCA of well-defined clades, such as lobster and human, here are some approaches:
Easy way:
Look at a tree diagram, e.g. this:
Find the tips that correspond to your species of interest (arthropods for lobster, chordata for humans).
Find where they join together in the diagram (the branch labeled "true coelom").
You have your answer, the MRCA is the group of organisms with a true coelom, coelomates.
A more involved way using a database
Go to this website.
Find the group of species 1 (arthropods, protostomes, etc. for lobster, chordata, deuterostomes etc. for human)
navigate around until you see the group containing the two groups (in this case listed as "bilateria"). In this case you are looking for the bilaterian common ancestor.
another database
Go to this website.
Point and click your way to a view where you see your 2 clades of interest (arthropods, chordates in this case). See figure.
Find where they join (in this case, it is less certain about the existence of a coelomate common ancestor, so it just says "bilaterians").
The following is multiple choice question (with options) to answer.
The largest phylum in the animal kingdom, arthropod, is primarily comprised of what? | [
"mammals",
"amphibians",
"reptiles",
"insects"
] | D | Arthropods are the largest phylum in the animal kingdom. Most arthropods are insects. The phylum also includes spiders, centipedes, and crustaceans. The arthropod body consists of three segments with a hard exoskeleton and jointed appendages. Terrestrial arthropods have adaptations for life on land, such as trachea or book lungs for breathing air. The earliest arthropods were trilobites. The earliest land arthropods were millipedes. |
SciQ | SciQ-2431 | geophysics, oceanography, topography
Title: What are the striations or ridges in the eastern Pacific Ocean? Messing around on Google Earth recently I noticed a number of striations in the Eastern Pacific. These appear in an East-West orientation and seem to start on the North and South American continental shelves, and extend for roughly half the Pacific Ocean. For example one of these striations start in Santa Rosa Island off California and ends at Hawaii. These striations also appear to be roughly equally spaced at 8 degree intervals. The North and South American striations are angled with respect to each other and seem to converge at roughly Tahiti.
What causes these? I'm a fascinated novice.
EDIT
Some images to make things clearer (North Pole is top left):
Note the regularly spaced East-West parallel striations starting from the Equator and stepping north. In fact the striation on the Equator covers the entire Pacific.
Here a closer shot also shows fainter striations fanning out from Los Angeles: They are fracture zones.
I've annotated your image with the names of these very long, tectonically important features. They even have names, such as the Mendocino Fracture Zone:
I also labelled some survey tracks (rather subtle, very straight, very regular in width), which are data artifacts — these are the things you noticed radiating from the vicinity of Los Angeles.
There are yet other types of linear feature on the sea floor:
Transform faults are strike-slip faults connecting segments of spreading centres in the oceanic crust.
The spreading centres themselves.
Roughly linear archipelagos like Hawaii.
The long, curved trenches at convergent plate margins.
Images from Google Maps. Note: I edited this answer substantially after the OP clarified the question... and I learned about the difference between transform faults and fracture zones.
The following is multiple choice question (with options) to answer.
Which country is formed by a hotspot along the mid-atlantic ridge? | [
"iceland",
"Switzerland",
"finland",
"norway"
] | A | Hotspots may also be active at plate boundaries. This is especially common at mid-ocean ridges. Iceland is formed by a hotspot along the Mid-Atlantic Ridge. |
SciQ | SciQ-2432 | ions, lewis-structure, formal-charge
There is nothing inherently wrong with a formal charge on the central atom, though. Take for example tetrahydridoborate $\ce{BH4-}$, the addition product of borane and hydride. Here, boron should only have three valence electrons but if bonded to four hydrogens it must have four. Thus, it carries a formal negative charge. (In reality, the hydrogens carry the negative charge, though, since they are again more electronegative than boron.)
The following is multiple choice question (with options) to answer.
What is an atom or group of bonded atoms that has a positive or negative charge? | [
"a neutron",
"an electron",
"an photon",
"an ion"
] | D | An ion is an atom or group of bonded atoms that has a positive or negative charge. Ions are formed when an atom gains or loses electrons from its valence shell ( Figure below ). This process causes an imbalance between the number of positively charged protons and negatively charged electrons, so the overall ion will carry a net positive or negative charge. |
SciQ | SciQ-2433 | genetics, botany, seeds
Title: What DNA does a self-fertile plant's seedling have? Some plants are said to be self-fertile. An example is Prunus tomentosa.
Assuming that no cross-pollination happened with other plants, if a self-fertile plant such as prunus tomentosa produces a seedling, what DNA will the seedling have? Is the seedling's DNA an exact copy of the parent plant's DNA, or do the genes get rearranged? Selfing (aka self-fertilizing) differs from cloning. When selfing occurs, the offspring is not an exact copy of the parent. When cloning occurs, the offspring is an exact copy (except for a few mutations) of the parent.
Selfing implies that an individual will produce two gametes (typically a spermatozoid and an ovule but that might be a bit more complicated) and these two gametes are fusing to give the zygote (egg or offspring if you prefer).
As a consequence, when selfing, meiosis is occurring (and therefore segregation and recombination) so that the offspring is not an exact clone of the parent but rather some kind of a rearrangement of the parent genome (with a few mutations of course).
The following is multiple choice question (with options) to answer.
What type of reproduction produces offspring from a single parent that share the exact same genetic material as the parent? | [
"microscopic reproduction",
"sexual reproduction",
"mutation",
"asexual reproduction"
] | D | When humans reproduce, there are two parents involved. DNA must be passed from both the mother and father to the child. Humans cannot reproduce with just one parent; humans can only reproduce sexually. But having just one parent is possible in other eukaryotic organisms, including some insects, fish, and reptiles. These organisms can reproduce asexually, meaning the offspring ("children") have a single parent and share the exact same genetic material as the parent. This is very different from reproduction in humans. Bacteria, being a prokaryotic, single-celled organism, must reproduce asexually. |
SciQ | SciQ-2434 | ecology, terminology, statistics, diet, community-ecology
Title: Is "aggregate percentage" still a valid term in ecology? Martin et al. 1946 define "aggregate percentage" as a metric that describes the mean percentage contribution of a group to the total mass/abundance of all samples. The metric is useful in datasets that are plagued by outliers and non-normality, something that is a commonplace with most ecological community and diet studies in my experience. Aggregate percentage is calculated as follows:
$AP_i = \frac{100\%}{N_y} \times \sum\limits_{j = 1}^{N}(\frac{a_{ij}}{\sum a_j})$
Where i is the i$^{th}$ taxon, j the j$^{th}$ sample, N total number of samples, a$_{ij}$ the abundance or mass of i$^{th}$ taxon in j$^{th}$ sample, and $\sum a_j$ the summed abundance or mass of all taxa in j$^{th}$ sample.
Martin et al. 1946 illustrate this as follows:
I am sure that "aggregate percentage" is a standard method in ecology, but I cannot find many studies using this term by googling. Probably the method has synonyms and there might be a more accepted term for the method nowadays. My question is what is the valid term to use for the method? The formula of "aggregate percentage" that you show is just the arithmetic mean of percentages, and I suspect that no special term is used in most studies that use mean percentages as a measure of e.g. prey composition in a certain predator (as seems to be the case in your example).
When searching for studies I think you will have more luck with using "mean prey percentages", "prey percentages" or "mean percentage composition". For instance, see Shoup & Lane (2015) which includes the text (with my emphasis):
Results of regressions correlating Secchi depth (mm) with prey percentages by weight in the stomach contents of Largemouth Bass sampled from Boomer.
Also (Ahlbeck et al, 2012):
The following is multiple choice question (with options) to answer.
Invertebrates make up what percentage of all animal species? | [
"30 percent",
"90 percent",
"50 percent",
"95 percent"
] | D | Invertebrates are animals that lack a vertebral column, or backbone. All the phyla in Table above , except the Phylum Chordata, consist only of invertebrates. Even the Phylum Chordata includes some invertebrate taxa. Invertebrates make up about 95 percent of all animal species. |
SciQ | SciQ-2435 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
What do monotremes lack though they have hair and produce milk? | [
"tail",
"skin",
"nipples",
"nerves"
] | C | |
SciQ | SciQ-2436 | ichthyology, vertebrates
Title: If an organism is supported only by cartilage, does it have an endoskeleton? Lamprey and sharks lack bones, but does this mean they are not classified as having an endoskelton? Does an organism need bone to be considered as having an endoskeleton? From wikipedia
An endoskeleton (From Greek ἔνδον, éndon = "within", "inner" + σκελετός, skeletos = "skeleton") is an internal support structure of an animal, composed of mineralized tissue.
Cartilage is a mineralized tissue so it counts as a skeleton from this definition. A bit further in the wikipedia article it says
The vertebrate endoskeleton is basically made up of two types of tissues (bone and cartilage)
The following is multiple choice question (with options) to answer.
What is muscle tissue that is attached to the bone called? | [
"skeletal tisse",
"cartilage",
"epithelial tissue",
"ligament"
] | A | Muscle tissue that is attached to bone is skeletal muscle . Whether you are blinking your eyes or running a marathon, you are using skeletal muscle. Contractions of skeletal muscle are voluntary, or under conscious control. Skeletal muscle is the most common type of muscle in the human body, so it is described in more detail below. |
SciQ | SciQ-2437 | thermodynamics, water, physical-chemistry
Title: How much entropy is produced in evaporating water due to irreversible evaporation towards equilibrium (humidity=100%)? $dS=dH/T_{boil}$ for the increase in entropy by changing a phase at saturation ($T=373\text K$ for $p=1\text {atm}$ for water). However, water also obviously evaporates below boiling point when equilibrium is not reached (below 100% relative humidity).
dS can also be interpreted using chemical potentials ($u$). The difference in the chemical of $u(p,T,N)$ between the 2 phases not at equilibrium is what drives the phase change. However, the increase in entropy when computed comes to
$$ds=(u_{liquid}-u_{gas})\times N/T$$
where $N$ is the number of moles converted. But should the temperature $T$ be the "average" temperature of the system (i.e. the ground level atmospheric conditions for say a lake that evaporates water), or should $T$ be the temperature at which the water boils?
I ask in multiple interests, but motivated to ask due to the temperature discrepancy. Other ideas that can quantify entropy produced by non-equilibrium thermodynamic state is also appreciated.
Thanks $T$ should be the actual temperature at which the water evaporates. That is, the temperature at the interface between the air and the water, not the boiling point.
This is simply because $dU = TdS + pdV - \sum_i \mu_i dN$ (where $T$ is most definitely the temperature of the system), or by rearranging,
$$
dS = \frac{1}{T}dU -\frac{p}{T}dV + \sum_i\frac{\mu_i}{T}dN_i,
$$
which means that
$$
\frac{\mu_i}{T} = \frac{\partial S}{\partial N_i},
$$
where $T$ is still the temperature of the system; the boiling point doesn't come into it.
The following is multiple choice question (with options) to answer.
What results from the evaporation of sea water? | [
"reef",
"oxygen",
"carbon-di-oxide",
"salt"
] | D | In many parts of the world, table salt is obtained from the evaporation of sea water. The heat for the process comes from the sun. |
SciQ | SciQ-2438 | human-biology, biochemistry, metabolism, food
Which seem to go in different, rather contradictory directions.
Also, Studies partially supporting either viewpoint can be found:
Study considering hemoglobin A1c levels
Study considering peak glucose levels
Study considering snacking
Which leaves the non-biologist asking themselves which is the "major effect" (certainly, there will be some truth to each position, but the question is which one(s) got the "main point"), and if there are any other important effects to be considered, hence this broad question here, so I understand, from a biological standpoint, what happens to the carbohydrates when I eat them, so I can conclude for myself how to adapt my diet for "optimal" health. Scope of Answer
The original poster provided ample context for his question, which related to health considerations. It was perhaps for this reason, among others, that the question had not received an answer at the time of writing: questions relating to medical or health advice are off-topic here. However, his actual question is primarily biochemical:
What are the biological differences between the digestion of sugar and
different types of carbs as constituents of different types of food in
humans?
Although this might be answered with a little internet search, I felt it would be hospitable if someone offered him an answer to this — and this only.
Definitions
The basic sugar unit is a mono-saccharide, those of relevance to this question being hexoses or pentoses, having six or five carbon atoms, respectively.
What in non-technical language is called sugar, refers to a specific molecule, sucrose, which is a disaccharide of covalently-bonded glucose and fructose.
What in non-technical language are referred to as dietary carbohydrates generally refers to the storage polysaccharide of plants such as potato and other root vegetables, rice, and other cereal crops used to make bread. This is a homo-polymer composed solely of glucose units.
Summary of the differences in metabolism
Arising from these definitions, the following differences in metabolism emerge:
Different enzymes (amylase for these polysaccharides, sucrase for saccharose) are used to catalyse the hydrolysis of the linkages between the monomeric units.
Absorption in the gut is different for glucose and fructose, as is transport into cells.
The following is multiple choice question (with options) to answer.
The human body regulates the use and storage of what simple sugar, a major cellular fuel? | [
"glucose",
"insulin",
"carbohydrate",
"secretion"
] | A | |
SciQ | SciQ-2439 | distances, photography
Title: In this image taken by Voyager 1, which is closer: the earth or the moon? NASA reports this photo was taken 19 Sep 1977 by Voyager 1:
It doesn't strike me as obvious how to determine which celestial body is closer to Voyager 1 as the photo was taken. My (not very scientific) guess is that the Earth is closer, since the moon seems more out of focus. It also seems more probable, since it was launched from earth.
Question: In this image taken by Voyager 1, which is closer: the earth or the moon? I used JPL Horizons to get the position vectors of each relative to the SSB on Sep 19, 1977.
Voyager X = 1.547492527774134E+08 Y = 2.045859856469853E+06 Z = 8.442122223290936E+05
Earth X = 1.503771470116906E+08 Y =-9.323322057091754E+06 Z =-1.007092461168021E+04
Moon X = 1.502869015003825E+08 Y =-9.680376320152178E+06 Z = 1.932598843803350E+04
Subtracting Voyager's position from each, and computing $ \sqrt{x^2+y^2+z^2} $ yields:
Earth 1.22E+07km
Moon 1.26E+07km
So, the Earth is closer.
The following is multiple choice question (with options) to answer.
What planet did the voyager 1 spacecraft visit in 1980? | [
"jupiter",
"saturn",
"mars",
"venus"
] | B | The Voyager 1 spacecraft visited Saturn in 1980. Voyager 2 followed in 1981. These probes sent back detailed pictures of Saturn, its rings, and some of its moons ( Figure below ). From the Voyager data, we learned what Saturn’s rings are made of. They are particles of water and ice with a little bit of dust. There are several gaps in the rings. These gaps were cleared out by moons within the rings. Gravity attracts dust and gas to the moon from the ring. This leaves a gap in the rings. Other gaps in the rings are caused by the competing forces of Saturn and its moons outside the rings. |
SciQ | SciQ-2440 | endocrinology
Excitement or stress response, including fast heart rate and breathing and anxiety: short term response: adrenaline; long-term response: cortisol
Appetite: ghrelin, leptin, adiponectin, cholecystokinin, insulin, glucagon-like peptide, gastrointestinal peptide...
Sexual drive: sex hormones, mainly testosterone and estradiol
Sleepiness: melatonin, cortisol
Depression: cortisol, sex hormones (mainly in women)
The point of this answer is to show that some of your feelings can be simply affected by hormones, which are note some ultimate forces, and that being aware of that can help you to control them to some extent.
The following is multiple choice question (with options) to answer.
What is the shortest phase of the sexual response cycle? | [
"the orgasm",
"resolution phase",
"plateau phase",
"sexual stimulation"
] | A | |
SciQ | SciQ-2441 | photosynthesis, cellular-respiration, energy, sugar
Basically, points 4-7 convey that Calvin-Benson cycle not only produces sugar but what it actually does is fix inorganic carbon (as CO2) to organic form (in the form of sugar). So, most (practically all) of the carbon that a photosynthetic plant has, comes from this carbon fixation process and that's how plants are photoautotrophic.
The following is multiple choice question (with options) to answer.
What is the name of the process by which plants use energy from sunlight to synthesize carbohydrates? | [
"photosynthesis",
"osmosis",
"pollination",
"cellular respiration"
] | A | Photosynthesis is the process by which plants use energy from sunlight to synthesize carbohydrates. |
SciQ | SciQ-2442 | metabolism, ecology, photosynthesis
Title: Why isn't phosphorus or nitrogen a limiting nutrient for animals? Nitrogen and Phosphorus are usually the limiting nutrient for plants, especially for algae. Phosphorus is used for DNA, ATP and phospholipids, and Nitrogen is used for pretty much every protein a cell might want to produce. That is, their need for biological processes is not tied specifically to photosynthesis: anything that lives is going to need them, pretty much for anything it might want to do. It would make sense for them to be a limiting nutrient for almost anything that's trying to grow, plant or animal.
Yet for animals the limiting "nutrient" seems to always be energy, ie: food. Why aren't animals limited by lack of nutrients in the same way that plants are? Obviously animals need these nutrients, too. Or to reverse the question, why do plants need so much more phosphorus/nitrogen than animals do?
My best guess is that an animal's digestion of plant material is relatively inefficient energy-wise but relatively efficient nutrient-wise. So for an animal to eat enough food to have sufficient energy to survive, it's probably eaten more than enough Nitrogen and Phosphorus for its needs. But I'm just guessing and I can't find any data that would back up that guess. Phosphorus
Your suggestion that if we are meeting our calorific requirement we will be getting enough is true for phosphorus.
Most foods contain lots of phosphorus. The maximum dietary requirement occurs during adolescent growth, estimated at 1250 mg per day. Assuming a calorie intake of 2500 kcal we can calculate a 2500 kcal equivalent phosphorus content for various foods:
skimmed milk contains 7,400 mg phosphorus per 2500 kcal
roasted chicken breast contains 7,500 mg phosphorus per 2500 kcal
cooked white rice contains 3840 mg per 2500 kcal
(Calculations are based upon values obtained via this site.)
Nitrogen
Our requirement for nitrogen is met by our protein intake: inadequate protein intake manifests as kwashiorkor which is essentially due to a dietary deficiency of essential amino acids. In other words, the only way to achieve a nitrogen-deficient diet is to not eat protein, and this would not be alleviated by any inorganic source of nitrogen, even if we could consume enough of such a N source.
The following is multiple choice question (with options) to answer.
Animals need plants for food and? | [
"energy",
"fuel",
"shelter",
"reproduction"
] | A | |
SciQ | SciQ-2443 | waves, frequency
Title: To calculate the frequency of some wave source, does the wave source have to emit waves continuously? I understand that the frequency is the number of waves that pass a place in a given amount of time. And it is shown like this:
But, the frequency of waves are always shown above as if the source of wave (let’s say it is light) is continuously emitting waves. What i mean is, isn’t there a time elapse between the individual pulses of waves.
For example light emitted from an hydrogen atom, the frequency of that light would be shown as above. But when each time the electron of hydrogen atom goes to an higher state and a lower state, i think there must be a time elapse. And if you were not to take that into account, wouldn't you get the wavelength of that wave source longer.
Note: My English language is not very good, so if i made mistakes that made the question harder to understand, I apologise. Your understanding of what constitutes a 'pulse' is flawed. If you excite an atom, then the emitted radiation will indeed be confined in time, forming a pulse, but this will take the form of a larger envelope that encases the individual oscillations at the resonance frequency.
A typical example looks like this:
The following is multiple choice question (with options) to answer.
The product of a wave's wavelength and its frequency is what? | [
"amplitude",
"speed",
"trough",
"velocity"
] | B | The product of a wave's wavelength (λ) and its frequency (ν), λν, is the speed of the wave. Thus, for electromagnetic radiation in a vacuum: c = 2.998 × 10 8 ms −1 = λν Wavelength and frequency are inversely proportional: As the wavelength increases, the frequency decreases. The inverse proportionality is illustrated in Figure 6.3. This figure also shows the electromagnetic spectrum, the range of all types of electromagnetic radiation. Each of the various colors of visible light has specific frequencies and wavelengths associated with them, and you can see that visible light makes up only a small portion of the electromagnetic spectrum. Because the technologies developed to work in various parts of the electromagnetic spectrum are different, for reasons of convenience and historical legacies, different units are typically used for different parts of the spectrum. For example, radio waves are usually specified as frequencies (typically in units of MHz), while the visible region is usually specified in wavelengths (typically in units of nm or angstroms). |
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