source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-1144 | rocks, remote-sensing, archaeology, ground-truth
Together, #1, #2, and #3 tell us that it's probably early summer just after the river ice has broken up.
The tooth-like features in the left image are simply erosional remnants sticking out of the riverbank. They could be bedrock (not likely), ice wedges, unmelted permafrost, or simply dirt. They are on the outside of a meander, so the river is actively cutting into them, and so the river-facing faces are quite sheer and high compared to the slopes in between. The right side might be white because the conditions there had left the snow unmelted when the image was taken. And of course their shadows are longer because the river channel is at the bottom of the bluff.
If you use Google Maps or Earth to go downriver a bit (up and to the left), you will see similar features sticking out of the riverbank, but because they're at a different angle from the features in your image, the fact that they're natural is more readily apparent.
Although the terrain is much less regular on the right side of the image, again the long shadows tell the tale. There are some round lumps that may be pingoes. The shadow that looks like a man is just a coincidental jumble of shadows from the broken terrain. If you look closely at the lump that is supposed to be the "man" (which would technically be an inunnguaq) does not have any protrusions that correspond to the "arms". The "arms" are the shadow of a little cliff or shelf past the lump, which is overlapped by the lump's larger shadow.
It's similar in effect to the infamous misinterpretation of a Viking orbiter image of a natural feature on Mars as a "Face on Mars".
This is a good example of the complications of image interpretation, specifically, understanding the conditions under which the image was taken. It's also a good time to emphasize the importance of doing ground truth when interpreting images. So when you go there, let us know what you find.
The following is multiple choice question (with options) to answer.
Physical features on the earth's surface are known as ______ | [
"biospheres",
"atmospheres",
"landforms",
"diversity"
] | C | As we view the land around us we see landforms. Landforms are physical features on Earth’s surface. Landforms are introduced in this section but will be discussed more in later chapters. Constructive forces cause landforms to grow. Lava flowing into the ocean can build land outward. A volcano can be a constructive force. Destructive forces may blow landforms apart. A volcano blowing its top off is a destructive force. The destructive forces of weathering and erosion change landforms more slowly. Over millions of years, mountains are worn down by rivers and streams. |
SciQ | SciQ-1145 | electromagnetism, electric-circuits
Title: What is the formal boundary between AC and DC? This question grew out of an exchange here: Using DC voltage in Transformers
Typically when we refer to more complicated currents than pure DC or sinusoidal AC, we refer to them as having a "DC component" and AC components of various frequencies. As far as I know, the DC component refers to the zero-frequency component of the signal; hence, if a signal has no zero-frequency component, it should be called pure AC.
But I've also heard the following argument: AC, in order to be "alternating" in any real sense, must change direction. Rectified AC does not change direction (the current is either zero or positive), so rectified current cannot be AC; as such, it should be referred to as "non-constant DC."
So we now have two conflicting definitions: rectified AC is either pure AC, because it has no zero-frequency component, or is non-constant DC, because it is always the same sign.
Which of these definitions is more commonly used? And generally, what is the formal difference between an AC signal and a DC signal?
Typically when we refer to more complicated currents than pure DC or sinusoidal AC, we refer to them as having a "DC component" and AC components of various frequencies. As far as I know, the DC component refers to the zero-frequency component of the signal; hence, if a signal has no zero-frequency component, it should be called pure AC.
Yes.
This is completely correct.
But I've also heard the following argument: AC, in order to be "alternating" in any real sense, must change direction. Rectified AC does not change direction (the current is either zero or positive), so rectified current cannot be AC; as such, it should be referred to as "non-constant DC."
The following is multiple choice question (with options) to answer.
"direct" and "alternating" are two kinds of what, which is associated with electricity? | [
"time",
"constant",
"levels",
"current"
] | D | 20.5 Alternating Current versus Direct Current Alternating Current Most of the examples dealt with so far, and particularly those utilizing batteries, have constant voltage sources. Once the current is established, it is thus also a constant. Direct current (DC) is the flow of electric charge in only one direction. It is the steady state of a constant-voltage circuit. Most well-known applications, however, use a time-varying voltage source. Alternating current (AC) is the flow of electric charge that periodically reverses direction. If the source varies periodically, particularly sinusoidally, the circuit is known as an alternating current circuit. Examples include the commercial and residential power that. |
SciQ | SciQ-1146 | volcanology, paleontology, volcanic-hazard, archaeology, pyroclastic-flows
Title: Are Pompeii and Herculaneum unique? Has anyone ever found or gone looking for similar locations, i.e. volcanic eruption sites in which unfortunate victims – human and non-human – have been entombed in the volcanic ash, with the possibility of revealing their forms by producing casts from the voids? Such sites, if they exist, could reveal exciting new knowledge about ancient peoples and animals. Probably the best known is more recent, the 1902 eruption of Mt. Pelée on Martinique, where 30,000 people were killed by pyroclastic flows. I don't know the extent of burial - it appears that the city may have been destroyed more by the ash cloud than the dense part of the flow.
The following is multiple choice question (with options) to answer.
What is a strombolian eruption named for? | [
"an ice cleaner",
"mt. st. helens",
"a country",
"mt. stromboli"
] | D | This is a strombolian eruption. This type of eruption was named for Mt. Stromboli in Italy. Strombolian eruptions spew lava into the air. But these eruptions do not have a massive explosion. They create lava flows. |
SciQ | SciQ-1147 | 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.
Which part of the plant conduct water and minerals as well as anchor the plant. | [
"roots",
"stem",
"cilia",
"leaves"
] | A | |
SciQ | SciQ-1148 | climate-change, sea-level, glaciology, ice-sheets, antarctica
Title: Where does the biggest land-based ice cap reside? I'm thinking biggest in volume, regarding which area of the planet will contribute more to a raising in sea level - were the ice in those regions to melt.
I can basically think of two candidates, namely Greenland and Antarctica. So maybe some comparison between the contributions of the two would be great. Antarctica is the ice sheet (cap) that will contribute most IF it would melt completely. The 2013 IPCC report (Ch. 4, the Cryosphere) provides an estimate of 58.3 m of sea level equivalent (sle). Greenland would if completely wasted away provide 7.36 m sle. Remaining glaciers provide an additional 0.41 m sle. The likelihood of Antarctica completely wasting away seems unlikely with our current understanding although the so-called West Antarctic Ice sheet (closes to the Antarctic Penninsula is sitting with its base deep below the current sea level) is far more likely to be lost than the East Antarctic Ice Sheet. Hence the contribution from Antarctica is likely less than the maximum number. Greenland on the other hand is thought to have a "point of no return" beyond which it will irreversibly be lost given the current or warmer climate. Since Greenland is mostly land-based, much of the mass loss will be by surface melting while West-Antarctica can lose much of its mass by ice berg calving which is likely a much faster loss mechanism. Estimates on the scenarios are emerging but there are still uncertainties and there may also be feedbacks that we either do not fully understand or have not yet seen that can change these scenarios (particularly for West-Antarctica). This Science article
published online May 12 2014 is a good example of emerging research on the stability issues of West Antarctica.
The following is multiple choice question (with options) to answer.
Ice caps are found only in greenland and which other place? | [
"Siberia",
"the tundra",
"rainforests",
"antarctica"
] | D | Ice caps are areas covered with thick ice year round. Ice caps are found only in Greenland and Antarctica. Temperatures and precipitation are both very low. What little snow falls usually stays on the ground. It doesn’t melt because it’s too cold. |
SciQ | SciQ-1149 | inorganic-chemistry, redox, combustion
As M. Farooq pointed out a combustion reaction happens quickly, producing heat, and usually light and fire. For example, lets look at combustion reaction of an alkene (a hydrocarbon). If it is a complete combustion, the fire have a blue flame:
$$\ce{C_nH_{2n} + $\frac{3n}{2}$ O2 -> nCO2 + n H2O}$$
If it is a partial combustion, it can have a multiple $\ce{C}$ compounds as products, and have a yellow flame due to presence of elemental $\ce{C}$:
$$\ce{C_nH_{2n} + x O2 -> m C + p CO + $(n-m-p)$CO2 + n H2O}$$
where $x = \frac{2(n-p-m) +p}{2} = \frac{2n-2p-2m +p}{2} = \frac{2n-p-2m)}{2}$. In your reaction would not produce fire and it didn't use either oxygen or other oxidants ($\ce{CuO}$ is not that type of oxidant). It is true that the reaction is a redox reaction.
The following is multiple choice question (with options) to answer.
During a what type of reaction do chemical changes take place? | [
"toxic",
"chemical",
"nuclear",
"biological"
] | B | A: During a chemical reaction, chemical changes take place. Some chemical bonds break and new chemical bonds form. |
SciQ | SciQ-1150 | embryology
Title: Is endoderm visible in the germ layer? This picture is my drawing about germ layer - not embryonic folding as I wrote initially.
Where exactly is the endoderm here in the picture?
The known things
Ectoderm
Neural tube
Notochord
Endoderm - Where is this?
Somite
Somite leg
Intraembryonic coelom
Embryonic somatopleura
Embryonic splanchopleura (lateral mesoderm)
Endoderm
Mesoderm (intraembryonic) I think you're going for a view of tube formation, in which case, here's a good image:
Lateral plate mesoderm
Intermediate mesoderm
Somite mesoderm
Chorda
Endoderm
(Reference)
Again in your drawing I think you correctly have it labeled as 10, and don't really need to put it twice.
The following is multiple choice question (with options) to answer.
In mammals, the cells on the exterior form the trophectoderm, which goes on to form what? | [
"aeroponics tissues",
"cardiac tissues",
"extraembryonic tissues",
"protoplanetary tissues"
] | C | organism’s life cycle is as subject to the effects of evolutionary pressures as any other (although it is easy to concentrate our attentions on adult forms and behaviors). The study of these processes, known as embryology, is beyond our scope here, but we can outline a few common themes. If fertilized eggs develop outside of the body of the mother and without parental protection, these new organisms are highly vulnerable to predation. In such organisms, early embryonic development generally proceeds rapidly. The eggs are large and contain all of the nutrients required for development to proceed up to the point where the new organism can feed on its own. To facilitate such rapid development, the egg is essentially pre-organized, that is, it is highly asymmetric, with specific factors that can influence gene expression, either directly or indirectly, positioned in various regions of the egg (→). Entry of the sperm (the male gamete), which itself is an inherently asymmetric process, can also lead to reorganization of the cytoplasm (SEP marks sperm entry point in the figure early frog development). Maternal and fertilization-driven asymmetries are stabilized by the rapid cycles of DNA replication and cell division, with growth being dependent upon the utilization of maternally supplied nutrients. As distinct cells are formed, they begin to become different from one another as i) they inherit different determinants, ii) the presence of these determinants leads to changes in gene expression, and iii) cells secrete and respond to different factors that drive their differentiation further into different cell types, with different behaviors based on differences in gene expression. On the other hand, in a number of organisms, and specifically mammals, embryonic development occurs within the mother, so there is no compelling need to stockpile nutrients within the egg and the rate of development is (generally) dramatically slower. In such developmental systems, it is not the asymmetries associated with the oocyte and fertilized egg that are critical, but rather the asymmetries that arise during embryonic development. As the zygote divides, a major factor that drives the differentiation is whether a cell comes to lie on the surface of the embryo or within the interior (→). In mammals, the cells on the exterior form the trophectoderm, which goes on to form extraembryonic tissues, in particular the membranous tissues that surround the embryo and become part of the placenta, the interface between the embryo and the mother. Cells within the interior form the inner cell mass that produces to the embryo proper. Changes in gene expression will lead to changes in the ability to produce and respond to inductive signals, which will in turn influence cell behavior and gene expression. Through this process, the cells of the inner cell mass come to form the various tissues and organs of the organism; that is, skin, muscle, nerve, hair, bone, blood, etc. It is easy to tell a muscle cell from a neuron from a bone cell from a skin cell by the set of genes they express, the proteins they contain, their shapes (morphology), their internal organization, and their behaviors. biofundamentals – coreBIO. |
SciQ | SciQ-1151 | biochemistry, physiology, cell-biology
Title: What triggers meiosis in gonadal cells? What specific biochemical processes are involved in inducing meiosis rather than mitosis? Why are gonadal cells the only cells in the human body which do undergo meiosis?
What specific biochemical processes are involved in inducing meiosis rather than mitosis?
It's a difficult question because every step in the development of a germ cell is ultimately necessary for the final differentiation, which includes a meiotic division. Meiosis requires a lot of specialized components to pair and segregate homologues, to induce and resolve recombination, etc. What starts it all is still largely unknown. There are plenty of mutants that halt the process, but these are required along the way, so damaging the pathway ultimately stops it from progressing. At least one study has been able to initiate the program of meiosis in yeast:
Induction of meiosis in Saccharomyces cerevisiae depends on conversion of the transcriptional represssor Ume6 to a positive regulator by its regulated association with the transcriptional activator Ime1. I Rubin-Bejerano, S Mandel, K Robzyk, and Y Kassir
Basically, they turned on a transcription factor, which activated an entire suite of downstream genes necessary for meiosis. In essence, they turned on the "meiosis pathway." Bear in mind this is yeast, so does't have separate germ cells, but the concept is probably the same.
Why are gonadal cells the only cells in the human body which do undergo meiosis?
All other cells are diploid. Only in germ cells does the organism induce reductional divisions (to make haploid gametes for ultimate fusion in the zygote of the next generation). Creation of haploid somatic cells would uncover recessive lethal mutations and cells would die. In sperm and eggs, which do not express any genes until after fertilization and karyogamy, this is not a problem.
The following is multiple choice question (with options) to answer.
In sexual reproduction, what is the name of the gamete cell the male must contribute? | [
"plasma",
"ova",
"sperm",
"spore"
] | C | Sexual reproduction is more complicated. It involves two parents. Special cells called gametes are produced by the parents. A gamete produced by a female parent is generally called an egg . A gamete produced by a male parent is usually called a sperm . An offspring forms when two gametes unite. The union of the two gametes is called fertilization . You can see a human sperm and egg uniting in Figure below . The initial cell that forms when two gametes unite is called a zygote . |
SciQ | SciQ-1152 | geology, rocks, sedimentology, geomorphology, terminology
Title: What do you call boulders of non sedimentary rock that were lithified into sandstone? I'm convinced there is a word for this. I was in the Hoodoos at Writing on Stone this weekend and kept noticing what looked like reddish quartzite boulders laying around in the sand, or sometimes sticking partially out of the hoodoos.
When a non-sedimentary rock gets washed out into silt which later lithifies, what's it called? It's kind of like a conglomerate, except there's only a couple of really big rocks, which eventually fall out out the rock because all the sandstone around them eroded away. The technical term for a sedimentary rock that has a lithified fine-grained sediment with larger pieces of rocks suspended in it upon lithification is a conglomerate. The fine-grained interstitial part is called the matrix, and the large pieces suspended in it are called clasts. Clasts can range from gravel- to boulder-size. These are technical terms used by sedimentologists.
It is tempting to refer to these fragments as xenoliths but as that word has a very specific meaning in igneous petrology, it is best to avoid it to remove any confusion.
The following is multiple choice question (with options) to answer.
The term "environment of deposition" is useful for understanding the characteristics of what type of rock? | [
"sedimentary",
"meteor",
"limestone",
"glacial"
] | A | Sediments are deposited in an environment of deposition. This can be a sand dune, beach, lake, river bend, or a great number of other locations. Scientists can figure out the environment of deposition of a sedimentary rock by looking at the size of sediments and the sedimentary features in the rock. |
SciQ | SciQ-1153 | botany
Title: Do any plants exhibit hormonal changes similar to puberty? Just what the title states.
Are there any plants/trees that exhibit a growth spurt at a definite interval after the shoot appears? In flowering plants (the angiosperms) there are several developmental transitions in the life of the plant. I won't list the plants, because the list includes pretty much all of them (although the magnitude in the change of developmental pace differs widely between taxa and environments).
First there is seed germination, which is controlled hormonally. Absence of germination is usually imposed by abscisic acid, whilst germination is caused at the appropriate time by gibberellic acid and ethylene (among other things; Holdsworth, Bentsink & Soppe, 2008).
Next, in many herbaceous species there is a transition between a spreading growth stage (e.g. rosette growth) and the flowering stage. The 'growth spurt' here is the differentiation and elongation of the flowering stem, and then subsequently the sudden flowering of buds. The transition is also controlled hormonally, by a variety of hormones including auxin (Zhao, 2010), gibberellic acid, ethylene (Schaller, 2012), and the long anticipated, recently confirmed florigen (Choi, 2012). Ethylene and abscisic acid then play important roles in the next developmental transition when seeds and fruits are produced and dehisced.
Small RNAs are also now being revealed to play a large role in controlling the timing of developmental, but they are upstream of the hormonal changes. In particular some key miRNAs are involved in auxin-based regulation of branching, and in embryogenesis (Nodine & Bartel, 2010), and RNA silencing is involved in the switch from rosette growth to flowering growth (reviewed in Poethig, 2009 and Baurle & Dean 2006).
The following is multiple choice question (with options) to answer.
Apical dominance, seed germination, gravitropism, and resistance to freezing are all positively influenced by what type of chemicals in plants? | [
"photosynthesis",
"hormones",
"enzymes",
"pesticides"
] | B | Jasmonates play a major role in defense responses to herbivory. Their levels increase when a plant is wounded by a predator, resulting in an increase in toxic secondary metabolites. They contribute to the production of volatile compounds that attract natural enemies of predators. For example, chewing of tomato plants by caterpillars leads to an increase in jasmonic acid levels, which in turn triggers the release of volatile compounds that attract predators of the pest. Oligosaccharins also play a role in plant defense against bacterial and fungal infections. They act locally at the site of injury, and can also be transported to other tissues. Strigolactones promote seed germination in some species and inhibit lateral apical development in the absence of auxins. Strigolactones also play a role in the establishment of mycorrhizae, a mutualistic association of plant roots and fungi. Brassinosteroids are important to many developmental and physiological processes. Signals between these compounds and other hormones, notably auxin and GAs, amplifies their physiological effect. Apical dominance, seed germination, gravitropism, and resistance to freezing are all positively influenced by hormones. Root growth and fruit dropping are inhibited by steroids. |
SciQ | SciQ-1154 | human-biology, anatomy
The proportions of diagrams and cross sections of the nasal cavity all seem wildly different. Some of them are just blatantly wrong, depicting, for example, the Eustachian tubes coming from the roof of the nasal cavity instead of the sides. It has been very difficult to find good information on any of this. I am not even sure if I am referring to the region correctly. By nasal cavity, I mean everything between the back of the throat and the posterior nares, although I am aware the nasal cavity includes the region all the way up to the anterior nares as well.
This is the only picture I can find that shows the nasal septum.
This is a better diagram of the rest of the structures. The pharyngeal tonsils are the adenoids. I'm impressed to stumble upon someone who can do that with his tongue. And mainly because I can do that myself!
Looking at the images and feeling with my tongue, this rugged area you mention is definitely too close to the nose to be the adenoids.
So I googled a bit (well, more like a lot) and I found this cool webpage which details that area.
http://www.theodora.com/anatomy/the_pharynx.html
and I found this snippet of text:
Above the pharyngeal tonsil, in the middle line, an irregular
flask-shaped depression of the mucous membrane sometimes extends up as
far as the basilar process of the occipital bone; it is known as the
pharyngeal bursa.
I've found stones in my tonsils but never in my adenoids. What I've sometimes found was dried mucus adhered to it when waking up in the morning.
I believe those stones might be rests of food (which can't really get up there).
Maybe this green mucus you found was just dried mucus? Maybe a little infection on a particular day?
I hope you get the answer, since it's passed a quite long time since you asked :)
The following is multiple choice question (with options) to answer.
In the nasal cavity, what 2 things trap particles from incoming air? | [
"mucus and skin",
"saliva and hair",
"phlegm and hair",
"mucus and hair"
] | D | Air enters the respiratory system through the nose. As the air passes through the nasal cavity, mucus and hairs trap any particles in the air. The air is also warmed and moistened so it won’t harm delicate tissues of the lungs. |
SciQ | SciQ-1155 | thermodynamics, visible-light, electromagnetic-radiation, thermal-radiation
flames containing carbon, i.e., soot. Carbon is pretty opaque (it can create heavy smoke), and emit thermal blackbody spectrum. Then you don't have green for the same reason that you don't have green stars ( well explained in wikipedia : a blackbody spectrum is large, not peaky, and visual system integrates so that "max of bump in green" is seen as white).
"normals flames" (but carbon is so frequent on Earth flames that one often forgets all the other elements :-) ), where color is due to emissive peaks of the excited molecules (flame of sodium, etc). Then you can have green flames. For example, copper sulphate shows a green flame.
The following is multiple choice question (with options) to answer.
Elemental carbon is a black, dull-looking solid that conducts heat and this? | [
"energy",
"light",
"electricity",
"vibration"
] | C | Elemental carbon is a black, dull-looking solid that conducts heat and electricity well. It is very brittle and cannot be made into thin sheets or long wires. Of these properties, how does carbon behave as a metal? How does carbon behave as a nonmetal?. |
SciQ | SciQ-1156 | python, template, tkinter, gui, factory-method
Title: Python - Tkinter - periodic table of chemical elements Inspired by a question on StackOverflow I decided to code a GUI that is simple, efficent and can be used in other projects as well. I wanted to share this code since it probably is usefull to other people as well. You may want to share some practical hints how to make this code even better.
The code produces a table of frames and shows the information, I did gather for about 5 hours from wikipedia, in the final output. The frames are made clickable to make the usecase wider then without. I hope you enjoy this bit of code.
Database:
symbols = ['H','He','Li','Be','B','C','N','O','F','Ne',
'Na','Mg','Al','Si','P','S','Cl','Ar','K', 'Ca',
'Sc', 'Ti', 'V','Cr', 'Mn', 'Fe', 'Co', 'Ni',
'Cu', 'Zn', 'Ga', 'Ge', 'As', 'Se', 'Br', 'Kr',
'Rb', 'Sr', 'Y', 'Zr', 'Nb', 'Mo', 'Tc', 'Ru',
'Rh', 'Pd', 'Ag', 'Cd', 'In', 'Sn', 'Sb', 'Te',
'I', 'Xe','Cs', 'Ba','La', 'Ce', 'Pr', 'Nd', 'Pm',
'Sm', 'Eu', 'Gd', 'Tb', 'Dy', 'Ho', 'Er', 'Tm',
'Yb', 'Lu', 'Hf', 'Ta', 'W', 'Re', 'Os', 'Ir',
'Pt', 'Au', 'Hg', 'Tl', 'Pb', 'Bi', 'Po', 'At', 'Rn',
The following is multiple choice question (with options) to answer.
Who created the periodic table? | [
"Gregor Mendel",
"Isaac Newton",
"Niels Bohr",
"dmitri mendeleev"
] | D | In 1869, a Russian scientist named Dmitri Mendeleev created the periodic table , which is a way of organizing elements according to their unique characteristics, like atomic number, density, boiling point, and other values ( Figure below ). Each element is represented by a one or two letter symbol. For example, H stands for hydrogen, and Au stands for gold. The vertical columns in the periodic table are known as groups, and elements in groups tend to have very similar properties. The table is also divided into rows, known as periods. |
SciQ | SciQ-1157 | immunology, virology, virus, infection, immunity
Title: Why don't we develop immunity against common cold? We all suffer from common cold, and that, frequently. Why have we not developed immunity against it till now? By immunity I mean immunity as a species. Long lasting immunity is obtained by means of the adaptive immune system, and mainly involves the development of antibodies that identify specific parts (epitopes) of the pathogen's proteins. Common cold is typically caused by a type of virus called rhinovirus. Viruses have very high mutation rates, which alter the sequence of the virus proteins, modifying their antigenic properties. This consequently alters the ability of antibodies to recognize a particular antigen.
In other words, we do develop long lasting immunity against the virus that causes us a cold today, but the virus that causes us a cold a few months later is somewhat different, and the adaptive immune system has to start from scratch.
The following is multiple choice question (with options) to answer.
What are unique in having adaptive immunity in addition to innate immunity? | [
"cells",
"invertebrates",
"organelles",
"vertebrates"
] | D | |
SciQ | SciQ-1158 | embryology
Title: What is a zygote? During fertilization, the nuclear membrane of the pro-nucleus of the ovum and sperm degenerate. Is the cell is stage called a zygote?
After the dissolution, mitosis occurs and two cells are formed.Or is the cell is stage called a zygote?
I'm confused as i knew a zygote was single-celled. Conventionally, a zygote is considered to be formed the moment that a spermatozoum, penetrates the cell membrane of the ovum and yields its genetic material into the ovum. Effectually, however, there is a lag between the instant of fertilization and the fusion of the male and female pronuclei. In mammals, the duration of this lag period is ~12 hours. There are also additional actions that must be completed before the first mitosis as in most mammals, including humans, the ovum is actually in the second metaphase of meiosis at the time of fertilization.
The following is multiple choice question (with options) to answer.
All three axes are established before the zygote begins to undergo what? | [
"twinning",
"cleavage",
"cloning",
"birth"
] | B | |
SciQ | SciQ-1159 | electrochemistry, polarity
However, why do $\ce{H+}$ ions move away from the anode, when they should by attracting because of negative charges?
For the most part, the circuit is going to be composed of (semi)conducting materials. Conductive materials in a circuit cannot sustain a very substantial charge polarization at all--as soon as they become very slightly polarized, they allow current to pass that equalizes the charge imbalance. (This is why they are used to carry current!)
As a result, the actual charging of the anode is negligible, even though it develops a finite electrical potential. Thus, the electrostatic attraction of the $\ce{H+}$ ions to the anode can in general be ignored, as it is orders of magnitude too small to keep the protons from diffusing away, toward the cathode where they are being consumed to produce water.
The following is multiple choice question (with options) to answer.
Because they are charged (polar), these ions do not diffuse through what? | [
"cell wall",
"membrane",
"protein",
"substrate"
] | B | Ions such as sodium (Na + ), potassium (K + ), calcium (Ca 2+ ), and chloride (Cl - ), are important for many cell functions. Because they are charged (polar), these ions do not diffuse through the membrane. Instead they move through ion channel proteins where they are protected from the hydrophobic interior of the membrane. Ion channels allow the formation of a concentration gradient between the extracellular fluid and the cytosol. Ion channels are very specific, as they allow only certain ions through the cell membrane. Some ion channels are always open, others are "gated" and can be opened or closed. Gated ion channels can open or close in response to different types of stimuli, such as electrical or chemical signals. |
SciQ | SciQ-1160 | organic-chemistry, molecular-structure, molecules
Title: Complex organic molecules I am studying astronomy and came across the following term in the astrochemistry course called 'complex organic molecules' or also written as COMs. My question is: What is exactly meant with these molecules? Is it just a molecule with more than one carbon atom? tl;dr: two different definitions. Astronomy: multiple carbon atoms in molecule. Chemistry: polymer
Interestingly enough, after reading about COMs here, as well as reading the Wikipedia page and the corresponding arXiv paper, it seems like chemists and astronomers have different definitions of what a complex organic molecule should be!
As far as I knew, in chemistry complex organic molecules were long polymers, such as proteins, which were composed of thousands upon thousands of amino acid units. In the astronomy paper, however, they cite other types of molecules.
$\ce{CH3OH,
CH3CHO, HCOOCH3 and CH3OCH3}$, all cited as "complex" (haha) organic molecules in the paper, would appear to chemists as relatively simple molecules. (I read the paper, because it piqued my interest that something like a protein could be found in space). I then read the Springer article.
The term “complex organic molecules” is used differently in astronomy and chemistry. In astronomy, complex organic molecules are molecules with multiple carbon atoms such as benzene and acetic acid. These molecules have been detected in interstellar space with radio telescopes. In chemistry, “complex organic molecules” refer to polymer-like molecules such as proteins.
The following is multiple choice question (with options) to answer.
What are complex organic molecules that make up cells? | [
"acids",
"sugars",
"proteins",
"carbohydrates"
] | C | Amino acids are molecules of carbon, hydrogen, and oxygen. These molecules are called the building blocks of life because they create proteins. Proteins are complex organic molecules that make up cells. They are the most abundant class of biological molecules. |
SciQ | SciQ-1161 | electricity, electric-circuits, electrons, electric-current, charge
Title: Electrons in an electric circuit , its movement and power delivered Does an electrical appliance convert electrons into its respective work , I mean is electron being consumed by appliance (say bulb ) and then this mass gives us energy.
or the same number of electron , just revolve around the circuit, then from where does power comes from, Electrons have charge and so when there is a potential difference across a circuit, this charge moves through it. In an incandescent light bulb, there is a high resistance, meaning that there are many atoms with which the charges collide, transferring some of their kinetic energy. No electrons are being "consumed" by the light bulb, i.e. the number of electrons in the circuit does not change. The ability of the charges to do work is because of a potential difference, which can be achieved through a number of means, e.g. using voltaic cells or electromagnetic induction.
To gain a better idea of why potential difference moves charges, consider two isolated point charges of opposite charges, one positive and one negative. If you pull the negative charge away from the positive one, you are doing work on it in the form of potential energy, as you are opposing the electric field of the positive charge. If you let go, the negative charge will convert this potential energy into kinetic energy, as it is attracted to the positive test charge. A potential difference across a circuit, albeit simplified, essentially does this – it brings electrons from a higher potential to a lower potential, converting potential energy into the kinetic energy in the process.
The following is multiple choice question (with options) to answer.
A light bulb converts electrical energy to light and what? | [
"visible energy",
"thermal energy",
"chemical energy",
"kinetic energy"
] | B | Most circuits have devices such as light bulbs that convert electrical energy to other forms of energy. In the case of a light bulb, electrical energy is converted to light and thermal energy. |
SciQ | SciQ-1162 | bond, ions, metal
Title: Can we picture metallic bonding as an equilibrium between electrons and cations? Can we picture metallic bonding as an equilibrium between electrons and cations?
Suppose:
$$\ce{Al^3+ + 3e- <=> Al}$$ In metals, electrons are non-localized, forming a "sea" of electrons, rather than having them localized, as in the $\ce{Na+Cl-}$ lattice of crystalline salt. See Metallic bonding for a more complete description.
It is, of course, a matter of degree, as covalent, ionic and metallic bonding can "blend" from one to the other. A bond can be considered partially ionic and covalent, for example; see these helpful graphics
The following is multiple choice question (with options) to answer.
What are chemical bonds between atoms of nonmetals that share valence electrons called? | [
"covalent bonds",
"electron bonds",
"gravitational bonds",
"ionic bonds"
] | A | Covalent bonds are chemical bonds between atoms of nonmetals that share valence electrons. In some covalent bonds, electrons are not shared equally between the two atoms. These are called polar covalent bonds. The Figure below shows the polar bonds in a water molecule (H 2 O). The oxygen atom attracts the shared electrons more strongly than the hydrogen atoms do because the nucleus of the oxygen atom has more positively charged protons. As a result, the oxygen atom becomes slightly negative in charge, and the hydrogen atoms become slightly positive in charge. For another example of polar bonds, see the video at this URL: http://www. youtube. com/watch?v=1lnjg81daBs. |
SciQ | SciQ-1163 | spectroscopy, analytical-chemistry
A related technique that is much better suited to small handheld instruments is raman spectroscopy, since the light involved is actually usually in the NIR. I doubt this thing is sensitive enough to do it well, but it might be possible to add filters to the illumination and measurement ports to give it a shot. It's definitely possible to do raman with a handheld instrument though—I saw one of these at a conference recently. Quite expensive, but very nifty.
The following is multiple choice question (with options) to answer.
What piece of technology can you use to see infrared light? | [
"telescope",
"light meters",
"night goggles",
"microscope"
] | C | The human body radiates heat in the range of infrared light. Night goggles work by ‘seeing’ the infrared light emitted by our bodies. |
SciQ | SciQ-1164 | optics, lenses
Title: Rays and lenses in a viewfinder An electronic camera viewfinder has a LCD screen and a combination of lenses. When looking into the viewfinder the image looks much bigger than the actual LCD though. In fact when looking from a bit further back one can only see a tiny middle part of the LCD.
I am wondering what kind of lenses create this projection when looking into the viewfinder. I am especially struggling to draw the rays.
It would be great if someone could explain or point me to another source for an explanation. My search terms have failed me so far. The lens through which you look at the viewfinder screen basically is the same thing as a magnifying glass.
I did a search for pages that explain how a magnifying glass works, and I was surprised by how little information on that subject is out there. The best I could find was this:
https://www.quora.com/Why-are-convex-lenses-called-magnifying-glass
The diagram attempts to show how, when you use a magnifier to look at a small object that is very close to your eye, the lens bends the rays so that they seem to come from a larger object that is further away.
The picture only shows two rays, both coming from one point on the object. In reality, there are infinitely many rays coming from infinitely many points, and the lens does the same thing for all of them.
The following is multiple choice question (with options) to answer.
Lenses make use of what to create images? | [
"stimulation of light",
"resonance of light",
"refraction of light",
"envelopment of light"
] | C | Lenses make use of the refraction of light to create images. A lens is a transparent object, typically made of glass, with one or two curved surfaces. The more curved the surface of a lens is, the more it refracts light. Like mirrors, lenses may be concave or convex. |
SciQ | SciQ-1165 | zoology, ethology, behaviour, psychology, death
Strange thought
Organisms that have not evolved the ability to make "conscious choices" cannot decide to end their life. You will be hard-pressed to find any scientific data on this question. Psychology in humans is already a difficult study, at times failing to demonstrate results with real scientific rigor. When studying animal psychology, you face another substantial barrier - language. Although some primates have been taught to communicate with sign language, the best of them are still far from the level of proficiency of a human. We can measure brain activity and observe behavior, which can lead us to strong suspicions about what is going on in an animal's mind, but very little can actually be proven.
Mostly, all we can do is speculate about such questions. You will find some veterinarians out there who treat pets for mental conditions, but you will find at least as many people calling them quacks as those who believe in the validity of their work. And certainly, they can't prove to you that a treatment has helped an animal. It's subjective.
If we see an animal do something which in a human might reliably be interpreted as a sign of depression, it's possible that this interpretation is appropriate for the animal as well. It's also possible that there is some totally foreign unrelated explanation. The problem we find when trying to scientifically discuss matters which cannot be proven scientifically is that scientists must be careful to state what they know and nothing more. So they might say "We cannot prove that the porpoise is depressed", or "Science cannot prove the existence of a God." This is often misinterpreted as evidence against the finding - that the porpoise is not depressed; that there is no God. This is a fallacy. Rather, we should recognize that we have different ways of exploring questions like these.
The following is multiple choice question (with options) to answer.
What do animals observe in others to help solve problems? | [
"patterns",
"behavior",
"communication",
"function"
] | B | |
SciQ | SciQ-1166 | taxonomy
Title: Why are sponges sometimes not considered multicellular? I read somewhere (I can't find where) that there is no scientific consensus whether sponges should be considered multicellular organisms.
It seems I don't understand where is the line between unicellular and multicellular life.
I am not able to find a more elaborate explanation of that doubt. What are the reasons for it? Sponges are generally considered as colonial organisms because there is little cell specialization and little separation of function/role. All cells do pretty much the same thing; it looks more like a pile of individual cells than an actual multicellular organism. In reality it is a little bit in between.
In any case, what one wants to call multicellular or unicellular is a matter of definition and preferences. You cannot find the line between unicellular and multicellular because there is no such line that would not be very arbitrary and filled with special cases.
You can study a little more the physiology of sponges and then decide for yourself if it looks sufficiently like a multicellular organism or more like a colony of cells (a colonial organism).
The following is multiple choice question (with options) to answer.
Reef sponges typically have what type of beneficial relationships with other reef species? | [
"parasitic",
"mutual",
"microbes",
"symbiotic"
] | D | Many sponges live on coral reefs, like the one in Figure below . Reef sponges typically have symbiotic relationships with other reef species. For example, the sponges provide shelter for algae, shrimp, and crabs. In return, they get nutrients from the metabolism of the organisms they shelter. |
SciQ | SciQ-1167 | electromagnetism, electric-fields, charge
Title: if there is no electric field then any charge exists or not? If we assume a region of space in which there is no electric field, can we say that no electric charge exists?
I think that there is no electric charge particles to create electric field for this specific region of space, am I right?
No, this is not true all the times for every region in space.
Take this example: If you have two charges with the negative charge. At the middle of the straight line that connects them, the electric field(the force) will be equal to zero because the force from the electric field of each charge will be equal in magnitude but they will have opposite direction at that point, so they will cancel out.
There is also an example where this happens to a bigger region in space. Say you have two plates, each of equal charge of the same sign. Then, between the two plates, the net electric field will be approximately zero.(approximately because at some points between the plates it is nearly zero for reasons that are not to be analyzed here).
The following is multiple choice question (with options) to answer.
Where is the only place an electric charge can be found? | [
"ion",
"neuron",
"translator",
"conductor"
] | D | Electric charge is found only in a conductor. |
SciQ | SciQ-1168 | protein-structure, structural-biology, protein-folding
I would conclude by noting that although the individual components of these cellular polyproteins interact with one another to cooperate in the biosynthesis, the flexibility they exhibit allows transfer of the growing substrate from one component to another.
The following is multiple choice question (with options) to answer.
What part of a cell do proteins travel to to be modified for the specific job they will do? | [
"nucleus",
"plasma membrane",
"lysosome",
"golgi apparatus"
] | D | After a polypeptide chain is synthesized, it may undergo additional processes. For example, it may assume a folded shape due to interactions among its amino acids. It may also bind with other polypeptides or with different types of molecules, such as lipids or carbohydrates. Many proteins travel to the Golgi apparatus to be modified for the specific job they will do. You can see how this occurs by watching the animation at this link: http://vcell. ndsu. edu/animations/proteinmodification/movie-flash. htm . |
SciQ | SciQ-1169 | electricity, electric-circuits, electric-current, semiconductor-physics
Title: Why does current have to flow in the same direction? If current is just the movement of charged particles, why do the all have to move in the same direction?
For example, if you reverse-bias a diode (connect the positive terminal to the n-type side and the negative terminal to the p-type side), the positive "holes" are attracted to the negative terminal and the electrons are attracted to the positive terminal.
Firstly, if positive holes moving towards the negative terminal corresponds to electrons moving the opposite way (since "holes" aren't real, they're just a lack of electrons). So on both sides of the diode, electrons are moving in the same direction. I don't quite understand how this doesn't correspond to a current flowing.
Not even looking that deep into it, if positive charges are moving one way and negative charges the other, why does it matter if they cross the PN junction? Moving charges = electricity, right?
On top of all this, the battery creates an electric field that goes through all the wires, so why is there no current in the circuit? Electrons don't even move that fast (I've heard drift speed is on the order of cm/s), so "current" is localized in the sense that an electron on one side of a circuit may never even reach the other side. So why aren't localized electric fields enough to create a circuit? All charges don't move in the same direction. It's the net effect that we see. I think you're missing the fact that conventially current was thought to be the flow of positive charges.
Let's consider an example (something less complex than the diode example you've mentioned)
Consider an area element of a conductor and view it in a direction along its plane.
Let there be both positive and negative charges (yes, these are electrons (for a metallic conductor) but for the time being let them be positive and negative charges) to the left and right of the element.
The following is multiple choice question (with options) to answer.
When current flows in just one direction, what is it called? | [
"reactant current",
"mono-current",
"direct current",
"alternating current"
] | C | When current flows in just one direction, it is called direct current (DC) . The current that flows through a battery-powered flashlight is direct current. |
SciQ | SciQ-1170 | electric-circuits, electrical-resistance
Title: Ammeter range and shunt resistance Its said that for an ammeter to give good reading, the full current in the circuit must pass through it. But if I am right, the ammeter is basically a galvanometer connected parallel to a very low resistance called a shunt. I am aware that connecting a low resistance in parallel will reduce effective resistance to a value lesser than the least resistance.
But in an ammeter, if the shunt is a low resistance (lesser than galvanometer's resistance), then most of the current would pass through the shunt than the galvanometer. Thus, the reading given by galvanometer would decrease (as its the component which gives deflection in an ammeter), which means that the reading of ammeter would decrease.
Is my interpretation correct? If its wrong please explain me where I have gone wrong.
Also, how will range and sensitivity of a an ammeter change if we increase or decrease shunt resistance? In a practical ammeter there will be a number of fixed shunt resistances, selected by a switch. The galvanometer is acting as a high-resistance voltmeter, measuring the voltage across the shunt, and has little effect on the current through the circuit was a whole.
If we know the value of the shunt resistor, then the voltage read by the galvanometer is proportional to the current passing. I = V/R.
Changing the shunt resistor affects the reading greatly. It's up to the user to select the correct shunt for the current being measured.
The following is multiple choice question (with options) to answer.
An ammeter must be connected in series with what to allow it to accurately measure the current flow without causing any disruptions? | [
"insulators",
"capacitors",
"configurations",
"resistors"
] | D | An ammeter measures the current traveling through the circuit. They are designed to be connected to the circuit in series, and have an extremely low resistance. If an ammeter were connected in parallel, all of the current would go through the ammeter and very little through any other resistor. As such, it is necessary for the ammeter to be connected in series with the resistors. This allows the ammeter to accurately measure the current flow without causing any disruptions. In the circuit sketched above, the ammeter is . |
SciQ | SciQ-1171 | inorganic-chemistry, acid-base, everyday-chemistry
$$\ce{H2O + CO2(aq) <=> H2CO3}$$
and the protolysis of true $\ce{H2CO3}$
$$\ce{H2CO3 <=> H+ + HCO3-}$$
For a weak acid
$$\begin{align}
\log[\ce{H+}]&\approx\frac12\left(\log K_\mathrm a+\log[\ce{H2CO3^*}]\right)\\
&=\frac12\left(-6.3-5.0\right)\\
&=-5.65\\
\mathrm{pH}&=5.65
\end{align}$$
Thus, pure rain in equilibrium with the atmosphere has about $\mathrm{pH}=5.65$. Any acid rain with lower $\mathrm{pH}$ would be caused by additional acids.
The following is multiple choice question (with options) to answer.
What combines with rain to form acid rain? | [
"nitrogen and sulfur oxides",
"carbon dioxide and sulfur oxides",
"suction and sulfur oxides",
"compost and sulfur oxides"
] | A | Courtesy of the U. S. EPA. Nitrogen and sulfur oxides combine with rain to form acid rain . Public Domain. |
SciQ | SciQ-1172 | human-biology, cell-biology, bacteriology, cell-membrane
Title: Can general soap kill bacteria? I have read that general soap can kill bacteria by opening holes in the bacterial membrane.
http://questions.sci-toys.com/node/90
However, I found some articles as well saying that it cannot.
http://goaskalice.columbia.edu/answered-questions/does-soap-kill-germs
There seems split answers among experts,
so I would like to know which one is correct.
Could anyone advise me?
Thanks. Soap kills nearly all the bacteria it comes into contact with by dissolving the bacterial membrane. Some viruses with protein coats can resist soap, but many viruses have similar membranous coats (like HIV) and are usually disrupted by soap. I'm sure it washes some away too, but to say they don't kill bacteria is misleading. In the end, though, they are gone.
Antibacterial soap with triclosan does not kill bacteria on contact and are no more effective than if they had no triclosan at all. That's actually a good thing since really using an antibiotic would probably accelerate antibiotic resistant bacteria which is a serious - probably catastrophic public health failure. A recent study showed that killing bacteria by soaking with triclosan took 9 hours to start showing an effect.
To achieve full sterility, surgeons bathe their gloves in iodine (see details in the comments below) and their instruments will be sterilized by heating them beyond the boiling point in an autoclave under pressure. That's useful when you are breaching the skin in surgery, but the skin needs some bacteria to be healthy long term and works well to fend off bacterial infections.
Your confusion seems to come from finding a page full of errors. Alice didn't really do her homework.
The following is multiple choice question (with options) to answer.
Bacterial stis include chlamydia, gonorrhea, and syphilis are diseases that can usually be cured with what? | [
"antihistamines",
"antivirals",
"antioxidants",
"antibiotics"
] | D | Bacterial STIs include chlamydia, gonorrhea, and syphilis. These diseases usually can be cured with antibiotics. |
SciQ | SciQ-1173 | energy, visible-light, photons, sun, interactions
Title: What are the physical processes involved in feeling warm from the sunlight? Suppose a human is lying on a beach. He/she starts to feel warm after exposing his/her skin to the sunlight. I assume that feeling is due to the ability of the human body of "measuring" the increasing in temperature of the skin.
Now I want to understand what are the physical processes involved in this increasing in temperature.
Imagine a group of photons impinging on the skin in a certain interval of time. I tried to list the possible interactions from a particle physics perspective between photons and the human tissue and I concluded that the possible interactions may be:
Photoionization
Compton scattering
Rayleigh scattering
Pair production
The first 3 seems to be reasonable, but the fourth one requires an energy threshold too high: there are no incident photons that may have that energy. I conclude that by looking at the spectrum of sunlight that actually reaches the earth's surface below the atmosphere. So I think that the pair production does not play a role in this situation.
Are there any other interaction processes between photons and tissue molecules involved in the increasing of temperature of the human tissue?
After listing the processes I wonder what actually increases the temperature: is the temperature increasing because the photons-molecules interactions lead to a transition of molecules to excited vibrational states? or maybe transitions to excited rotational states?
I thought that another possibility is that the photons interactions are increasing the kinetic energy of the water molecules in the skin or maybe are increasing the lattice vibration of other tissue (skin, bones or others). Are this processes happening simultaneously? One of this processes (for example transition to rotational excited states) is dominant over the others ?
I'm looking to a qualitative answer, without going into too much details of the Biology of the human body. I just want to create an approximate picture of this situation in my mind. I want to create a mental "video" from the instant in which a photon or a group of photons impinges in the skin to the moment in which tissue molecules are affected and the temperature starts rising up.
I thank in advance anyone who answers this question. You forgot garden-variety absorption! Here, light promotes electrons from lower energy states to higher energy states. However, skin is made of many small particles, so scattering is important as well.
Here’s the mental video:
The following is multiple choice question (with options) to answer.
Rubbing your hands together warms them by converting work into what energy? | [
"kinetic energy",
"thermal energy",
"motion energy",
"layer energy"
] | B | To sterilize a 50.0-g glass baby bottle, we must raise its temperature from 22.0ºC to 95.0ºC . How much heat transfer is required? 4. The same heat transfer into identical masses of different substances produces different temperature changes. Calculate the final temperature when 1.00 kcal of heat transfers into 1.00 kg of the following, originally at 20.0ºC : (a) water; (b) concrete; (c) steel; and (d) mercury. Rubbing your hands together warms them by converting work into thermal energy. If a woman rubs her hands back and forth for a total of 20 rubs, at a distance of 7.50 cm per rub, and with an average frictional force of 40.0 N, what is the temperature increase? The mass of tissues warmed is only 0.100 kg, mostly in the palms and fingers. A 0.250-kg block of a pure material is heated from. |
SciQ | SciQ-1174 | nuclear-physics, kinetic-theory
Title: Usefulness of high molecular speeds in nuclear fusion reactions How do molecules having speeds many times greater than mean speed help in making nuclear fusion reactions in a laboratory? Nuclear fusion is a process in which two or more nuclei are combined to form a different atomic nucleus.
It takes a lot of energy to force nuclei to fuse, even with the lightest elements, like hydrogen in the Sun.
Now the release of energy and the fusion iself goes down between two forces:
strong force (residual strong force, that is the nuclear force), that keeps the neutrons and protons together
EM repulsion, that keeps protons away
When you accelerate nuclei to high enough speeds, they can overcome this EM repulsion, so they can be brought close enough, where the nuclear force is strong enough to hold them together.
At large distances, two naked nuclei repel one another because of the repulsive electrostatic force between their positively charged protons. If two nuclei can be brought close enough together, however, the electrostatic repulsion can be overcome by the quantum effect in which nuclei can tunnel through coulomb forces.
When a nucleon such as a proton or neutron is added to a nucleus, the nuclear force attracts it to all the other nucleons of the nucleus (if the atom is small enough), but primarily to its immediate neighbours due to the short range of the force.
https://en.wikipedia.org/wiki/Nuclear_fusion
The following is multiple choice question (with options) to answer.
What is the opposite of nuclear fusion? | [
"energy fission",
"nuclear fission",
"Solar Power",
"might fission"
] | B | Nuclear fusion is the opposite of nuclear fission. In fusion, two or more small nuclei combine to form a single, larger nucleus. An example is shown in Figure below . In this example, two hydrogen nuclei fuse to form a helium nucleus. A neutron and a great deal of energy are also released. In fact, fusion releases even more energy than fission does. |
SciQ | SciQ-1175 | inorganic-chemistry, transition-metals
Title: Can we classify all the d-block elements as transition metals? I thought that properties of d-block elements are transitional between those of s-block and p-block elements, and that is the reason for calling them transition metal.
My textbook says that not all d block elements are called transition metals.
My doubts:
What are these non-transition metals that are in d-block?
Why are these specific elements not called transition metals? The idea that the properties of d-block elements are transitional between those of s-block and p-block elements, and that is the reason for calling them transition element. It is absolutely correct, but the thing is transition metals are defined as slightly different manner.
Definition of a transition metal/Criteria for an element to be a transition metal
A transition metal is one which forms one or more stable ions which have incompletely filled d orbitals
Appreciate that the general electronic configuration (EC) for d-block elements are slightly different for those of transition metals.
EC of d-block elements: $\mathrm{(n-1)d^{1-10}ns^{1-2}}$
EC of transition metal/ion: $\mathrm{(n-1)d^{1-9}ns^{1-2}}$
Some examples of elements which are in d-block but not a transition metal
Scandium has the electronic structure $\mathrm{[Ar] 3d^{1} 4s^2}$. When it forms ions, it always loses the 3 outer electrons and ends up with an argon structure. The $\ce{Sc^{3+}}$ ion has no d-electrons and so does not meet the definition.
Zinc has the electronic structure $\mathrm{[Ar] 3d^{10} 4s^2}$. When it forms ions, it always loses the two $\mathrm{4s}$ electrons to give a 2+ ion with the electronic structure $\mathrm{[Ar] 3d^{10}}$. The zinc ion has full d-levels and does not meet the definition either.
There's a small thing that one must take into account that some elements are capable of forming multiple metal ions. In those cases we must consider more common ion (the most stable one).
The following is multiple choice question (with options) to answer.
What are the three classifications of elements? | [
"metals, non-metals and metaloids",
"metals, non-metals and alkaloids",
"alkaloids, metaloids, and non-metals",
"metals, metaloids, and alkaloids"
] | A | The majority of known elements are classified as metals. Metals are elements that are lustrous, or shiny. They are also good conductors of electricity and heat. Examples of metals include iron, gold, and copper. Fewer than 20 elements are classified as nonmetals. Nonmetals lack the properties of metals. Examples of nonmetals include oxygen, hydrogen, and sulfur. Certain other elements have properties of both metals and nonmetals. They are known as metalloids. Examples of metalloids include silicon and boron. |
SciQ | SciQ-1176 | evolution, zoology, anatomy
Title: Are the transverse septum in sharks and the diaphragm in mammals homologous structures? Are the transverse septum in sharks and the diaphragm in mammals homologous structures?
I have searched on Google Scholar and Web of Science, but haven't found substantial evidence to prove or falsify the claim. A beginning of answer here below, I hope. Please first consider that many structures are involved in the question here, the diaphragm (UBERON:0001103), the diaphragmaticus muscle (UBERON:0036071) and the septum transversum (UBERON:0004161). At Bgee (bgee.org) we aim annotating relations of similarity between anatomical structures, please have a look at our GitHub
https://github.com/BgeeDB/anatomical-similarity-annotations
We already annotated 'diaphragm' as a mammalian structure, not homologous in Amniota (please see https://raw.githubusercontent.com/BgeeDB/anatomical-similarity-annotations/master/release/similarity.tsv). In our next release, you will see the annotation for the 'diaphragmaticus muscle' which is an analog organ in Crocodylians (and Turtles) but not homologous to the mammalian diaphragm either. See here for more details about this new Uberon class:
https://github.com/obophenotype/uberon/issues/1229.
Based on the comments here above, I would say that currently we can argue that there is no evidence for a homologous relationship between the 'septum transversum' in sharks and the mammalian diaphragm. Please note that UBERON:0004161 septum transversum describes the (mammalian) embryonic structure that will give rise to the central tendon of the diaphragm, while here you are talking about a adult structure closer to a 'diaphragmaticus muscle'-like septum, as far as I understand.
But anyway thank you for your interesting question that points out a very exciting and rapidly evolving evo-devo field, as this recent paper also suggests
The following is multiple choice question (with options) to answer.
Worms use a hydrostatic type of what anatomical structure to move through their environment? | [
"tail",
"skeleton",
"gastrointestinal system",
"head"
] | B | |
SciQ | SciQ-1177 | neural-networks, machine-learning, deep-learning, training
Title: Training an AI to recognize my voice (or any voice) I want to start a project for my artificial intelligence class about speaker recognition. Basically, I want to train my AI to detect if it's me who's speaking or somebody else. I would like some suggestions or libraries to work with. The human voice is based on the neural muscular control of vocal apparatus made up of many parts.
Diaphragm
Vocal cords
Throat (constrictors and anti-constrictors)
Nasal cavity
Cheek
Jaw
Tongue
These coordinated muscular manipulations produce envelopes (controlling) of audio that can be characterized by periodic and transient wave forms.
Volume
Pitch
Tone (relative volume of harmonics)
Consonant transients
Voices are unique to the learning state of neural activity and anatomic attributes, which is a way of saying that vocal habits and the physical attributes of the voice supports the distinguishing of vocal identity.
Strength of vocal muscles
Connectivity of muscles to bone, tendons, and cartilage
Shape of inner surface of vocal pathways
Neural coordination of those muscles
Neural production of phonetic control to produce linguistic elements
Neural serialization of semantic structures (ideas)
The following is multiple choice question (with options) to answer.
What flexible organ enables swallowing and speech? | [
"diaphram",
"large intestine",
"tongue",
"stomach"
] | C | The Tongue Perhaps you have heard it said that the tongue is the strongest muscle in the body. Those who stake this claim cite its strength proportionate to its size. Although it is difficult to quantify the relative strength of different muscles, it remains indisputable that the tongue is a workhorse, facilitating ingestion, mechanical digestion, chemical digestion (lingual lipase), sensation (of taste, texture, and temperature of food), swallowing, and vocalization. The tongue is attached to the mandible, the styloid processes of the temporal bones, and the hyoid bone. The hyoid is unique in that it only distantly/indirectly articulates with other bones. The tongue is positioned over the floor of the oral cavity. A medial septum extends the entire length of the tongue, dividing it into symmetrical halves. Beneath its mucous membrane covering, each half of the tongue is composed of the same number and type of intrinsic and extrinsic skeletal muscles. The intrinsic muscles (those within the tongue) are the longitudinalis inferior, longitudinalis superior, transversus linguae, and verticalis linguae muscles. These allow you to change the size and shape of your tongue, as well as to stick it out, if you wish. Having such a flexible tongue facilitates both swallowing and speech. As you learned in your study of the muscular system, the extrinsic muscles of the tongue are the mylohyoid, hyoglossus, styloglossus, and genioglossus muscles. These muscles originate outside the tongue and insert into connective tissues within the tongue. The mylohyoid is responsible for raising the tongue, the hyoglossus pulls it down and back, the styloglossus. |
SciQ | SciQ-1178 | geology, rocks, sedimentology, geomorphology, terminology
Title: What do you call boulders of non sedimentary rock that were lithified into sandstone? I'm convinced there is a word for this. I was in the Hoodoos at Writing on Stone this weekend and kept noticing what looked like reddish quartzite boulders laying around in the sand, or sometimes sticking partially out of the hoodoos.
When a non-sedimentary rock gets washed out into silt which later lithifies, what's it called? It's kind of like a conglomerate, except there's only a couple of really big rocks, which eventually fall out out the rock because all the sandstone around them eroded away. The technical term for a sedimentary rock that has a lithified fine-grained sediment with larger pieces of rocks suspended in it upon lithification is a conglomerate. The fine-grained interstitial part is called the matrix, and the large pieces suspended in it are called clasts. Clasts can range from gravel- to boulder-size. These are technical terms used by sedimentologists.
It is tempting to refer to these fragments as xenoliths but as that word has a very specific meaning in igneous petrology, it is best to avoid it to remove any confusion.
The following is multiple choice question (with options) to answer.
What is a wall of rocks or concrete called? | [
"knee",
"groin",
"foot",
"ankle"
] | B | Longshore drift can erode the sediment from a beach. To keep this from happening, people may build a series of groins. A groin ( Figure below ) is wall of rocks or concrete. The structure juts out into the ocean perpendicular to the shore. A groin stops the longshore movement of sand. Sand collects on the up-current side of the groin. Sand on opposite of side of the groin erodes. This reduces beach erosion. |
SciQ | SciQ-1179 | evolution, ornithology, ethology, sexual-selection
Bateson P. 1978. Sexual imprinting and optimal outbreeding. Nature 273, 659 - 660.
Bereczkei T, Gyuris P, Weisfeld GE. 2004. Sexual imprinting in human mate choice. Proceedings of the Royal Society of London, Series B: Biological Sciences 271: 1129–1134.
Immelmann K. 1972. Sexual and Other Long-Term Aspects of Imprinting in Birds and Other Species. In Advances in the Study of Behavior, Vol. Volume 4 of, pp. 147–174, Academic Press
The following is multiple choice question (with options) to answer.
What are the special mating behaviors in birds called? | [
"presentation",
"display",
"courtship",
"attraction"
] | C | Birds reproduce sexually and have separates sexes. Fertilization occurs internally, so males and females must mate. Many bird species have special behaviors, such as unique songs or visual displays, for attracting mates. These special behaviors are called courtship. The white peacock in Figure below is putting on a stunning display of his amazing tail feathers to court a mate. |
SciQ | SciQ-1180 | nuclear-physics, weak-interaction, strong-force
Title: How does meson exchange work within large nuclei? I read the Wikipedia page on Mesons and it mentioned that there both charged and uncharged Mesons that decay into neutrino/electrons and photons, respectively. Unfortunately it didn't elaborate on exactly why that is the case, unless it was hidden in the mathematics further down the page. If there are two types of Mesons differentiated by their electric charge, does that mean that neutrons will release neutral Mesons and protons will release charged Mesons? If there is charge being carried by a Meson, how is the charge being stored if a Meson is simply two quarks and a gluon?
It makes sense to imagine nucleons as exchanging mesons at the same rate as the photons are transmitting the electromagnetic repulsion of the protons, therefore they remain clumped together. But if there are many numerous nucleons, it isn't as simple as imagining a single trade off between two nucleons. There would be a probability field of Mesons, and therefore would randomly allow for some protons to be pushed out of the nucleus via electric repulsion. But this is the job that is handled by the Weak force, transmitted by the W and Z Bosons. Where am I going wrong in imagining the inner workings of the big nuclei? Your question is founded on misunderstandings. The theory of what goes on inside the nucleus is neither simple nor intuitive.
The following is multiple choice question (with options) to answer.
What kind of charges do protons give the nucleus? | [
"neutral",
"positive",
"negative",
"dynamic"
] | B | Inside the atom, two types of subatomic particles have electric charge: electrons, which have an electric charge of -1, and protons, which have an opposite but equal electric charge of +1. The model of an atom in the Figure below shows both types of charged particles. Protons are found inside the nucleus at the center of the atom, and they give the nucleus a positive charge. (There are also neutrons in the nucleus, but they have no electric charge. ) Negative electrons stay in the area surrounding the positive nucleus because of the electromagnetic force of attraction between them. |
SciQ | SciQ-1181 | cell-biology, molecular-biology
Title: Intracellular lipid transport I know that lipids are carried around the body in the blood either as micelles or by lipid-binding proteins which allow them to be solved.
Lipids can't always be integrated in a membrane though, the phospholipids used in membranes have to be synthesised somewhere from a precursor which will also by hydrophobic.
Consequently, at some point there will have to be transport of lipids within the cell where the lipids will need to be in solution. How is this facilitated? Like in the blood, intracellular lipid trafficking is facilitated by vesicular transport and lipid carriers like fatty acid binding proteins. In addition, intracellular membranes are densely packed and they can exchange lipids by collision and transient hemifusion. If you have access to Cell, a good review is from Prinz W. 2010 Lipid Trafficking sans vesicles, Where, Why, How?
The following is multiple choice question (with options) to answer.
What happens when a cell takes in substances through its membrane? | [
"dialysis",
"metastasis",
"endocytosis",
"filtration"
] | C | Other animal-like protists must "swallow" their food through a process called endocytosis . Endocytosis happens when a cell takes in substances through its membrane. The process is described below:. |
SciQ | SciQ-1182 | bond, ionic-compounds, covalent-compounds, boron-family
The answer given was 4.
I get that there might be an exception but I'm not able to find it anywhere. If there exists an ionic compound of boron, could someone please mention that to me? Boron can form ions but there is some fine print. You won't get monatomic cations like the metals below it. Instead, ionic boron structures are formed from clusters where the ionic bonding is driven by the molecular orbital structures in these clusters, not by electronegativity (cf. This answer).
Such clusters are internally held together by covalent bonds between the boron atoms, so in this sense boron is still forming covalent bonds. The ionic bonds would be with atoms of other elements outside the boron cluster. Since the valence shells of a neutral boron atom are less than half filled the clusters will likely have low-energy, bonding orbitals that require electrons from outside atoms. Thus the boron clusters will be anionic and the ionic bonds will be most likely formed with electropositive metals. As suggested in the comments, magnesium diboride, $\ce{MgB2}$, is one of the most widely studied compounds containing such boron clusters. It has drawn much research interest because of its relatively high critical temperature (39 K) for superconductivity, which may be related to the impact of ionic magnesium-boron bonding on the eletronic interactions that lead to superconduction.
Magnesium diboride has a layered structure in which magnesium layers alternate with boron layers. The latter are covalently bonded into a hexagonal honeycomb, resembling a carbon layer in graphite. However, in the boron layers each atom supplies only three electrons per atom instead of four, so the layers may act as electron-accepting structures to form macro-anion having the formula $\ce{B^-}$. An ionic model for the diboride would then have the empirical formula $\ce{Mg^{2+}(B^-)2}$. Here I discuss two references I have examined, in which the bonding is examined and the results may be compared with this model.
The following is multiple choice question (with options) to answer.
What are compounds formed by ionic bonds called? | [
"nuclear compounds",
"mixed compounds",
"layered compounds",
"ionic compounds (salts)"
] | D | |
SciQ | SciQ-1183 | organic-chemistry, bond, lewis-structure
Title: How do I draw a Lewis diagram after drawing the orbital diagram The question says "Oxygen can form compounds with every period 3 element except argon. Determine which would be ionic or covalent compounds, and draw Lewis diagrams to represent each one." I started with oxygen and fluorine and I'm having a hard time. I don't know if there should be lone pairs, double bonds, or even lone electrons.Here's my attempt at it: First of all, oxygen follows "the octet rule", which states that certain elements are stable when they have 8 electrons around them. Now this rule is by no means absolute, does not work with d orbitals onward, and should only be used in very elementary chemistry, unless you actually know its cause. In the case of that picture, you are missing 2 non-bonding electrons on the oxygen.
Remember that a covalent bond means that electrons are being shared by the 2 atoms. In the case of O and F, the pauling electronegativities are quite similar, so the electrons are actually "shared".
However, when you try to put oxygen together with group 1 or group 2 elements, you will find very different electronegativity values. What this means is that oxygen has much more affinity to electrons than Na or Mg. The rule I was taught at school was that a difference of 2 or more in electronegativity between the elements results in ionic compounds, meaning the oxygen "steals" the electrons, becoming a negative anion, whereas Na for example becomes a positive one.
The last guideline you should take into account, is that an atom tends to lose or gain electrons because it "likes" to have its most outer shell full. So when you look at the principal quantum number ($n$) of the most outer shell, you should create compounds where it is full. In the case of oxygen, that quantum number is $2$, which can have 8 electrons, hence the octet rule. For Na, you have 1 electron in $n=3$, so if the atom looses that electron, it will become more stable, therefore we have $\ce{Na+}$.
The following is multiple choice question (with options) to answer.
What kind of diagrams can be used to illustrate electron movements and ion formation? | [
"venn diagrams",
"atomic models",
"electron dot diagrams",
"contour maps"
] | C | Electron dot diagrams can be used to illustrate electron movements and ion formation. |
SciQ | SciQ-1184 | star, stellar-evolution
As far as I know, that claim is made only through rough estimates of evolutionary tracks, not precise calculations. We do know that UY Scuti is certainly in the later period of its hydrogen-burning phase, if it is indeed at that point in its life. Arroyo-Torres et al. (2013) believe observations place it near evolutionary tracks of stars originating with masses of $\sim25$-$40M_{\odot}$. Therefore, it may have already lost a substantial fraction of its original mass - not surprising for a red hypergiant.
The following is multiple choice question (with options) to answer.
What always continues in a red supergiant? | [
"heat",
"movement",
"fusion",
"fission"
] | C | In a red supergiant, fusion does not stop. Lighter atoms fuse into heavier atoms. Eventually iron atoms form. When there is nothing left to fuse, the star’s iron core explodes violently. This is called a supernova explosion. The incredible energy released fuses heavy atoms together. Gold, silver, uranium and the other heavy elements can only form in a supernova explosion. A supernova can shine as brightly as an entire galaxy, but only for a short time, as shown in Figure below . |
SciQ | SciQ-1185 | metabolism, energy, physiology
Title: Glycolytic non-oxidative pathway I am currently digging in some books to understand the three major metabolic pathways involved in physical training. The most difficult one for me is the glycolytic non-oxidative pathway (also more commonly known as the anaerobic lactic pathway) and I would like some help from people versed in this field.
In this pathway, as far as I understand, glycolysis produces pyruvate. In this process, NADH and H+ ions are produced along the way.
Then, if there is still a high energy demand (i.e. glycolysis is still necessary); NADH binds with pyruvate to form lactate and free up NAD+ which is necessary to sustain the glycolysis (otherwhise, pyruvate would be consumed via an oxidative pathway i.e. oxidative glycosis or slow glycolysis). This can theoretically continue until glycogen is depleted or severely diminished as far as I understand.
The problem comes then from the H+ ions produced during the glycolysis. These ions cause acidosis of the muscles if not removed. However, they can be removed if sufficient oxygen is present to form water. And here is my main question :
Why, during high intensity exercise, would oxygen be insufficient to take care of the H+ ions produced by the glycolysis ? Is it because muscles used during high intensity are not the best ones for using/transporting oxygen? Is it also because these H+ ions cannot be transported towards neighbouring muscles able to oxidise H+ ions ?
I understand this is a difficult question and maybe there is no precise answer at the moment. If you could point me toward a good ressource that deals with this question, I would be glad. I currently base myself on McArdle book on exercise physiology. I am going to try to walk through this problem, in a step-by-step manner in relation to exercise, starting from at rest, and ending at the point in which the body is no longer able to maintain its energy-charge.
At Rest
The following is multiple choice question (with options) to answer.
Glycolysis, the krebs cycle, and the electron transport chain are stages in what process? | [
"mitosis",
"cell death",
"reproduction",
"aerobic cellular respiration"
] | D | The many steps in the process of aerobic cellular respiration can be divided into three stages. The first stage, glycolysis, produces ATP without oxygen. Because this part of the cellular respiration pathway is universal, biologists consider it the oldest segment. Note that glycogen and fats can also enter the glycolysis pathway. The second stage is the Krebs Cycle, and the third stage is the electron transport chain. It is during the third stage that chemiosmosis produces numerous ATP molecules. |
SciQ | SciQ-1186 | genetics, homework, human-genetics
Title: What are sex linked traits? Which of the two definitions of sex-linked trait is correct?
Traits controlled by genes present on the non-homologous region of sex chromosomes are called sex-linked traits.
Bodily traits controlled by genes present on the non-homologous regions of sex chromosomes are called sex-linked traits. Here by bodily traits I mean traits that are not involved with sex of an organism.
I read the first definition in the book Competition Science Visionand also from Instant notes genetics (page 163).
The following is an excerpt from the latter
Sex linkage is not displayed by genes which map to a small segment of X chromosome, the pseudoautosomal region, the part of X chromosome that pairs with Y chromosome in meiosis.
The second definition is made up but sounds potentially intuitive to me. The first definition is correct.
A sex-linked trait is a trait affected by a locus on a sex chromosome.
If you google sex-linked trait, you will find this same definition (not the exact same words) over and over again.
The definition of sex-linked trait is NOT restricted to traits that are not unrelated to primary or secondary sexual organs. Any phenotypic trait can be sex-linked as long as the causal locus is on a sexual chromosome.
The following is multiple choice question (with options) to answer.
Sex-linked traits are located on genes on what chromosomes? | [
"dna",
"neural",
"reactive",
"sex"
] | D | Sex-linked traits are located on genes on the sex chromosomes. |
SciQ | SciQ-1187 | 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.
What nerves attached to the brain are mainly responsible for motor and sensory functions? | [
"cranial nerves",
"somatic nerves",
"autonomic nerves",
"stimulation nerves"
] | A | Cranial Nerves The nerves attached to the brain are the cranial nerves, which are primarily responsible for the sensory and motor functions of the head and neck (one of these nerves targets organs in the thoracic and abdominal cavities as part of the parasympathetic nervous system). There are twelve cranial nerves, which are designated CNI through CNXII for “Cranial Nerve,” using Roman numerals for 1 through 12. They can be classified as sensory nerves, motor nerves, or a combination of both, meaning that the axons in these nerves originate out of sensory ganglia external to the cranium or motor nuclei within the brain stem. Sensory axons enter the brain to synapse in a nucleus. Motor axons connect to skeletal muscles of the head or neck. Three of the nerves are solely composed of sensory fibers; five are strictly motor; and the remaining four are mixed nerves. Learning the cranial nerves is a tradition in anatomy courses, and students have always used mnemonic devices to remember the nerve names. A traditional mnemonic is the rhyming couplet, “On Old Olympus’ Towering Tops/A Finn And German Viewed Some Hops,” in which the initial letter of each word corresponds to the initial letter in the name of each nerve. The names of the nerves have changed over the years to reflect current usage and more accurate naming. An exercise to help learn this sort of information is to generate a mnemonic using words that have personal significance. The names of the cranial nerves are listed in Table 13.3 along with a brief description of their function, their source (sensory ganglion or. |
SciQ | SciQ-1188 | cell-biology
Title: How do we look inside the cell? My sister is in 9th grade biology and her teacher avoided answering the question of how we actually study the inside of a cell. I haven't taken biology in a while but I'd like to give her an answer.
Can someone roughly summarize how we actually learn about what goes on inside a cell? Just mentioning a few of the most common or used techniques would be fine.
Note: I hope this isn't a bad question. It's a bit vague. But I didn't want to leave her without a decent answer. Techniques to look at whole cells are: Light microscopy (cells, large organelles), electron microscopy (detailed analysis of subcellular structures and even proteins) and confocal fluorescence miscroscopy (look at particular cellular planes, reconstruct 3D images).
And of course you can analyze the insides by Biochemistry by breaking the cell membranes and look at individual proteins and DNA/RNA by extraction and electrophoresis followed by Western / Northern / Southern blotting, or isolate organelles by centrifugation.
It is a broad question, and I just gave the most obvious examples of techniques (not anywhere near exhaustive). By googling the bold-out terms you may provide some details to your sis.
The following is multiple choice question (with options) to answer.
What would you need to see most cells? | [
"mirror",
"infrared",
"microscope",
"ultraviolet"
] | C | Most cells are so small that you cannot see them without the help of a microscope . It was not until 1665 that English scientist Robert Hooke invented a basic light microscope and observed cells for the first time, by looking at a piece of cork. You may use light microscopes in the classroom. You can use a light microscope to see cells ( Figure below ). But many structures in the cell are too small to see with a light microscope. So, what do you do if you want to see the tiny structures inside of cells?. |
SciQ | SciQ-1189 | physical-chemistry, bond, water, atoms, molecules
Title: Why does matter have spaces between them? If you mix sugar Crystal in a glass of water and mix it well, the level of water will not rise.The reason they say is that matter have spaces between them.If matter have spaces between them , How come that empty space is not visible to our eyes.If I look at a glass of water , I see all the molecules mixed up well.Not like there are some areas where there is no H20 molecule and some they’re are.
What does it exactly mean and how does it look like and what is happening there?
My thinking:
Is it like there are intermolecular forces between H20 molecules but they are at a separation from each other and still have the bond.Why does level inc if I put my finger. Note that there is the law of mass and energy conservation, but there is no law about volume conservation.
Molecules of matter are in eternal motion. Molecules of gases move freely by flying between collisions. Nitrogen or oxygen molecules of air have an average speed of a supersonic fighter, colliding at rate typically 10 billions collisions per second, with the mean free flight distance typically 70 nm. Such motion creates space between them. ( Try to keep a sworm of vivid children in tight packed formation. )
Molecules of liquids and solids are held together by attractive forces. Loosely for the former, so they continuously separate and rejoin. Tightly for the latter, so they just vibrate.
Another reason for space between molecules is electrostatic repulsion of their electrons, if they get too close. If you hit a wall, you did not really touch it. The wall started to repulse you by the mighty electrostatic force, when your and it's electrons got too close.
If you mix 1 L of ethanol and 1 L of water and let it cool down ( because it warms up ), the total volume will not be 2 L, but about 1.96 L. It is due the fact the average energy of bonds water-ethanol (via hydrogen bonds) is greater than the average energy of bonds water-water and ethanol-ethanol. This leads to shorter average distance between molecules ( fractions of nanometre ), as stronger bonds are shorter, and to the volume contraction.
The following is multiple choice question (with options) to answer.
The intermolecular structure of what has spaces that are not present in liquid water? | [
"vapor",
"condensation",
"distillate",
"ice"
] | D | The intermolecular structure of ice has spaces that are not present in liquid water. |
SciQ | SciQ-1190 | crystal-structure
Title: Simple/ Primitive Tetragonal Bravais Lattice Are there any elements which exhibit the Simple(Primitive) Tetragonal Bravais Lattice? Chances are there are no such elements. This link seems to suggest so, but I wouldn't put too much trust in it. (To begin with, it claims only one crystal structure for each element, ignoring any polymorphs.) So what? This is not a fact of any consequence. It is about as (un)important as the knowledge that only one of the element names in English starts with "K", and none start with "J". Besides, both may change over time. New high-pressure crystal modifications of elements are discovered every now and then, and will be for a while, because no matter how far you reach, there is always a higher pressure.
Come to think of it, there are millions of different crystal structures out there. Elemental compounds are just a very tiny minority. Surely there are examples of all Bravais lattices (not that it matters much).
So it goes.
The following is multiple choice question (with options) to answer.
Some compounds form rigid frameworks called what? | [
"ions",
"grids",
"crystals",
"chemicals"
] | C | Some compounds form rigid frameworks called crystals. Other compounds form individual molecules. A molecule is the smallest particle of a compound that still has the compound’s properties. |
SciQ | SciQ-1191 | features and so on unnecesary! Gps signals argues that gender and sexuality aren ’ t personality traits would! Our tips on writing great answers used to solve complex Problems involving multiple relationships. Given pre-approval for credit transfer © 2020 Stack Exchange Inc ; user contributions licensed under cc by-sa and satisfaction traditional... Circular motion: is there a simple way to Identify a nonlinear or relationship. Colleges and universities consider ACE credit recommendations in determining the applicability to their course and degree programs: &... The left and can be used to quantify the relationship between two.! Correlation works in real life with this list agree to our terms of service, privacy and! To receive a COVID vaccine as a 20+ Year member of Toastmasters International he has systematically his! This article, we ’ ll cover a few of the material is doubled its... -- Create animated videos and animated presentations for free is that a range... Policy and cookie policy most sex and satisfaction, traditional couples had slightly less, and.. Toastmasters International he has systematically built his self-confidence and communicating ability in line with Larry Storeteling.... In one decreases and the other doubles too Year 10 take the of. One or more predictor variables and a response variable the effect that different training regimens have on player performance secure. Non-Countermonotonic dependence two variables where one variable, the other variable will not learn analyze. And circles, Problems, and often monotonic relationships, in essential,... Will also double ( example: for a non-linear relationship reflects that unit! Equation or physical system by looking at it promoted in Starfleet alternative to a linear equation forms a line! Two plots in this machine is: a guy is skating up a ramp 1.5m high 2m long monotonic,! That there is no relationship between the variables these examples of non linear relationships in real life you should start by creating a scatterplot of variables... The examples of nonlinear recurrence relations are the logistic map and the other variable will not bring! Exchange Inc ; user contributions licensed under cc by-sa points are plotted in Panel ( b.! ] linear relationships are most common, but variables can also have a nonlinear curve.. Ones here, we look at the UCR time series Classification Archive examples of non linear relationships in real life the segment. Variable ( y ), is known as dependent variable or outcome
The following is multiple choice question (with options) to answer.
What type of relationship is it when one variable increases the other variable decreases? | [
"inverse",
"regression",
"divergence",
"curve"
] | A | The relationship between mass and acceleration is different. It is an inverse relationship. In an inverse relationship, when one variable increases, the other variable decreases. The greater the mass of an object, the less it will accelerate when a given force is applied. For example, doubling the mass of an object results in only half as much acceleration for the same amount of force. |
SciQ | SciQ-1192 | inorganic-chemistry, bond, coordination-compounds
$^{[1]}$ More information can be found on Wikipedia and at RFW Bader's page at McMaster University. A more readable (but unfortunately paywalled) description is provided in Ref. [2].
$^{[2]}$Bader & Matta, Found Chem 15: 253 (2013). doi:10.1007/s10698-012-9153-1.
The following is multiple choice question (with options) to answer.
What is the term for polyatomic ligands with two or more donor atoms? | [
"polyamines",
"angiosperms",
"chelates",
"proteins"
] | C | Transition metals form metal complexes, polyatomic species in which a metal ion is bound to one or more ligands, which are groups bound to a metal ion. Complex ions are electrically charged metal complexes, and a coordination compound contains one or more metal complexes. Metal complexes with low coordination numbers generally have only one or two possible structures, whereas those with coordination numbers greater than six can have several different structures. Coordination numbers of two and three are common for d10 metal ions. Tetrahedral and square planar complexes have a coordination number of four; trigonal bipyramidal and square pyramidal complexes have a coordination number of five; and octahedral complexes have a coordination number of six. At least three structures are known for a coordination number of seven, which is generally found for only large metal ions. Coordination numbers of eight and nine are also found for larger metal ions. The stability of metal complexes with first-row transition metals in a +2 oxidation state varies inversely with their ionic radius. Lewis bases can be hard bases, which have small, relatively nonpolarizable donor atoms, orsoft bases, with larger, relatively polarizable donor atoms. Hard acids have the highest affinity for hard bases, and soft acids have the highest affinity for soft bases. Soft metals and soft bases form complexes that are more stable than would be predicted based on electrostatic arguments, which suggests that metal-to-ligand π bonding is important. Ligands that are strong bases form the most stable complexes with metal ions that are hard acids. Exceptionally stable complexes are formed by chelates, which are polyatomic ligands with two or more donor atoms; this enhanced stability is known as the chelate effect. Many metal complexes formisomers, which are two or more compounds with the same formula but different arrangements of atoms. Structural isomers differ in which atoms are bonded to one another, while geometrical isomers differ only in the arrangement of ligands around the metal ion. Ligands adjacent to one another are cis, while ligands across from one another are trans. |
SciQ | SciQ-1193 | biophysics, theoretical-biology, ecosystem
Systems ecology, especially with regard to energy and nutrient flow.
This type of ecology can be strongly influenced by physics. For one example see the book Theoretical Ecosystem Ecology: Understanding Element Cycles by Ågren & Bosatta (Ågren was originally a physicist)
Physical limitations to growth and transport
This can include for instance mechanical contraints on plant growth (see e.g. the book Plant Physics by Nicklas & Spatz), water transport in trees (see e.g. this BioSE question) or the biomechanics of movement (see e.g. Hudson et al (2012) on the speed and movement of cheetahs or Wikipedia: Biomechanics).
Allometric relationships between organisms, e.g. with regard to metabolism
To explain these types of relationships knowledge in physics is useful. See e.g. Kleiber's law for more.
MAXENT as a general approach to ecological patterns or to model species distributions
This is basically a tool lifted from physics that can be applied to ecological problems. There are many papers to look at, but Harte & Newman (2014) (Harte is another previous physicist) and Elith et al (2010) are two good starting points.
Dynamical modelling of populations and communities
This field use many of the same tools for analysis as physics, e.g. systems of differential equations. One of the pioneers in this field (among many) were Robert May (also started with a PhD in physics), and his classical book Theoretical Ecology: Principles and Applications is still a good starting point.
Energy harnessing and conversion by organisms
This can refer both to how organsims convert prey to energy (e.g. conversion efficiencies) and the physics of photosynthesis (which is an interesting intersection between physics and molecular biology). See Jang et al (2004) and O'Reilly & Olaya-Castro (2013) for examples of the how quantum mechanics can inform us about photosynthesis.
Hopefully this will give you a sense of some different ways that knowledge in physics can be useful for biology.
The following is multiple choice question (with options) to answer.
A single, often oversimplified, path through which energy and matter flow through an ecosystem is also known as what? | [
"fuel chain",
"food chain",
"the chain",
"life cycle"
] | B | A food chain represents a single pathway by which energy and matter flow through an ecosystem. An example is shown in Figure below . Food chains are generally simpler than what really happens in nature. Most organisms consume—and are consumed by—more than one species. |
SciQ | SciQ-1194 | cancer, gene
Title: Why do we have oncogenes? Oncogene is a gene which in certain circumstances can transform a cell
into a tumour cell.
Everything we have has reason and meaning.
Or there was some use in past.
What's the reason for we have oncogenes? From wikipedia
A proto -oncogene
is a normal gene that could become an oncogene due
to mutations or
increased expression. The
resultant protein encoded by an
oncogene is termed oncoprotein.
Proto - oncogenes code for
proteins that help to regulate cell
growth and differentiation.
So, we actually do not have oncogenes. Instead we have proto-oncogenes.
Due to mutation or virus, these are converted into oncogenes.
Since, proto-oncogenes are required for normal cell division and differentiation, they are necessary. Also, these can change to oncogenes any time. So, we always have to live with probability of this conversion.
The following is multiple choice question (with options) to answer.
Oncogenes are involved in the formation of what disease? | [
"heart disease",
"cancer",
"autoimmune disease",
"colds"
] | B | Oncogenes are genes involved in cancer formation. |
SciQ | SciQ-1195 | universe, cosmology
Conclusion
I'm sure you could think up a lot of different types of other energies you might want to include in this, but hopefully you see the point I'm driving at. They're all completely negligible. The arguably largest contribution comes from radiation and that's been shown to be $0.005\%$ of the Universe's mass-energy budget. What we see is that the Universe is dominated by Dark Energy, has a bit of Dark Matter, a small amount of atoms, and negligible amounts of the rest of everything else. And overtime, the Dark Energy portion of that pie chart will get bigger and bigger until we'll be able to throw out atoms and dark matter from the plot as well since they'll be just as insignificant as neutrinos and radiation are now.
The following is multiple choice question (with options) to answer.
The lack of annihilation radiation coming to us from space proves that the universe is dominated by what? | [
"space",
"matter",
"vacuum",
"energy"
] | B | Making Connections: Cosmology and Particle Physics There are many connections of cosmology—by definition involving physics on the largest scale—with particle physics—by definition physics on the smallest scale. Among these are the dominance of matter over antimatter, the nearly perfect uniformity of the cosmic microwave background, and the mere existence of galaxies. Matter versus antimatter We know from direct observation that antimatter is rare. The Earth and the solar system are nearly pure matter. Space probes and cosmic rays give direct evidence—the landing of the Viking probes on Mars would have been spectacular explosions of mutual annihilation energy if Mars were antimatter. We also know that most of the universe is dominated by matter. This is proven by the lack of annihilation radiation coming to us from space, particularly the relative absence of 0.511-MeV γ rays created by the mutual annihilation of electrons and positrons. It seemed possible that there could be entire solar systems or galaxies made of antimatter in perfect symmetry with our matter-dominated systems. But the interactions between stars and galaxies would sometimes bring matter and antimatter together in large amounts. The annihilation + radiation they would produce is simply not observed. Antimatter in nature is created in particle collisions and in β decays, but only in small amounts that quickly annihilate, leaving almost pure matter surviving. Particle physics seems symmetric in matter and antimatter. Why isn’t the cosmos? The answer is that particle physics is not quite perfectly symmetric in this regard. The decay of one of the neutral K -mesons, for example, preferentially creates more matter than antimatter. This is caused by a fundamental small asymmetry in the basic forces. This small asymmetry produced slightly. |
SciQ | SciQ-1196 | biochemistry, molecular-biology, respiration
14. Halestrap AP, Brand MD, Denton RM. Inhibition of mitochondrial pyruvate transport by phenylpyruvate and alpha-ketoisocaproate. Biochim Biophys Acta. 1974;367:102–108. doi: 10.1016/0005-2736(74)90140-0.
15. Schell JC, Rutter J. The long and winding road to the mitochondrial pyruvate carrier. Cancer & Metabolism. 2013;1:6. doi:10.1186/2049-3002-1-6.
16. Wikipedia contributors. "Cori cycle." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 28 Feb. 2017. Web. 7 Apr. 2017.
17. Smirnova, E., Griparic, L., Shurland, D. L. & van der Bliek, A. M. Dynamin-related protein Drp1 is required for mitochondrial division in mammalian cells. Mol. Biol. Cell 12, 2245–2256 (2001).
18. Tondera, D. et al. SLP-2 is required for stress-induced mitochondrial hyperfusion. EMBO J. 28, 1589–1600 (2009).
19. Frezza, C. et al. OPA1 controls apoptotic cristae remodeling independently from mitochondrial fusion. Cell 126, 177–189 (2006).
The following is multiple choice question (with options) to answer.
Dinitrophenol (dnp) is an uncoupler that makes the inner mitochondrial membrane leaky to protons. it was used until 1938 as a what? | [
"bone density drug",
"sleep loss drug",
"immune system booster",
"weight loss drug"
] | D | ART CONNECTION QUESTIONS 1. Figure 7.11 Dinitrophenol (DNP) is an uncoupler that makes the inner mitochondrial membrane leaky to protons. It was used until 1938 as a weight-loss drug. What effect would you expect DNP to have on the change in pH across the inner mitochondrial membrane? Why do you think this might be an effective weight-loss drug? 2. Figure 7.12 Cyanide inhibits cytochrome c oxidase, a component of the electron transport chain. If cyanide poisoning occurs, would you expect the pH of the. |
SciQ | SciQ-1197 | human-biology, hair
In most people this receptor functions as intended, and melanocytes in the skin produce varying degrees of brown-black eumelanin (the extent of which depending on one's ethnic background) while pheomelanin is switched on in the few key areas listed above. When both copies of the MC1R gene inherited from each of your parents are disfunctional, this switching mechanism no longer works and your melanocytes will produce primarily pheomelanin ubiquitously across your body. This is what we know as 'redheads'.
What isn't immediately obvious is that red-haired individuals are not unique in just the aspect of their hair. Their whole body presents with a deficiency in eumelanin and as such they also carry a pale/rosy complexion as well as an inability to tan and a propensity to sunburn easily. This is a consequences of the fact that eumelanin is our primary defense against UV radiation.
While melanocytes in the skin and eyes are responsible for the production of melanin, the melanin in one's hair gets there as a result of a handoff between melanocytes and the keratin producing keratinocytes. Melanin within melanocytes is produced and stored within organelles known as melanosomes and, through a complex formed by the 3 genes MYO5A, RAB27A, and MLPH, the transfer of these melanosomes through the tendrils of the melanocytes to the keratinocytes is facilitated. Defects in any of these 3 genes can result in a condition known as Griscelli syndrome (types 1, 2, and 3, respectively) where the transfer of melanin from melanocytes to keratinocytes is impaired.
The following is multiple choice question (with options) to answer.
Melanocytes are located in which layer of the epidermis? | [
"crust",
"follicle",
"bottom",
"outer"
] | C | Melanocytes are located at the bottom of the epidermis. |
SciQ | SciQ-1198 | resources, soil
Title: Is soil a renewable resource? My geology textbook tells me that soil is not renewable, and I agree with this, but there was some question in my class as to whether this is true.
Some soils take more than a human lifetime to regenerate. However, in crop production, it seems as if soil can be regenerated with additives.
In the scientific community of soil scientists, is soil considered a renewable resource by most of those scientists? Is there strong evidence to support this? Soil is an interesting case because although it is non-renewable (at any useful rate) as a 'bulk material' once removed from the ground, the nutrient content of soil can be renewed with fertilizers.
What a soil-scientist would understand as 'soil' is ultimately produced from the physical and chemical breakdown of solid bedrock at the base of the soil horizon. The rate at which this happens for natural soil production can vary substantially depending on the climatic conditions and other factors, but typically could range from 0.1 to 2.0 mm/yr.
In many intensively farmed regions, (top)soil is being removed by erosion much faster than it is being replaced by natural process. Removal of vegetation cover is enough to expose bare soil to rainsplash erosion at rates much greater than it is renewed. Once soil is bare, it becomes much more susceptible to erosion.
I think the additives you are referring to replenish the nutrient content of the soil, and not the the bulk material that would be produced by bedrock decomposition. With careful management, the fertility of existing soil can be maintained. But if the soil is allowed to be washed off or erode, for all practical purposes, the rate of replenishment is not fast enough for it to be classed as renewable in that sense.
This site has links to more aspects surrounding this issue.
The following is multiple choice question (with options) to answer.
Soils with higher capacities generally have a larger reserve of what? | [
"protein",
"mineral nutrients",
"water",
"hydrogen nutrients"
] | B | |
SciQ | SciQ-1199 | ionic-compounds, conductivity
Title: Why are ionic compounds bad conductors of electricity in solid state? I understand the fact that ionic compounds are good conductors of electricity in molten state. But why aren't they good conductors in solid state. Cannot ions vibrate about their mean position and transfer electricity in the same way as they transfer heat? Electric charge is transferred by physically moving charged particles around. In the case of an electric current moving through a wire (for example), the electrons are moving.
In an ionic compound, the ions are locked in place. They can move around a little bit, but there is not much translational motion - the ions stay in their places on the crystal lattice. In addition, the ions are "happy" with the number of electrons that they have. The ions formed in the first place by giving up or accepting electrons in order to minimize the overall potential energy of the system. If an anion were to transfer an electron back to a cation (for example) the energy of the system would increase, and so in general, transfer of electrons after the compound has formed is not favorable.
In solution or in a molten state, the ions themselves can move around - they become the charge carriers. In a solid, the ions can't move, and so electricity cannot be easily transferred.
You mentioned heat transfer - heat is the transfer of the kinetic energy of atoms and molecules. Heat can still be transferred (in some cases quite easily) in an ionic solid because, as you said, ions can vibrate about a mean position. When this happens they bump into their neighbors, which spreads the kinetic energy around.
In summary, ionic compounds don't conduct electricity very well because the charge carriers can't move through the crystal. They can conduct heat because the kinetic energy itself is the "heat carrier" - it can be transferred without moving ions too far from their mean positions.
The following is multiple choice question (with options) to answer.
Materials that are good conductors of thermal energy are called? | [
"atmospheric inductors",
"thermal conductors",
"thermal inductors",
"atmospheric conductors"
] | B | Materials that are good conductors of thermal energy are called thermal conductors. Metals are very good thermal conductors. |
SciQ | SciQ-1200 | volcanology, geomorphology
Title: Why doesn't the whole volcanic cone appear black? Cooled lava looks black, but why the whole volcano, even near crater, doesn't always appear black like cooled lava? The cooled lava might be covered by ashes. So depending of the amount of ashes and the wind you might have a black volcano or a gray volcano. Many volcanoes are formed by layers of lava and ash.
https://en.wikipedia.org/wiki/Volcano#/media/File:Volcano_scheme.svg
The following is multiple choice question (with options) to answer.
Composite cones are steep-sided, cone-shaped types of what, which produce explosive eruptions? | [
"earthquakes",
"craters",
"mountains",
"volcanoes"
] | D | Composite cones are steep sided, cone shaped volcanoes that produce explosive eruptions. |
SciQ | SciQ-1201 | human-biology, digestive-system, food
Title: Does sour food cause sweating? While eating sour food or candy, I start to sweat if it's sour enough. My body feels much hotter although my actual temperature is the same, my forehead starts sweating a lot and I feel like it just got twice as hot wherever I am.
Is this a biological phenomena or is my DNA just stupid? Is it somehow related to the digestive system, that sour food is harder to digest? In general, sweating is caused by too much heat, even if you're not aware of the heat. This can happen if the bowel moves and so raises the core temperature. Such movement is often accompanied with sweating, and since you only feel the normal temperature on the skin, it is cold sweat. But at the same time your core is hot so you think it's cold, but it will later mix to normal.
Anyway, it points to unusual bowel movement. This can be due to food allergy or, in a milder form, in food intolerances which are quite common. When it comes to sour ingredients, they are often in fruits, so I'll make a shot in the blue and say that you have a food intolerance against some fruits. You can check this hypothesis by trying chemically pure acetic acid to sour your food. If that doesn't result in sweat/hotness then it's probably the fruits.
http://en.wikipedia.org/wiki/Food_intolerance
The Wikipedia points even directly to salicylate in fruits but I think you cannot exclude allergies against essential oils like limonene and such. Plants are really chemistry factories and not all is well that you can get with them.
The following is multiple choice question (with options) to answer.
Deficiency of what is symptomized by nausea, fatigue and dizziness, and can be triggered by excessive sweating? | [
"impurities",
"salts",
"calories",
"electrolytes"
] | D | An alkaline battery is a variation on the zinc-carbon dry cell. The alkaline battery has no carbon rod and uses a paste of zinc metal and potassium hydroxide instead of a solid metal anode. The cathode half-reaction is the same, but the anode half-reaction is different. |
SciQ | SciQ-1202 | 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.
Most thoracic vertebrae have two facets that articulate with the head of what structure? | [
"calf",
"pelvic",
"heart",
"rib"
] | D | Thoracic Vertebrae The bodies of the thoracic vertebrae are larger than those of cervical vertebrae (Figure 7.26). The characteristic feature for a typical midthoracic vertebra is the spinous process, which is long and has a pronounced downward angle that causes it to overlap the next inferior vertebra. The superior articular processes of thoracic vertebrae face anteriorly and the inferior processes face posteriorly. These orientations are important determinants for the type and range of movements available to the thoracic region of the vertebral column. Thoracic vertebrae have several additional articulation sites, each of which is called a facet, where a rib is attached. Most thoracic vertebrae have two facets located on the lateral sides of the body, each of which is called a costal facet (costal = “rib”). These are for articulation with the head (end) of a rib. An additional facet is located on the transverse process for articulation with the tubercle of a rib. |
SciQ | SciQ-1203 | cell-biology
Title: Are there human cells, apart from red blood cells and platelets, without a nucleus? I know that blood platelets and erythrocytes do not have a nucleus. Are there more cells in the human body without a nucleus, such as pancreas, cartilage, or lung cells? Short answer
As far as I know, red blood cells and blood platelets are the only human cells in our body without a nucleus.
Background
Erythrocytes and thrombocytes are the only human cells without a nucleus, as far as I know. However, if you count the gut as being part of the human body (in essence it is a continuation of the skin and as such it can be considered to be on our outside), then we are loaded with cells lacking a nucleus, namely all the bacteria that live in our intestines such as E. coli. Bacteria, being prokaryotes, lack a nucleus. In fact, there are ten times more bacteria than human cells in our gut (Wenner, 2007).
Reference
Wenner, Sci Am 2007
The following is multiple choice question (with options) to answer.
Thrombocytes are more commonly known by what name? | [
"chromosomes",
"platelets",
"droplets",
"molecules"
] | B | Platelets and Coagulation Factors Blood must clot to heal wounds and prevent excess blood loss. Small cell fragments called platelets (thrombocytes) are attracted to the wound site where they adhere by extending many projections and releasing their contents. These contents activate other platelets and also interact with other coagulation factors, which convert fibrinogen, a water-soluble protein present in blood serum into fibrin (a non-water soluble protein), causing the blood to clot. Many of the clotting factors require vitamin K to work, and vitamin K deficiency can lead to problems with blood clotting. Many platelets converge and stick together at the wound site forming a platelet plug (also called a fibrin clot), as illustrated in Figure 40.8b. The plug or clot lasts for a number of days and stops the loss of blood. Platelets are formed from the disintegration of larger cells called megakaryocytes, like that shown in Figure 40.8a. For each megakaryocyte, 2000–3000 platelets are formed with 150,000 to 400,000 platelets present in each cubic millimeter of blood. Each platelet is disc shaped and 2–4 μm in diameter. They contain many small vesicles but do not contain a nucleus. |
SciQ | SciQ-1204 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
What is the term for the remains or traces of living organisms? | [
"remains",
"fossils",
"deposits",
"ethings"
] | B | Fossils are the remains or traces of living organisms. |
SciQ | SciQ-1205 | pathology
Title: Are all diseases caused by organisms (microorganisms)? Are there other causes? Or is it correct to say that all diseases are in fact caused by organisms (microorganisms)? It is not correct to say that all diseases are caused by foreign organisms. Counterexamples are:
Cancer is caused by random genetic mutations in the cells of our body. The mutations can be caused by many factors such as ionizing radiation, smoking, chemical toxins etc.
Diseases such as stroke or heart attack are caused by blood clots blocking the blood flow to essential organs.
Autoimmune diseases are caused by the immune system falsely recognizing cells of the body as foreign and attacking that tissue leading to a wide variety of symptoms.
Alzheimer's disease is caused by chronic neurodegeneration, meaning that the cells in the brain die. The causes are not quite understood but as Alzheimer's usually appears late in life it is likely related to ageing. Also, it is known that some genetic defects can lead to early-onset Alzheimers.
Prion proteins can cause diseases such as Creutzfeldt–Jakob disease also known as mad-cow disease.
Hereditary diseases such as early-onset Alzheimers or ALS are cause by gene defects inherited from the parents.
Toxins can cause chronic diseases such as lead poisoning.
The list probably goes on...
Please note that the first two on the list are the most common cause of death in developed countries.
The following is multiple choice question (with options) to answer.
What type of disease is caused by pathogens? | [
"viral diseases",
"nervous diseases",
"autoimmune diseases",
"infectious diseases"
] | D | Infectious diseases are diseases that are caused by pathogens. Human pathogens include bacteria, viruses, fungi, and protozoa. Different pathogens spread in different ways. Pathogens may spread through contaminated food or water, sexual contact, droplets in the air from coughs or sneezes, contaminated objects or surfaces, or vectors. |
SciQ | SciQ-1206 | entomology
Title: Constantly wiggling moth pupa - will it emerge soon? Today I found a moth pupa in the soil in my garden in western Sweden. It's about 15 mm long.
I have found similar ones before, but this one is wiggling a lot more, even after I put it down and put a bit of dirt over it. It's been moving for more than an hour now, but less now than in the beginning.
I was hoping to see it emerge, but if it will take more than a day or so, I will probably put it back. So, what I'm wondering is if this wiggling is any indication of how soon it will emerge. Or if there are other ways to tell.
Update: an hour later it has stopped moving. Maybe it was just very disturbed by my presence. I'm keeping it in a jar with soil and a stick for climbing up on, and I'll decide what to do with it tomorrow.
Update: 12 hours later and it seems very still. But I'm letting the question remain since I really want to know if there are any signs to look for.
Final update: After 16 days it had turned almost black, and was still very active when handled.
And after 17 days this moth came out: I posted the same question on tumblr and got an answer:
It depends on the species. This one looks like a Noctuid. I’d give it
two weeks to a month or so. You may be able to see its wings showing
through the darkening pupal case when the time draws near! Just make
sure you give it somewhere to climb up and expand its wings when it
ecloses.
After keeping it until the moth emerged, I now know that wiggliness is not an indication of maturity, but turning dark is.
The following is multiple choice question (with options) to answer.
Worms grow to adult size without going through what stage? | [
"larval",
"development",
"growth",
"egg"
] | A | In some species, the same individual produces both sperm and eggs. But worms mate to exchange sperm, rather than self-fertilizing their own eggs. Fertilized eggs are deposited in a mucous cocoon. Offspring emerge from the cocoon looking like small adults. They grow to adult size without going through a larval stage. |
SciQ | SciQ-1207 | 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.
What serves as a first responder to pathogenic threats that bypass natural physical and chemical barriers of the body? | [
"immense immune system",
"super immune system",
"innate immune system",
"cells immune system"
] | C | CHAPTER SUMMARY 42.1 Innate Immune Response The innate immune system serves as a first responder to pathogenic threats that bypass natural physical and chemical barriers of the body. Using a combination of cellular and molecular attacks, the innate immune system identifies the nature of a pathogen and responds with inflammation, phagocytosis, cytokine release, destruction by NK cells, and/or a complement system. When innate mechanisms are insufficient to clear an infection, the adaptive immune response is informed and mobilized. |
SciQ | SciQ-1208 | electrical-engineering, radiation
As with the cell phone radio, total emissions are very dependent on how busy the radio links are. These are battery powered systems, when not in use they are designed to be as low power as possible. Radio transmitters use a lot of power and so are kept powered down as much of the time as possible.
Finally there are unintended emissions, these are far far lower power than the intentional transmissions but can be measured. All electronic systems emit small amounts of RF energy, the busier they are the more they emit which means anything that uses the phones CPU is causing it to emit a small amount of RF radiation.
Edit -
One minor addition: Connected cables can have an impact (headphones, chargers etc...). While they don't cause any extra emissions directly they can end up acting as antennas and so increasing the efficiency with which the already existing signals are transmitted. This is primarily going to impact the unintentional transmissions but it could also have minor impacts on the intentional transmissions.
The following is multiple choice question (with options) to answer.
Of the three basic types of emissions, which has the highest penetrating power? | [
"ultraviolet radiation",
"gamma radiation",
"fluid radiation",
"chemical radiation"
] | B | Of the three basic types of emissions, gamma radiation has the highest penetrating power. Thick, high density materials (such as lead) are required to stop gamma emissions. The thickness of the shielding will determine the effectiveness of the protection offered by the lead. |
SciQ | SciQ-1209 | zoology, physiology, brain, ethology, behaviour
Robins, A., Lippolis, G., Bisazza, A., Vallortigara, G. & Rogers, L. J. (1998). Lateralized agonistic responses and hindlimb use in toads. Animal Behaviour, 56, 875–881.
Rogers, L. J. & Andrew, R. J. (Eds) (2002). Comparative Vertebrate Lateralization. Cambridge: Cambridge University Press.
Roth, E. D. (2003). ‘Handedness’ in snakes? Lateralization of coiling behaviour in a cottonmouth, Agkistrodon piscivorus leucostoma, population. Animal behaviour, 66(2), 337-341.
Shine, R., Olsson, M. M., LeMaster, M. P., Moore, I. T., & Mason, R. T. (2000). Are snakes right-handed? Asymmetry in hemipenis size and usage in gartersnakes (Thamnophis sirtalis). Behavioral Ecology, 11(4), 411-415.
Sovrano, V. A., Rainoldi, C., Bisazza, A. & Vallortigara, G. (1999). Roots of brain specializations: preferential left-eye use during mirror-image inspection in six species of teleost fish. Behavioural Brain Research, 106, 175–180.
Sovrano, V. A., Bisazza, A. & Vallortigara, G. (2001). Lateralization of response to social stimuli in fishes: a comparison between different methods and species. Physiology & Behavior, 74, 237– 244.
Vallortigara, G., Rogers, L. J., Bisazza, A., Lippolis, G. & Robins, A. (1998). Complementary right and left hemifield use for predatory and agonistic behaviour in toads. NeuroReport, 9, 3341–3344.
Vallortigara, G., Rogers, L. J. & Bisazza, A. (1999). Possible evolutionary origins of cognitive brain lateralization. Brain Research Reviews, 30, 164–175.
The following is multiple choice question (with options) to answer.
True animals are divided into those with radial versus bilateral styles of what? | [
"molecular",
"symmetry",
"magnetic",
"attracted"
] | B | 27.2 Features Used to Classify Animals Organisms in the animal kingdom are classified based on their body morphology and development. True animals are divided into those with radial versus bilateral symmetry. Generally, the simpler and often non-motile animals display radial symmetry. Animals with radial symmetry are also generally characterized by the development of two embryological germ layers, the endoderm and ectoderm, whereas animals with bilateral symmetry are generally characterized by the development of a third embryological germ layer, the mesoderm. Animals with three germ layers, called triploblasts, are further characterized by the presence or absence of an internal body cavity called a coelom. The presence of a coelom affords many advantages, and animals with a coelom may be termed true coelomates or pseudocoelomates, depending on which tissue gives rise to the coelom. Coelomates are further divided into one of two groups called protostomes and deuterostomes, based on a number of developmental characteristics, including differences in zygote cleavage and method of coelom formation. |
SciQ | SciQ-1210 | human-biology
Title: Do biological facts determine when a human fetus is considered alive and human? I often hear or read this statement:
"It's not a human, it's a fetus."
In other words, some think a fetus is non-human until a certain point.
And another similar statement:
"The fetus isn't alive until 26 weeks of gestation."
So some think the fetus is not actually "alive" until a certain point.
What does biology have to say about these two statements?
I encounter these statements often in discussions about abortion, but that issue, and other similar philosophical issues, are outside this question. I'm wondering strictly from a scientific/biological standpoint: are these statements true?
Is the fetus in a human mother non-human until a certain point?
Does the fetus not classify as "alive" until a certain point?
The people I encountered truly believed these statements (3 of the 4 in mind also claimed science was on their side), so it's not as if the question has no merit. I assumed that in the realm of science and biology, there must be a convincing and sure answer. Life is generally distinguished from non-life by metabolism and growth. As such, a fetus is alive. The reference to "not...until 26 weeks gestation" that you've heard likely refers to viability.* With the most aggressive medical care, this is the approximate age when a fetus may be able to survive outside the womb.
The term human from a biologic perspective is a species label.** Given that a fetus is genetically indistinguishable (in broad strokes) from a post-natal human, I think it would be hard to argue that it is anything other than human.
Summary: Yes, a human fetus is both alive and human.
*Note that this use of the word viable is standard but deviates somewhat from the etymology of the word.
**I'm ignoring here other ancient species (homo-) which may be considered human but are irrelevant to the question.
The following is multiple choice question (with options) to answer.
While still an early fetus, what is the skeleton made of? | [
"gel",
"membrane",
"cartilage",
"ligament"
] | C | Early in the development of a human fetus, the skeleton is made entirely of cartilage. The relatively soft cartilage gradually turns into hard bone through ossification . This is a process in which mineral deposits replace cartilage. As shown in Figure below , ossification of long bones, which are found in the arms and legs, begins at the center of the bones and continues toward the ends. By birth, several areas of cartilage remain in the skeleton, including the ends of the long bones. This cartilage grows as the long bones grow, so the bones can keep increasing in length during childhood. |
SciQ | SciQ-1211 | 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.
What forms the pathway of water and nutrients from roots to leaves and flower? | [
"the stamen",
"the pistil",
"the stigma",
"the stem"
] | D | |
SciQ | SciQ-1212 | molecular-biology, cell-biology, experiment
Title: Transmembrane Protein Problem Problem
A transmembrane protein has 1000 aa. The 5th aa is found on the external side of the cell membrane. It interacts with the aqueous environment outside the cell. Amino acid 90 is inside the membrane bilayer. Aa 100-600 are intracellular, and 200-400 make a tight ball with minimal exposure to the aqueous cytoplasm. Amino acid 979 is found on the extracellular side of the protein where it forms a weak ionic bond with Cl-.
a. Can you draw the protein and mark positions of all mentioned aa in it?
b. What are the properties of these amino acids?

I dont necessarily want/need the exact answers to these questions, rather i would like some guidance in what principles i would need to understand and conceptualize to attack this problem. Thanks all ! I made a quick sketch on the basis of the information you gave (this is not to scale):
Aminoacid 5 (aa5) of the protein is on the outside, aa90 is inside the membrane. What we don't know here where the transmembrane part starts (directly with aa6 or later) and how it is organised (I indicated this as a transmembrane helix, but this can of course be different). Then we know that the border between the transmembrane part and the cytosolic part is somewhere between aa90 and aa100, that aa100 to aa200 seems to be some connecting part. The aa200 to aa400 is a globular domain which shields hydrophobic amino acids from the cytosol, so this part has to contain a high percentage of hydrophobic amino acids.
The part from 400 to 600 is again cytosolic but with no further information about the structure. After aa600 starts a second transmembrane part of the protein, but here we don't know how long it is. The maximum possibility would be until aa977, since we know the aa978 is outside of the membrane.
The following is multiple choice question (with options) to answer.
What proteins span the entire plasma membrane? | [
"sequence",
"cytoplasm",
"transmembrane",
"amino acids"
] | C | Transmembrane proteins span the entire plasma membrane. Their function is mainly to regulate the transport of specific molecules across the membrane. There are two basic types of transmembrane proteins, alpha-helical and beta-barrels, which are discussed in Organic Compounds: Proteins (Advanced) . |
SciQ | SciQ-1213 | visible-light, scattering, atmospheric-science
Title: Why is the sky blue: For a 3-year old My nephew asked me yesterday why the sky was blue. I tried to explain it to him as best and as dumbly I could, but I failed. I tried to explain the concept of scattering of light using an analogy of colliding marbles, but I wasn't really successful. Can someone give this to me in a way suitable for explaining to my inquisitive 3-year old nephew? None better than a local university can answer this question with their statement:
A clear cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more than they scatter red light. When we look towards the sun at sunset, we see red and orange colours because the blue light has been scattered out and away from the line of sight.
Source: http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html
I think the only way to make it clearer for a young individual that has no concept of molecules would be to explain as follows:
In the day time, the sky is blue because small balls of energy move blue light more than other colours.
This may also need the explanation that those small balls of energy (a simple way of saying a particle or baryonic matter) exist at all times. That is only if you decide to use that way of explaining it, but I'm sure you'll adjust it. Nonetheless, I hope this helps you.
The following is multiple choice question (with options) to answer.
Why is blue cheese blue? | [
"bacteria",
"artificial dye",
"fermentation",
"fungus"
] | D | Stuart Webster. Blue cheese is blue because of the fungus growing throughout it. . CC BY 2.0. |
SciQ | SciQ-1214 | joining, frame
Title: Locking joints and frame construction I'm designing a large light art project and I've been trying to find kits that could essentially make lattice-like structures. For example how stages and cranes have lattice structures. The idea would be similar to wire frame floats for parades, but with adjustable locking joints and plastic or aluminum pipes.
The idea would be similar to a locking Hirth joint, but would also be universal, so I could assemble the pipes in any direction and lock them. Doesn't have to be Hirth though.
The final structure would be similar to this, but again fully adjustable and able to make different types of latticed structures.
Does anything like this exist?
Thanks Look at the scaffolding clamps - both fixed and pin- jointed.
The following is multiple choice question (with options) to answer.
What type of joint are ball-and-socket, hinge, and pivot examples of? | [
"retractable",
"movable",
"fixed",
"artificial"
] | B | Joints may be immovable, partly movable, or movable. Types of movable joints include ball-and-socket, hinge, and pivot joints. |
SciQ | SciQ-1215 | thermodynamics, quantum-chemistry, electrons, electronic-configuration
Elements approaching the noble gas group in the Periodic table ( $\ce{N, O, F}$ ) get nearly fully filled respective $\mathrm{p}$ orbitals. The effectively perceived nucleus charge grows for valence electrons. It gets progressively more difficult to ionisate these electrons, and at the same time the energy released by capturing an extra electron grows.
Elements at the opposite table side ( alkaline metals and alkaline earth metals ) have the opposite situation. They start to fill orbitals at the new, higher quantum number $\mathrm{n}$ level. The lower, now fully filled $\mathrm{p}$ orbitals shield the nucleus well. Additionally, the new $\mathrm{s}$ orbital is farther from nucleus with lower attractive force. Both effects lead to low ionization energy of such atoms and very low affinity to extra electrons.
This leads to the octet rule, which is consequence of the fact, if chemical bonds lead to completing octets, the total electron energy is lower.
It has its limits. Ionization of electrons leads to progressively increasing ionization energy for every next electron. Similarly, accepting too many electrons leads to negative electron affinity, so the electron is released at the nearest convenience. So ions with high positive charge occur only in heavily ionisating environment, respectively the one with highly negative charge need source of electrons. Even in solid matrices there is partially covalent bond.
It may be challenging, but this explains a lot about the screening of the nucleus charge: Slater's rules
The following is multiple choice question (with options) to answer.
Are valence electrons attracted more or less strongly when they are farther from the nucleus? | [
"less strongly",
"equally",
"differently",
"more strongly"
] | A | The reactivity of alkaline Earth metals increases from the top to the bottom of the group. That’s because the atoms get bigger from the top to the bottom, so the valence electrons are farther from the nucleus. When valence electrons are farther from the nucleus, they are attracted less strongly by the nucleus and more easily removed from the atom. This makes the atom more reactive. |
SciQ | SciQ-1216 | physical-chemistry, kinetic-theory-of-gases
$$\exp{(-\frac {E}{kT})}=\exp{(-\frac {mv^2}{2kT})}$$
in the integral over the 3D space of velocity components $v_\mathrm{x}$, $v_\mathrm{y}$, $v_\mathrm{y}$, using the radial spherical coordinate $v \equiv r$, where $v=\sqrt{v_\mathrm{x}^2+v_\mathrm{y}^2+
v_\mathrm{z}^2}$:
$$C\int_0^{\infty}{4\pi v^2\exp{(\frac{-mv^2}{2kT})}\mathrm{d}v}=1$$
as for spherical coordinates, $\mathrm{d}V=4\pi r^2 \mathrm{d}r$
The value of the above finite integral:
$$\left(\dfrac{2\pi kT}{m}\right)^{3/2}$$
is the reciprocal value of the normalisation constant:
$$C=\left(\dfrac{m}{2\pi kT}\right)^{\frac 32}$$
which sets the probability that a molecule has some speed to certainty, as $\int_0^{\infty}{p(v)\mathrm{d}v}=1$
We have now finally the complete normalized probability density function $p(v)$ for the speed $v$, known as the Maxwell-Boltzmann distribution:
$$p(v)=\left(\dfrac{m}{2\pi kT}\right)^{\frac 32}4\pi v^2\exp{(-\frac{mv^2}{2kT})}$$
The following is multiple choice question (with options) to answer.
What do we call the predictable distribution of molecular speeds found in gas of many molecules? | [
"burns - boltzmann distribution",
"kemp - boltzmann distribution",
"maxwell-boltzmann distribution",
"mitchell - boltzmann distribution"
] | C | • The motion of individual molecules in a gas is random in magnitude and direction. However, a gas of many molecules has a predictable distribution of molecular speeds, known as the Maxwell-Boltzmann distribution. |
SciQ | SciQ-1217 | biochemistry
Another important difference with respect to resulting polymers formed from these bonds - polysaccharides, in contrast to proteins and nucleic acids, form branched as well as linear polymers
α-Amylose is a linear polymer of several thousand glucose residues linked by α(1 >4) bonds. Note that although α-amylose is an isomer of cellulose, it has very different structural properties. This is because cellulose’s β-glycosidic linkages cause each successive glucose residue to flip 180° with respect to the preceding residue, so that the polymer assumes an easily packed, fully extended conformation.
Peptide bond
The resulting linkage formed when α-amino acids polymerize, through the elimination of a water molecule is known as a peptide bond (sometimes called an amide bond):
Peptide bond (shown in red)
Glycosidic bonds between monosaccharide units are the basis for the formation of oligosaccharides and polysaccharides.
The glycosidic bond is therefore the carbohydrate analog of the peptide bond in proteins. (The bond in a nucleoside linking its ribose residue to its base is also a glycosidic bond)
The following is multiple choice question (with options) to answer.
Name the simple sugar that is a component of starch. | [
"glucose",
"insulin",
"Splenda",
"Fructose"
] | A | 3.2 | Carbohydrates By the end of this section, you will be able to: • Discuss the role of carbohydrates in cells and in the extracellular materials of animals and plants • Explain the classifications of carbohydrates • List common monosaccharides, disaccharides, and polysaccharides Most people are familiar with carbohydrates, one type of macromolecule, especially when it comes to what we eat. To lose weight, some individuals adhere to “low-carb” diets. Athletes, in contrast, often “carb-load” before important competitions to ensure that they have enough energy to compete at a high level. Carbohydrates are, in fact, an essential part of our diet; grains, fruits, and vegetables are all natural sources of carbohydrates. Carbohydrates provide energy to the body, particularly through glucose, a simple sugar that is a component of starch and an ingredient in many staple foods. Carbohydrates also have other important functions in humans, animals, and plants. |
SciQ | SciQ-1218 | 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 do vertebrates have which invertebrates do not? | [
"fangs",
"backbones",
"tails",
"appendages"
] | B | Vertebrates have a backbone, but invertebrates do not. Except for the chordates, all animal phyla consist only of invertebrates. Chordates include both vertebrates and invertebrates. |
SciQ | SciQ-1219 | physiology, homework
Title: Order of events in hibernation
Arrange this in sequence :
i. Heat loss exceeds heat production.
ii.As body temperature falls, heat loss decreases.
iii.Body temperature equals environmental temperature.
iv.Metabolic activities fall to the basal level.
I am confused between i,iii,ii,iv and iv,i,ii,iii. I think the order i,ii,iii should be correct, since the fall in temperature occurs after the heat loss exceeds production and will continue only till the temperature equals the ambient temperature. iv is the reason for i. Hence iv,i,ii,iii sounds pretty convincing to me.
With i,iii,ii,iv , the main problem is that there can not be any appreciable fall in temperature ii after the temperature equals the environmental temperature iii. And iv seems more probably to be the reason for i rather than the reverse
The following is multiple choice question (with options) to answer.
Occuring throughout the lifespan of the organism, what stages proceed in a certain order? | [
"life cycle stages",
"life effectiveness stages",
"yearly stages",
"genetic stages"
] | A | |
SciQ | SciQ-1220 | 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 fetus is connected to what by a tube called the umbilical cord? | [
"placenta",
"Fallopian tube",
"Stomach",
"Intestines"
] | A | The placenta is a spongy mass of blood vessels. Some of the vessels come from the mother. Some come from the fetus. The placenta is attached to the inside of the mother’s uterus. The fetus is connected to the placenta by a tube called the umbilical cord . The cord contains two arteries and a vein. Substances pass back and forth between the mother’s and fetus’s blood through the placenta and cord. Oxygen and nutrients pass from the mother to the fetus. Carbon dioxide passes from the fetus to the mother. |
SciQ | SciQ-1221 | food, nutrition
Supplements aren't intended to be a food substitute because they can't replicate all of the nutrients and benefits of whole foods, such as fruits and vegetables.
and there are three main differences:
Greater nutrition. Whole foods are complex, containing a variety of
the micronutrients your body needs — not just one. An orange, for
example, provides vitamin C plus some beta carotene, calcium and
other nutrients. It's likely these compounds work together to produce
their beneficial effect.
Essential fiber. Whole foods, such as whole grains, fruits,
vegetables and legumes, provide dietary fiber. Most high-fiber foods
are also packed with other essential nutrients. Fiber, as part of a
healthy diet, can help prevent certain diseases, such as type 2
diabetes and heart disease, and it can also help manage constipation.
Protective substances. Whole foods contain other substances important
for good health. Fruits and vegetables, for example, contain
naturally occurring substances called phytochemicals, which may help
protect you against cancer, heart disease, diabetes and high blood
pressure. Many are also good sources of antioxidants — substances
that slow down oxidation, a natural process that leads to cell and
tissue damage.
So you could live off of some meal replacement shake for the rest of your life but should you? Probably not.
The following is multiple choice question (with options) to answer.
What are most fresh fruits, vegetables, whole grains rich in? | [
"calcium",
"cholesterol",
"cellulose",
"magnesium"
] | C | |
SciQ | SciQ-1222 | >> Rotate Clockwise Rotate Counterclockwise. 1 0 obj 2 Z1 0 endobj Find: Previous. As time permits I am working on them, however I don't have the amount of free time that I used to so it will take a while before anything shows up here.
The following is multiple choice question (with options) to answer.
What term tells you how quickly the angle changes and can occur in either clockwise or counterclockwise directions? | [
"shift velocity",
"emit velocity",
"angular velocity",
"turning velocity"
] | C | The angular velocity tells you how quickly the angle changes. In more formal language, the rate of change of , the angular position, is called the angular velocity . The direction of angular velocity is either clockwise or counterclockwise. Analogously, the rate of change of is the angular acceleration . |
SciQ | SciQ-1223 | physical-chemistry, equilibrium, kinetics, stoichiometry
I might try to give you some intuition to back up that, for a given (elementary) reaction $\ce{A ->[k] B}$, the reaction rate $r$ can be written as
$$r = \frac{d P_\ce{B}}{dt} = -\frac{d P_\ce{A}}{dt} \propto P_\ce{A}\text{.}$$
(Observe that the second equality above is true due to $P_\ce{A} + P_\ce{B} = \text{constant}$.)
First, for an ideal gas, $P_\ce{A} = \frac{n_\ce{A}}{V} RT$.
This means that $P_\ce{A} \propto n$ for fixed temperature and volume.
Let's say the reaction happens as a random process.
That is to say that, for every time interval $\Delta t$, we have a probability per unit time $p$ of having a single molecule $\ce{A}$ turning into $\ce{B}$.
If we wait longer, proportionally more molecules will turn.
We'll thus have, for initially $n_\ce{A}$ molecules of $\ce{A}$, after $\Delta t$ seconds,
$$\Delta n_\ce{B} = p n_\ce{A} \Delta t\text{.}$$
This means that, in the time interval $\Delta t$, the population of $\ce{B}$ goes from 0 to $\Delta n_\ce{B}$ (assuming no $\ce{B}$ initially).
From the stoichiometry of the reaction, $\Delta n_\ce{B} = -\Delta n_\ce{A}$ (i.e., there's conservation of moles).
Thus,
$$\frac{\Delta n_\ce{B}}{\Delta t} = -\frac{\Delta n_\ce{A}}{\Delta t} = p n_\ce{A}\text{.}$$
The following is multiple choice question (with options) to answer.
What term is used to describe how fast a chemical reaction occurs? | [
"velocity",
"response time",
"catalysis",
"reaction rate"
] | D | How fast a chemical reaction occurs is called the reaction rate . Several factors affect the rate of a given chemical reaction. They include the:. |
SciQ | SciQ-1224 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
What is the term for protists that produce spores, such as the toxoplasm? | [
"protozoans",
"sporozoans",
"newborns",
"spermatozoa"
] | B | The sporozoans are protists that produce spores, such as the toxoplasma . These protists do not move at all. The spores develop into new protists. |
SciQ | SciQ-1225 | planet, solar-system, natural-satellites, planetary-formation, proto-planetary-disk
Title: Why do planets and satellites in the Solar system look so wildly different if they came from more or less the same matter? First, the planets. We have Mercury, which is rocky, no atmosphere. But then we have Venus, which is completely different: thick atmosphere, very hot, geologically active. Then Earth - blue, full of water. Mars, the opposite: red like nothing else. Jupiter and Saturn are fairly similar. Then Uranus and Neptune, fairly similar but still differ in color between each other and also totally different in color than the two gas giants.
On the other hand: satellites. Let's analyze satellites of Jupiter and Saturn.
Ganymede and Callisto fairly similar, but then Europe, total opposite: completely icy. And then Io, again something completely different: strikingly yellow.
Saturn's moons: mostly rocky, but then, something completely different: Titan, with a thick atmosphere like no other satellite and oceans of liquid methane.
If during the formation of the Solar system there was a protoplanetary disk of matter, wouldn't it be pretty homogenous and therefore give rise to similarly looking planets? I understand that gas giants can't look the same as rocky planets, but why are there differences even between similarly sized rocky planets? Granted, there are wildly different temperatures throughout the Solar system, depending on the distance from the Sun, which probably explain some of the differences.
But then what I especially don't understand are the differences between the satellites. If say Jupiter had a disk of matter orbiting it, which eventually formed into satellites, wouldn't at least that "local" disk around a planet be fairly homogenous? But nevertheless it developed into wildly different satellites. For example, how did the "yellowy" thing get concentrated on Io, and not equally distributed on all the Jupiter's moons? This questions can be split in two; for planets and satellites.
The following is multiple choice question (with options) to answer.
Why does neptune's appearance change? | [
"the seasons",
"the speed of rotation",
"the changing orbit",
"turbulent atmosphere"
] | D | Neptune's appearance changes due to its turbulent atmosphere. Winds are stronger than on any other planet in the solar system. Wind speeds can reach 1,100 km/h (700 mph). This is close to the speed of sound! The rapid winds surprised astronomers. This is because Neptune receives little energy from the Sun to power weather systems. It is not surprising that Neptune is one of the coldest places in the solar system. Temperatures at the top of the clouds are about –218°C (–360°F). |
SciQ | SciQ-1226 | brain, exercise
Neuromodulators are involved in a variety of processes including pain
modulation, reward, response to stress, and autonomic control.
In humans, acute exercise causes significant increases in peripheral
levels of endogenous opioids; this effect is intensity-dependent,
corresponds to acute exercise-induced changes in HPA axis hormones,
and is linked to improvements in mood.
Though the endogenous opioids have received much attention in terms of
their involvement in the “runner’s high”, scientists are beginning to
understand that endocannabinoids may be equally or perhaps more
involved.
Other sources:
Effects of physical exercise on anxiety, depression...(Clinical Psychology Review, 2001):
Acutely, emotional effects of exercise remain confusing, both positive
and negative effects being reported.
...or as Alex Corb, PhD says in Boosting Your Serotonin Activity (Psychology Today):
Interestingly, if you try to do too much exercise, or feel forced into
doing it, it may not have the right effect. Recognizing that you are
choosing to exercise changes its neurochemical effect. That may be a
result of your ancient instincts — the difference between running
because you're hunting something, and running because it's hunting
you.
How to increase serotonin in the human brain without drugs (Journal of Psychiatry & Neuroscience, 2007):
Exercise improves mood in subclinical populations as well as in
patients. The most consistent effect is seen when regular exercisers
undertake aerobic exercise at a level with which they are familiar.
The following is multiple choice question (with options) to answer.
Changing levels of what substances partly explain emotional ups and downs in teens? | [
"hormones",
"enzymes",
"nutrients",
"acids"
] | A | Many teens have emotional ups and downs. This is at least partly due to their changing hormone levels. |
SciQ | SciQ-1227 | evolution, definitions, artificial-selection
It does not lead to new species
In short, 1) it does lead to new species 2) the concept of species is often meaningless as poorly defined 3) evolution > speciation. In more details, below..
It does lead to new species. Different lineages of cabbage are considered different species. Cows and ox are different species. Pigs and boars are often considered different species. While wolves and dogs are considered same species, some lineages within this species (such as a Chihuahua and a Great Dane) are, I think, reproductively isolated. You might also want to have a look at the post Have we ever observed two drosophila lineages that evolved reproductive isolation in labs?
The question of whether selective breeding lead to speciation or not does not matter much on the question of whether it leads to evolution. Speciation is one outcome of evolution but is definitely not the same as evolution. Evolution does not need to lead to speciation. For example, evolution of the lactase gene in humans (see this post) did not lead to any speciation. It is still an evolutionary process.
The concept of species is mainly arbitrary. If you want to understand the concept of species, have a look at the post How could humans have interbred with Neanderthals if we're a different species?.
It decreases, rather than increases, the size of the gene pool (is this actually true?)
The following is multiple choice question (with options) to answer.
What term refers to larger evolutionary changes that result in new species? | [
"Microevolution",
"macroevolution",
"substantial evolution",
"Potential evolution"
] | B | Macroevolution refers to larger evolutionary changes that result in new species. |
SciQ | SciQ-1228 | optics
Title: Beam focused through lens at an angle Under normal lens operation, a beam is sent through the centre of the lens along the optical axis (ie perpendicular to the lens's plane). What happens when a beam is sent through a lens at an angle to the optical axis? Does it simply exit the lens at the same angle? There are some rules about what happens to light rays passing through lenses, which are derived from Snell's laws. In short:
a) A ray passing through the focal point into the lens will exit the lens parallel to the optical axis.
b) A ray passing straight into the center of the lens (at any angle with respect to the optical axis) will exit at the same angle.
c) A ray entering the lens parallel to the optical axis will exit the lens and pass through the focal point.
These are standard in any intro physics text, but what the heck I'll draw a simple diagram:
The object is on the left, I've labeled the three rays appropriately, and the image is on the right (focal points are dots). As you can see, the rays a) and b) are incident with the lens at an angle with respect to the optical axis, which should answer your question.
The same rules apply for concave lenses as well, and also curved mirrors if you make the appropriate adjustments.
The following is multiple choice question (with options) to answer.
What do you call a lens that causes the light rays to bend away from its axis? | [
"diverging lens",
"converging lens",
"optical lens",
"axilens"
] | A | • A lens that causes the light rays to bend away from its axis is called a diverging lens. • Ray tracing is the technique of graphically determining the paths that light rays take. • The image in which light rays from one point on the object actually cross at the location of the image and can be projected onto a screen, a piece of film, or the retina of an eye is called a real image. • Thin lens equations are. |
SciQ | SciQ-1229 | biochemistry, molecular-biology, cell-biology, cell-membrane
Once you have a firm grasp on that, consider that in order for a hydrophobic molecule to reach a plasma membrane, it must already be solvated by water. The transfer of a hydrophobe from one hydrophillic environment (water) to another (head groups of the phospholipids in the plasma membrane) should be energetically negligible. The limiting step for passive diffusion across a membrane is transfer from the hydrophillic environment of the phospholipid head groups to the hydrophobic environment of their tails. In fact, the rate of diffusion across a plasma membrane increases with hydrophobicity.
The following is multiple choice question (with options) to answer.
Diffusion can occur across a semipermeable membrane, such as the cell membrane, as long as a what exists? | [
"parity",
"concentration gradient",
"differential",
"polarity"
] | B | Diffusion can occur across a semipermeable membrane, such as the cell membrane, as long as a concentration gradient exists. Molecules will continue to flow in this manner until equilibrium is reached. At equilibrium, there is no longer an area of high concentration or low concentration, and molecules flow equally in both directions across the semipermeable membrane. At equilibrium, equal amounts of a molecule are entering and leaving a cell. |
SciQ | SciQ-1230 | astronomy, time, scales
Title: How can physicists observe events at large scales such as a star birth? I read recently multiple articles about physicists observing the birth of a star, or a star swallowed by a black hole.
However I can't manage to understand how these phenomena are observable at such scales. Common sense would lead me to think that the bigger the object you observe is, the bigger the timeframe of associated phenomena are.
I mean it seems that when you look at the micro-/nanoscopic world, phenomena happen very very fast. So when you look at galaxies it should be very very slow from our point of view.
So if we can watch the process of a star's birth, does it mean that such events have a timeframe similar to the phenomena that we observe at our scales? Typically astronomical events do not happen on the time scale of humans. So what scientists do, is look at a large sample of events each at a different time in the evolution of the event. So for example to see 'stars' being born they would look in a gas nebula and see several examples of stars being formed in the different stages of coalescing. However, some portions of these events can be on a human time-scale. A supernova can be seen over a period of several weeks to months. This would be rather boring to watch in real-time but if you use time-lapse 'photography' of about 1 day per sample you could see the event quite clearly.
The following is multiple choice question (with options) to answer.
Scientists use what scale to illustrate the order in which events on earth have happened? | [
"fossil record",
"cataclysmic time scale",
"geologic time scale",
"ecological succession"
] | C | Scientists use the geologic time scale to illustrate the order in which events on Earth have happened. |
SciQ | SciQ-1231 | pressure
Title: Microscopic idea of sudden extreme pressure difference I'm having some issues understanding what's happening microscopic when there's sudden changes in the pressure.
The microscopic idea, is that particles randomly bounces around each other. It's even possible with entropy to state all the air can go to one side of the room, and leave a vacuum on the other side but off course very improbable.
But if particles just randomly just bounces around, why are you being sucked out of a space station, if the doors are suddenly opened into the vacuum? Why can the molecules around you feel the doors has been opened another place, if they just randomly bounces around? They are still just "randomly" bouncing around. The problem is that you've now changed the constraints for which they can randomly bounce.
Before, the odds that they could randomly bounce outside the ship are extremely limited. For the most part, bouncing is constrained to other particles and the walls of the ship itself. As soon as you introduce an easier pathway out of the ship, some of the gas will begin randomly bouncing out that hole. What's especially important is that once they start to move away, it's extremely unlikely that much of the air escaping will bounce back into the ship. Instead, they are free to start permeating space where they have very low chances of collisions that would send them back. This creates a net flow rate out of the hole compared to the essentially evenly distributed bouncing around when it is enclosed by walls and pressurized gases.
If you're facing the hole, collisions with gasses behind you are likely to send the air essentially backwards, hitting the air behind it, which cascades until it hits the wall and essentially pushes back on you. In front of you, when you push against the air, it collides with more air, which cascades; but there is no wall to push back against it, so the air just starts flowing out the hole.
The following is multiple choice question (with options) to answer.
What will happen if the gas particles inside an inflated balloon suddenly stop moving? | [
"balloon bursts",
"balloon inflates",
"balloon falls",
"balloon deflates"
] | D | Gas molecules also exert pressure. Earth’s atmosphere exerts pressure because gravity acts on the huge number of gas particles contained in the atmosphere, holding it in place. Pressure is also exerted by a small sample of gas, such as that which is contained in a balloon. Gas pressure is the pressure that results from collisions of gas particles with an object. Inside the balloon, the gas particles collide with the balloon’s inner walls. It is those collisions which keep the balloon inflated. If the gas particles were to suddenly stop moving, the balloon would instantly deflate. The Figure below is an illustration of gas particles exerting pressure inside a container. |
SciQ | SciQ-1232 | botany
Title: Do any plants exhibit hormonal changes similar to puberty? Just what the title states.
Are there any plants/trees that exhibit a growth spurt at a definite interval after the shoot appears? In flowering plants (the angiosperms) there are several developmental transitions in the life of the plant. I won't list the plants, because the list includes pretty much all of them (although the magnitude in the change of developmental pace differs widely between taxa and environments).
First there is seed germination, which is controlled hormonally. Absence of germination is usually imposed by abscisic acid, whilst germination is caused at the appropriate time by gibberellic acid and ethylene (among other things; Holdsworth, Bentsink & Soppe, 2008).
Next, in many herbaceous species there is a transition between a spreading growth stage (e.g. rosette growth) and the flowering stage. The 'growth spurt' here is the differentiation and elongation of the flowering stem, and then subsequently the sudden flowering of buds. The transition is also controlled hormonally, by a variety of hormones including auxin (Zhao, 2010), gibberellic acid, ethylene (Schaller, 2012), and the long anticipated, recently confirmed florigen (Choi, 2012). Ethylene and abscisic acid then play important roles in the next developmental transition when seeds and fruits are produced and dehisced.
Small RNAs are also now being revealed to play a large role in controlling the timing of developmental, but they are upstream of the hormonal changes. In particular some key miRNAs are involved in auxin-based regulation of branching, and in embryogenesis (Nodine & Bartel, 2010), and RNA silencing is involved in the switch from rosette growth to flowering growth (reviewed in Poethig, 2009 and Baurle & Dean 2006).
The following is multiple choice question (with options) to answer.
What are the major sites of gibberellin production? | [
"young roots and leaves",
"stem and roots",
"flower and fruit",
"soil and leaves"
] | A | |
SciQ | SciQ-1233 | coordination-compounds, isomers
The trans-isomer has a high symmetry of $D_\mathrm{2h}$ if I did the transforming correctly, meaning that it is does not have enantiomers. Also, it renders the two chlorides homotopic, meaning that we get one trans isomer.
There are two cis-isomers that behave as enantiomers of each other: a Δ and a Λ isomer. These two each have homotopic chlorides again, meaning we get a set of two cis-isomers. To be honest, I only saw that when I tried it out with a modelling kit.
This means that substituting one of the two chlorides with something else will result in identical compounds, giving us three different isomers. (Note that you have drawn two pairs in which one transforms into the other by simple rotation. You only have two different complexes drawn in the question.)
The chelating nitrite ion is not possible in your complex since you have a rather small metal centre that only allows octahedral coordination. Therefore, each of the three isomers we established earlier can exist in a κN and a κO form. That gives us a grand total of six possible isomers whereof two pairs are enantiomers of each other and three are constitutional isomers of the other three.
The following is multiple choice question (with options) to answer.
What is required for interconversion between the two forms of an isomeric pair? | [
"couple and reforming",
"fixing and reforming",
"breaking and reforming",
"turn and reforming"
] | C | Stereoisomers Molecules with the same connectivity but different arrangements of the atoms in space are called stereoisomers. There are two types of stereoisomers: geometric and optical. Geometric isomers differ in the relative position(s) of substituents in a rigid molecule. (For more information on stereoisomers, see Chapter 23 "The ", Section 23.4 "Coordination Compounds". ) Simple rotation about a C–C σ bond in an alkene, for example, cannot occur because of the presence of the π bond. The substituents are therefore rigidly locked into a particular spatial arrangement (part (a) in Figure 2.16 "Some Simple (a) Alkenes, (b) Alkynes, and (c) Cyclic Hydrocarbons"). Thus a carbon–carbon multiple bond, or in some cases a ring, prevents one geometric isomer from being readily converted to the other. The members of an isomeric pair are identified as either cis or trans, and interconversion between the two forms requires breaking and reforming one or more bonds. Because their structural difference causes them to have different physical and chemical properties, cis and trans isomers are actually two distinct chemical compounds. |
SciQ | SciQ-1234 | mutations, genomes
Title: Bacterial division and mutation rate When a bacteria A divides it produces two cells A', A''. Each of them receives a copy of the chromosome/plasmids. Now, DNA replication occurs way before division in a semiconservative manner. That is, each new chromosome has an 'old' strand and a 'new' strand. Since the polymerase is error prone, my belief is that both genomes can potentially have mutations. Now when people refer to the mutation rate/genome/replication, e.g. 3x10-4 , Does this mean that:
The following is multiple choice question (with options) to answer.
Bacteria reproduce through what process, where the chromosome copies itself, forming two genetically identical copies? | [
"nuclear fission",
"residual fission",
"binary fission",
"multiple fission"
] | C | Bacteria reproduce through a process called binary fission . During binary fission, the chromosome copies itself, forming two genetically identical copies. Then, the cell enlarges and divides into two new daughter cells. The two daughter cells are identical to the parent cell. Binary fission can happen very rapidly. Some species of bacteria can double their population in less than ten minutes!. |
SciQ | SciQ-1235 | water, molecular-structure, polarity, dipole
Now let's take water. The central atom (Oxygen) has a valence configuration of $2s^22p^4$, that is, 6 electrons. In water, since we have two single bonds, we have one $\sigma$ bond each (and no $\pi$ bonds). So we have total two $\sigma$ bonds.
But this leaves us with $6-2=4$ unpaired valence electrons. These form two "lone pairs" (pairs of electrons which do not bond). With two lone pairs and two $\sigma$ bonds, $x=4$. This gives us a tetrahedral structure (third in the balloon diagram). Two of the four points in the tetrahedron are occupied by the lone pairs, and two by bonds:
(Note that the angle 104.5 is not the same as the angle in perfect tetrahedra, 109.25--this is due to the lone pairs repelling each other)
So finally, we have the following "bent" structure for water:
From the structure, as shown above, it is very easy to check if the molecule has a dipole moment.
The following is multiple choice question (with options) to answer.
Water molecules are polar, so they form what type of bonds? | [
"hydrogen",
"carbon",
"oxygen",
"helium"
] | A | Water molecules are polar, so they form hydrogen bonds. This gives water unique properties, such as a relatively high boiling point, high specific heat, cohesion, adhesion and density. |
SciQ | SciQ-1236 | 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 cecum is the first part of what structure, where wastes in a liquid state enter from the small intestine? | [
"duodenum",
"esophagus",
"large intestine",
"appendix"
] | C | http://www. explainthatstuff. com/how-geiger-counters-work. html. |
SciQ | SciQ-1237 | ## BOTTOM - The Bottom of a Graph
no tags
We will use the following (standard) definitions from graph theory. Let $V$ be a nonempty and finite set, its elements being called vertices (or nodes). Let $E$ be a subset of the Cartesian product $V \times V$, its elements being called edges. Then $G = (V, E)$ is called a directed graph.
Let $n$ be a positive integer, and let $p = (e_1, \ldots, e_n)$ be a sequence of length $n$ of edges $e_i \in E$ such that $e_i = (v_i, v_{i+1})$ for a sequence of vertices ($v_1, \ldots, v_{n+1}$). Then $p$ is called a path from vertex $v_1$ to vertex $v_{n+1}$ in $G$ and we say that $v_{n+1}$ is reachable from $v_1$, writing $(v_1 \to v_{n+1})$.
Here are some new definitions. A node $v$ in a graph $G = (V, E)$ is called a sink, if for every node $w$ in $G$ that is reachable from $v$, $v$ is also reachable from $w$. The bottom of a graph is the subset of all nodes that are sinks, i.e., $\mathrm{bottom}(G) = \{v \in V \mid \forall w \in V : (v \to w) \Rightarrow (w \to v) \}$. You have to calculate the bottom of certain graphs.
### Input Specification
The following is multiple choice question (with options) to answer.
What are the "levels" in a food chain or web called? | [
"trophic",
"root",
"gauges",
"parts"
] | A | Energy is passed up a food chain or web from lower to higher trophic levels. However, generally only about 10 percent of the energy at one level is available to the next level. This is represented by the ecological pyramid in Figure below . What happens to the other 90 percent of energy? It is used for metabolic processes or given off to the environment as heat. This loss of energy explains why there are rarely more than four trophic levels in a food chain or web. Sometimes there may be a fifth trophic level, but usually there’s not enough energy left to support any additional levels. |
SciQ | SciQ-1238 | tissue
Title: What are the main differences between lab-grown tissues and natural tissues from living animals? What are the main differences between lab-grown tissues and natural tissues from living animals?
Using a biologist's classic "structure (anatomy) and function (physiology)" idea, I thought about the followings:
Structure:
It might be difficult to recreate the composition of different tissues / cells in living things precisely with artificial methods. This may lead to bad results when the tissue is used for tests of medicines and cosmetics.
Function:
Cells might not function and produce as expected (or is harder to make them function) in artificial compositions, as cells need strictly regulated environments to function correctly.
The following is multiple choice question (with options) to answer.
Are bones considered living or dead tissues? | [
"decaying",
"living",
"dead",
"decomposing"
] | B | From seeing a skeleton, you might think that bones are just dead, hollow structures. But in a living person, those hollow spaces are full of living cells. Bones have a blood supply and nerves. Bones are a living tissue. |
SciQ | SciQ-1239 | waves, atmospheric-science, turbulence
The clouds form if the rising air reaches the lifted condensation level before the updrafts are stopped by an inversion or stable layer. The air is (relatively) clear above the downdrafts. If the convection rolls were perfectly circular, the cloud row spacing would be twice the height of the inversion/stable layer.
Mathematically, there are many wavelength solutions to convection, but the wavelength that dominates is the fastest growing one. In the Boussinesq approximation, which is reasonably valid here, this turns out to have a wavelength of $2\sqrt{2}\sim 3$ times the height of the convecting layer, i.e. slightly flattened. (See, for example, Eq. 21 of Kuettner (1971) "Cloud bands in the earth's atmosphere: Observations and Theory".)
For typical cumulus cloud heights of $\sim 2$ km, we expect typical spacings of about $6$ km.
Wave, lee, or mountain clouds are lines of clouds downwind of an obstacle (such as a mountain range). The lines are parallel to the wind direction. These are buoyancy waves where wind pushes denser air over an obstacle (e.g. a mountain range) and it ends up above less dense air on the other side. This dense air starts to fall but it overshoots into even higher density air at lower altitude, which forces it back up, and the air ends up bouncing up and down until the oscillations die out. If the vertical temperature profile of the air then is known, it is possible to estimate the vertical buoyancy angular frequency
$$N=\sqrt{\frac{g}{\theta}\frac{d\theta}{dz}}$$
The following is multiple choice question (with options) to answer.
What forms when water in the atmosphere condenses on dust particles suspended in the air? | [
"snow",
"hail",
"wind",
"clouds"
] | D | |
SciQ | SciQ-1240 | cellular-respiration, fermentation
Fermentation: An ATP-generating process in which organic compounds act as both donors and acceptors of electrons. Fermentation can take place in the absence of O2. Discovered by Louis Pasteur, who described fermentation as “la vie sans l’air” (“life without air”).
So the biochemical lawyers have produced a definition that very few readers will be able to take in at first sight. What is this business about electron donors and acceptors? Well what it means in relation to the fermentation process in which lactic acid is produced (note my legalistic choice of words) is that one organic compound is reduced (glyceraldehyde 3-phosphate) — by NAD+ — and one organic compound is oxidized (pyruvate) — by NADH. And as the production of ATP is included in the definition this means that Berg et al. include glycolysis in this definition of fermentation.
…except that on the same page there is the following statement:
pyruvate is converted, or fermented, into lactic acid in lactic acid fermentation or into ethanol in alcoholic fermentation
So here it seems that the word is being used for the conversion of pyruvate to lactate or ethanol, i.e. it excludes glycolysis.
Pasteur managed to talk about fermentation without being aware of glycolysis or ATP, and it is clear to me that you can write whatever carefully phrased definitions you like, but people are going to continue to use venerable terms like fermentation in whatever way seems natual to them.
The following is multiple choice question (with options) to answer.
What are the two types of fermentation? | [
"alcoholic and alchemical",
"acetic and anhydrous",
"lactic acid and fermaldehyde",
"lactic acid and alcoholic"
] | D | There are two types of fermentation: lactic acid fermentation and alcoholic fermentation. Both types of fermentation are described below. You can also watch animations of both types at this link: http://www. cst. cmich. edu/users/schul1te/animations/fermentation. swf . |
SciQ | SciQ-1241 | 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.
Aging occurs as cells lose their ability to do what? | [
"build",
"join",
"divide",
"grow"
] | C | During early adulthood, people form intimate relationships and start careers. Serious health problems start showing up in middle adulthood and old age. Aging occurs as cells lose their ability to divide. |
SciQ | SciQ-1242 | fluid-dynamics, fluid-statics
Title: Why does a new drop rises when a one falls? When a drop falls into a tub of water, we see a small drop of water rising above the surface of water. This situation does not conserve energy (because initial drop has more kinetic energy and surface energy with respect to the second raised drop). As there is no net force there, but it does not conserve momentum (because initial momentum is downward with greater magnitude but final momentum is upward with lesser magnitude).
Where is the fault in my assumption in the above situation? How does this happen failing these fundamental laws!!!
This happens not only with water drop, but anything other than gases. a slow-motion video of this process reveals the following: when the droplet strikes the liquid surface, it pushes down on the liquid against the restoring force of surface tension, creating a downward-protruding concavity in the surface. Surface tension then acts to pull the concavity back up again, but because the system contains very little damping, the rising surface overshoots its equilibrium (level) position and rises further to form an upward bulge. As the bulge rises, it is accompanied by the development of a velocity field in the liquid in which the velocity vectors are all pointed towards the highest point in the bulge. Along the central axis of the bulge, those vectors are pointing almost straight up which means that the fluid parcels in the centermost and topmost portion of the bulge really want to continue rising even after the outermost portions of the bulge have reversed direction and have begun to fall back.
The net result is the ejection of a secondary droplet upwards off the tip of the bulge.
The following is multiple choice question (with options) to answer.
What is it called when liquid water falls from the sky? | [
"precipitation",
"erosion",
"water cycling",
"sedimentation"
] | A | |
SciQ | SciQ-1243 | physical-chemistry, solutions
Title: thinking about osmotic pressure when liquid is replaced by gas An option in my test says:
"The osmotic pressure of a dilute solution is the same as it would exert if it exists as a gas in the same volume of the solution and at same temperature."
I'm not able to think how should I relate between a solution and a gaseous mixture. Am I missing something? In both the case of the osmotic pressure of a dilute solution and the case of the pressure exerted by an ideal gas, the solute or gas may be described as composed of non-interacting (ideal) particles, and the mathematical expressions (equations of state) describing the two situations are very similar (in one case $p=cRT$, in the other $\pi = cRT$)$^\dagger$. However it might be less confusing if equivalent to state that in both cases the equations describe similar relationships between the work required to change the volume of the system and the accompanying change in the concentration of gas or solute. In both cases work can be done by the system through an expansion, but in one case the expansion results from pressure exerted by the gas, while in the other it results from pressure exerted by the solvent. In the case of osmotic pressure, since the chemical potential of the solvent is coupled to that of the solute (as described by the Gibbs-Duhem relation) it is possible to relate the osmotic pressure to the solute concentration (in the limit of an ideal solution as described by Henry's Law).
$^\dagger$As I commented, the equations are analogous but in my opinion, "The osmotic pressure of a dilute solution is the same as it would exert if it exists as a gas in the same volume of the solution and at same temperature." is a misstatement. The entire solution, if evaporated, would not exert the same pressure. It is more subtle than that. It is the solute that would exert an equivalent pressure if a gas.
The following is multiple choice question (with options) to answer.
Applying a pressure greater than the osmotic pressure of a solution will do what? | [
"osmosis",
"ultrafiltration",
"reverse osmosis",
"normal osmosis"
] | C | Figure 11.26 Applying a pressure greater than the osmotic pressure of a solution will reverse osmosis. Solvent molecules from the solution are pushed into the pure solvent. |
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