source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-2444 | evolution
Title: Homologous structures under Lamarck I've read that Lamarck's theory doesn't explain homologous structures.
But, what about the following hypothetical under Lamarck's theories:
A population develops an adaptation to its environment
Part of the adapted population moves away
The adaptation is passed onto the population's offspring
All offspring of the original population have the adaptation, regardless of whether or not their ancestors moved away
Isn't this adaptation a homologous structure? I agree with you that I can't see why Lamarck's hypothesis could not explain the presence of homologous structures.
The link you offer also claim that Larmarck's hypothesis would fail to explain "Biogeographical diversity patterns". While this expression is a little vague, I would fail to understand why Lamarck's hypothesis would fail to explain patterns of biogeographical diversity.
The phrasing of your scenarios (absence of the term allopatric speciation, usage of the term "develops" instead of "evolves" of just "adapts") suggests that you may take advantage of an intro course to evolutionary biology such as the short and good course by UC Berkeley called Understanding Evolution
The following is multiple choice question (with options) to answer.
How did lamarck believe species change over time? | [
"became larger",
"ecological of acquired characteristics",
"lose of acquired traits",
"inheritance of acquired characteristics"
] | D | Jean Baptiste Lamarck (1744–1829) was an important French naturalist. He was one of the first scientists to propose that species change over time. However, Lamarck was wrong about how species change. His idea of the inheritance of acquired characteristics is incorrect. Traits an organism develops during its own life time cannot be passed on to offspring, as Lamarck believed. |
SciQ | SciQ-2445 | genetics, cell-biology, embryology, meiosis, gamete
Title: Fertilization of the human egg- where does our centrosome come from? Is there a centrosome in a human egg cell? Is the reason why the egg cell remains paused before meiosis 2 because there isn't a centrosome, and it only divides when the sperm fertilizes it thus it can have a centrosome? If this is so, then how did oogenesis happen? ? To answer the first part of your question. The sperm actually introduces two centrosomes. The centrosome then nucleates the new microtubule assembly to form the sperm aster — a step essential for successful fertilization. You can visit these sites Simerly, et al as well as Paweltz, et al
The following is multiple choice question (with options) to answer.
Which is larger: the human sperm or the human egg? | [
"same size",
"human sperm",
"zygote",
"human egg"
] | D | A human sperm is a tiny cell with a tail. A human egg is much larger. Both cells are mature haploid gametes that are capable of fertilization. What process is shown in this photograph?. |
SciQ | SciQ-2446 | gas-phase-chemistry
Title: Is there any kind of reaction with two types of reactants (gases) and one product (also gas) such that the total volume after the reaction increases? I would like to think of the following equation:
$$\ce{aA(g) + bB(g) -> cC(g)}$$
where $a + b < c$ and $\ce{A},$ $\ce{B}$ and $\ce{C}$ are different gases.
Is there such chemical reaction? This is a fun question. The essence of what makes it challenging is that you're doing a synthesis -- combining two different species into one -- yet ending up with more particles, not (as is typical) less. This limits the number of possible reactions significantly. Here, however, is one that meets the conditions:
Octasulfur ($\ce {S_8}$) boils at 444.6 $^\circ \text{C}$ at standard pressure. So, above that temperature, one could have:
$$\ce{ S_{8(g)} + 4O_{2(g)}-> 8SO_{(g)}},$$
where $1+4 < 8$.
Of course, if octasulfur were combusted with oxygen, it's likely that many other species of sulfur oxides (i.e., compounds of the form $\ce {S_xO_y}$) would be produced as well.
The following is multiple choice question (with options) to answer.
What kind of reaction is a reaction in which two or more substances combine to form a single new substance? | [
"chemical reaction",
"combination reaction",
"power reaction",
"compounding reaction"
] | B | A combination reaction is a reaction in which two or more substances combine to form a single new substance. Combination reactions can also be called synthesis reactions. The general form of a combination reaction is:. |
SciQ | SciQ-2447 | galaxy, exoplanet, cosmology, life
Title: can a life exist outside the universe? can a life exist outside of universe. but we know that in our universe many galaxies have life without water and oxygen and it is possible that life exist outside the universe so help me to find the right answer??and what is the possibility of this??
can a life exist outside of universe.
There's no way to define "outside of universe" I know of.
we all know that life can not exist without water and oxygen
We don't know that. It's an assumption, and not one I would make. I would not even make it about Earth.
but we know that in our universe many galaxies have life without water and oxygen
We certainly do not know that. It contradicts your original statement, but there's been no evidence found of life anywhere except on Earth ( to date ). There are many theories saying life probably exists ( in some basic form, like cells ) outside of Earth, but they are simply theories at this point. Science is not about excepting theories without evidence, it's about theories fitting evidence. At this point we have no theories on life outside Earth that we have evidence to back.
and it is possible that life exist outside the universe
Again, we cannot define "outside the universe" so that has no real meaning.
so help me to find the right answer??
Perhaps try the PBS Space Time channel on YouTube, as it discusses these things at a reachable level. It recently discussed life ( advanced technological civilizations ) and why we cannot see any evidence of them in several videos. Worth a look and they also make great introductions to advanced current thinking in space-time physics, including ideas like the multiverse, which often mislead people. They usually supply links for people who want to get more serious about study as well as the video overview.
The following is multiple choice question (with options) to answer.
What is beyond the atmosphere? | [
"object",
"air",
"space",
"vacuum"
] | C | The chapter focuses on the atmosphere. Beyond the atmosphere is space. The next chapter introduces the study of space. |
SciQ | SciQ-2448 | thermodynamics, molecules
Title: Why do methane molecules have 15 degrees of freedom? I've just been learning a little thermal chemistry including the equipartition theorem. As part of this, my textbook discusses how to figure out the degrees of freedom for different chemicals.
The answer to one of the exercises says methane has 15 degrees of freedom: 3 for translation, 3 for rotations and 9 for vibrations. I am confused by two of these.
Firstly the text says that diatomic molecules like oxygen gas only have 2 rotational degrees of freedom, because they can't rotate about their axis of symmetry. However methane has an axis of symmetry, so why does it have 3 rotational degrees?
Secondly I don't understand where all the vibration degrees of freedom come from. The molecule has 4 bonds, so wouldn't each bond have one degree for kinetic energy and one for potential energy, for a total of 8 degrees, not 9? 15 is there because you have 5 atoms which can move independently, and we live in a 3D space, and $3\ \times\ 5\ =\ 15$.
3 of these are translational degrees of freedom, which you seem to agree with, so I'll just leave it at that.
3 are for rotations, because the methane molecule is not linear. Axes of symmetry are irrelevant: indeed, you may rotate methane around the axis of symmetry as well as around any other axis. Being or not being diatomic is hardly relevant either, except for the fact that all diatomic molecules are necessarily linear; however, the converse is not true.
Subtracting 3 and 3 from 15, we get 9, and that's how many vibrational degrees of freedom we have, because they can't be anything else. To visualize them is another story, and a great deal more difficult. Counting bonds doesn't help much. The separation of degrees into kinetic and potential is not a thing at all. You don't have to do that anyway. Write $15\ -\ 3\ -\ 3\ =\ 9$ and call it a day.
The following is multiple choice question (with options) to answer.
What structure does methane have? | [
"three dimensional oxyhedra",
"two dimensional tetrahedra",
"three dimensional tetrahedra",
"two dimensional oxyhedra"
] | C | Methane has a three-dimensional, tetrahedral structure. |
SciQ | SciQ-2449 | 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.
What is the blastocyst called after implantation? | [
"an produce",
"trophoblast",
"an nucleus",
"an embryo"
] | D | After implantation occurs, the blastocyst is called an embryo . The embryonic stage lasts through the eighth week following fertilization. During this time, the embryo grows in size and becomes more complex. It develops specialized cells and tissues and starts to form most organs. For an interactive animation of embryonic development, go to this link: http://health. howstuffworks. com/adam-200129. htm . |
SciQ | SciQ-2450 | terminology, metabolism, energy-metabolism
As Wikipedia puts it (emphasis mine):
An endotherm is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions instead of relying almost purely on ambient heat.
That really does seem to better match the "exo-" prefix.
Is there a real inconsistency here, or do I just understand this incorrectly? The prefix "endo" comes from the Greek "endon" meaning "inner". "Therm" comes likewise from the Greek "therme" meaning heat.
Thus Endo = inner, Therm = heat, heat from inside!
The confusion applies in chemistry, not in that someone has it wrong, but that molecular reactions sometimes release heat - this is obviously to the outside so it must be "exo". The Greek opposite of exo is endo, so the converse reaction (absorbing heat) must be endothermic.
Note also that in the case of an endothermic reaction, the heat supplied for the reaction to work comes from within the materials of the reaction, it's just that in the process of the reaction occurring the heat is "used up" so the reaction vessel feels cold. Because the heat is coming from inside the reaction "endo" makes sense here too.
I did my basic chemistry too long ago for me to remember for endothermic reactions if environmental heat is needed for the reaction to proceed, but I suspect that at any temp above 0 K, the answer is generally no; the heat comes from breaking of intra-molecular bonds.
The following is multiple choice question (with options) to answer.
What rate is generally higher for endotherms than for ectotherms? | [
"metabolic",
"mortality",
"respiration",
"reproduction"
] | A | |
SciQ | SciQ-2451 | species-identification, invertebrates
Title: Identification of odd jellyfish-like creature in the Mediterranean My parents encountered this unknown creature on a beach in Karpathos, Greece.
None of the locals have seen it before, it may be a species that has moved further north due to ocean warming.
Any ideas what it is? It seems to be a "Hula skirt siphonophore" - Physophora hydrostatica
Physophora hydrostatica, also known as hula skirt siphonophore, is a
species of siphonophores in the family Physophoridae.1
https://en.wikipedia.org/wiki/Physophora_hydrostatica
The following is multiple choice question (with options) to answer.
What phylum includes snails, squids and clams? | [
"porifera",
"mollusca",
"protozoa",
"cnidaria"
] | B | Mollusks are mainly aquatic invertebrates in Phylum Mollusca. They include snails, squids, and clams. Mollusks have a coelom and several organ systems. Most also have a shell, head, foot, and radula, which is a feeding organ. Mollusks are either free-living heterotrophs or parasites. |
SciQ | SciQ-2452 | evolution
Title: How to define "evolution"? The standard answer found in intro course to evolutionary biology to the question:
what is evolution?
is:
It is a change in allele frequency over time!
I believe a complete definition should encompass the following concepts:
mutations
copy number variation (CNV)
codon usage
chromosome numbers
phenotypic change (whether heritable or not)
Complex phenotypic trait such as plasticity and developmental noise
maybe some other things...
My questions are:
Would it be worth it to talk about phenotype in a definition of evolution?
What are the alternative definitions that have been proposed?
What is your definition?
Note: I would rather talk about genetic evolution, but if you think it is worth making one definition for genetic and cultural (and some other stuff maybe) evolution, you're free to suggest it! What is evolution?
In a non-biological sense, evolution means change:
"a process of [...] change"
Biological evolution (seeing as this is Biology stack exchange) then needs to be tweaked to give a biologically specific context. Many textbooks etc. give definitions of evolution and here are a few good ones from across the history of evolutionary biology:
Charles Darwin:
"Descent with modification".
Mark Ridley1:
"Evolution means change, change in the form and behaviour of organisms between generations. ... When members of a population breed and produce the next generation we can imagine a lineage of populations, made up of a series of populations through time. Each population is ancestral to the descendant population in the next generation: a lineage is an ancestor-descendent series of populations. Evolution is then change between generations within a population lineage."
Brian and Deborah Charlesworth2:
"Evolution means cumulative change over time in the characteristics of a population of living organisms. ... All evolutionary changes require initially rare genetic variants to spread among the members of a population, rising to high frequency..."
All of these have a common theme. Biological information is moving through time, descending with a degree of directionality (e.g. parent $\rightarrow$ offspring), and the information is modified with time.
Personally I would define evolution as:
The following is multiple choice question (with options) to answer.
What is the change in a species over time? | [
"variation",
"evolution",
"transformation",
"phenomenon"
] | B | Scientists do the same thing when they classify , or put into categories, living things. Scientists classify organisms not only by their physical features, but also by how closely related they are. Lions and tigers look like each other more than they look like bears, but are lions and tigers related? Evolutionarily speaking, yes. Evolution is the change in a species over time. Lions and tigers both evolved from a common ancestor. So it turns out that the two cats are actually more closely related to each other than to bears. How an organism looks and how it is related to other organisms determines how it is classified. |
SciQ | SciQ-2453 | bioinformatics, proteins, structural-biology, protein-structure, xray-crystallography
Title: Subset of Protein Crystal Structures (from PDB) Is there a well-accepted subset of the Protein Data Bank set of protein structures that:
Has only "high quality" structures (may be differing metrics of this; e.g. resolution, size, or structural completeness)
Has minimal redundancy (e.g. nothing with exact sequence identity from the same species)
Is still as large as possible, spanning as many molecules and species as possible
[Optionally but better] Is not too biased (e.g. certain classes of proteins are highly over-represented in the PDB)
It is possible to download the entire PDB and make up rules for myself, but this seems like something people might have already considered reasonably extensively. I'm hoping for a dataset I can just download and cite, in the best case. :) Richardsons' Lab has a top8000 list.
See their paper from 2016.
They also have top500 list, but it hasn't been updated for many years.
The following is multiple choice question (with options) to answer.
What are the largest known proteins? | [
"keratins",
"titins",
"actins",
"hormones"
] | B | Proteins can differ from one another in the number and sequence (order) of amino acids. It is because of the side chains of the amino acids that proteins with different amino acid sequences have different shapes and different chemical properties. Small proteins can contain just a few hundred amino acids. Yeast proteins average 466 amino acids. The largest known proteins are the titins, found in muscle, which are composed from over 27,000 amino acids. |
SciQ | SciQ-2454 | ecology
Title: Do invasive species cause long-term damage to ecosystems they invade? Growing up in the U.S., I was warned at various times of the dire consequences of a variety of introduced pests (usually insects).
Japanese beetles, gypsy moths, and most recently the brown marmorated stink bug are all introduced pests that, at various times, were described as serious threats to our ecology.
These threats aren't confined to arthropods, either. The giant African land snail is causing a stir in Florida (indeed, Florida seems to suffer from an excessive variety of introduced species.
"Lack of native predators" is frequently cited as the primary reason many invasive species are considered such a risk to the ecology.
I understand that these introduced species can place tremendous pressure on native species that fill similar ecological niches, and may even push these species out of the region due to competition for food and habitat. However, do the overall ecologies that these species are introduced to adjust over long periods of time?
The numbers of Japanese beetles and gypsy moths don't seem anywhere as high as when I was a child. Has the ecosystem adjusted, or has the overpopulation self-corrected as the species ran low on food through over-consumption? Or are the populations still just as problematic now as they were 30 years ago, and I just am not seeing the bigger picture?
What is the long-term impact that we've seen from invasive, introduced species? Is there a significant difference on the long-term impact between introduced flora, arthropods, or mammals? The answer really depends on how you think of invasive. One extreme answer is to say that all things are relative, and that the concepts of local and invasive are all relative. This matters to a certain extent because ecologists draw a fuzzy line between invasive and naturalized. You could start with some basic species that we all think of as either good, local, or neutral. Take the earthworm. Most people think of it as a common native species, but the earthworm is actually an invasive species that has radically changed much of North America that came over with the Europeans. Similarly, brown trout are also invasive, coming to the US in the 1800's.
The following is multiple choice question (with options) to answer.
What term is used to describe the organism that is invaded and often harmed by a pathogen? | [
"host",
"guardian",
"parent",
"initial"
] | A | Introduction The environment consists of numerous pathogens, which are agents, usually microorganisms, that cause diseases in their hosts. A host is the organism that is invaded and often harmed by a pathogen. Pathogens include bacteria, protists, fungi and other infectious organisms. We are constantly exposed to pathogens in food and water, on surfaces, and in the air. Mammalian immune systems evolved for protection from such pathogens; they are composed of an extremely diverse array of specialized cells and soluble molecules that coordinate a rapid and flexible defense system capable of providing protection from a majority of these disease agents. Components of the immune system constantly search the body for signs of pathogens. When pathogens are found, immune factors are mobilized to the site of an infection. The immune factors identify the nature of the pathogen, strengthen the corresponding cells and molecules to combat it efficiently, and then halt the immune response after the infection is cleared to avoid unnecessary host cell damage. The immune system can remember pathogens to which it has been exposed to create a more efficient response upon re-exposure. This memory can last several decades. Features of the immune system, such as pathogen identification, specific response, amplification, retreat, and remembrance are essential for survival against pathogens. The immune response can be classified as either innate or active. The innate immune response is always present and attempts to defend against all pathogens rather than focusing on specific ones. Conversely, the adaptive immune response stores information about past infections and mounts pathogen-specific defenses. |
SciQ | SciQ-2455 | cell-biology, toxicology, growth-media, bacterial-toxins
Title: Can botulinum toxin be grown or kept from denaturing in an UNWRAPPED 50 pound hay bale? Botulinum toxin is the neurotoxin protein created when botulism spores grow. The requirements for growth and/or for keeping the toxin from denaturing would seem to be very difficult to create in bale of hay.
There are well documented incidents of botulism in horses who are eating hay, all the references I found were centered around hay in large plastic wrapped bales.
I have been involved in an event where the presumed DX is botulism secondary to ingestion from hay from last year. In this case the hay is second cutting timothy hay (making it 6 plus months old), in rectangular 50 pound (22 kg) bales that are not wrapped, have been barn kept, and when purchased from the vendor where stacked in rows 4 feet wide, by 6 feet (2 meters) high. The bale then spent more then a week on an shelf (chrome platted heavy wire) with good air circulation.
Three pet house rabbits appear to have been effected. with 2 dead and one recovering from a case of descending paralysis. Several tests are underway, but my understanding is that it may be difficult to conclusively show either the botulism in the rabbits, or significant presence of 'botulinum toxin' or 'clostridium botulinum' in the hay (samples from the mangers of effected animals are being tested).
Is it possible to logically conclude that Botulinum toxin could, or could not, be created and/or survive in a bale of hay meeting the above criteria?
Note
If there is an awareness of a plant based neurotoxin that would cause similar symptoms that may be growing in the hay field please offer that in an answer at Gardnening. As an addendum to Spinorial's answer, and after some research, the Center for Food Security and Public Health specifically lists hay / grass / decaying vegetable matter as a potential source for C. botulinum growth in their (very informative) Botulism PDF.
The following is multiple choice question (with options) to answer.
Untreated botulism is typically fatal because muscles required for breathing fail to contract when the release of what chemical is blocked? | [
"carbon dioxide",
"hydrogen",
"acetylcholine",
"monoxide"
] | C | |
SciQ | SciQ-2456 | electromagnetism, magnetic-fields
Then I went on reading and realized that the situation might be more complicated than I originally believed: I started wondering what is actually $\mathbf{f}_{mag}$?
Let's for example consider problem $7.7$ (pag.311, I'll add a picture for calrity). The free charges in the metal bar experience a vertical force ($\mathbf{v \times B}$) that sets them in motion. We can compute the emf via the flux rule and obtain the expression for the induced current by applying:
$$\mathcal{E} = R I$$
Now the bar experiences a magnetic force:
$$\mathbf{F}_{mag} = \oint (\mathbf{v} \times \mathbf{B})dq$$
which is directed in the opposite direction of $\mathbf{v}$ (aka, towards the left of the bar). Now then, the same force now acts upon the charges in the metal bar but it acts simultaneously in two different directions. Is this actually possible?
No, at least to me, therefore I conclude that:
$$\mathbf{f}_{mag} \ne \mathbf{F}_{mag}$$
although they are evidently the same thing.
What am I misinterpreting? Is Griffiths' explanation clear, or is there some subtleties hidden that I missed while reading?
Any help is much appreciated, as always. Yes, there are very fine subtleties.
The following is multiple choice question (with options) to answer.
The combined magnetic force of the magnetized wire coil and iron bar makes an electromagnet what? | [
"Very light",
"very heavy",
"very strong",
"very reduced"
] | C | The combined magnetic force of the magnetized wire coil and iron bar makes an electromagnet very strong. |
SciQ | SciQ-2457 | evolution, zoology, anatomy, species
Title: Examples of animals with 12-28 legs? Many commonly known animals' limbs usually number between 0 and 10. For example, a non-exhaustive list:
snakes have 0
Members of Bipedidae have 2 legs. Birds and humans have 2 legs (but 4 limbs)
Most mammals, reptiles, amphibians have 4 legs
Echinoderms (e.g., sea stars) typically have 5 legs.
Insects typically have 6 legs
Octopi and arachnids have 8 legs
decapods (e.g., crabs) have 10 legs
....But I can't really think of many examples of animals containing more legs until you reach 30+ legs in centipedes and millipedes. Some millipedes even have as many as 750 legs! The lone example I am aware of, the sunflower sea star, typically has 16-24 (though up to 40) limbs.
So my question is: what are some examples of animals with 12-28 legs? As a couple of counterexamples, species in the classes Symphyla (Pseudocentipedes) and Pauropoda within Myriapoda have 8-11 and 12 leg pairs respectively, so between 16 to 24 legs (sometimes with one or two leg pair stronlgy reduced in size).
(species in Symphyla, from wikipedia)
Another common and species-rich group with 14 walking legs (7 leg pairs) is Isopoda.
(Isopod, picture from wikipedia)
You also need to define 'legs' for the discussion to be meaningful. As you say, decapods have 10 legs on their thoracic segments (thoracic appendages), but they can also have appendages on their abdomens (Pleopods/swimming legs), which will place many decapods in the 10-20 leg range.
(Decapod abdominal appendages/legs in yellow, from wikipedia)
So overall, in Arthropoda, having 12-28 legs doesn't seem all that uncommon. There are probably other Arthropod groups besides those mentioned here that also have leg counts in this range.
However, for a general account, the most likely answer (if there is indeed a relative lack of 12-28 legged animals) is probably evolutionary contingencies and strongly conservative body plans within organism groups.
The following is multiple choice question (with options) to answer.
Where do two or more bones of the skeleton meet? | [
"muscle paths",
"junctures",
"valves",
"joints"
] | D | Joints are places where two or more bones of the skeleton meet. With the help of muscles, joints allow the body to move with relatively little force. Some joints can move more than others. |
SciQ | SciQ-2458 | 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.
Lacking a bony endoskeleton, sharks, rays, and ratfish belong to what group of fish? | [
"freshwater fish",
"cartilaginous",
"invertebrates",
"crustaceans"
] | B | Cartilaginous Fish Cartilaginous fish include sharks, rays, and ratfish. Their endoskeleton is made of cartilage instead of bone. They also lack a swim bladder. However, they have a complete vertebral column and jaws. They also have a relatively big brain. shark. |
SciQ | SciQ-2459 | thermodynamics
You can use Fourier analysis to solve this for any configuration and boundary conditions. Bottom line is that the heat that is leaving the hotter object will warm up the cooler object, and reduce the thermal gradient. This will slow down the heat flow.
If you are interested, there is quite an extensive set of cases solved in this paper.
And here is a diagram of how the heat diffusion causes an initial step function to "diffuse" with time (from this lecture):
The following is multiple choice question (with options) to answer.
What process involves the flow of heat from warmer objects to cooler objects? | [
"radiation",
"conduction",
"convection",
"activation"
] | B | Through the process of conduction, heat flows from warmer objects to cooler objects ( Figure below ). The lower mantle is heated directly by conduction from the core. In conduction , heat is transferred as atoms collide. |
SciQ | SciQ-2460 | zoology, ichthyology, marine-biology
Switek goes on to to talk about exceptions in some marine mammals:
At this point some of you might raise the point that living pinnipeds like seals and sea lions move in a side-to-side motion underwater. That may be true on a superficial level, but pinnipeds primarily use their modified limbs (hindlimbs in seals and forelimbs in sea lions) to move through the water; they aren’t relying on propulsion from a large fluke or caudal fin providing most of the propulsion with the front fins/limbs providing lift and allowing for change in direction. This diversity of strategies in living marine mammals suggests differing situations encountered by differing ancestors with their own suites of characteristics, but in the case of whales it seems that their ancestors were best fitted to move by undulating their spinal column and using their limbs to provide some extra propulsion/direction.
The following is multiple choice question (with options) to answer.
What broad category of animals shows adaptations from water-dwelling to land-dweller, including the ability to breathe air and legs to move on land? | [
"herbivores",
"reptiles",
"amphibians",
"birds"
] | C | Amphibians! In order for water-dwelling animals to adapt to life on land, many new adaptations had to take place. First, they needed to be able to breathe air instead of obtaining oxygen from water. And fins don't work well as legs! They needed to be able to move around well on land. |
SciQ | SciQ-2461 | inorganic-chemistry, physical-chemistry, crystal-structure, crystallography, chemistry-in-fiction
Figure 4.1 Two examples of directional-dependant properties in diamond. The cleavage planes are parallel to the octahedral faces, which are also planes of near
maximum hardness. The easiest direction for sawing is at right-angles to the dodecahedral plane, which is also the plane of minimum hardness.
References
Read, P. G. Gemmology, 3rd ed.; Elsevier Butterworth Heinemann: Amsterdam; Boston, 2005. ISBN 978-0-7506-6449-3.
The following is multiple choice question (with options) to answer.
What term is used to describe the tendency of a mineral to break along certain planes? | [
"erosion",
"cleavage",
"porosis",
"tooth decay"
] | B | Cleavage is the tendency of a mineral to break along certain planes. When a mineral breaks along a plane, it makes a smooth surface. Minerals with different crystal structures will break or cleave in different ways ( Figure below ). Halite tends to form cubes with smooth surfaces. Mica tends to form sheets. Fluorite can form octahedrons. |
SciQ | SciQ-2462 | electromagnetism, astrophysics, plasma-physics, magnetohydrodynamics, solar-wind
Title: How does a solar wind plasmoid split when it touches the magnetosphere? I want to try to render (computer graphics) auroras in a physical manner as realistic and realizable as possible. I'm aware that the phenomenon hasn't been completly explained yet (as far as my own research goes). But while searching for information, I've seen many different statements about how the plasma behaves when it hits the magnetosphere. So, here is how I currently understand the journey of a plasma to the earth. Maybe I'm somewhere wrong or I'm missing physics education:
The sun emits solar winds or coronal mass ejections which are both plasmas. And although the plasma contains ions, it is in of itself not charged in any way. The plasma "blob" is neutral.
The plasma travels pretty fast towards earth (light speed?). When it hits the bow shock, it gets slowed down.
And a short time after it touches the magnetosphere. What will happen next depends if the plasma is a solar wind or a CME?
CME case: The plasma has still such a high velocity that a magnetic reconnection happens. So the outer field lines of the magnetosphere are splitting at the magnetic equator and are folding upwards/downards towards the earth's poles. (I'm looking from the side of the earth. So the solar wind comes from left/right)
Solar wind case: The ions of the plasma travel along the outer field lines of the magnetosphere in a spinning fashion. (Due to Lorentz force? Or by what influence is it possible that the electrons can travel upwards AND downwards along the field lines which are vectors that are solely pointing upwards to the earth's magnetic south pole?)
Sorry if I've butchered a weird question here. As stated above, I'm no physics student and the acquired knowledge came all from the internet, NASA-webpages and a few papers.
The plasma travels pretty fast towards earth (light speed?). When it hits the bow shock, it gets slowed down.
The following is multiple choice question (with options) to answer.
What controls earth's magnetosphere? | [
"magnetic field",
"gravitational field",
"stratosphere",
"ionosphere"
] | A | Earth's magnetosphere is controlled by the magnetic field. The magnetosphere protects the planet from the solar wind . The solar wind is ions that fly from the Sun to Earth very fast. The magnetosphere protects Earth's ozone layer. So life on Earth needs the protection of the magnetosphere. |
SciQ | SciQ-2463 | 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 humans, pharyngeal slits later develop into what? | [
"middle ear",
"inner ear",
"outer ear",
"long ear"
] | A | In some chordates, all four traits persist throughout life and serve important functions. However, in many chordates, including humans, all four traits are present only during the embryonic stage. After that, some of the traits disappear or develop into other organs. For example, in humans, pharyngeal slits are present in embryos and later develop into the middle ear. |
SciQ | SciQ-2464 | concentration
Title: Why would sodium ions want to go down just because of one side is more positive than the other? From Khan Academy starting from 1:25, the narrator, while talking about the Electrochemical gradients, said that sodium ions would naturally want to diffuse
down when having a high concentration up here and a low concentration down there.
My question is Why would sodium ions want to go down just because of one side is more positive than the other, I mean, isn't the same charges repelling each other? I don't think the degree of positivity will enable them to be attracted to each other.
Could anyone help me explain this? This has more to do with the diffusion gradient. Sodium ions move from the region of their higher concentration to a region of their lower concentration.
In the example given by you, I believe, there are additional negatively charged molecules present in the inner side of the membrane, resulting in an influx of sodium ions to balance the same. However, like charges do repel, so this influx is not indefinite, but only up to a certain extent- until the electrical potential difference across the membrane exactly balances the concentration gradient. This point is known as the equilibrium potential.
(This question and answer might be more appropriate in the Biology SE, I think).
The following is multiple choice question (with options) to answer.
What phenomenon involves the forcing of a substance into a cell against its concentration gradient? | [
"secondary transport",
"primary active transport",
"active absorption",
"osmosis"
] | B | During active transport, specialized integral membrane proteins recognize the substance and allows it access. Essentially this process is forcing a ion or molecule to cross the membrane when normally it would not. Moving a substance against its concentration gradient is known as primary active transport , and the proteins involved in it as "pumps". This process uses the energy of ATP. In secondary active transport , energy from an electrochemical gradient is used to transport substances. This process involves pore-forming proteins that form channels through the cell membrane. |
SciQ | SciQ-2465 | transcription, translation
Ralston, A. (2008) Operons and prokaryotic gene regulation. Nature Education
From Genes to Genomes: Concepts and Applications of DNA Technology
Molecular cell biology
Analysis of Genes and Genomes
The following is multiple choice question (with options) to answer.
What are used as model organisms in molecular biology and genetics? | [
"electromagnetic slime molds",
"cellular slime molds",
"convergent slime molds",
"weather slime molds"
] | B | Cellular slime molds are used as model organisms in molecular biology and genetics. They may be the key to how multicellular organisms evolved. Can you explain why?. |
SciQ | SciQ-2466 | species-identification, zoology, marine-biology, ichthyology, bone
Title: Identification of a strange skull My father is a fisherman in the Baltic sea, and he has found this very strange skull. I would like to know to which animal it belonged. Can someone help identify it? Looks like this is a neurocranium of a tuna or a similar species (dorsal view on this site).
I've also found a very similar picture of Atlantic blue tuna from USA, which seems to support that this is indeed a neurocranium.(source of the picture).
Thank you all for your help!
The following is multiple choice question (with options) to answer.
The bones of the newborn skull are not fully ossified and are separated by large areas called what? | [
"fontanelles",
"sutures",
"pores",
"fissures"
] | A | Figure 7.33 Newborn Skull The bones of the newborn skull are not fully ossified and are separated by large areas called fontanelles, which are filled with fibrous connective tissue. The fontanelles allow for continued growth of the skull after birth. At the time of birth, the facial bones are small and underdeveloped, and the mastoid process has not yet formed. |
SciQ | SciQ-2467 | homework, ecology, population-dynamics, growth
The Attempt
Looking at the values, I recognize the carrying capacity is reached at hour $13$ with $600$ cells, signifying a logistic growth model. The formula given to me for logistic growth is:
$\frac{dN}{dt} = rN[\frac{(K - N)}{K}]$
From what I have researched:
$dN$ = population size change
$dt$ = time interval
$r$ = (max) growth rate
$N$ = starting population size
$K$ = carrying capacity
So:
$dN = 600 - 2 = 598$?
$dt = 21$ hours
$r = $?
$N = 2$
$K = 600$
Plugging the values in gives me:
$598/21$ = $r2[(600 - 2)/600]$
Update 25/01/19
With some help, I have discovered how to determine the r/rmax value and have the following formula:
$r = (90+100)/2$
$r = 95/hour$
$dN/dt = 95N[(K - N)/K]$
With $N= 2$
$dN/dt=95(2)[(K-2)/K]$
and if $K$ value is carrying capacity, $K = 600$
$dN/dt=95(2)[(600-2)/600]$
$dN/dt=190(598/600)$
$dN/dt=190(0.997)$
$dN/dt=189?$
However, the question asks me to "Write out the mathematical equation it follows." So am I supposed to leave a value unknown? I think your problem arises from misunderstanding the $r$ coefficient. I've tried to explain it below, let me know if you need more clarification.
Instantaneous vs Average Growth
The following is multiple choice question (with options) to answer.
With logistic growth, how does population growth start out? | [
"slowly",
"exponentially",
"rapidly",
"steadily"
] | A | With logistic growth, the population starts out growing slowly, and then the rate of growth increases—but only to a point. The rate of growth tapers off as the population size approaches its carrying capacity. Carrying capacity is the largest population size that can be supported in an area without harming the environment. This type of growth characterizes many populations. |
SciQ | SciQ-2468 | quantum-mechanics, visible-light, reflection, optical-materials
Can someone explain me the interaction between the photon and the molecules in case of a reflection on a solid surface with white color?
I am not asking about direction of light, not asking how the photon knows where to go. (This is well explained already by Feynman's QED.) I realized that I got a downvote, which normally means the answer is wrong, while I think it is true. But the OP has updated the question, so I take this as a chance to also update my answer.
Udate
It seems you expect one simply answer why different things in nature appear white, but the truth is there are different reasons for different things.
For example, clouds are white because of Mie scattering, that is scattering of photons on particles (here small water droplets). There is almost no wavelength-dependence of the scattering efficiency in the visible range, so that all wavelengths in the incoming sunlight are scattered with the same probability, and as a result the cloud is white. But notice, the incoming light has to contain all wavelengths for that. During sunset for example, the cloud base is sometimes red because illuminated by the sun, which is red when close to the horizon during sunset (the reason is that blue light is scattered out of the direct beam due to Rayleigh scattering that prefers to scatter blue light and is responsible for the blue sky during the day).
Another white material is milk, which is a liquid. It is also white because of scattering, this time on particles within the milk. But again, you need an illumination of a light source containing all wavelengths to get a white substance. In a green room, a glass if milk will appear greenish of course...
The following is multiple choice question (with options) to answer.
What determines the color of visible light? | [
"exact wavelength",
"wavelength density",
"molecular wavelength",
"wavelength speed"
] | A | Human beings and other primates also have the ability to see in color. We have special cells inside our eyes that can distinguish different wavelengths of visible light. Visible light is light in the range of wavelengths that the human eye can sense. The exact wavelength of visible light determines its color. |
SciQ | SciQ-2469 | bacteriology
Saier, MH. & Bogdanov, V. (2013) Membranous Organelles in Bacteria. JOURNAL OF MOLECULAR MICROBIOLOGY AND BIOTECHNOLOGY 23: 5-12 DOI: 10.1159/000346496
Free full text here.
The language used in this review seems to support the existence of mesosomes as some sort of intermediate in the formation of intracellular membranes in prokaryotes. This review is a polemic in favour of the idea that prokaryotes do indeed contain intracellular membrane-bounded compartments. It has no abstract, but the first paragraph gives a flavour of its stance:
The traditional view of life on Earth divides the living world into two major groups, prokaryotes and eukaryotes. These two groups were originally suggested to differ in very basic respects. While eukaryotes had complex cell structures including a cytoskeleton and intracellular membrane-bounded organelles, prokaryotes were believed to lack them. In fact, numerous textbooks and current sources still note this distinction and hold it to be true. For example, in Campbell’s Biology [Campbell, 1993, p. 515] it is stated without equivocation: ‘Prokaryotic cells lack membrane-enclosed organelles.’ In ‘Functional Anatomy of Prokaryotic and Eukaryotic Cells’ [Tortora et al., 2009, chapt. 4] it is similarly claimed that ‘Prokaryotes lack membrane-enclosed organelles, specialized structures that carry on various activities’. In the current Wikipedia, under ‘Prokaryote’ the following statement can be found: ‘The prokaryotes are a group of organisms whose cells lack a cell nucleus (karyon) or any other membrane-bounded organelles’. In the same online compendium under ‘Organelle’, one can read: ‘whilst prokaryotes do not possess organelles per se, some do contain protein-based microcompartments’. Proteinceous microcompartments will be the subject of a forthcoming Journal of Molecular Microbiology and Biotechnology written symposium, but this one will show that these generalizations, suggesting a lack of subcellular compartmentalization in prokaryotes, are blatantly in error [Murat et al., 2010a].
The following is multiple choice question (with options) to answer.
What do eukaryotic cells have that compartmentalize their functions? | [
"cell walls",
"internal membranes",
"cytoplasm",
"vacuoles"
] | B | 6.2 Eukaryotic cells have internal membranes that compartmentalize their functions. |
SciQ | SciQ-2470 | astrophysics, orbital-motion
Title: Is Each Day the Same Duration? Since Earth's orbit is elliptical surely each day does not have the same duration. My understanding is that at the perigee the Earth would have to rotate more than at the apogee due to its larger tangential velocity with respect to the Sun.
My question is prompted by the idea of a siderial Day which I imagine IS a constant value since in that case assuming a constant rotational speed of the Earth the angle through which the earth has to rotate is a constant 360 degrees? Yes, the solar day length varies from 24 hours - ~22 seconds to 24 hours + ~30 seconds. Here's a graph for 2022, computed for apparent solar noon at Greenwich, using data from JPL Horizons
The difference of apparent solar time minus mean solar time is known as The Equation of Time. I have further details in this answer.
The sidereal day length is fairly constant. The precise details of Earth's rotation are quite complex. The Earth's rotation is monitored by the IERS, the International Earth Rotation and Reference Systems Service. There are various articles on this topic on the IERS website.
The following is multiple choice question (with options) to answer.
Earth rotates on its axis once each day and revolves around the sun how often? | [
"once each year",
"every other year",
"once each month",
"ever 3 years"
] | A | Earth rotates on its axis once each day and revolves around the Sun once every year. |
SciQ | SciQ-2471 | human-biology, biochemistry
Omega-3 fatty acids have been shown to lower triglycerides, which are a type of fat in the bloodstream. Experts aren't sure of the exact mechanism. Omega-3 fatty acids may also slow down the growth of plaques in the arteries and reduce inflammation throughout the body.
A number of studies going back years have shown the benefits of fatty fish. In an important review of studies, researchers found that getting daily omega-3 fatty acids from fish oil could lower triglyceride levels by 25%-30%. The results were published in The American Journal of Clinical Nutrition in 1997.
BUT, I would also like to point out that the question itself "omega-3 fatty acids found in fish are a good way to prevent/reduce cholesterol problems" seems to be a matter of debate because of articles like this:
New data presented this week provide clues as to why eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)--both components of omega-3 fatty acids--have differential effects on LDL cholesterol.
Presenting the results of the laboratory study here at the National Lipid Association (NLA) 2011 Scientific Sessions, senior investigator Dr Preston Mason (Brigham and Women's Hospital, Boston, MA) said that EPA is an inhibitor of lipid oxidation at normal and elevated cholesterol levels in the presence and absence of DHA, while DHA seems to have no real effect on lipid peroxidation. This trial was one of a number of studies that attempted to address the clinical question as to why LDL-cholesterol levels increase in patients treated with the triglyceride-lowering omega-3 fatty acids. In his trial, Mason et al compared the effects of EPA and DHA--alone or in combination with statins--on lipid peroxidation in polyunsaturated fatty-acid– and cholesterol-enriched vesicles.
The following is multiple choice question (with options) to answer.
What are the two types of fatty acids? | [
"saturated and unsaturated",
"hydrochloric and carboxylic",
"saturated and endogenous",
"saturated and biodegradable"
] | A | A lipid is an organic compound such as fat or oil. Organisms use lipids to store energy, but lipids have other important roles as well. Lipids consist of repeating units called fatty acids. There are two types of fatty acids: saturated fatty acids and unsaturated fatty acids. |
SciQ | SciQ-2472 | biochemistry, molecular-biology, fat-metabolism, carbohydrates
Title: What is the source of the fat in adipose tissue? I have heard the opinion that all of it comes from de novo lipogenesis of carbohydrates, but I'm skeptical. Is there evidence either way - either that dietary fat definitely gets stored in the adipose tissue, or that it never does, and all of it is from carbohydrate transmutation? The proximal source of adipocyte lipids is mainly fatty acids from circulating lipoproteins (1) after hydrolysis by lipoprotein lipase (LPL).
LPL is activated by ApoC-II, which is present in hepatic-originating VLDL and IDL lipoprotein, but also chylomicron of direct dietary source. Insulin, secreted after meals, stimulates LPL production by adipocytes.
Thus the ultimate source of these lipids is both hepatic lipogenesis (from other substrates like glucids) and dietary fats.
Lipid transport in blood, for reference purpose (Michal G. Schomburg D., Biochemical Pathways, 2012)
The following is multiple choice question (with options) to answer.
Lipids are available to the body from how many sources? | [
"three",
"two",
"five",
"one"
] | A | 24.3 Lipid Metabolism Lipids are available to the body from three sources. They can be ingested in the diet, stored in the adipose tissue of the body, or synthesized in the liver. Fats ingested in the diet are digested in the small intestine. The triglycerides are broken down into monoglycerides and free fatty acids, then imported across the intestinal mucosa. Once across, the triglycerides are resynthesized and transported to the liver or adipose tissue. Fatty acids are oxidized through fatty acid or β-oxidation into two-carbon acetyl CoA molecules, which can then enter the Krebs cycle to generate ATP. If excess acetyl CoA is created and overloads the capacity of the Krebs cycle, the acetyl CoA can be used to synthesize ketone bodies. When glucose is limited, ketone bodies can be oxidized and used for fuel. Excess acetyl CoA generated from excess glucose or carbohydrate ingestion can be used for fatty acid synthesis or lipogenesis. Acetyl CoA is used to create lipids, triglycerides, steroid hormones, cholesterol, and bile salts. Lipolysis is the breakdown of triglycerides into glycerol and fatty acids, making them easier for the body to process. |
SciQ | SciQ-2473 | molecular-orbital-theory, metal, melting-point
You are right on the fact that alkaline earth metals should not bond if we only considered their highest atomic energy levels. The dissociation energy for diatomic clusters of alkaline earth metals is low.
However, the disassociation energy gets higher for tetra-atomic as shown in this computational study: http://www.sciencedirect.com/science/article/pii/0039602885902328
Now, the reason why alkaline earth metals have higher melting points to be due to the p orbitals. The previous study relates p hybridization with bond strength. And so does this study: http://scitation.aip.org/content/aip/journal/jcp/77/8/10.1063/1.444313
Both journals state that p orbitals are involved in bonding. And the more involved the p orbitals in bonding, the stronger the bond. This trend is shown for alkaline earth metals. Beryllium, which has the highest melting point, also has more p orbital character. Also, take a look at the density of states of alkali metals and alkaline earth metals:
http://www.colorado.edu/engineering/MCEN/MCEN5024/
You can see that not all p orbitals are entirely above the s orbitals.
So, to answer your question. The reason why alkaline earth metals have higher melting points is due to p orbitals. As Pauli states in his review, the np orbitals "hybridize" with the s orbitals. This allows for more bonds to form.
I think that p orbitals participate in bonding in alkali metals. But I couldn't find information that compares p orbital "hybridization" of alkali and alkaline earth metals directly.
The following is multiple choice question (with options) to answer.
What is a silver-colored alkaline earth metal that is even softer than calcium? | [
"magnesium",
"lithium",
"mercury",
"strontium"
] | D | Strontium is a silver-colored alkaline Earth metal that is even softer than calcium. Strontium compounds are quite common and have a variety of uses—from fireworks to cement to toothpaste. In fireworks, strontium compounds produce deep red explosions. In toothpaste, like the one pictured in the Figure below , the compound strontium chloride reduces tooth sensitivity. |
SciQ | SciQ-2474 | physical-chemistry, polymers, optical-properties
Title: Optical activity of starch In this German Wikipedia article about optical activity, I found the beautiful picture of starch granules:
Unfortunately, I have no idea what I am looking at. What are these crosses and why are they blue (i.e., same as the background color)? The figures you see are isogyres and arise in substances that are optically active, which means that polarized light is transmitted through the material in different ways depending on the orientation of the sample. These figures are called interference figures. I highly recommend that you peruse this excellent write-up on the optical properties of minerals, particularly the sections pertaining to uniaxial and biaxial crystals, birefringence, and how a petrographic microscope works.
From the Wikipedia entry on conoscopic interference pattern:
The figures are produced by optical interference when diverging light rays travel through an optically non-isotropic substance - that is, one in which the substance's refractive index varies in different directions within it.
Starch is uniaxial and the figures you see are characteristic of uniaxial materials when viewed using a petrographic microscope. See this reference (The Principles of Pharmacognocy. F. A. Flückiger and A. Tscirch. William Wood & Company, New York, 1887), pages 118-119.
As for the color seen in the image you reference: that arises from using a mica (or tint) plate which in turn indicates whether the substance is uniaxial positive or uniaxial negative, which refer to the propagation of light along differing optical axes. However, in your figure, the color of the isogyres and the background are both blue, which indicates to me that the blue color is simply a result of polarized light passing through the substance.
The following is multiple choice question (with options) to answer.
Statoliths are starch-filled plastids that enable plant roots to detect what force? | [
"current",
"gravity",
"impact",
"variation"
] | B | |
SciQ | SciQ-2475 | biochemistry, molecular-biology, dna, cell-biology, bacteriology
Title: Functioning of EDTA I know that EDTA chelates metal ions. It weakens bacterial cell wall and inactivates the DNases.
What is the reason why it can do so ? I guess it can inactivate DNases by altering the microenvironment. What exactly happens ? The lipopolysaccharide layer of the Gram-negative bacterial cell wall is stabilised by divalent cations. Most recipes for disrupting E. coli cells include Tris-EDTA for this reason. I seem to just know this, so no reference at the moment.
All nucleases require Mg2+, which is why there is EDTA in the stop buffer added to restriction digests. Carry-over of EDTA in DNA pellets can sometimes inhibit digests.
The following is multiple choice question (with options) to answer.
How does lysozyme destroy bacteria? | [
"by paralyzing them",
"by eating them",
"by antibiotic use",
"by digesting their cell walls"
] | D | Another barrier is the saliva in the mouth, which is rich in lysozyme—an enzyme that destroys bacteria by digesting their cell walls. The acidic environment of the stomach, which is fatal to many pathogens, is also a barrier. Additionally, the mucus layer of the gastrointestinal tract, respiratory tract, reproductive tract, eyes, ears, and nose traps both microbes and debris, and facilitates their removal. In the case of the upper respiratory tract, ciliated epithelial cells move potentially contaminated mucus upwards to the mouth, where it is then swallowed into the digestive tract, ending up in the harsh acidic environment of the stomach. Considering how often you breathe compared to how often you eat or perform other activities that expose you to pathogens, it is not surprising that multiple barrier mechanisms have evolved to work in concert to protect this vital area. |
SciQ | SciQ-2476 | 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.
The primary role of leaves is to collect what? | [
"sunlight",
"precipitation",
"insects",
"pollen"
] | A | Plants have specialized organs that help them survive and reproduce in a great diversity of habitats. Major organs of most plants include roots, stems, and leaves. Leaves are the keys not only to plant life but to all terrestrial life. The primary role of leaves is to collect sunlight and make food by photosynthesis . Despite the fundamental importance of the work they do, there is great diversity in the leaves of plants. However, given the diversity of habitats in which plants live, it’s not surprising that there is no single best way to collect solar energy for photosynthesis. |
SciQ | SciQ-2477 | thermodynamics, statistical-mechanics, temperature, atomic-physics, speed
Title: Is it safe to say that temperature is a measure of molecular activity? In Wikipedia
Temperature is a physical quantity that expresses the hotness of matter or radiation.
There are three types of temperature scale: those, such as the SI scale, that are defined in terms of the average translational kinetic energy per freely moving microscopic particle, such as atom, molecule, or electron, in a body
https://en.wikipedia.org/wiki/Temperature
========
I wonder is it save to say that temperature is a measure of molecular activity? You can say that but it would be rather vague, because there are other physical concepts which might also be called a measure of molecular activity, such as energy, speed, fugacity, etc.
Temperature is property (in formal language, a function of state) of a system in thermal equilibrium, such that two systems at the same temperature will show no net heat flow between them when brought into thermal contact. In microscopic terms, it is a measure of the distribution of energy in the microscopic motions and positions in a system. A higher temperature gives a wider distribution.
The following is multiple choice question (with options) to answer.
Temperature can be defined as the average of what type of energy of the molecules? | [
"kinetic",
"magnetic",
"optical",
"potential"
] | A | Temperature is the average kinetic energy of the molecules. |
SciQ | SciQ-2478 | optics, refraction, lenses, vision
Title: Refractive screen for myopia Is it possible to create a screen for a computer monitor to allow a Myopic person to see the screen without glasses? Myopia shortens the maximum focus length of an eye, i.e., the converging action of a myopic eye is too strong and, as a result, the image of a distant object is formed in front of the retina - not on the retina.
Nearsighted vision is corrected by placing a corrective concave lens in front of the eye - its diverging action compensating the excessive converging action of the eye. We can also say that, by its diverging action, the concave lens brings distant objects closer to the eye - to some short distance from which a myopic eye can focus them properly.
The stronger the myopia, the stronger the required concave lens action, the shorter that "clear vision" distance.
For this paradigm to work, the corrective lens has to be located closer to the eye than the clear vision distance and a distant object, which requires correction, has to be located further from the eye than the clear vision distance.
Obviously, under these conditions, the monitor and its corrective lens would have to be separated in space, which means that the corrective lens cannot be built into the screen.
Of course, we could have a giant magnifying glass built into the screen, like it was done in early TV's with tiny screens. This would magnify the image and make it easier to make out the details, but the image would still be out of focus.
The following is multiple choice question (with options) to answer.
What lens shape corrects myopia? | [
"concave",
"flat",
"convex",
"curve"
] | A | Myopia is corrected with a concave lens, while hyperopia is corrected with a convex lens. |
SciQ | SciQ-2479 | human-biology, plant-physiology, stem-cells
Title: Is that true that plant stem cells can be used in humans? I was reading an article (which seems very fake to me) on sensitive topics, but there was one astonishing statement:
Stem cells are obtained from certain plants that grow all over the world. Once the stem cells have been obtained, the doctor will inject them on the target organ...
I want to ask specialists if this particular statement can be true. If yes, does it imply nucleus replacement in stem cells, or anything like that?
Sorry guys, for the stupid question. https://stemcells.nih.gov/info/basics/6.htm
...
Viruses are currently used to introduce the reprogramming factors into adult cells, and this process must be carefully controlled and tested before the technique can lead to useful treatment for humans. In animal studies, the virus used to introduce the stem cell factors sometimes causes cancers. Researchers are currently investigating non-viral delivery strategies. In any case, this breakthrough discovery has created a powerful new way to "de-differentiate" cells whose developmental fates had been previously assumed to be determined. In addition, tissues derived from iPSCs will be a nearly identical match to the cell donor and thus probably avoid rejection by the immune system. The iPSC strategy creates pluripotent stem cells that, together with studies of other types of pluripotent stem cells, will help researchers learn how to reprogram cells to repair damaged tissues in the human body.
So as that all points out, no, the genetics of it will cause a plant stem cell to be genetically not a match, where it might do something for a little while, but upon that cells first interactions, it will stimulate the immune system to get rid of it, rather than incorporate it.
Anymore, I want to know about how Bone Morphinogenic Proteins (BMP-4 or above) can be injected into an organ, and if that will help stem cells for reviving an organ at all.
The following is multiple choice question (with options) to answer.
What serves to replace nonreproducing specialized cells as needed in the adult body? | [
"monocyte cells",
"dendritic cells",
"osteoclast cells",
"stem cells"
] | D | |
SciQ | SciQ-2480 | fluid-dynamics, pressure, drag
Title: What is the resistance of an object travelling through static fluid at different pressures? I'm interested in the resistance a body feels as it travels through a static fluid in a tube (of a fixed radius), at different pressures.
I would assume that as the pressure is reduced, the resistance will also be decreased. Does this relate to the Drag Force equation, or is there a better explanation, such as Bernoulli? As mentioned in one of the comments, if the fluid is incompressible (i.e. - has constant density) then the absolute level of the pressure will not affect the drag.
However if the fluid is a gas, then the pressure and density will be strongly related (directly proportional for ideal gases). And the density of the fluid enters into the equation for the dynamic pressure, so it does affect the drag.
For a constant drag coefficient, the drag will be directly proportional to the density, so for streamlined shapes at sufficiently large Reynolds' numbers, the drag will be approximately proportional to the pressure.
This should be true even if the Mach number of the flow is small enough for the incompressible flow equations to be used.
The following is multiple choice question (with options) to answer.
In physics, resistance is opposition to the flow of what? | [
"temperature charges",
"electrical charges",
"surface flow",
"capacitance"
] | B | In physics, resistance is opposition to the flow of electric charges in an electric current as it travels through matter. The SI unit for resistance is the ohm. Resistance occurs because moving electrons in current bump into atoms of matter. Resistance reduces the amount of electrical energy that is transferred through matter. That’s because some of the electrical energy is absorbed by the atoms and changed to other forms of energy, such as heat. You can see an animation of resistance at the level of atoms and electrons at this URL: http://www. physics. org/explorelink. asp?id=1738&q=electricalresistance¤tpage=1&age=0&knowledge=0&item=3. |
SciQ | SciQ-2481 | organs, lifespan
Title: Organs lifespan out of the body What organ can be conserved outside of the body for the longest time and still function when reimplanted? Depends what you consider an organ. Typically though it's the cells which require the most metabolic activity which have the shortest life span. The kidney is the most of the major internal organs with up to 36 hours with liver coming second at up to 16 hours.
The following is multiple choice question (with options) to answer.
What organs are the main organs of the urinary system? | [
"kidneys",
"gall bladder",
"spleen",
"prostate"
] | A | The kidneys are the main organs of the urinary system. |
SciQ | SciQ-2482 | reproduction, endocrinology, pregnancy, ovulation
The decline of the corpus luteum is correlated with a decline in serum levels of ovarian hormones including progesterone, estradiol, and inhibin A. Release from negative feedback provided by these hormones at the level of the hypothalamus and pituitary permits FSH to rise, and the cycle begins again.
You should now be able to see that:
Around the time of ovulation, the uterine lining is not fully developed and is stable due to the hormonal milieu. Menstruation does not occur.
Around the time of menstruation, FSH and LH are suppressed in a way that is not conducive to ovulation.
In theory, yes, of course there would be a lower chance of initiating a viable pregnancy (implantation rather than conception is the most obvious problem) were the endometrial lining to be unstable at the time of ovulation. The problem of luteal phase deficiency is along these lines. In this condition, the corpus luteum does not produce adequate progesterone during the luteal phase to develop the endometrial lining in such a way as to support a healthy pregnancy. However, ovulation and menstruation are still time-separated events for the reasons outlined above.
*Note that the first term is with respect to the endometrium; the second is with respect to the ovary.
Abbreviations:
GnRH - Gonadotropin Releasing Hormone; LH - Luteinizing Hormone; FSH - Follicule Stimulating Hormone
References
1. Anatomy & Physiology, Connexions Web site. Illustration is also from here.
2. Jerome Strauss, Robert Barbieri. Yen & Jaffe's Reproductive Endocrinology. September, 2013. Saunders.
The following is multiple choice question (with options) to answer.
What phase follows ovulation? | [
"telophase",
"varicose phase",
"interstitial phase",
"luteal phase"
] | D | |
SciQ | SciQ-2483 | electrical-engineering, pressure
Title: Trasmitting data from pressure transducer to phone/web server I am creating a 24 hour blood pressure monitor that is designed to be sleek and comfortable, I have decided on The Honey Well Series NBP AN transducer (see more info here: Basic Board Mount Pressure Sensors, p13) I want to connect that to a board so that the data can be transmitted wirelessly, or by cable to a phone or computer, how would I go about doing that? Since your sensor has an analog output. If your comfortable with prototype level work, get an Arduino that has analog inputs then connect a bluetooth module such as the HC-05. Then, you can transmit that data using some code that I wrote to send multiple sensors in columns. You can modify this code to your needs.
sending sensor data - serial over bluetooth
Your next task would be to write software, but you can view this data on a PC or phone using a terminal program like Teraterm.
The following is multiple choice question (with options) to answer.
What is used to measure blood pressure? | [
"barometer",
"spectrometer",
"sphygmomanometer",
"anemometer"
] | C | Chemistry in Everyday Life Measuring Blood Pressure Blood pressure is measured using a device called a sphygmomanometer (Greek sphygmos = “pulse”). It consists of an inflatable cuff to restrict blood flow, a manometer to measure the pressure, and a method of determining when blood flow begins and when it becomes impeded (Figure 9.6). Since its invention in 1881, it has been an essential medical device. There are many types of sphygmomanometers: manual ones that require a stethoscope and are used by medical professionals; mercury ones, used when the most accuracy is required; less accurate mechanical ones; and digital ones that can be used with little training but that have limitations. When using a sphygmomanometer, the cuff is placed around the upper arm and inflated until blood flow is completely blocked, then slowly released. As the heart beats, blood forced through the arteries causes a rise in pressure. This rise in pressure at which blood flow begins is the systolic pressure—the peak pressure in the cardiac cycle. When the cuff’s pressure equals the arterial systolic pressure, blood flows past the cuff, creating audible sounds that can be heard using a stethoscope. This is followed by a decrease in pressure as the heart’s ventricles prepare for another beat. As cuff pressure continues to decrease, eventually sound is no longer heard; this is the diastolic pressure—the lowest pressure (resting phase) in the cardiac cycle. Blood pressure units from a sphygmomanometer are in terms of millimeters of mercury (mm Hg). |
SciQ | SciQ-2484 | organs, lifespan
Title: Organs lifespan out of the body What organ can be conserved outside of the body for the longest time and still function when reimplanted? Depends what you consider an organ. Typically though it's the cells which require the most metabolic activity which have the shortest life span. The kidney is the most of the major internal organs with up to 36 hours with liver coming second at up to 16 hours.
The following is multiple choice question (with options) to answer.
Are the lungs organs of the excretory system, the respiratory system, or both? | [
"excretory",
"respiratory",
"neither",
"both"
] | D | The lungs release carbon dioxide into the air. Carbon dioxide is a gaseous waste product of the cells. Wastes are excreted from the body by the excretory system. Therefore, the lungs are organs of the excretory system as well as the respiratory system. |
SciQ | SciQ-2485 | quantum-mechanics, waves, particle-physics, wave-particle-duality
Title: What is a wave? What is a particle? I am reading a David Bohm book on quantum theory. He says the idea that light is both a particle and a wave is incompatible:
(1) we know light has particle-like properties through the photoelectric effect
(2) we know light also has wave like properties because of slit experiments.
He then explains why they are incompatible.
But what is a "particle"? What is a "wave"? What do these terms mean precisely? I know what they mean loosely. A particle means something occupying a spatial position. A wave is like a density or something defined with peaks, troughs, and nodes over a spatial region. But I want something more rigorous and more accurate than these loose definitions so that I know what I mean when I use the term.
I'd like the definitions stated like we state axioms in math, clearly and specifically. In math, I say a vector space is closed under addition if $x,y\in V$ implies $x+y \in V$. Those are very specific claims.
Can someone do something similarly clear and specific with wave and particle? The concepts "particle" and "wave" started from classical physics and from the everyday use of the terms, to begin with. A particle of dust got into one's eye, and the sea had huge waves.
Physics came into its reign when mathematics was seriously used to model observations.
For classical physics "particle" means an entity with small mass and a center of mass tracked at coordinates (x,y,z) at time t. Solutions of kinematic differential equations described the trajectory with accuracy determined by experimental errors.
For classical physics, waves are modeled by sinusoidal functions, i.e. functions that were the solution of "wave equations", could describe the behavior of sea waves, sound waves, and finally electromagnetic waves. Classically a wave is a variation of a measurable quantity like energy, or electric field, in space at a given time t, and the theoretical models were very successful in describing the observations of periodic energy distributions in bulk matter, and even in empty space ( electromagnetic waves).
Then quantum mechanics became necessary, from the discreteness of atoms, the black body radiation spectrum, the photoelectric effect it was finally understood that there were regions in the variables measured that displayed a quantization of energy.
The following is multiple choice question (with options) to answer.
Light has the properties of both a wave and what else? | [
"nucleus",
"atom",
"particle",
"electron"
] | C | Light has properties of both a wave and a particle. |
SciQ | SciQ-2486 | species-identification, zoology, marine-biology, ichthyology, bone
Title: Identification of a strange skull My father is a fisherman in the Baltic sea, and he has found this very strange skull. I would like to know to which animal it belonged. Can someone help identify it? Looks like this is a neurocranium of a tuna or a similar species (dorsal view on this site).
I've also found a very similar picture of Atlantic blue tuna from USA, which seems to support that this is indeed a neurocranium.(source of the picture).
Thank you all for your help!
The following is multiple choice question (with options) to answer.
Hagfishes have a skull made of what? | [
"bone",
"chitin",
"cartilage",
"gelatin"
] | C | |
SciQ | SciQ-2487 | microbiology, cancer, toxicology
Title: Molds associated with Aflatoxin? I've been reading how some molds may be carcinogenic. In particular, molds associated with the fungus metabolite, Aflatoxin.
Are the types of mold that produce this toxin, present in buildings/showers/domestic environments, or do they only grow on food-stuffs? Strictly speaking the common bread mould Rhizopus sp. does not produce aflatoxin.
The fungus Aspergillus flavus which belongs to the class Ascomycetes secretes aflatoxin. It attacks cereal grains , legumes, tree nuts. The fungi are green in colour and 'mould' like in appearance.
The fungus attacks the food stuffs and storage grains. So under favourable conditions it may grow in your store room if it finds food for its growth. Also Aspergillus can grow at temperatures as high as 48°C and even at low temperatures like 5-8°C.
Edit: On being asked for sources I include some which strongly support my claim
1. For suitable conditions of growth of the fungi visit https://en.m.wikipedia.org/wiki/Aspergillus_flavus and read under the Environment heading.
2. Visit https://bioweb.uwlax.edu/bio203/s2013/ernst_ale2/habitat.htm and read from " Aspergillus flavus is omnipresent " upto " Aspergillus may also grow on or inside walls in homes, especially if the house is damp or has been damaged by flooding. "
3.https://www.moldbacteria.com/mold-types.html this site provides a list of different fungi found in our homes. Here you can find Aspergillus flavus to grow in flower pot soil. Moreover other species of Aspergillus are found in kitchens and bathrooms.
The following is multiple choice question (with options) to answer.
Water molds are commonly found in moist soil and where else? | [
"crust water",
"surface water",
"standing water",
"methane water"
] | B | Water molds are commonly found in moist soil and surface water. Many water molds are plant pathogens or fish parasites. |
SciQ | SciQ-2488 | dna, human-genetics, dna-sequencing, genomics
Title: Is it possible to deduce facts about a person's parents just by studying his/her genome? As an example, suppose Anne had abusive parents. Is it theoretically possible to deduce this from her genome even if she didn't inherit this quality (of being an abusive parent)? It might seem pernickety but you often can't deduce from a genome; you can only infer from it. For many characteristics about a person, there are only rough, probabilistic associations between genotype and phenotype. Not one-to-one relationships.
You can take an educated guess that someone with a certain genotype could be a social person of European ethnicity with a low risk of psychosis, which might suggest things about their parents. But there are likely many genes that influence those characteristics and still more non-genetic factors. So you couldn't be certain.
For a factor like whether the persons parents had abusive personalities, I think the genetic differences would be so subtle (if existent) and there would be so many other factors (such as the habits and choices of the parents) that you would be very unlikely to be able to draw any conclusive associations. Articles and studies about linking human genetics with a person's characteristics are listed below. If any of the genes in question are linked with those characteristics then the parents of someone with the gene could possibly have those genes and characteristics too.
Personality types including belligerence, charisma, cynicism, housekeeping, lack of personality, obsessive-compulsive behaviour and gullibility.
Psychosis and Schizophrenia risks.
Ethnicity and European ethnicity, which in turn correlate with geographical location, language and certain phenotypes.
Height.
If anyone would like to suggest additions to that list, I'll happily add them.
The following is multiple choice question (with options) to answer.
What is considered to be a person's entire genetic information? | [
"genome",
"organism",
"chromosome",
"biosphere"
] | A | A person’s genome is all of his or her genetic information. In other words, the human genome is all the information that makes us human. And unless you have an identical twin, your genome is unique. No one else has a genome just like yours, though all our genomes are similar. |
SciQ | SciQ-2489 | evolution, biochemistry, mitochondria
Title: Is there any advantage of having mitochondria for aerobic respiration? If we consider the pathway of breakdown of glucose which includes glycolysis, the citric acid cycle and the electron transport chain, all these processes takes place in some prokaryotes and eukaryotes. In prokaryotes all these processes take place in cytoplasm while in eukaryotes the last two processes take place in mitochondria.
So is there any advantage of performing the last two processes in the mitochondria? Does it yield more energy? If there is no advantage, what is the point of having a mitochondria (at least for this process)? From the evolutionary point of view, the eukaryotes acquired these metabolisms (except glycolysis) from their prokaryotic endosymbionts. Not all prokaryotes have the ETC. The free living ancestor of mitohondria is supposed to be the alpha-proteobacterium.
Now, glycolysis is a common pathway in lot of lifeforms perhaps because of abundance of glucose. TCA cycle is coupled with ETC at certain steps which makes it essentially a part of aerobic metabolism.
The reason for having a dedicated organelle for respiration
ATP synthesis is a membrane process. Imagine a large prokaryotic cell- as big as an animal cell. Such a cell cannot take care of its energetic demands which primarily consists of protein synthesis with the given area of membrane i.e it needs much more ATP-synthases than it can have to cope up with the energy demands of maintaining such a huge cell (this index is approximated based on surface to volume ratio). Therefore it is wise to harbor multiple efficient organelles i.e. mitochondria which themselves have just a small essential genome and proteome to maintain.
For a better understanding, please read this article. I just loved it.
There is also a book by the same author about mitochondria called Power, Sex, Suicide.
The following is multiple choice question (with options) to answer.
Where does cellular respiration occur? | [
"chloroplasts",
"mitochondria",
"nucleus",
"Golgi apparatus"
] | B | Yes. Photosynthesis occurs in the chloroplasts, whereas cellular respiration occurs in the mitochondria. Photosynthesis makes glucose and oxygen, which are then used as the starting products for cellular respiration. Cellular respiration makes carbon dioxide and water (and ATP), which are the starting products (together with sunlight) for photosynthesis. |
SciQ | SciQ-2490 | species-identification, ichthyology
Title: What type of jellyfish is this? Friends of mine recently came back from a visit in kenya and on the kenyan beach they said they found several jellyfish with "sails" on their head. We tried finding out what they were and found one image online that was exactly the type of jellyfish they found:
What kind of jellyfish is it?
The guide told them that they're dangerous and those are just the corpses without stings or something, but nobody knew it's name. If the jellyfish your friends saw actually look like this and if they were small (Wikipedia says they're usually less than 7 cm in length), they're likely Vellela vellela or sometimes called By-the-wind Sailors for the way the raised part catches the wind and is blown along the ocean's surface.
Wikipedia writes
...all possess nematocysts, in some species the nematocysts and toxins
therein are more powerful than other species. V. velella's nematocysts
are relatively benign to humans, although each person may respond
differently to contact with the nematocyst toxin. It is wise to avoid
touching one's face or eyes after handling V. velella, and itching may
develop on parts of the skin that have been exposed to V. velella
nematocysts.
Some photos.
Source
Source
The following is multiple choice question (with options) to answer.
What are jellyfish and other cnidarian's stingers called? | [
"necrocytes",
"prokaryotes",
"phenocrysts",
"nematocysts"
] | D | Cnidarians such as jellyfish have radial symmetry. Flatworms and roundworms, which you will read about next, have bilateral symmetry. |
SciQ | SciQ-2491 | terminology, human-physiology, organs
Title: Medical term for "holding urine for a long time" Sometimes I get/feel pain in my stomach because of holding urine for long time. Is there any medical terminology describing: "holding urine for a long time", or pain associated with this activity? A swollen organ may be described as distended if the swelling is symptomatic of a medical disfunction.
The purpose of most bladders is to collect and retain a fluid; if that fluid needs to be discharged periodically, and is not able to do so, then there is usually pain as a result of the distension.
Inability to urinate is known as ischuria or urinary retention, and could be the result of obstruction to the urethra, could be a failure of the bladder to fully contract during urination, or could many other possible causes.
The following is multiple choice question (with options) to answer.
What is tube-shaped and brings urine from the kidneys to the urinary bladder? | [
"gametophytes",
"vas deferens",
"fallopian tube",
"ureters"
] | D | Ureters are tube-shaped and bring urine from the kidneys to the urinary bladder. |
SciQ | SciQ-2492 | diffusion
The reverse process is also happening with molecules diffusing from right to left at a rate proportional to their concentration in the right side solution. As the concentration on the right side increases to be equal to the concentration on the left, so the diffusion rates become equal and there is zero nett diffusion and the system approaches equilibrium.
Note that this assumes a "perfect" system where there is no chemical reaction occurring between the solutes or between the solutes and the membrane. In practice this means that either the interaction between solutes A and B is the same as the interaction between the solutes and the solvent or that the solute molecules are so greatly outnumbered by the solvent molecules that the solute-solute interactions are not significant.
The rate of diffusion of solute A may be different from B (i.e. the proportionality constant between rate and concentration may be different). This means that before reaching equilibrium the relative concentrations of A and B may change but at equilibrium, the relative concentration will be the same as initially.
If we define "reaching equilibrium" as having some fraction (say 99.99%) of the final concentration then increasing the initial global concentration will increase the lag for both solutes equally and will not change their relative concentrations.
The following is multiple choice question (with options) to answer.
When solvent molecules selectively pass through a membrane from a dilute solution to concentrated solution, what process is occurring? | [
"active transport",
"plasmolysis",
"osmosis",
"diffusion"
] | C | (a) Two solutions of differing concentrations are placed on either side of a semipermeable membrane. (b) When osmosis occurs, solvent molecules selectively pass through the membrane from the dilute solution to the concentrated solution, diluting it until the two concentrations are the same. The pressure exerted by the different height of the solution on the right is called the osmotic pressure. The osmotic pressure of a solution is easy to calculate:. |
SciQ | SciQ-2493 | hydrology, water, rainfall, groundwater
Title: How much time does water takes to reach to the ground? I want to understand the phenomena where water droplets after precipitation reaches to the ground.
How much time does it take to become ground water or in other words how much time is taken by water to recharge the ground after rain.
I am assuming the water droplets falls in the plain having no concrete human constructions. It depends upon the hydraulic conductivity, the degree of saturation, and the depth to water table. Generally, water seeping down in the unsaturated zone moves very slowly. Assuming a typical depth to water table of 10 to 20 metres, the seepage time could be a matter of minutes in the case of coarse boulders, to months or even years if there is a lot of clay in fine sediment. Under saturated conditions, the water might move a lot faster. Other factors include the configuration of the wetting front, the unsaturated storage, temperature, and the hydraulic gradient. So basically, there is no simple answer - it's all a matter of the local hydrogeology.
There is no substitute for local measurement - water levels in an observation bore, in the case of water table conditions, or tensiometry in the case of the unsaturated zone.
The following is multiple choice question (with options) to answer.
Water seeping into the ground is known as? | [
"accumulation",
"invasion",
"infiltration",
"precipitation"
] | C | Infiltration is the process by which water soaks into the ground. Some of the water may seep deep underground. Some may stay in the soil, where plants can absorb it with their roots. |
SciQ | SciQ-2494 | human-biology, cell-biology
Title: Body's decomposition Does a human body decompose in a completely sterile environment ? If yes, what decomposes it ? And how fast ? What happens in vacuum ? Can it remain exactly the same ?
Thanks
Does a human body decompose in a completely sterile environment ?
No it wont. Unstable molecules like ATP will quickly degrade spontaneously. The stable ones like many proteins and lipids wont degrade spontaneously. Enzymes are essential to degrade them and are to be supplied extraneously.
What happens in vacuum ?
Body will dry up :P
The following is multiple choice question (with options) to answer.
What body system gets rid of waste? | [
"nervous system",
"digestive system",
"excretory system",
"Muscular system"
] | C | So what happens to your body's wastes? Obviously, you must get rid of them. This is the job of the excretory system. You remove waste as a gas (carbon dioxide), as a liquid (urine and sweat), and as a solid. Excretion is the process of removing wastes and excess water from the body. |
SciQ | SciQ-2495 | electromagnetism, thermodynamics, energy, work, radiation
Title: Is energy only transmitted through electromagnetic and particle radiations? Which are the other ways of transmission if any? If energy does not require any medium for transmission(as for sunlight reaching earth, the heat too), is it transmitted in quanta in particle radiation too? Energy transfer can be thought to occur via the exchange of a 'virtual particle'. In nature, there are 4 fundamental forces, namely:
1. Electromagnetic force
2. Gravitational force
3. Strong force
4. Weak force
Each of these forces have a different exchange particle:
For instance, the exchange particle for EM is a photon whereas that for the strong force is the gluon. The nature of the interaction is characterised by the properties of the exchange particle.
Now if you want to connect this rather abstract idea to a bigger picture of the more 'real world', you just have to carefully think about what the process you are considering actually involved on a deeper level.
For example: suppose you are pushing a box across your room. What you are actually doing is repelling the electrons on the box by the electrons on your hands, thus causing it to move. Therefore, you the interaction is an electromagnetic interaction and hence the exchange particles involved are photons.
If you think of energy transfer in this way, then indeed all energy transfers occur via 'particle exchanges' or radiation (since you a particle is essentially a wave packet [wave particle duality]).
The following is multiple choice question (with options) to answer.
Through what form of energy transfer does the sun's energy travel? | [
"solar burst",
"radiation",
"Fusion",
"convection"
] | B | Radiation is the transfer of energy by waves. Energy can travel as waves through air or empty space. The Sun's energy travels through space by radiation. After sunlight heats the planet's surface, some heat radiates back into the atmosphere. |
SciQ | SciQ-2496 | quantum-mechanics, atomic-physics, atoms, orbitals
The regions in the diagram correspond to single orbitals if the electron was only in that orbital (no superpositions)
The regions in the diagram just show part of the probability density. Technically the probability density is defined in all space, so all orbitals "overlap" at all points in space
The "location" of the electron does not determine which orbital it is in. If the electron is in some given orbital, we can then use the diagram to determine the most likely region the electron could be observed to be in.
The following is multiple choice question (with options) to answer.
What are the only regions of space that electrons can occupy? | [
"inside nuclei",
"inside protons",
"galaxies",
"orbits"
] | D | Electrons can occupy only certain regions of space, called orbits. |
SciQ | SciQ-2497 | meteorology, clouds, weather-satellites
Title: Great Lakes - cookie cutter clouds On 2014-07-10, in the afternoon, the GOES East satellite image in the visible showed a mass of cloud in central North America. However, in the middle, the Great Lakes stood out in a most extraordinary way, since they were almost completely free of cloud. It was like a cookie-cutter. The cloud followed the outline of the lakes precisely. Why is that?
Here is a second view, from MODIS data: MODIS image of the Great Lakes There are a couple reasons for this. First, Lake Michigan is still cold this time of year, relative to the land that surrounds it. Warm air flowing over the lake will exchange heat and cool, reducing its buoyancy, which will alter the heights at which clouds will form and inhibit lift for surface parcels to achieve that height.
That helps explain the cloudlessness over the lake, but this extends a bit inland as well. I'd have to do a little digging to verify this, but just from that image it looks like that demarcation of cloud/no cloud around the lake is a sea breeze front (or in this case, a lake breeze). The daytime lake breeze flows inland from the water, rises over land and then flows back to the lake where it descends. This will promote clouds where the circulation rises and inhibit them where the circulation falls.
There may also be an orographic effect on along the northern portion of western MI shore, as there are large sand dunes and hills in that area. The upslope flow could be the reason the clouds hug that shore a bit closer than other regions around the lake.
In summary, that looks like a really well defined lake breeze circulation, which explains the shape and location of the clouds.
The following is multiple choice question (with options) to answer.
What appears in autumn when cool air moves over a warm lake? | [
"steam fog",
"feature fog",
"movement fog",
"misty fog"
] | A | Steam fog appears in autumn when cool air moves over a warm lake. Water evaporates from the lake surface. As the water vapor cools, it condenses. The fog appears like steam. |
SciQ | SciQ-2498 | cell-biology, proteins, transcription, cell-signaling, intracellular-transport
Time is in minutes, and zeroed at first contact between the two cells. I've put a red dot on the T-cell and a blue one on the APC in the DIC images (left panes); hopefully that proves more informative than annoying. The right panes show GFP fluorescence and thus CD3 localization. As time progresses, CD3 is re-localized from one part of the membrane to another (the synapse). There is supposedly a video of this is in the supplementary information of the article, though I was unable to open it.
The rate and directionality of the movement implies that an active process is occurring, rather than simple diffusion. However, they did not find the actual mechanism for movement and I haven't found any follow-up papers in a brief search (though many subsequent papers implicate the cytoskeleton in this movement). Just to show that movement of transmembrane proteins can, in fact, be actively directed by the cytoskeleton, I refer you to this paper:
Grabham PW, Foley M, Umeojiako A, Goldberg DJ. 2000. Nerve growth factor stimulates coupling of beta1 integrin to distinct transport mechanisms in the filopodia of growth cones. J Cell Sci 113:3003-3012.
They show that membrane-spanning integrins are moved along actin filaments of the cytoskeleton by myosin motor proteins. Expectedly, the abstract does a good job of summarizing the paper:
The cycling of membrane receptors for substrate-bound proteins via their interaction with the actin cytoskeleton at the leading edge of growth cones and other motile cells is important for neurite outgrowth and cell migration. Receptor delivered to the leading edge binds to its ligand, which induces coupling of the receptor to a rearward flowing network of actin filaments. This coupling is thought to facilitate advance... [T]ransport was dependent on an intact actin cytoskeleton and myosin ATPase...
The following is multiple choice question (with options) to answer.
All cells need what for processes like active transport? | [
"energy",
"sunlight",
"oxygen",
"hydrogen"
] | A | All cells, including both plant and animal cells, need energy for processes such as active transport. How do cells obtain the energy they need?. |
SciQ | SciQ-2499 | chromosome, genomes, dna-helix
Of course, "present" in that paper refers to the late 90's but, in my admittedly brief search, I have been unable to find too much in the way of more recent results. The following paper seems somewhat promising, but I don't have access to it and can only quote from the abstract. It's not much more recent, either.
Schubert I. 2001. Alteration of chromosome numbers by generation of minichromosomes -- is there a lower limit of chromosome size for stable segregation? Cytogenet Cell Genet 93:175-181.
[A] lower size limit for a stable chromosome transmission … might be based, for instance, on insufficient lateral support of centromeres or on insufficient bivalent stability due to the incapability of chiasma formation.
The following is multiple choice question (with options) to answer.
In certain populations, some of the chromosomes have become what? | [
"fused",
"elongated",
"composed",
"dissolved"
] | A | |
SciQ | SciQ-2500 | electricity
Title: Static Electricity I just took a flannel shirt off and it crackled with static. I threw it on a metal chair and I hear it crackle some more. I played with a stray string with my hand, watching it rise to meet my hand and fall when I move it away. But this leaves me with a question to which I cant find an answer on Google. I know later I will pick up the shirt and the static will be gone. Where does static electricity go if its not grounded? Does it dissipate into the air? Or into the object its on? The charges on your shirt will disappear due to discharging through the small conductivity of air and the conductivity of the object where you have put your shirt on.
The following is multiple choice question (with options) to answer.
What occurs as a result of the discharge of static electricity? | [
"clouds",
"lightning",
"drought",
"thunder"
] | B | Zachary Wilson. Lightning is the result of the discharge of static electricity . CC BY-NC 3.0. |
SciQ | SciQ-2501 | biochemistry, enzymes
Title: Can an enzyme be activated without allosteric inhibition or activation? Are there ways by which an enzyme may be activated or inhibited by non substrate molecules other than allosteric activation or inhibition? Apart from what Phototroph mentioned in their answer (competitive and non-competitive inhibition), an enzyme can be activated/inhibited via covalent modification of the protein (post-translational modification) such as phosphorylation by protein kinases (phosphorylation is the most common modification).
The following is multiple choice question (with options) to answer.
Enzymes are a type of what, and as such, they are not reactants in the reactions they control? | [
"neurotransmitter",
"catalyst",
"hormone",
"metabolite"
] | B | Like other catalysts, enzymes are not reactants in the reactions they control. They help the reactants interact but are not used up in the reactions. Instead, they may be used over and over again. Unlike other catalysts, enzymes are usually highly specific for particular chemical reactions. They generally catalyze only one or a few types of reactions. |
SciQ | SciQ-2502 | blood-circulation, blood-pressure, tissue
Title: Blood circulation and blood pressure in different tissues The volume of blood coursing the blood circulation is approximately five litres. A typical vein will stretch about eight times as much as corresponding artery. Because veins have high capacitance, large changes in blood volume have little effect on arterial blood pressure.
If the volume rise or falls, the elastic walls stretch or recoil, changing the volume of blood thus blood pressure in the nervous system.
What else tissues can we consider?
I am interested in blood circulation and blood pressures in different tissues. I'm not sure I understand your question very well-maybe try and rephrase it? As another example, low blood pressure in the kidneys is sensed by the juxtaglomerular apparatus which secretes renin into the circulation. Renin converts angiotensinogen (released by the liver) into angiotensin I. Angiotensin I is then converted into angiotensin II by angiotensin converting enzyme (this is the target of anti-hypertensives called ACE inhibitors) secreted by the lungs. Angiotensin II is a potent vasoconstrictor which directly increases the blood pressure (and hence glomerular filtration rate). Angiotensin II also causes the release of aldosterone which acts on the kidneys to re-absorb salt and water again all facilitating an increase in blood pressure. I hope I've answered your question, if not please edit the question so it very clear.
The following is multiple choice question (with options) to answer.
The entire volume of what is filtered through the kidneys about 300 times per day? | [
"gastric juice",
"saliva",
"urine",
"blood"
] | D | 25.5 Physiology of Urine Formation The entire volume of the blood is filtered through the kidneys about 300 times per day, and 99 percent of the water filtered is recovered. The GFR is influenced by hydrostatic pressure and colloid osmotic pressure. Under normal circumstances, hydrostatic pressure is significantly greater and filtration occurs. The hydrostatic pressure of the glomerulus depends on systemic blood pressure, autoregulatory mechanisms, sympathetic nervous activity, and paracrine hormones. The kidney can function normally under a wide range of blood pressures due to the autoregulatory nature of smooth muscle. |
SciQ | SciQ-2503 | quantum-mechanics, atomic-physics, orbital-motion, physical-chemistry, elements
2 &\hskip1cm (2,0) &\hskip1cm 1 \\
3 &\hskip1cm (2,1) &\hskip1cm 0 &\hskip1cm \text{neon}\\
3 &\hskip1cm (3,0) &\hskip1cm 2 \\
4 &\hskip1cm (3,1) &\hskip1cm 1 &\hskip1cm \text{argon} \\
4 &\hskip1cm (4,0) &\hskip1cm 3 \\
5 &\hskip1cm (3,2) &\hskip1cm 0 \\
5 &\hskip1cm (4,1) &\hskip1cm 2 &\hskip1cm \text{krypton} \\
5 &\hskip1cm (5,0) &\hskip1cm 4 \\
6 &\hskip1cm (4,2) &\hskip1cm 1 \\
6 &\hskip1cm (5,1) &\hskip1cm 3 &\hskip1cm \text{xenon} \\
6 &\hskip1cm (6,0) &\hskip1cm 5 \\
7 &\hskip1cm (4,3) &\hskip1cm 0 \\
7 &\hskip1cm (5,2) &\hskip1cm 2 \\
7 &\hskip1cm (6,1) &\hskip1cm 4 &\hskip1cm \text{radon} \\
7 &\hskip1cm (7,0) &\hskip1cm 6 \\
8 &\hskip1cm (5,3) &\hskip1cm 1 \\
\end{align}
The following is multiple choice question (with options) to answer.
The elements in group 2 are called what? | [
"noble gases",
"metal alloys",
"alkaline earth metals",
"halogens"
] | C | The elements in Group 2 (beryllium, magnesium, calcium, strontium, barium, and radium) are called the alkaline earth metals (see Figure below ). These elements have two valence electrons, both of which reside in the outermost s sublevel. The general electron configuration of all alkaline earth metals is n s 2 . The alkaline earth metals are still too reactive to exist in nature as free elements, but they are less reactive than the alkali metals. They tend to be harder, stronger, and denser than the alkali metals, and they also form numerous compounds with nonmetals. |
SciQ | SciQ-2504 | b) how long would it take this sample to decay to 20% of its original amount. Half-life is the time required for the amount of something to fall to half its initial value. It is usually used to describe quantities undergoing exponential decay (for example, radioactive decay) where the half-life is constant over the whole life of the decay, and is a characteristic unit (a natural unit of scale) for the exponential decay equation. Hence, (afterwards) complete the given example underneath. A half-life is the period of time it takes for a substance undergoing decay to decrease by half. Therefore, if we know how much carbon-14 was originally present in an object and how much carbon-14 remains, we can determine the age of the object. The larger the value of k, the faster the decay will occur.. Half-Life in Exponential Decay. Radium-221 has a half-life of 30 seconds. t 1/2: Half life time However, if you must learn about these in school, then this is the place to learn it. Half-life (symbol t 1â2) is the time required for a quantity to reduce to half of its initial value.The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo, or how long stable atoms survive, radioactive decay.The term is also used more generally to characterize any type of exponential or non-exponential decay. You can calculate half life if you know how much of the substance is left after a certain time, though typically it works the other way - the half life is known, and used to calculate age. N(0) is the initial quantity of this substance. Solution : Half-Life Decay Formula : A = P(1/2) t/d. Polonium 210 has a half life of 140 days (a) if a sample of Po has a mass of 300 micrograms find a formula for the mass after t days. Half-life formula: If the half-life is: Carbon-14 dating: is the amount of carbon-14 when the plant or animal died is the amount of carbon-14 remaining today is the age of the fossil in years: Doubling time formula: If the doubling time is: Newtonâs Law of Cooling: where is the ambient temperature, and is the continuous rate of cooling. Substitute. The e function is raised to a negative value, which means that is exponential decline in value. The half-life of
The following is multiple choice question (with options) to answer.
What term decribes the amount of time required for half of the original material to decay in an isotope? | [
"half-life",
"Geiger count",
"life cycle",
"radioactive isotope"
] | A | 11.6 End-of-Chapter Material Chapter Summary To ensure that you understand the material in this chapter, you should review the meanings of the bold terms in the following summary and ask yourself how they relate to the topics in the chapter. Some atoms have unstable nuclei that emit particles and high-energy electromagnetic radiation to form new elements that are more stable. This emission of particles and electromagnetic radiation is called radioactivity. There are three main types of spontaneous radioactive emission: alpha particles, which are equivalent to helium nuclei; beta particles, which are electrons; and gamma radiation, which is highenergy electromagnetic radiation. Another type of radioactive process is spontaneous fission, in which large nuclei spontaneously break apart into smaller nuclei and, often, neutrons. In all forms of radioactivity, new elements are formed from the radioactive reactants. Radioactive isotopes decay at different rates. The rate of an isotope’s decay is expressed as a half-life, which is the amount of time required for half of the original material to decay. The length of its half-life is a characteristic of the particular isotope and can range from less than microseconds to billions of years. Amounts of radioactivity are measured in several different ways. A becquerel is equal to one radioactive decay per second. A curie represents 3.7 × 1010 decays per second. Other units describe the amount of energy absorbed by body tissues. One rad is equivalent to 0.01 joule of energy absorbed per gram of tissue. Different tissues react differently to different types of radioactivity. The rem unit takes into account not only the energy absorbed by the tissues, but also includes a numerical multiplication factor to Saylor URL: http://www. saylor. org/books. |
SciQ | SciQ-2505 | thermodynamics, evaporation, gas, liquid-state
On the water surface, knowing the temperature, we can estimate the vapor pressure and vapor mixture fraction. Then there will be an diffusion process for the water vapor to move out and for the ambient air to move in. Because the water surface doesn't allow the air to further move, a circulation forms. When the water vapor moves out, the water vapor pressure drops, so more liquid water evaporates to fill up the loss of water vapor. The evaporation associates latent heat so water surface area temperature drops (you may see dew on the bowl wall). Then a heat transfer process starts which may initiate water circulation as well.
As this is complex, doing test might be a quick way to get the K value if you assume it is a constant, which is questionable.
The following is multiple choice question (with options) to answer.
What occurs when water lost by transpiration is not replaced by absorbtion from room? | [
"wilting",
"shedding",
"perspiration",
"rotting"
] | A | |
SciQ | SciQ-2506 | meteorology, climate-change, gas, pollution
Title: Regarding various types of atmospheric pollution Does all the car pollution (from about 150 million cars at least in the U.S. and a lot more in all of North America and the rest of the world) all the smoke-stack pollution of various factories and all the Airline pollution running day after day have a deleterious and damaging effect on the general atmosphere and, over time, the climate?
Given all the observed pollution that China has caused itself and some of the resulting weird weather events there this certainly seems to be evidence of the damaging effects of car and factory pollution. Has anyone calculated how much exhaust from cars is produced in one day on average in a 'moderate' sized city?
Of course it seems with all the increased oil production in the U.S. and elsewhere we, human beings are going to keep are love-affair with gas-powered cars for the next 200 or 300 years. That is if we don't use up all the oil and gas in the ground before then. As a USA resident, the EPA is the best place to start when wondering about the emissions inventory of atmospheric pollutants or pollutant precursors that affect the National Ambient Air Quality Standards (e.g. Particulate Matter, Carbon Monoxide, Sulfur Dioxide, Lead, Nitrogen Oxides, Volatile Organic Compounds). The EPA compiles a comprehensive emissions inventory of all criteria pollutants at the county level which is available in the National Emissions Inventory (compiled once every 3 years). You can see the summary of your county at http://www.epa.gov/air/emissions/where.htm. As for the effects of atmospheric pollution, it is important to consider the lifetime of said pollutants in the atmosphere in order to put their environmental impacts into perspective. For instance, the air pollutants covered by the National Ambient Air Quality Standards have immediate health effects when high concentrations are breathed in regularly. Both animals and plants are adversely affected by these irritating and sometimes toxic chemicals, but these pollutants are also reactive and do not last long in the atmosphere unless they are constantly being replenished (e.g. daily traffic). Air quality also impacts critical nitrogen loads on ecosystems and possible production of acid rain.
The following is multiple choice question (with options) to answer.
Molds, pollen, and pet dander are examples of air pollution with what type of source? | [
"physical",
"biological",
"chemical",
"ecological"
] | B | Biological sources of air pollution include molds, pollen, and pet dander. |
SciQ | SciQ-2507 | neural-networks, deep-learning
I suppose connections between neurons do not generally arrange themselves in the way described, though, so it would still be interesting to get insight into whether there are patterns of how the inter-neuron connections arrange themselves in neural networks trained to solve actual problems.
The following is multiple choice question (with options) to answer.
Neurons are classified based on the direction in which they carry what? | [
"energy",
"neurotransmitters",
"nerve impulses",
"metabolism impulses"
] | C | Neurons are classified based on the direction in which they carry nerve impulses. |
SciQ | SciQ-2508 | deep-learning, data-mining, bigdata, pca
Title: What is the difference between observation and variable? I have a matrix with size m×n that is built from n number of individuals for person identification. So, n is the number of person and m is the number of feature's value for the person.
It makes me confused about observation and variables. What will I call n and m? Which one represents observation and which one represents variable? My confusion will be cleared to you if you visit the following link: How to do SVD and PCA with big data? In your case, 'n' is the number of observations, and 'm' is the number of variables. Think of a table in a database - each row is a 'record', and each record has various properties. A record corresponds to an observation. Each property is a variable or property of that observation.
In some contexts people make a distinction between data (i.e. observations, things observed) and variables (parameters to learn - things that vary in a mathematical sense). But in the context of the link you sent, a variable is a feature.
The following is multiple choice question (with options) to answer.
What is the process of making an observation in terms of a numerical scale and recording the value? | [
"measurement",
"graduation",
"respiration",
"ambient"
] | A | Measurement is the process of making an observation in terms of a numerical scale and recording the value. |
SciQ | SciQ-2509 | evolution, zoology, taxonomy, phylogenetics
The apomorphy that defines the tetrapods is "paired limbs". You have Amphibia to the left and Amniota to the right, whose apomorphy is " egg with extraembrionic membranes". Inside them, you have Reptilia, whose apomorphies are "skull with upper and lower fenestra and beta-keratin in epidermis". Turtles came from an ancestor with these characteristics. So, turtles belong to the monophyletic group of "Reptiles".
Post scriptum: You wrote that "turtles (specifically sea turtles) live on both land and water, very much like amphibians". Just a curiosity: the reason why sea turtles leave the water (sea) from time to time shows exactly that they are not amphibians! Amphibians, being non-amniotes, have eggs that survive under water (actually, with few exceptions, they need to be under water). Turtles, on the other hand, are amniotes, and the amniotic egg cannot be laid under water. That's why the turtles have to leave the water to lay eggs: because, contrary to the amphibians, they cannot lay eggs under water.
The following is multiple choice question (with options) to answer.
What makes monotremes different than other mammals? | [
"they lay eggs",
"they lack backbones",
"they spawn",
"they reproduce asexually"
] | A | 29.6 Mammals Mammals in general are vertebrates that possess hair and mammary glands. The mammalian integument includes various secretory glands, including sebaceous glands, eccrine glands, apocrine glands, and mammary glands. Mammals are synapsids, meaning that they have a single opening in the skull. A key characteristic of synapsids is endothermy rather than the ectothermy seen in other vertebrates. Mammals probably evolved from therapsids in the late Triassic period, as the earliest known mammal fossils are from the early Jurassic period. There are three groups of mammals living today: monotremes, marsupials, and eutherians. Monotremes are unique among mammals as they lay eggs, rather than giving birth to young. Eutherian mammals are sometimes called placental mammals, because all species possess a complex placenta that connects a fetus to the mother, allowing for gas, fluid, and nutrient exchange. |
SciQ | SciQ-2510 | acid-base, experimental-chemistry, ph
Title: Determining (approximately) the amount of a strong base needed to change a buffer's pH by a certain number of units I'm measuring buffer capacity by titrating $\ce{NaOH}$ into a buffer of $\ce {H3PO4 + NaH2PO4}$. I'm measuring buffer capacity by recording the amount of $\ce{NaOH}$ required to increase the $\mathrm{pH}$ of the buffer by 2 units, and then taking the ratio.
My problem is that I have no idea how much $\ce{NaOH}$ I'll need to change the $\mathrm{pH}$ by that much. If I've underestimated the strength of my buffer, I might have to reduce the drop in $\mathrm{pH}$ to just one unit. I need to have a rough idea so I can organize how much of each I'll need to prepare.
Basically, is there any way I can predict (roughly) how much $\ce{NaOH}$ I'll need?
Details:
The following is multiple choice question (with options) to answer.
The strength of bases is measured on what scale? | [
"pneumatic scale",
"acid test",
"ph scale",
"litmus test"
] | C | The strength of bases is measured on a scale called the pH scale, which ranges from 0 to 14. On this scale, a pH value of 7 indicates a neutral solution, and a pH value greater than 7 indicates a basic solution. The higher the pH value is, the stronger the base. The strongest bases, such as drain cleaner, have a pH value close to 14. |
SciQ | SciQ-2511 | organic-chemistry, isomers
Title: Why are some strucutres isomers while others are not? Why are some structures considered isomers but others are not? Take C3H9N for instance, according to https://www.chegg.com/homework-help/questions-and-answers/four-constitutional-isomers-molecular-formula-c3h9n-q17859870 , only the four checked boxes are isomers, but why are the other 4 not? The other four seem to also satisfy all Lewis rules and do have same formula but with different arrangements. Also, how do we determine which structure is the "original" while which are the isomer(s)? Thanks for all help The supposed answers are wrong. The Lewis dot structures are based on forming an octet of electrons around each atom using the s and p orbitals, typically hybridized to sp3. The four isomers are:
Ethylmethylamine
Isopropylamine
Propylamine (which isn't even shown on shown key...)
Trimethylamine
Error 1 - This structure isn't valid since the double bond shown in red box gives carbon and nitrogen both 10 electrons instead of 8.
Error 2 - This structure isn't valid since the double bond shown in red box gives both carbon atoms 10 electrons instead of 8.
Error 3 - This structure isn't valid since the double bond shown in red box gives carbon and nitrogen both 10 electrons instead of 8.
Error 4 - This structure isn't valid since the double bond shown in red box gives carbon and nitrogen both 10 electrons instead of 8.
The following is multiple choice question (with options) to answer.
What type of isomers contain the same number of atoms of each kind but differ in which atoms are bonded to one another? | [
"structural isomers",
"different isomers",
"constitutional isomers",
"unique isomers"
] | A | Isomers that contain the same number of atoms of each kind but differ in which atoms are bonded to one another are called structural isomers. Isobutane and n-butane are examples of structural isomers. One kind of isomerism consists of two compounds that have the same empirical formula but differ in the number of formula units present in the molecular formula. An example in coordination compounds is two compounds with the empirical formula Pt(NH 3)2Cl2. One is a simple square planar platinum(II) complex, Pt(NH3)2Cl2, and the other is an ionic compound that contains the [Pt(NH 3)4]2+ cation and the [PtCl4]2− anion, [Pt(NH3)4][PtCl4]. As you might expect, these compounds have very different physical and chemical properties. One arrangement of the Cl− and NH3 ligands around the platinum ion in the former gives the anticancer drug cisplatin, whereas the other arrangement has no known biomedical applications. |
SciQ | SciQ-2512 | safety, gas
Title: Rotten Egg Gas Smell Background context for question
When I was young, we'd go fishing. And Dad would put a camper on the back of the truck. One time we came back in after fishing and the camper smelled like rotten eggs. He used that as an opportunity to teach us how some gases are tasteless/odorless. And as a result that sort of rotten egg smell is added as a safety measure.
Question:
My question is this: What are those gases that are odorless that then have that rotten egg smell added to them? Rotten eggs happen much less frequently than 50-60 years ago because of better hen-consumer refrigeration. Most people today have not had the pleasure of smelling them. H2S and low molecular weight mercaptans [AKA thiols] have distinct more or less unpleasant odors tho at low concentrations they can smell sweet, and we can develop tolerances to many at higher concentrations when they can be deadly. H2S is supposedly the active ingredient in rotten eggs; Methylsulfide CH3SH the active gas in human feces, and thioglycolic acid in eau de skunk.
Manufactured gas, no longer used, was a mix of H2 and CO and is toxic. It was flavored with mercaptan at rather high levels; smelling gas then was almost a death sentence, we were trained to open windows and leave immediately. There was also the explosion hazard. Manufactured gas was replaced by "natural", really fossil fuel, gas that is mostly methane CH4. Methane is odorless, not toxic, but it can be soporific, and it can explode. A warning is still necessary tho it seems to me the odorant is now less noxious and less intense than before [It could be my sense of smell has waned.]. It is to protect from explosion, again evacuate and ventilate. Odorants are added to propane and LPG, I do not know about hydrogen. Perfumes are added to many products to overcome odors or enhance odors and Bitrex is added to some drugs to make them less palatable so it works both ways.
The following is multiple choice question (with options) to answer.
What is the gas that gives rotten eggs and sewage their distinctive smell? | [
"calcium sulfide",
"hydrogen peroxide",
"hydrogen sulfide",
"methane"
] | C | Prokaryotes have a wide range of metabolisms, and this determines where they live. They live in a particular habitat because they are able to “eat” whatever is around them. For example, there are bacteria and archaea that break down hydrogen sulfide to produce ATP. Hydrogen sulfide is the gas that gives rotten eggs and sewage their distinctive smell. It is poisonous to animals, but some prokaryotes depend on it for life. |
SciQ | SciQ-2513 | blood-circulation, blood-pressure, tissue
Title: Blood circulation and blood pressure in different tissues The volume of blood coursing the blood circulation is approximately five litres. A typical vein will stretch about eight times as much as corresponding artery. Because veins have high capacitance, large changes in blood volume have little effect on arterial blood pressure.
If the volume rise or falls, the elastic walls stretch or recoil, changing the volume of blood thus blood pressure in the nervous system.
What else tissues can we consider?
I am interested in blood circulation and blood pressures in different tissues. I'm not sure I understand your question very well-maybe try and rephrase it? As another example, low blood pressure in the kidneys is sensed by the juxtaglomerular apparatus which secretes renin into the circulation. Renin converts angiotensinogen (released by the liver) into angiotensin I. Angiotensin I is then converted into angiotensin II by angiotensin converting enzyme (this is the target of anti-hypertensives called ACE inhibitors) secreted by the lungs. Angiotensin II is a potent vasoconstrictor which directly increases the blood pressure (and hence glomerular filtration rate). Angiotensin II also causes the release of aldosterone which acts on the kidneys to re-absorb salt and water again all facilitating an increase in blood pressure. I hope I've answered your question, if not please edit the question so it very clear.
The following is multiple choice question (with options) to answer.
What two values does a blood pressure reading include? | [
"biotic and abiotic",
"high and low",
"cholesterol and systolic",
"systolic and diastolic"
] | D | Blood pressures are expressed in millimeters of mercury. What would be the blood pressure in atmospheres if a patient’s systolic blood pressure is 120 mmHg and the diastolic blood pressure is 82 mmHg? (In medicine, such a blood pressure would be reported as “120/82,” spoken as “one hundred twenty over eighty-two. |
SciQ | SciQ-2514 | cardiology, embryology, pain, central-nervous-system
Title: At what stage is the nervous system developed enough to interpret neuronal signals as 'pain'? According to this article in Live Science, one of the reasons the fetus can't feel pain until 19 weeks is because the nervous system isn't fully developed.
But according to this article, the heart starts beating at day 16.
And according to this article, the nervous system controls the rate beating of the heart.
Then my question is, **how can it be assured that the nervous system isn't developed until 19 weeks, when the nervous system controls the heart beating rate since day 16? First, there is some confusion on your part about heart cells and pain perception. Heart cells generate an action potential intrinsically; they do not need the central nervous system to beat (your second article explains this; read the part about the importance of calcium.) So yes, long before a fetus can feel pain, the heart is beating, because there must be circulation of nutrients throughout the embryo.
Secondly, the vagus nerve and sympathetic nerves can affect heart rate (the former by slowing it down when firing). These nerves start to reach their endpoints late in week 4 of development. So 19 days is not correct.
Cardiac sympathetic system
Although the primitive human heart starts to beat at 21 to 22 d, heart development continues to day 50, and it is near the end of this period, during the fifth week, that thoracic neural crest cells migrate from the neural tube through the somites and form aggregations (ganglia) near the dorsal aorta. [emphasis mine]
To experience pain, however, requires maturation of certain parts of the brain, most importantly, part of the thalamus and the cerebral cortex:
Current theories of pain consider an intact cortical system to be both necessary and sufficient for pain experience. In support are functional imaging studies showing that activation within a network of cortical regions correlate with reported pain experience. Furthermore, cortical activation can generate the experience of pain even in the absence of actual noxious stimulation. These observations suggest thalamic projections into the cortical plate are the minimal necessary anatomy for pain experience. These projections are complete at 23 weeks' gestation. [emphasis mine]
The following is multiple choice question (with options) to answer.
In humans, what period lasts from the ninth week of development until birth? | [
"fetal period",
"plasma period",
"third trimester",
"development period"
] | A | 28.3 Fetal Development The fetal period lasts from the ninth week of development until birth. During this period, male and female gonads differentiate. The fetal circulatory system becomes much more specialized and efficient than its embryonic counterpart. It includes three shunts—the ductus venosus, the foramen ovale, and the ductus arteriosus—that enable it to bypass the semifunctional liver and pulmonary circuit until after childbirth. The brain continues to grow and its structures differentiate. Facial features develop, the body elongates, and the skeleton ossifies. In the womb, the developing fetus moves, blinks, practices sucking, and circulates amniotic fluid. The fetus grows from an embryo measuring approximately 3.3 cm (1.3 in) and weighing 7 g (0.25 oz) to an infant measuring approximately 51 cm (20 in) and weighing an average of approximately 3.4 kg (7.5 lbs). Embryonic organ structures that were primitive and nonfunctional develop to the point that the newborn can survive in the outside world. |
SciQ | SciQ-2515 | standard-model, quarks, protons
Title: What's inside a proton? What constitutes protons? When I see pictures, I can't understand. Protons are made of quarks, but some say that they are made of 99% empty space. Also, in this illustration from Wikipedia, what's between the quarks? Ah, I know this one!
What's in a proton?
A proton is really made of excitations in quantum fields (kind of like localized waves). Remember that. Any time you hear any other description of the composition of a proton, it's just some approximation of the behavior of quantum fields in terms of something people are likely to be more familiar with. We need to do this because quantum fields behave in very nonintuitive ways, so if you're not working with the full mathematical machinery of QCD (which is hard), you have to make some kind of simplified model to use as an analogy.
One of the more confusing things about quantum field excitations is that they react differently depending on how they are observed. More specifically, the only way to measure the properties of an excitation in a quantum field is to make it interact with another excitation and see how the excitations affect each other. Or in particle language, you have to hit the particle with another particle (the "probe") and see what comes out. Depending on the charge, energy, momentum and other properties of the probe, you can get various results.
The following is multiple choice question (with options) to answer.
Where are protons found in the atom? | [
"in the orbital",
"within electrons",
"in the nucleus",
"outside the nucleus"
] | C | Rutherford proposed a new atomic model that described the atom as comprised of a positively charged nucleus surrounded by negatively charged electrons. In this model, most of the atom was thought to be empty space. *Protons are positively charged and have a relatively large mass compared to electrons. Protons can be found in the nucleus of the atom. |
SciQ | SciQ-2516 | 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.
What is produced when haploid gametes fuse in sexual reproduction? | [
"cell cluster",
"deformity",
"isolated zygote",
"diploid zygote"
] | D | Fertilization of an egg cell by a sperm cell. In sexual reproduction, haploid gametes fuse to produce a diploid zygote. |
SciQ | SciQ-2517 | botany, homework, terminology, plant-anatomy, tissue
Interfascicular cambium differentiates from parenchyma or collenchyma cells located between the vascular bundles (mainly in stem)
The following is multiple choice question (with options) to answer.
What are the two different types of vascular tissues called? | [
"biotic and abiotic",
"xylem and phloem",
"acid and base",
"epidermis and dermis"
] | B | The vascular tissues for which these plants are named are specialized to transport fluid. They consist of long, narrow cells arranged end-to-end, forming tubes. There are two different types of vascular tissues, called xylem and phloem. Both are shown in Figure below . |
SciQ | SciQ-2518 | evolution, brain, development
Title: Why does it take so long for the human brain to develop from an evolutionary point of view?
I have read that it takes about 25 years for the brain to be fully developed.
Coincidentally, humans from the Neolithic and Bronze Age had a very short life expectancy, in fact most of their life their brain wasn't fully developed.
My question is:
from an evolutionary point of view, is there a reason why humans spend so much of their life not being fully developed even long after being sexually fully developed? We can say that brain and our nerve system is the first system in embryo that starts to develop and as you said this system is continuing to develop until after birth.
So here is a question that why our brain don't develop completely before the birth ? Evolution has gone so far as to limit the development of the brain in the human embryonic phase and to allow it to continue into the postnatal phase. This helps the infant to be born and ease the birth both for mother and the new born because if the brain had fully grown, the size of the head would have made problem in birth. Now, after birth, the brain continues to grow and develop majorly between ages 2-3 and becomes more mature after that . The ability of the brain to grow over the years gives us the ability to adapt to different environments , learnings and new issues and other capabilities That happens with the subsequent creation and pruning of dendritic spines.
The following is multiple choice question (with options) to answer.
During which stage of development do all the major organs begin to form? | [
"transgenic",
"third trimester",
"nascent",
"embryonic"
] | D | After cells differentiate, all the major organs begin to form during the remaining weeks of embryonic development. A few of the developments that occur in the embryo during weeks 4 through 8 are listed in Figure below . As the embryo develops, it also grows in size. By the eighth week of development, the embryo is about 30 millimeters (just over 1 inch) in length. It may also have begun to move. |
SciQ | SciQ-2519 | electrolysis
Title: Electrolysis on aqeuous solution I know when electrolysis on a concentration aqeuous solution which contains halide ions($Cl^-$ , $Br^-$ , $I^-$). The halide ions is discharged although $OH^-$ is more easily to discharged.
For example, electrolysis of concentration aqueous sodium chloride. The cation $Cl^-$ and $OH^-$ will attract to the anode. The $Cl^-$ ions will be discharged although according to the electrochemical series that the $OH^-$ will be more easily discharged.
Why do that happen? Let's explain this using an example. Consider a cell in which an aqueous solution of sodium chloride is electrolyzed. The $\ce{Na^+}$ ions migrate toward the negative electrode and the $\ce{Cl^-}$ ions migrate toward the positive electrode. But indeed at the anode, there are two substances that can be oxidized at the anode: $\ce{Cl^-}$ ions and water molecules.
$$\ce{2Cl^- \rightarrow Cl_2 + 2e^-}$$ $$\ce{2H_2O \rightarrow O_2 + 4H^+ + 4e^-}$$
The standard-state potentials for these half-reactions are $E^0_{ox}= -1.36 V$ for the first couple and $E^0_{ox}= -1.23 V$ for the second couple.
At first glance, it would seem easier to oxidize water ($E^0_{ox}= -1.23 V$) than $\ce{Cl^-}$ ions ($E^0_{ox}= -1.36 V$).
The following is multiple choice question (with options) to answer.
At the anode, liquid chloride ions are oxidized to what? | [
"nitrogen gas",
"elemental gas",
"chlorine gas",
"Heavy Gas"
] | C | In a Down’s cell, the liquid sodium ions are reduced at the cathode to liquid sodium metal. At the anode, liquid chloride ions are oxidized to chlorine gas. The reactions and cell potentials are shown below. |
SciQ | SciQ-2520 | genetics, dna-sequencing, human-genetics, genomics, biotechnology
Yes, it is counted on the haploid genome. I would not make any sense to count it on the diploid genome. When looking at my last paragraph you might see why: Remember, we are looking at (i) fixed differences (both copies of a diploid human genome differ from both copies of a diploid chimpanzee genome) or (ii) at variable sites. Assume you find one site in one haploid genome that fulfills either (i) or (ii). If you then look at the same site in the other copy of the genome you already know that the position is either (i) or (ii). This means that it has already been counted as a difference. If you counted it again, in the worst case, over the complete genome, you would count everything twice. In general, you would strongly overestimate the absolute difference.
Also ,I'm not sure that about one percent difference is calculated on one base pair or one nucleotide every thousand base pairs or nucleotides .Because he mentioned the both.
I do not understand this. I had a brief look at the video and heard him talking of one nucleotide per thousand. He compares the sequence difference between human-chimpanzee (98.8% overlap, approx. 1 per 100, about 1.2% fixed differences and SNPS) and human-human (99.9% overlap, approx. 1 per 1000, 0.1% SNP), pairs. Note that in the last case we cannot look at fixed differences as there are no fixed differences between human populations. The 0.1% difference are the percentage of SNP in the human genome.
The following is multiple choice question (with options) to answer.
A diploid cell contains two sets of what? | [
"chromosomes",
"ribosomes",
"atoms",
"neutrons"
] | A | The surface of Venus is shrouded by thick clouds. Radar images show a complex surface. There are volcanoes and craters like those found on other planets and moons. The surface is not nearly as complex as the surface of Earth. |
SciQ | SciQ-2521 | cholesterol
Some LDL cholesterol circulating through the bloodstream tends to deposit in the walls of arteries. This process starts as early as childhood or adolescence.
White blood cells swallow and try to digest the LDL, possibly in to digest the LDL, possibly in an attempt to protect the blood vessels.
In the process, the white blood cells convert the LDL to a toxic (oxidized) form.
More white blood cells and other cells migrate to the area, creating steady low steady low-grade inflammation in the artery wall.
Over time, more LDL cholesterol and cells collect in the area. The ongoing process creates a bump in the artery wall called a plaque. The plaque is made of cholesterol, cells, and debris.
The process tends to continue, growing the plaque and slowly blocking the artery.
There is a good overview of the general physiology here in Robbins The Pathologic Basis of Disease. Chapter 5, Genetic Disorders, reviews the physiology, and the relevance to disease, in the section on Familial Hypercholesterolemia. The review is relevant to hypercholesterolemia in general.
The following is multiple choice question (with options) to answer.
On what basis are lipoproteins classified? | [
"diameter",
"density",
"mass",
"weight"
] | B | Other lipoproteins also transport lipids throughout the body, but different types of lipoproteins tend to serve different functions. We will discuss some of these differences in the section below on cholesterol and heart disease. Lipoproteins are often classified into five different groups based on their densities. In increasing order of density, these groups include chylomicrons, very-low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL). |
SciQ | SciQ-2522 | molecular-biology, molecular-genetics, development, sex
Quote from a Review (Yao 2005):
We have just begun to glimpse into the mechanisms underlying ovarian development. Convincing evidence challenges us to reconsider the existing paradigm that describes ovarian development as a default system. The default concept was first proposed in the early 1950s when Jost performed the groundbreaking experiments to demonstrate mechanisms of sex differentiation of reproductive tracts (Jost, 1947, 1953, 1970). The term “default” was not originally intended to describe the developmental status of the ovary. Instead, it is referred to the female reproductive tract or the Mullerian duct based on the fact that the female reproductive tract forms in both XX and XY individuals in the absence of gonads. Indeed, now it has become evident that early ovarian development is an active process involving intrinsic cell fate decisions and complex crosstalks between germ cells and somatic cells. Most intriguingly, the appearance of testicular structures in XX individuals where Sry and its downstream components are absent further raises the improbable question: Could the testicular development be default after all?
The following is multiple choice question (with options) to answer.
The two ovaries are small, oval organs on either side of what part of the body? | [
"pancreas",
"uterus",
"heart",
"lungs"
] | B | The two ovaries are small, oval organs on either side of the uterus. Each ovary contains thousands of eggs, with about 1-2 million immature eggs present at birth and 40,000 immature eggs present at puberty, as most of the eggs die off. The eggs do not fully develop until a female has gone through puberty. About once a month, on average one egg completes development and is released by the ovary. The ovaries also secrete estrogen , the main female sex hormone. |
SciQ | SciQ-2523 | respiration
Here is what happens at the molecular level.
The $\rm CN^-$ ions diffuse into the mitochondria. They have high affinity to the ferrous ion of the mitochondrial enzyme cytochrome c oxidase involved in the electron transport chain (ETC), one of the phases of cellular respiration where $\rm ATP$ is generated from $\rm NADH$ and $\rm FADH_2$. And it is this process that actually requires oxygen. The inhibited cytochrome c oxidase is of no good in transporting electrons, thus no $\rm ATP$ molecules are generated. The oxygen molecules waiting for those electrons remain empty handed resulting in the increase in the concentration of molecular oxygen. Remember, ETC occurs in almost all living cells except a few like RBC which get their major share of ATP from the highly inefficient anaerobic glycolysis. Also, $\rm ATP$ is the energy currency of our body and is required in a wide variety of bodily processes like osmotic balance, nerve impulse transmission, muscle contraction etc. With no $\rm ATP$ your heart and respiratory muscles can't contract, your medulla can't regulate breathing, your kidneys can't concentrate urine and the list goes on. Death is imminent if a high concentration of cyanide gets into your blood.
The symptoms of panic like tachypnea and tachycardia (that result due to low oxygen in blood) are not usually seen unless the victim himself knows he is poisoned. The end effects like cardiac and respiratory arrest, seizures and coma, however, are similar to those of suffocation.
For further read:
The Mechanism of Cyanide Intoxication and its Antagonism
The following is multiple choice question (with options) to answer.
Gas exchange during respiration occurs primarily through what? | [
"activation",
"vaporization",
"secretion",
"diffusion"
] | D | Basic Principles of Gas Exchange Gas exchange during respiration occurs primarily through diffusion. Diffusion is a process in which transport is driven by a concentration gradient. Gas molecules move from a region of high concentration to a region of low concentration. Blood that is low in oxygen concentration and high in carbon dioxide concentration undergoes gas exchange with air in the lungs. The air in the lungs has a higher concentration of oxygen than that of oxygen-depleted blood and a lower concentration of carbon dioxide. This concentration gradient allows for gas exchange during respiration. Partial pressure is a measure of the concentration of the individual components in a mixture of gases. The total pressure exerted by the mixture is the sum of the partial pressures of the components in the mixture. The rate of diffusion of a gas is proportional to its partial pressure within the total gas mixture. This concept is discussed further in detail below. |
SciQ | SciQ-2524 | proteins, food, digestive-system, amino-acids, digestion
Title: How are proteins reused in the body? Part of what we eat are proteins,
and our body is in part build of proteins.
Are the proteins of the body build based on proteins in food at all?
Are proteins in food directly reused in the body,
or are proteins first disassembled?
How far are they disassembled, randomly in various pieces, or systematically to keep what can optimally be used to build new proteins, while nothing is wasted for energy?
(The question Can proteins/peptides pass through the intestine? and it's answers are related, and provide some context and relevant parts, but is not a duplicate.) Short answer: Indeed the proteins in our body are based on amino acids from external food sources. BUT, proteins up-taken from food are ALWAYS disassembled first into amino acids, through specialized enzymes, proteases, (for instance Pepsin in the stomach's gastric juices and Tripsin in the pancreatic juices), during digestion, in the alimentary canal, (gut). This enables the body's liver to build the proteins most needed by the organism itself, through the processes of transamination, that allows conversion betwixt amino acids, and deamination, that removes N2 from the amino acid, (let's say the "amino" part is removed, and then expelled as urea), to excrete amino acids in excess. In addition this breaking down of external proteins is necessary, since they can act as labels for pathogens, and external organisms in general, and thus would soon be destroyed by the immune system if reused straight away.
The following is multiple choice question (with options) to answer.
Enzymes in the stomach and small intestine break down proteins into what components? | [
"lactic acids",
"antioxidants",
"amino acids",
"atoms"
] | C | Figure 24.17 Digestive Enzymes and Hormones Enzymes in the stomach and small intestine break down proteins into amino acids. HCl in the stomach aids in proteolysis, and hormones secreted by intestinal cells direct the digestive processes. |
SciQ | SciQ-2525 | photosynthesis, respiration, ecosystem, decomposition
Maybe you should study the metabolic processes of plants and life in general to better understand this. All life consists of chemical reactions that build up structures; in order to build them up you need energy (because of the second law of thermodynamics), and all living things create that energy by breaking down complex molecules into simpler ones. (as such it would be more accurate to say that all life consists of chemical reactions that build up and break down various structures). You might be wondering "but what about the difference between autotrophs and heterotrophs I heard about"; the difference between those is where they get the complex molecules from in the first place. Autotrophs use a different source of energy to build them up while heterotrophs get them from their environment. As such, you can think of every living thing as being made of two kind of molecules: those that actually form their structure (in humans, the molecules that make up cell membranes, bones, muscles, etc) and those that are stored in order to be broken down to power the whole system (in humans that's fat, glycogen, glucose, etc). Of course a molecule can do both; if you're starving your body may start to break down structural molecules for power. There are many different ways of breaking down those big molecules for power; the most efficient one, that starts with a big chain of carbon atoms and cuts it down into individual CO2 molecules using O2 molecules, is called aerobic respiration (i.e. respiration that uses oxygen).
Because those complex molecules are required to power all life, autotrophs (the organisms that actually make them) are very important, and the processes they use to make them are very important too. The process that makes almost all of the molecules that power almost all life on earth is photosynthesis, which uses the energy from the sun to power a reaction that converts CO2 from the atmosphere into big carbon-based molecules we'll call carbohydrates. This is called "fixing carbon", since the carbon atom is the most important one; measuring how much photosynthesis is happening is another way of measuring how many carbon atoms move from being part of a CO2 molecule to being part of a plant.
The following is multiple choice question (with options) to answer.
Organisms incapable of photosynthesis that must therefore obtain energy and carbon from food by consuming other organisms are called what? | [
"chemoautotrophs",
"heterotrophs",
"autotrophs",
"photoautotrophs"
] | B | Heterotrophs are organisms incapable of photosynthesis that must therefore obtain energy and carbon from food by consuming other organisms. The Greek roots of the word heterotroph mean “other” (hetero) “feeder” (troph), meaning that their food comes from other organisms. Even if the food organism is another animal, this food traces its origins back to autotrophs and the process of photosynthesis. Humans are heterotrophs, as are all animals. Heterotrophs depend on autotrophs, either directly or indirectly. Deer and wolves are heterotrophs. A deer obtains energy by eating plants. A wolf eating a deer obtains energy that originally came from the plants eaten by that deer. The energy in the plant came from photosynthesis, and therefore it is the only autotroph in this example (Figure 5.3). Using this reasoning, all food eaten by humans also links back to autotrophs that carry out photosynthesis. |
SciQ | SciQ-2526 | cosmology, universe, big-bang, space-expansion, popular-science
The better a theory is, the more it seems valid as a function of how much people try to tear it apart, and fail. This process often leads to additional unexpected discovery.
Don't get discouraged by your first or currently favorite idea not turning out to be good - in a class I took a few years ago on evolutionary computation, our teacher told us that Einstein invented and mentally tested several ideas PER MINUTE when he was a patent clerk. This is less impressive (yet still very impressive) than it sounds if you understand that in science often discovery is a process of search-and-evaluate. Ideas are a dime a dozen, quite literally. What makes good ideas live longer than bad ones is that they withstand scrutiny.
The toolkit that competent scientists have which many regular citizens lack is refined training for knowing what is plausible and what not, in the physical world. You can have a theory that contradicts existing theories, but it had better be EXPLANATORY, not just POSTULATORY. Because existing theories explain a lot, a new theory that hopes to replace existing ones needs to be better at everything the other theories do.
Harsh, honest and educated scrutiny is the best way to sort good ideas from bad ones.
Good luck!
The following is multiple choice question (with options) to answer.
What allows theories to be widely accepted? | [
"theory",
"evidence",
"hypothesis",
"observation"
] | B | The term theory is used differently in science than it is used in everyday language. A scientific theory is a broad explanation that is widely accepted because it is supported by a great deal of evidence. Because it is so well supported, a scientific theory has a very good chance of being a correct explanation for events in nature. Because it is a broad explanation, it can explain many observations and pieces of evidence. In other words, it can help connect and make sense of many phenomena in the natural world. |
SciQ | SciQ-2527 | star, galaxy, history, definition, stellar-structure
Title: Metallicity of Celestial Objects: Why "Metal = Non-metal"? Metallicity of objects refers to the amount of chemical elements present in it other than Hydrogen and Helium.
Note: The other elements may or may not be actual metals in the true sense of their defintion.
The following is multiple choice question (with options) to answer.
Elements that specifically are noted to have properties of both metals and nonmetals are known as what? | [
"alloys",
"compund metals",
"alkali metals",
"metalloids"
] | D | Metalloids are elements that have properties of both metals and nonmetals. Some can conduct electricity but only at certain temperatures. They may be shiny but brittle. All metalloids are solids at room temperature. |
SciQ | SciQ-2528 | kinematics, acceleration, velocity, displacement
Title: How can I understand if an object stay (zero velocity) or moving with constant velocity (zero acceleration) I thought a scenario like; lets say I am looking an object and there is nothing except this object. Is there a way to understand that if this object is stay on its position or if object moving with a constant speed and also I am moving as same constant speed with this object ? (consider there is not any friction etc.) You cannot tell the difference. In fact many would say there is no difference. If you're really in a universe where there's nothing except the object like you say, there would be no difference between just sitting still and moving at a constant speed. There are no stars to see whizzing by, no atmosphere to make you feel the wind, nothing to make the light so you can measure redshift with special relativity.
If you're curious, this is one of the fundamental assumptions of special relativity.
The following is multiple choice question (with options) to answer.
What is the measure of change in velocity of a moving object? | [
"vibration",
"acceleration",
"transmission",
"kinetic energy"
] | B | Acceleration is a measure of the change in velocity of a moving object. It shows how quickly velocity changes. Acceleration may reflect a change in speed, a change in direction, or both. Because acceleration includes both a size (speed) and direction, it is a vector. |
SciQ | SciQ-2529 | black-holes, astronomy, supernova, elements
Fourth: There are chemical differentiation processes in the protoplanetary disc and the planet formation phase that ensure heavy elements are very much over-represented say compared with the Sun.
The solar system formed from an interstellar cloud with only about 2% elements heavier than Helium. Those heavier elements all come from around a 10 billion dead stars (supernovae, novae, AGB stars), though the Uranium is all produced in around a billion supernovae.
The following is multiple choice question (with options) to answer.
What celestial events are the source of elements heavier than iron? | [
"supernovas",
"galaxies",
"neutrons",
"Space"
] | A | Figure 32.21 Supernovas are the source of elements heavier than iron. Energy released powers nucleosynthesis. Spectroscopic analysis of the ring of material ejected by Supernova 1987A observable in the southern hemisphere, shows evidence of heavy elements. The study of this supernova also provided indications that neutrinos might have mass. (credit: NASA, ESA, and P. Challis). |
SciQ | SciQ-2530 | botany
All
142
45.01± 5.23
2306
45.64± 4.95
18 124
46.85± 3.98
3754
47.88± 3.49
For an algal estimate, see here:
Carbon is obtained from the post-carbon-capture flow and compressed to 1 MPa for transport and supply to the growth volume (requiring 248 kJ/kg of gas). Carbon uptake efficiency is 79%. The algal biomass productivity is 82.5 t/ha-yr (23.8 g/m2-d) with an elemental composition consisting of 48% carbon, 6.3% nitrogen, and 0.6% phosphorus (Huntley et al., 2015).
The following is multiple choice question (with options) to answer.
Algae are similar to plants in that they both produce their food through what process? | [
"photosynthesis",
"mitosis",
"hydrolysis",
"cell division"
] | A | Why are algae considered plant-like? The main reason is that they contain chloroplasts and produce food through photosynthesis. However, they lack many other structures of true plants. For example, algae do not have roots, stems, or leaves. Some algae also differ from plants in being motile. They may move with pseudopods or flagella. Although not plants themselves, algae were probably the ancestors of plants. |
SciQ | SciQ-2531 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
What do fungi produce to digest nutrients? | [
"pores",
"amino",
"sporozoans",
"exoenzymes"
] | D | The ability of fungi to degrade many large and insoluble molecules is due to their mode of nutrition. As seen earlier, digestion precedes ingestion. Fungi produce a variety of exoenzymes to digest nutrients. The enzymes are either released into the substrate or remain bound to the outside of the fungal cell wall. Large molecules are broken down into small molecules, which are transported into the cell by a system of protein carriers embedded in the cell membrane. Because the movement of small molecules and enzymes is dependent on the presence of water, active growth depends on a relatively high percentage of moisture in the environment. As saprobes, fungi help maintain a sustainable ecosystem for the animals and plants that share the same habitat. In addition to replenishing the environment with nutrients, fungi interact directly with other organisms in beneficial, and sometimes damaging, ways (Figure 24.19). |
SciQ | SciQ-2532 | optics, electromagnetic-radiation, speed-of-light, refraction
Title: Difference in velocity of light in change in medium It is often seen that according to physics the light changes it's velocity according to the medium through which it is traveling. So can it be explained that why so happen? The speed of light is always constant. The speed doesn't change, but the distance it travels might change. For example the speed of light "decreases" with about 35% when traveling in optical fiber. This happens because light doesn't go straight trough the fiber, it bounces in all directions. It's like putting a lot of mirrors. So the distance that we measure (the length of the optical fiber) is not the same is the distance light travels
So if you would have vacuum then the distance light travels would be the same as the distance you "can" measure, but if you don't have vacuum light will bounce from one atom to another. The photon will be absorbed by the atom, the atom's energy will rise for a few moments, and then it will fall back again to his original state, releasing the photon. This creates first of all a different wave length(a different color) and a longer path for light to travel. Because the photon doesn't go in a straight line from one atom to another.
The following is multiple choice question (with options) to answer.
When light passes from one medium to another, it changes what? | [
"color",
"speed",
"density",
"temperature"
] | B | When light passes from one medium to another, it changes speed. For example, when light passes from air to glass, it slows down. If light strikes a sheet of glass at a 90° angle, or perpendicular to the glass, it slows down but still passes straight through the glass. However, if light enters the glass at an angle other than 90°, the light bends as it slows down. The bending of light as it changes speed in a new medium is called refraction . The Figure below shows how refraction occurs. Notice that the speed of light changes again as it passes from the glass back to the air. In this case, the speed increases, and the ray of light resumes its initial direction. For a more detailed explanation of refraction, watch this video: http://www. youtube. com/watch?v=8RM46yvDOHI . |
SciQ | SciQ-2533 | waves, interference, wavelength, superposition
The wavelength is the distance of a "cycle". Take the horizontal length between any two crests, or any two troughs, and what you get is called the wavelength. In physics, this is notated with the $\lambda$ symbol (the Greek letter Lambda). In the plot above, the wavelength has a value of $\pi$.
The amplitude is the height from the centre line to either the crest or the trough.
Destructive interference happens when the squared amplitude of the sum of the waves is lower than the sum of the squared amplitudes of the waves.
Therefore, the interference between two waves is the "most destructive" when the phase difference is an odd number of half-wavelengths, as shown in the plot above with the "$\pi/2$", "$3\pi/2$", "$5\pi/2$" points on the horizontal axis.
The following is multiple choice question (with options) to answer.
The distance between the crests of electromagnetic waves is called what? | [
"variation",
"trough",
"crest",
"wavelength"
] | D | |
SciQ | SciQ-2534 | immune-system, digestion
In CD, deamidation of gluten by tissue transglutaminase (tTG) in the
small-bowel lamina propria promotes presentation of gluten peptides
(gliadin in wheat, secalin in rye and hordein in barley) by
HLA-DQ2 or HLA-DQ8 dendritic cells to pathogenic local CD4+ T
cells...The most widely used serological test is anti-tTG IgA
(Medscape)
3) Can barley affect the gut differently than wheat?
Possibly.
Nutrition and Celiac Disease (Nutrients, 2014):
There is very limited data looking at the effect of barley hordein or
rye secalin on CD outcomes in the published literature (e.g.,
[66,67]), but evidence exists that these prolamins induce effects
different to wheat gluten, at least at an immunologic level.
4) Do positive DGP and TTG test confirm celiac disease?
The specificity of IgG deaminated gliadin peptide (DGP) is 98% and of IgA tissue transglutaminase (TTG) 95% (American Family Physician, 2014), so when both tests are positive, celiac disease is very likely. The final diagnosis is by histological examination of a tissue sample obtained by duodenal biopsy.
5) Is it possible that, in celiac disease, symptoms disappear after removing only beer, but not wheat and rye from the diet?
It could be possible to have celiac disease confirmed by blood tests without any symptoms despite consuming wheat, barley and rye. Beer could trigger symptoms by irritating the bowel, not by gluten, but by alcohol or other substances, like in people with irritable bowel syndrome (American Journal of Gastroenterology, 2013).
The following is multiple choice question (with options) to answer.
People with celiac disease have an immune response to what, which ultimately leads to malnutrition, cramping, and diarrhea? | [
"gluten",
"fish",
"seeds",
"lactose"
] | A | The plasma membranes of cells that specialize in absorption are folded into fingerlike projections called microvilli (singular = microvillus). This folding increases the surface area of the plasma membrane. Such cells are typically found lining the small intestine, the organ that absorbs nutrients from digested food. This is an excellent example of form matching the function of a structure. People with celiac disease have an immune response to gluten, which is a protein found in wheat, barley, and rye. The immune response damages microvilli, and thus, afflicted individuals cannot absorb nutrients. This leads to malnutrition, cramping, and diarrhea. Patients suffering from celiac disease must follow a gluten-free diet. |
SciQ | SciQ-2535 | 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.
Chlorophyll is used in what food-making process that plants carry out? | [
"digestion",
"colorization",
"photosynthesis",
"isolation"
] | C | |
SciQ | SciQ-2536 | electromagnetism, electric-current, torque
Title: How does galvanometer measure more current than is passing through it? My textbook clearly states:
after putting a shunt in parallel to it, a galvanometer becomes an ammeter.
The diagram is quite similar to this:
source
This is fine. I have problem with this:
Now the same acale of the galvanometer which was recording the maximum current $I_g$ before conversion into ammeter will record maximum current I after conversion into ammeter. It means each division of scale in ammeter will be showing higher current than that of galvanometer.
I don't understand how can galvanometer measure current which is not even passing through it? I know we can calculate I from Ig as:
$I_g = I \times S \div (G+S)$
So if we know Ig (which galvanometer is measuring) we can find I. But how does that mean that galvanometer's scale changes and it starts measuring the current which is not even paasing through it? Galvanometer still shows maximum deflection when maximum current is passing through it. But out of the total current in the circuit only some of it goes towards galvanometer and rest goes to shunt. So the actual current in the circuit is more than which is passing through galvanometer.
But the galvanometer is calibrated accordingly that it will show the reading of $I$ and not $I_g$.
Galvanometer still shows deflection proportional to $I_g$ but the reading is different as the calibration is different. Hence the reading is I though current in galvanometer though the current through it is Ig because the 1 divisions or marking on ammeter is actually different than what actual current is passing through it.
So though $I_g$ is current it shows $I_g+I_s$ as it is calibrated as such.
So suppose there are 10 divisions then Ig is maximum current so when Ig/10 current passes it shows deflection of one division but the galvanometer is calibrated as 1 division =I/10. That maximum current measured by ammeter is I.
The following is multiple choice question (with options) to answer.
What does an ammeter measure the flow of? | [
"water under pressure",
"wind",
"magnetic fields",
"current through a circuit"
] | D | When a contractor builds a new home, she uses a set of plans called blueprints that show her how to build the house. The blueprints include circuit diagrams. The diagrams show how the wiring and other electrical components are to be installed in order to supply current to appliances, lights, and other electric devices. You can see an example of a very simple circuit in the Figure below . Different parts of the circuit are represented by standard circuit symbols. An ammeter measures the flow of current through the circuit, and a voltmeter measures the voltage. A resistor is any device that converts some of the electricity to other forms of energy. For example, a resistor might be a light bulb or doorbell. |
SciQ | SciQ-2537 | meteorology, climate-change, gas, pollution
Title: Regarding various types of atmospheric pollution Does all the car pollution (from about 150 million cars at least in the U.S. and a lot more in all of North America and the rest of the world) all the smoke-stack pollution of various factories and all the Airline pollution running day after day have a deleterious and damaging effect on the general atmosphere and, over time, the climate?
Given all the observed pollution that China has caused itself and some of the resulting weird weather events there this certainly seems to be evidence of the damaging effects of car and factory pollution. Has anyone calculated how much exhaust from cars is produced in one day on average in a 'moderate' sized city?
Of course it seems with all the increased oil production in the U.S. and elsewhere we, human beings are going to keep are love-affair with gas-powered cars for the next 200 or 300 years. That is if we don't use up all the oil and gas in the ground before then. As a USA resident, the EPA is the best place to start when wondering about the emissions inventory of atmospheric pollutants or pollutant precursors that affect the National Ambient Air Quality Standards (e.g. Particulate Matter, Carbon Monoxide, Sulfur Dioxide, Lead, Nitrogen Oxides, Volatile Organic Compounds). The EPA compiles a comprehensive emissions inventory of all criteria pollutants at the county level which is available in the National Emissions Inventory (compiled once every 3 years). You can see the summary of your county at http://www.epa.gov/air/emissions/where.htm. As for the effects of atmospheric pollution, it is important to consider the lifetime of said pollutants in the atmosphere in order to put their environmental impacts into perspective. For instance, the air pollutants covered by the National Ambient Air Quality Standards have immediate health effects when high concentrations are breathed in regularly. Both animals and plants are adversely affected by these irritating and sometimes toxic chemicals, but these pollutants are also reactive and do not last long in the atmosphere unless they are constantly being replenished (e.g. daily traffic). Air quality also impacts critical nitrogen loads on ecosystems and possible production of acid rain.
The following is multiple choice question (with options) to answer.
Burning forests, growing rice and raising livestock all cause a release of what into the atmosphere? | [
"oxide gases",
"glucose gases",
"carbonate gases",
"greenhouse gases"
] | D | Burning forests also releases carbon dioxide into the atmosphere. Other human activities release greenhouse gases into the atmosphere. For example, growing rice and raising livestock both produce methane. |
SciQ | SciQ-2538 | meteorology, climate-change, gas, pollution
Title: Regarding various types of atmospheric pollution Does all the car pollution (from about 150 million cars at least in the U.S. and a lot more in all of North America and the rest of the world) all the smoke-stack pollution of various factories and all the Airline pollution running day after day have a deleterious and damaging effect on the general atmosphere and, over time, the climate?
Given all the observed pollution that China has caused itself and some of the resulting weird weather events there this certainly seems to be evidence of the damaging effects of car and factory pollution. Has anyone calculated how much exhaust from cars is produced in one day on average in a 'moderate' sized city?
Of course it seems with all the increased oil production in the U.S. and elsewhere we, human beings are going to keep are love-affair with gas-powered cars for the next 200 or 300 years. That is if we don't use up all the oil and gas in the ground before then. As a USA resident, the EPA is the best place to start when wondering about the emissions inventory of atmospheric pollutants or pollutant precursors that affect the National Ambient Air Quality Standards (e.g. Particulate Matter, Carbon Monoxide, Sulfur Dioxide, Lead, Nitrogen Oxides, Volatile Organic Compounds). The EPA compiles a comprehensive emissions inventory of all criteria pollutants at the county level which is available in the National Emissions Inventory (compiled once every 3 years). You can see the summary of your county at http://www.epa.gov/air/emissions/where.htm. As for the effects of atmospheric pollution, it is important to consider the lifetime of said pollutants in the atmosphere in order to put their environmental impacts into perspective. For instance, the air pollutants covered by the National Ambient Air Quality Standards have immediate health effects when high concentrations are breathed in regularly. Both animals and plants are adversely affected by these irritating and sometimes toxic chemicals, but these pollutants are also reactive and do not last long in the atmosphere unless they are constantly being replenished (e.g. daily traffic). Air quality also impacts critical nitrogen loads on ecosystems and possible production of acid rain.
The following is multiple choice question (with options) to answer.
What type of pollution comes from sewage, storm drains, septic tanks, boats, and runoff from yards? | [
"urban",
"social",
"collective",
"municipal"
] | D | “Municipal” refers to the community. Households and businesses in a community can pollute the water supply. Municipal pollution comes from sewage, storm drains, septic tanks, boats, and runoff from yards. For example:. |
SciQ | SciQ-2539 | ozone
Title: Ozonated oil Mixed with water. I wish to emulsify ozonated oil with water and other ingredients to make a cream. Will mixing the ozone oil and water together with an emulsifier lessen the potency of the ozone oil as an oxidant? what if i were to ozonate the water and oil together and add an emulsifier at the end and blend them? with emulsifying wax for example. THankyou! I've tried this with a sota ozonator and it doesn't work out that well using water. First when you ozonate oil by itself it gets really thick which clogs up your aerator for use with anything else so if you do this you have to use a separate aerator for oil and water.
I'm looking at doing something similar with bees wax and colloidal silver and placing the contents into a chap stick like container, when I figure something out I'll let you know. Water can be mixed with oil with out using an emulsifier. Dr Gerald Pollack from the University of Washington goes into what he calls the The Fourth Phase of Water "EZ water" and this type of water is known to mix with oil based substances. https://youtu.be/p9UC0chfXcg
His work can be found here
http://faculty.washington.edu/ghp/
Oil and water aren’t suppose to mix but they can see interview below
https://www.youtube.com/watch?v=4KQwh6j-uOg&feature=youtu.be&t=28m17s
The following is multiple choice question (with options) to answer.
What does oil do when mixed with water? | [
"forms droplets",
"precipitates",
"dissolves",
"dissappears"
] | A | Figure 2.13 Oil and water do not mix. As this macro image of oil and water shows, oil does not dissolve in water but forms droplets instead. This is due to it being a nonpolar compound. (credit: Gautam Dogra). |
SciQ | SciQ-2540 | zoology, ecology, species-distribution, migration
Title: How do animals end up in remote areas? I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.
They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.
So this brings me to my question: how do each of these spots end up with frogs in them? I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it? This question pertains to organism dispersal, which is a very active field of study with relation to it's impact on conservation efforts. Much of what I will say below has been covered in this wiki.
Definition: From the Wiki
Technically, dispersal is defined as any movement that has the
potential to lead to gene flow.
It can be broadly classified into two categories:
Density dependent dispersal
Density independent dispersal
The question of frogs and fishes both refer to Density independent dispersal, while an example of density independent dispersal can be the competition for habitat space between big cats and humans (this is a WWF pdf)
From the wiki:
Density-independent dispersal
Organisms have evolved adaptations for dispersal that take advantage
of various forms of kinetic energy occurring naturally in the
environment. This is referred to as density independent or passive
dispersal and operates on many groups of organisms (some
invertebrates, fish, insects and sessile organisms such as plants)
that depend on animal vectors, wind, gravity or current for dispersal.
Density-dependent dispersal
Density dependent or active dispersal for many animals largely depends
on factors such as local population size, resource competition,
habitat quality, and habitat size.
Currently, some studies suggest the same.
This study in particular studied the movement and habitat occupancy patterns within ephemeral and permanent water bodies in response to flooding. They found that during flooding these frogs moved out to flooded ephemeral water bodies and later on moved back again to the permanent ones.
Other suggested readings for those highly interested in the subject may include this (a phd thesis) and this (a project report)
The following is multiple choice question (with options) to answer.
What is the term for the movement of individuals out of a population? | [
"immigration",
"succession",
"colonization",
"emigration"
] | D | Emigration is the movement of individuals out of a population. This decreases the population size and growth rate. |
SciQ | SciQ-2541 | algorithms, software-testing
Do people actually verify their algorithms usually? I doubt it, unless they are in a field such as computational geometry in which their algorithms are actually being used. What people usually do is do their best to check their proofs, crossing all ts and dotting all is. That means avoiding phrases such as it is easy to see that. Having done that, they kindly ask a few other people to read through their proofs. Then they submit the paper to a journal, and if they're lucky then the referees will do another pass.
Even after all this, mistakes are occasionally found, but this is just part of life. Usually, these mistakes can be corrected easily, demonstrating that our formal sense of certainty is limited: true mathematics "works" even if not completely valid formally, as has been argued by a few philosophers, most of them coming from the ranks of practicing mathematicians. Wrong algorithms point the way to correct algorithms, as they bring new ideas. So don't worry too much, just do your best.
The following is multiple choice question (with options) to answer.
What might a scientist do to confirm the work of another? | [
"question their methods",
"replicate their work",
"study their work",
"develop a completely different experiment"
] | B | Scientists may work together on a project. One reason is that they can share equipment and personnel. Another reason is that they can share ideas. Scientists may also work separately. Even then, they use each other's data and interpretations. When one scientist publishes a paper, others will replicate the work to make sure they get the same result. If they do, the work is valid. If they don't, someone needs to find the source of the problem. Scientists openly communicate with each other on their results. They also discuss and sometimes disagree on their interpretations. If scientists do disagree, they will look for evidence so that they may resolve the disagreement. |
SciQ | SciQ-2542 | bond, electronegativity, polarity
Title: Why are bonds ionic when the electronegativity difference between bonded atoms is greater than 1.7? I'm learning about how to recognise whether a bond is ionic or covalent, based on the difference in electronegativity between the two bonding partners, $\Delta \chi$.
What I have now is a formula:
If $\Delta \chi = 0$, then the bond is nonpolar
If $0 < \Delta\chi \leq 1.7$, then the bond is polar covalent
If $\Delta \chi > 1.7$, then the bond is ionic
But I don't know how scientists determined that formula, the history of it and which experiment indicates that formula. The first thing to consider is the difference between covalent and ionic bonding, from the UCDavis ChemWiki site Ionic and Covalent Bonds,
In ionic bonding, atoms transfer electrons to each other. Ionic bonds require at least one electron donor and one electron acceptor. In contrast, atoms that have the same electronegativity share electrons in covalent bonds since donating or receiving electrons is unfavorable.
The electron donor has a low electronegativity and the electron acceptor has a higher elelctronegativity - so there is a difference in electronegativity $\Delta{EN}$, effectively creating a positive and negative end, an example is below:
Image source: Japan Synchrotron Radiation Research Institute (JASRI)
When the differences in electronegativities of various compounds are graphed against % ionic character, as shown below:
Image source: University of Florida Chemical Bonding page
Values of $\Delta{EN}$ greater than 1.7 correspond to an ionic character of greater than 50%, from the University of Florida website:
What determines how the electrons are shared is the relative electronegativity (electron greed) of the bonding atoms. The degree of polarity or degree of ionic bonding of any given bond can vary continuosly zero to nearly 100%. We normally say that bonds between atoms with electronegativity difference ($\Delta{EN}$) greater than 1.7 are ionic, although this really means only more than about half ionic in character.
Another resource is from the University of Washington Lecture 23: Ionic to Covalent Bonds.
The following is multiple choice question (with options) to answer.
Polar molecules result from differences in electronegativity of what in the molecule? | [
"atoms",
"iron",
"ions",
"protons"
] | A | Polar molecules result from differences in electronegativity of the atoms in the molecule. |
SciQ | SciQ-2543 | fluid-dynamics, density, buoyancy
IN ANSWER TO THE QUESTION IN YOUR EDIT
Intuitively you would think that increasing the pressure of the air increases the downward force on the block, making it sink lower in the water, but this is not the case. In both cases what happens to the block does not depend on the pressure of the air but the pressure gradient in the air. If the pressure is uniform throughout the air space, an increase or decrease has no effect on the depth at which the object floats in the water. But if there is a pressure gradient (which necessarily increases downwards) then an increase in the average pressure makes the object rise up in the water, and a decrease makes it sink lower.
Explanation
The explanation is similar to that in Why does a helium filled ballon move forward in a car when the car is accelerating?
The forces on the block are initially balanced. The vertical forces are the weight $W$ of the block and the pressure-forces $F_1$ of the air on the upper face and $F_2$ of the water on the lower face of the block : $$F_2=W+F_1$$ To avoid complications I assume that the block is cuboid so that the areas of upper and lower faces are equal.
Suppose the air pressure is constant throughout the upper part of the container. Then an increase in air pressure increases the forces $F_1, F_2$ equally, so the depth at which the block floats in the water does not change. The increase in pressure at the upper face is transmitted through the air and water to the lower face, increasing it by the same amount.
The air pressure would be approximately constant throughout its volume if the air is only slightly compressible and its density is low compared with that of the water. Both these conditions usually apply at typical atmospheric pressures.
However, if there is a significant pressure gradient in the air then the pressure at the surface of the water will be greater than at the upper face of the block. It is the pressure at the water surface which is transmitted to the lower face of the block, so the increase in force on the lower face would be greater than that on the upper face, and the block would rise up in the water.
Another way of seeing this is to imagine that the air becomes as dense as the water. Then since the block floats in water it will also float upwards into the dense air.
The following is multiple choice question (with options) to answer.
A diver's air bubbles increase in size as he approaches the surface because what decreases? | [
"water pressure",
"water direction",
"water weight",
"water energy"
] | A | A scuba diver, like the one in Figure below , releases air bubbles when he breathes under water. As he gets closer to the surface of the water, the air bubbles get bigger. Boyle’s law explains why. The pressure of the water decreases as the diver gets closer to the surface. Because the bubbles are under less pressure, they increase in volume even though the amount of gas in the bubbles remains the same. |
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