source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-744 | 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.
Which organ system defends the body from pathogens and other causes of disease? | [
"respiratory system",
"digestion system",
"nervous system",
"immune system"
] | D | Vertebrates have an adaptive immune system. The immune system is the organ system that defends the body from pathogens and other causes of disease. Being adaptive means that the immune system can learn to recognize specific pathogens. Then it can produce tailor-made chemicals called antibodies to attack them. This allows the immune system to launch a rapid attack whenever the pathogens invade the body again. |
SciQ | SciQ-745 | soft-question
Title: Publication Authorship Credits Many physics papers now have dozens of authors per paper. Experimental physics may have multi-organizational and multi-country contributing staffs, but I'd guess that most of the names don't contribute a word or equation to a paper, yet they get individual authorship credit.
My question is who determines the author list, does everybody listed have editing privilages, and perhaps most importantly, who decides on their listed order? OK, this is for experimental high energy physics as I worked in the field for over 40 years.
There are groups in institutions, universities and research ones. There are many such in each country, and there are many countries. The group leaders in the group decide who signs a paper, mainly by the man hours put in the construction and running of the experiment and also considering contributions in analysis of present and other papers. The order is alphabetical per author within a group, per name of institution. There have been long discussions on changing the credit attribution, but I see that the same holds for LHC papers.
Why are there so many names? In my carreer I worked on one large ( previous had about 50 people) experiment( 350 people) from inception of the idea to taking data and analysis. It took 10 years to build the detector by hundreds of people, years that yielded very few publications from the full work put in, certainly over 8 hours a day. Credit was accumulating from analysis published/worked-on previous experiment papers. Then another 15 years of data analysis where there are also large numbers of working groups, made up from people from all groups, and many people working on the same subject with their own analysis. The final paper is decided by the working group, a joining of all individual analysis. The names are still the ones the individual institute group leader gives to the working group. The working group proposes a preprint to the collaboration editing board, and if the board approves of the paper it goes to the full collaboration meeting, passed by consensus. Every person who signs can comment and ask for changes. They usually do not, as there is trust that the working groups are doing their job well.
The system is completely open. Any group member can join in the analysis and comment.
The following is multiple choice question (with options) to answer.
What is the process where scientific articles are checked and analyzed by other scientists before publication? | [
"peer review",
"process review",
"mechanism review",
"embrace review"
] | A | Scientists may publish articles about their research in peer-reviewed science journals. Peer review means that the work is analyzed by peers, in other words, by other scientists. The articles are published only if the other scientists are convinced that the research is accurate and honest. |
SciQ | SciQ-746 | evolution, natural-selection, biostatistics
One of the concepts people most often lack when dealing with evolution is of scale. You're looking at a tiny, tiny, tiny fraction of all the mutations that could have possibly happened and thinking, "What are the odds that that happened, it seems so improbable!" But that's because you're not seeing the trillions and trillions and trillions of mutations that could have happened if random chance had taken things in an ever so slightly different direction. SOMETHING had to happen, it's the laws of physics. You're only able to see and be amazed by what did happen... well, because it's the thing that ended up happening. The more you think about it, the easier it is to wrap your mind around.
The following is multiple choice question (with options) to answer.
A mutation is a random change in an organism's what? | [
"genes",
"power",
"babies",
"structure"
] | A | At some point, the variation probably came from a mutation. A mutation is a random change in an organism's genes. Mutations are natural. Some are harmful, but many are neutral. If the trait from the mutation is beneficial, that organism may have a better chance to survive. An organism that survives is likely to have offspring. If it does, it may pass the mutation on to its offspring. The offspring may be more likely to survive. |
SciQ | SciQ-747 | gazebo
Title: What are the various joint types available in gazebo?
Revolute, prismatic, continuous and what else?
Could somebody point me to the right resource to look at to get such information.
Thanks.
Originally posted by pmaini on Gazebo Answers with karma: 33 on 2014-12-09
Post score: 3
You can find the joint types supported by SDF in the SDF documentation:
The type of joint, which must be one
of the following: (revolute) a hinge
joint that rotates on a single axis
with either a fixed or continuous
range of motion, (gearbox) geared
revolute joints, (revolute2) same as
two revolute joints connected in
series, (prismatic) a sliding joint
that slides along an axis with a
limited range specified by upper and
lower limits, (ball) a ball and socket
joint, (universal), like a ball joint,
but constrains one degree of freedom,
(piston) similar to a Slider joint
except that rotation around the
translation axis is possible.
Originally posted by NickDP with karma: 186 on 2014-12-09
This answer was ACCEPTED on the original site
Post score: 6
The following is multiple choice question (with options) to answer.
Synovial and ball-and-socket are both types of what? | [
"bonds",
"muscles",
"joints",
"cells"
] | C | 9.5 | Types of Body Movements By the end of this section, you will be able to: • Define the different types of body movements • Identify the joints that allow for these motions Synovial joints allow the body a tremendous range of movements. Each movement at a synovial joint results from the contraction or relaxation of the muscles that are attached to the bones on either side of the articulation. The type of movement that can be produced at a synovial joint is determined by its structural type. While the ball-and-socket joint gives the greatest range of movement at an individual joint, in other regions of the body, several joints may work together to produce a particular movement. Overall, each type of synovial joint is necessary to provide the body with its great flexibility and mobility. There are many types of movement that can occur at synovial joints (Table 9.1). Movement types are generally paired, with one being the opposite of the other. Body movements are always described in relation to the anatomical position of the body: upright stance, with upper limbs to the side of body and palms facing forward. Refer to Figure 9.12 as you go through this section. |
SciQ | SciQ-748 | soft-question, electricity, history, units, si-units
Title: Why there is no "Edison" unit in physics? In the popular culture the XIX-XX century competition between Thomas Edison and Nikola Tesla is well-known. The example could be the Prestige movie, where there are some "Edison's agents" who sabotage Tesla's efforts. From electrical engineers' point of view the most known problem between them is whether to use DC or AC (the War of Currents).
We can say that Edison is better known, because of the invention of a bulb or his first urban electricity system. Tesla is almost unknown, some people say about magic and so on. (That's why I recall the Prestige movie.)
In electricity it seems that Tesla has won, even if he's widely forgotten. We use AC mainly because of it's easy in transformers. We have an SI unit $\text{T}$ (tesla), which is for measuring magnetic induction.
But -- we can't forget Edison's impact on electricity. Even if he was mostly a great businessman, no-one can say he's done nothing but the bulb. Here is some list of his patents.
So why isn't he honored (like Tesla, Ampère, Volta, Siemens, Ohm, Faraday, ...) by his "own" unit in physics? Patents are for inventions, which are feats of engineering, not advances in physics. Edison was a great businessman as well as a great inventor: he took understood principles of physics and turned them into useful machines. These machines are codified in the patents. He did not, however, contribute to the understanding of the laws of physics.
Now, admittedly, Tesla did not advance our understanding much either. He, too, was predominantly an engineer/inventor. However, by experimenting with high-voltage current, X-rays and radio waves, he indirectly helped our understanding of electromagnetic radiation and the electromagnetic force.
The following is multiple choice question (with options) to answer.
Who invented dynamite in 1866? | [
"Louis Pasteur",
"Madame Curie",
"Albert Einstein",
"alfred nobel"
] | D | Dynamite was invented by Alfred Nobel in 1866. Nitroglycerin, a very unstable explosive, was already known. Nobel mixed the nitroglycerin with silica to stabilize it and form a solid material. He made a fortune with this discovery and established the Nobel Foundation, which funds the Nobel Prizes every year. |
SciQ | SciQ-749 | hydrology, mountains, rivers
Title: Why do rivers have 'wells' in mountains? Why/how can rivers have sources in places high above the sea level? The presence of water underground has nothing to do with sea level in mountainous country.
When rain fails on a mountain, or snow falls on a mountain and the snow eventually melts, the water from the rain or snow melt mostly travels downhill via rivers to the sea.
In getting to a river some of the water will fall on the ground. In places where the ground is covered by soil, water can travel through the soil via the pore spaces between the grains of soil. Similarly if porous rock, such as sandstone lies beneath the soil water can travel through the pores in the rock.
If a layer of impervious rock lies under the porous rock or soil, the water cannot move downwards, due to gravity, any further. This can lead to water accumulating in the soil or porous rock and saturating the soil or rock. In such situations an aquifer can form. The top of the saturated zone in an aquifer is called a water table.
The ground beneath a river is saturated and the surface of the river shows the water table exposed to atmosphere. Thus in mountainous regions the ground beneath rivers will be saturated and capable of supporting a well developed from the bank of a river.
The following is multiple choice question (with options) to answer.
Most liquid freshwater is under the ground in layers of what? | [
"soil",
"forest",
"sand",
"rock"
] | D | Only a tiny fraction of Earth’s freshwater is in the liquid state. Most liquid freshwater is under the ground in layers of rock. Of freshwater on the surface, the majority occurs in lakes and soil. What percentage of freshwater on the surface is found in living things?. |
SciQ | SciQ-750 | molecular-biology, cell-biology, neuroscience
Title: What is a gain-of-function assay in neuroscience? I am reading this paper and I have come across the following statement:
"We sought to test whether exogenous Kirrel3 expression induces synapse formation via a gain-of-function assay... Because most CA1 neurons do not express Kirrel3, we used this in
vitro specificity to our advantage and tested whether exogenous
Kirrel3 expression in CA1 neurons could induce ectopic DG-to-CA1
synapses".
In the above statement, I am trying to figure out what is meant by a "gain-of-function assay".
I have searched online for a definition for gain-of-function, and all the search results talk about it in the context of virology, e.g. this paper states:
"Gain-of-function (GOF) research involves experimentation that aims or
is expected to (and/or, perhaps, actually does) increase the
transmissibility and/or virulence of pathogens"
I was wondering, in the context of neuroscience research, what is a gain-of-function assay? In this context, does it simply refer to the fact that the researchers overexpressed Kirrel3 in CA1 neurons (which normally do not express Kirrel3)?
Any advice is appreciated. Nothing special is meant here except the standard English meaning of these words.
The second half of the quoted passage explains what they intend to do:
Because most CA1 neurons do not express Kirrel3, we used this in vitro specificity to our advantage and tested whether exogenous Kirrel3 expression in CA1 neurons could induce ectopic DG-to-CA1 synapses
To find out what Kirrel3 does, they're going to add Kirril3 ("exogenous...expression") and see what happens, and use that to infer something about the function of Kirril3. The cells that don't normally have Kirill3 are gaining its function. The opposite approach would be to remove Kirril3 from someplace that it normally is, which you could call "loss of function" - that might be a knockout animal, RNAi, use of an antagonist or other pharmacological manipulation, etc.
The following is multiple choice question (with options) to answer.
What phenotype do gain-of-function mutations usually result in? | [
"submissive",
"dominant",
"external",
"internal"
] | B | Gain-of-function mutations result in the gene product or protein having a new and abnormal function and usually result in a dominant phenotype. Examples of gain of function mutations occur in the thyroid hormone receptor gene. |
SciQ | SciQ-751 | physical-chemistry, equilibrium
Lets say the first reaction reached equilibrium and then $\ce{N_2O_3}$ started decomposing. This means more amount of $\ce{O_2}$ will be produced and the equilibrium for the first reaction will get disturbed
Without the second reaction, the first will attain equilibrium when $a$ is about 1.85 M. The second reaction makes F and uses up B, so the first reaction almost stays at equilibrium, and the concentration of A does not change much.
Will it ever stop?
Due to this the oxygen level will drop and equilibrium for the second reaction will get disturbed and $\ce{N_2O_3}$ will decompose further to form oxygen.
But this process will go on forever. There is definitely wrong with this. Will this really happen or is there some other mechanism at work?
If you look at this step-wise (figure out how much one reaction would go, disregarding the other), you are never done. This is similar to Zeno's paradox. However, the corrections get smaller and smaller, and your approximation gets better and better.
In general, reactions approach equilibrium, they don’t reach it. Nothing special about this system.
The following is multiple choice question (with options) to answer.
What occurs if oxygen cannot be obtained at a sufficient rate? | [
"aerobic respiration",
"anaerobic respiration",
"malolactic respiration",
"hyperventilation"
] | B | Phil Roeder. Anaerobic respiration occurs if oxygen cannot be obtained at a sufficient rate . CC-BY 2.0. |
SciQ | SciQ-752 | evolution, definitions, artificial-selection
It does not lead to new species
In short, 1) it does lead to new species 2) the concept of species is often meaningless as poorly defined 3) evolution > speciation. In more details, below..
It does lead to new species. Different lineages of cabbage are considered different species. Cows and ox are different species. Pigs and boars are often considered different species. While wolves and dogs are considered same species, some lineages within this species (such as a Chihuahua and a Great Dane) are, I think, reproductively isolated. You might also want to have a look at the post Have we ever observed two drosophila lineages that evolved reproductive isolation in labs?
The question of whether selective breeding lead to speciation or not does not matter much on the question of whether it leads to evolution. Speciation is one outcome of evolution but is definitely not the same as evolution. Evolution does not need to lead to speciation. For example, evolution of the lactase gene in humans (see this post) did not lead to any speciation. It is still an evolutionary process.
The concept of species is mainly arbitrary. If you want to understand the concept of species, have a look at the post How could humans have interbred with Neanderthals if we're a different species?.
It decreases, rather than increases, the size of the gene pool (is this actually true?)
The following is multiple choice question (with options) to answer.
What are the key to species evolving? | [
"radiation",
"parasites",
"microbes",
"mutations"
] | D | Mutations are the key to species evolving. Lets say an organism "mutates" due to a new allele for a gene that determines coat color. There are, theoretically, only three outcomes of that mutation:. |
SciQ | SciQ-753 | cancer
Title: do tumour cells begin with abnormal characteristics? At what point in the cell cycle do cells start to become tumorous? Do they have abnormal characteristics to begin with; if so what are they? Cancer cells don't start to become cancerous at a specific stage of the cell cycle; you will find that while uncontrolled proliferation is a hallmark of cancer, different cancers acquire alterations in different phases of the cell cycle. BRCA-deficient cancers for example have a compromised G2-M checkpoint [1], while Rb deficient cancers have a compromised G1-S [2] checkpoint in the cell cycle.
The cell cycle is simply a property of proliferating cells and the same broad phases of the cell cycle are universal to both normal and malignant cells.
As for when abnormally growing cells actually become a cancer - this has nothing to do with phases of the cell cycle, and everything to do with the ability to break through the basement membrane of the original site (indicating the potential to be invasive/spread), because the ability to invade is a hallmark of cancer [3]
References
[1] http://cancerres.aacrjournals.org/content/67/13/6286
[2] https://www.ncbi.nlm.nih.gov/pubmed/16936740
[3] https://www.ncbi.nlm.nih.gov/pubmed/21376230
The following is multiple choice question (with options) to answer.
Cancer develops when what process is unregulated? | [
"meiosis",
"cellular respiration",
"metabolism",
"cell division"
] | D | In the Cell Cycle: Cancer (Advanced) concept, cancer is described as developing due to unregulated cell division. That is, cancer is a disease characterized by a population of cells that grow and divide without respect to normal limits. These cancerous cells invade and destroy adjacent tissues, and they may spread throughout the body. The process by which normal cells are transformed into cancer cells is known as carcinogenesis . This process is also known as oncogenesis or tumorigenesis. Oncogenes are mutated genes involved in the development of cancer. |
SciQ | SciQ-754 | halides, oxidation-state
Title: Can fluorine ever have a positive oxidation state? I know fluorine is the most electronegative element but can we humans ever synthesize fluorine in a positive oxidation state like +1? As noted in the referenced question, fluorine is not in the +1 oxidation state in hypofluorous acid (which, incidentally, is the only hypohalous acid that has been isolated) nor in any other compound where its bonds give it a complete octet. Even where the fluorine has a positive formal charge, attaching it to less electronegative atoms will lead to an oxidation state of -1.
However, it is possible for fluorine to show a zero oxidation state and for a fluorine atom to apparently show a positive charge. As one might expect, this occurs in one of the most unusual compounds in all of chemistry.
Striking gold -- and a lucky 7
That compound is "gold heptafluoride", $\ce{AuF7}$, whose unusual structure is reflected in the IUPAC name: instead of gold(VII) fluoride, it is officially called difluorinegold(V) fluoride. It is more accurately formulated $\ce{AuF5\cdot F2}$. It has been isolated at liquid nitrogen temperatures [1].
Himmel and Riedel [2] give calculations showing that unlike other heptafluorides, not all seven fluorine atoms are bonded to the central (gold) atom. Rather, the gold is bonded octahedrally to five individual fluorine atoms and a difluorine ($\ce{F2}$) ligand, the latter attached end on and rotated so that in the most stable conformation (according to most of the several optimization schemes used), the remote fluorine atom is eclipsed with one of the other ligands as if attracted to it (a, below, picture from [2]). The staggered arrangement one might expect (b) is instead a transition state in this fluxional molecule. If we assume that the individual fluorine ligands are negatively charged as usual, this interaction indicates that at least the remote fluorine atom, labeled $\text{F}_b$, is positively charged.
And indeed, Table 2 of the paper shows the following charge distribution:
The following is multiple choice question (with options) to answer.
What are needed to oxidize the noble gases to form compounds in positive oxidation states? | [
"potent oxidants",
"protein oxidants",
"bacteria oxidants",
"metal oxidants"
] | A | Potent oxidants are needed to oxidize the noble gases to form compounds in positive oxidation states. |
SciQ | SciQ-755 | zoology, ecology
Giraffes' this is an energy saving feature. Giraffes don't need to use muscles to hold their neck. They just use when flexing their necks down, when drinking water etc.
According to Wikipedia, for an alternative hypothesis Ouranosaurus have a hump. (Other hypothesis is display sail or termoregulation sail of course. Also spinosaurus have this kind of alternative hypotesis but this hypothesis not accepted much as sail. and spinosaurus' spine different from bisons. Bison spines concentrating at shoulder but spinosaurs' not at the shoulder. You can find spinosaurus info from this page.)
The following is multiple choice question (with options) to answer.
Which muscles raise the hyoid bone, the floor of the mouth, and the larynx during deglutition? | [
"suprahyoid",
"Hybrid",
"spirogyra",
"spicule"
] | A | The suprahyoid muscles raise the hyoid bone, the floor of the mouth, and the larynx during deglutition. These include the digastric muscle, which has anterior and posterior bellies that work to elevate the hyoid bone and larynx when one swallows; it also depresses the mandible. The stylohyoid muscle moves the hyoid bone posteriorly, elevating the larynx,. |
SciQ | SciQ-756 | energy, electrostatics, potential-energy
Title: where is electrostatic potential energy stored?
Potential energy can be defined as the capacity for doing work which arises from position or configuration.In the electrical case, a charge will exert a force on any other charge and potential energy arises from any collection of charges.
Where is this potential energy stored and how? That actually gets a bit tricky at the advanced level, but at the basic level, you should find somewhere in your textbook the equation $U = \int d^3x \left(\frac{1}{2} |\vec{E}|^2 \right)$ (maybe with a different constant up front, depending on what system of units the book is using). So at any point in space, the electric field $\vec{E}(\vec{x})$ at that point "stores" an amount of potential energy $\frac{1}{2} |\vec{E}|^2$.
The following is multiple choice question (with options) to answer.
What type of energy is stored in an object because of its position or shape? | [
"potential",
"kinetic",
"mechanical",
"magnetic"
] | A | Potential energy is the energy stored in an object because of its position or shape. It includes gravitational potential energy and elastic potential energy. Gravitational potential energy depends on an object’s weight and height above the ground. |
SciQ | SciQ-757 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
Like plants, animals are multicellular what? | [
"prokaryotes",
"eukaryotes",
"isolates",
"membranes"
] | B | Like plants, animals are multicellular eukaryotes. However, animals differ from plants in other important ways. |
SciQ | SciQ-758 | mechanical-engineering, gears
Title: Looking for a gear similar to bicycle freewheel I have an engineering application where I would like to use a single 24v DC Stepping Motor to power two different axles of opposing direction. Basically when the motor turns clockwise, Axel A will spin and Axel B will be stationary. When the motor turns counter-clockwise, Axel A will be stationary and Axel B will spin.
I need it to be as cheap and simple as possible. So far, the best solution that I could come up with to accomplish this is by using two gears similar to the bicycle Freewheel / Freehub. The problem is, I cannot for the life of me find a gear that is similar to that application, but for uses outside of bicycles (possibly because I don't know that specific gear's name). Can anyone recommend a gear or something that is similar to the application that I need?
I have a general idea of the function that I need, but I don't know the name of this type of ratcheting gear. You can get one way bearings which rotate freely on one direction and lock in the other.
So if you use one to attach a gear or pulley to your motor output shaft then the pulley will be coupled to the shaft in one direction and not in the other so with two mounted in opposite orientation each with a pulley driving a separate shaft (A and B) you should be able to achieve what you want.
The following is multiple choice question (with options) to answer.
A doorknob and a ferris wheel are examples of what type of simple machine? | [
"wheel and axle",
"ball and socket",
"lever and pulley",
"ball and axle"
] | A | A wheel and axle is a simple machine that consists of two connected rings or cylinders, one inside the other. Both rings or cylinders turn in the same direction around a single center point. The inner ring or cylinder is called the axle, and the outer one is called the wheel. Besides the Ferris wheel, the doorknob in the Figure below is another example of a wheel and axle. For more examples, go to this URL:. |
SciQ | SciQ-759 | water, chemical-biology, precipitation
Title: In the wet medium of an ocean, how does a hard shell form? In general, if you were to try make something hard in a liquid medium (especially water) it is quite difficult to make the material solid.
Things such as mollusks though, have no problem generating hard shells in a wet medium.
What exactly are the physics behind this formation? Carbon dioxide from the atmosphere (or from decaying matter in the ocean) reacts with water to form carbonic acid:
$$ \ce{ CO2 + H2O -> H_2CO_3 }$$
and this reacts with calcium ions to form calcium carbonate:
$$ \ce{H2CO3 + Ca^{2+} -> CaCO3 + 2H+ }$$
The solubility of calcium carbonate is about $13~\mathrm{mg \over L}$, so if the concentration of calcium carbonate is greater than this the excess will precipitate out as solid calcium carbonate.
Shell-forming organisms actively absorb calcium from the water around them, so they are able to increase the concentration of calcium carbonate to above $13~\mathrm{mg\over L}$ and precipitate the excess to form their shells. They can get the carbon dioxide from the water around them or from their own metabolism. The actual details of shell formation is far more complex than this as it's controlled by processes with the cells of the organism rather than just being uncontrolled precipitation. I'm not sure how well the details are understood even today.
Incidentally, this is why shelly fauna are not keen on the acidification of the oceans that results from increased atmospheric carbon dioxide. The solubility of calcium carbonate is strongly $\mathrm{pH}$-dependent and rises sharply as the water gets more acid. Given that the shell is usually intended to stop other animals eating you, having your shell dissolve is generally not good for life expectancy.
The following is multiple choice question (with options) to answer.
What do ocean mollusks use to absorb oxygen from the water? | [
"scales",
"gills",
"shells",
"pores"
] | B | Most ocean mollusks have a gill or gills to absorb oxygen from the water. |
SciQ | SciQ-760 | paleontology
Title: How to start studying dinosaurs and pre-historic mammals/sea creatures I'm kind new to this hole thing of dinosaurs that I'm really interested in, are there any good books/websites/webpages to study the biology of pre-historic creatures? Dinosaurs, mammals, fishes, anything that is not alive anymore. Also, any good books about the history of how these species evolved and the history behind them would be appreciated. Here's what it takes to really study this: you need to go through the whole bachelor program for geoscientists, that includes fundamental geodynamics like plate tectonics, magmatism, volcanism, volcanic and metamorphic rocks and generally the cycles that make up earth's internal dynamics.
Then there is the huge field of external factors, like sediment geology (that's really complicated stuff), weathering and transport and how soils come to being, diagenesis and the structures sediments can form and their classifications. Role of the ocean (that's where it starts, before all) and the atmosphere, of course.
When through that, usually 4 semesters or so, you can start to specialize. For paleontolgy you need knowledge of earth history, of course, it's subdivision, and the conditions at certain times as far as they are known. Once that's done, then comes real paleontology: Animals (invertebrates and vertebrates), plants, and their development, biological evolution (that's frequently underrated, I find), taphonomy, ... For a sturdy base count another 2-4 semesters.
You may see that even a bunch of websites, maybe all of them together, cannot replace actual study. I am not aware of any site that even gives a reasonable overview of the field. Geoscience, and thus paleontology, touch many fields of natural science.
That said, when asked "How to learn about animal paleontology ?" I allways mention Micheal Benton, Vertebrate Paleontology. It needs a basic understanding of geoscience, evolution and skeleton anatomy. Functional morphology, phylogeny and an overview over sediment geology and earth history also won't harm, but you could give it a try. Some things are explained in between.
The following is multiple choice question (with options) to answer.
What is paleobotany? | [
"study of fresh plants",
"study of new plants",
"study of extinct plants",
"study of diseased plants"
] | C | Paleobotanist How organisms acquired traits that allow them to colonize new environments—and how the contemporary ecosystem is shaped—are fundamental questions of evolution. Paleobotany (the study of extinct plants) addresses these questions through the analysis of fossilized specimens retrieved from field studies, reconstituting the morphology of organisms that disappeared long ago. Paleobotanists trace the evolution of plants by following the modifications in plant morphology: shedding light on the connection between existing plants by identifying common ancestors that display the same traits. This field seeks to find transitional species that bridge gaps in the path to the development of modern organisms. Fossils are formed when organisms are trapped in sediments or environments where their shapes are preserved. Paleobotanists collect fossil specimens in the field and place them in the context of the geological sediments and other fossilized organisms surrounding them. The activity requires great care to preserve the integrity of the delicate fossils and the layers of rock in which they are found. One of the most exciting recent developments in paleobotany is the use of analytical chemistry and molecular biology to study fossils. Preservation of molecular structures requires an environment free of oxygen, since oxidation and degradation of material through the activity of microorganisms depend on its presence. One example of the use of analytical chemistry and molecular biology is the identification of oleanane, a compound that deters pests. Up to this point, oleanane appeared to be unique to flowering plants; however, it has now been recovered from sediments dating from the Permian, much earlier than the current dates given for the appearance of the first flowering plants. Paleobotanists can also study fossil DNA, which can yield a large amount of information, by analyzing and comparing the DNA sequences of extinct plants with those of living and related organisms. Through this analysis, evolutionary relationships can be built for plant lineages. Some paleobotanists are skeptical of the conclusions drawn from the analysis of molecular fossils. For example, the chemical materials of interest degrade rapidly when exposed to air during their initial isolation, as well as in further manipulations. There is always a high risk of contaminating the specimens with extraneous material, mostly from microorganisms. Nevertheless, as technology is refined, the analysis of DNA from fossilized plants will provide invaluable information on the evolution of plants and their adaptation to an ever-changing environment. |
SciQ | SciQ-761 | temperature, weather, humidity
Title: Why does relative humidity appear limited for temperatures above 80°F? I recently compiled ten years of NOAA local climatological data. I noticed that the maximum relative humidity dropped linearly from 100% at about 80°F to 20% at about 110°F. Nothing obvious comes to mind that explained this observation.
Here is my scatterplot:
Here is graph showing the edge of interest:
I would have expected to see relative humidity values at or near 100%, even for temperatures near 100°F. Obviously, that's not what I see. Maybe this has something to do with a limit of absolute humidity or density?
Nothing obvious comes to mind that explained this observation.
Consider a simple model with the following aspects/assumptions:
The coastal regions of large bodies of water on Earth are at most as hot as about 80°F. (Some exceptions exist, such as the Persian Gulf. If the data are taken from weather stations near areas of human occupancy, such as airports, note also that regions with a wet-bulb temperature much greater than about 80°F are generally hazardous to humans.)
Water enters the atmosphere predominantly through evaporation from these large bodies of water, up to the maximum relative humidity at that maximum temperature. That fixes one point of the line you observed: 100% relative humidity at 80°F (300 K).
The vapor pressure $P_\text{vapor}$ of water increases with increasing temperature $T$; a simple model of this exponential relation is the August equation $P_\text{vapor}\approx\exp\left(20- \frac{5100}{T}\right)$, with $T$ measured in kelvins.
The relative humidity corresponds to the actual partial pressure of water vapor relative to the saturation vapor pressure at that temperature. We characterize this behavior in part through psychrometric charts.
Therefore, we should expect a downward-sloping maximum relative humidity with increasing temperature as the saturated vapor is transported inland to regions over land that may be hotter. The maximum mass of water vapor remains the same, as does the maximum absolute humidity, but the maximum relative humidity drops with increasing temperature.
The following is multiple choice question (with options) to answer.
What happens to the level of relative humidity in the evening as air temperature declines? | [
"nothing",
"it rises",
"it goes up and down",
"it falls"
] | B | The expression “it’s not the heat, it’s the humidity” makes a valid point. We keep cool in hot weather by evaporating sweat from our skin and water from our breathing passages. Because evaporation is inhibited by high humidity, we feel hotter at a given temperature when the humidity is high. Low humidity, on the other hand, can cause discomfort from excessive drying of mucous membranes and can lead to an increased risk of respiratory infections. When we say humidity, we really mean relative humidity. Relative humidity tells us how much water vapor is in the air compared with the maximum possible. At its maximum, denoted as saturation, the relative humidity is 100%, and evaporation is inhibited. The amount of water vapor in the air depends on temperature. For example, relative humidity rises in the evening, as air temperature declines, sometimes reaching the dew point. At the dew point temperature, relative humidity is 100%, and fog may result from the condensation of water droplets if they are small enough to stay in suspension. Conversely, if you wish to dry something (perhaps your hair), it is more effective to blow hot air over it rather than cold air, because, among other things, the increase in temperature increases the energy of the molecules, so the rate of evaporation increases. The amount of water vapor in the air depends on the vapor pressure of water. The liquid and solid phases are continuously giving off vapor because some of the molecules have high enough speeds to enter the gas phase; see Figure 13.33(a). If a lid is placed over the container, as in Figure 13.33(b), evaporation continues, increasing the pressure, until sufficient vapor has built up for condensation to balance evaporation. Then equilibrium has been achieved, and the vapor pressure is equal to the partial pressure of water in the container. Vapor pressure increases with temperature because molecular speeds are higher as temperature increases. Table 13.5 gives representative values of water vapor pressure over a range of temperatures. |
SciQ | SciQ-762 | ionic-compounds, conductivity
Title: Why are ionic compounds bad conductors of electricity in solid state? I understand the fact that ionic compounds are good conductors of electricity in molten state. But why aren't they good conductors in solid state. Cannot ions vibrate about their mean position and transfer electricity in the same way as they transfer heat? Electric charge is transferred by physically moving charged particles around. In the case of an electric current moving through a wire (for example), the electrons are moving.
In an ionic compound, the ions are locked in place. They can move around a little bit, but there is not much translational motion - the ions stay in their places on the crystal lattice. In addition, the ions are "happy" with the number of electrons that they have. The ions formed in the first place by giving up or accepting electrons in order to minimize the overall potential energy of the system. If an anion were to transfer an electron back to a cation (for example) the energy of the system would increase, and so in general, transfer of electrons after the compound has formed is not favorable.
In solution or in a molten state, the ions themselves can move around - they become the charge carriers. In a solid, the ions can't move, and so electricity cannot be easily transferred.
You mentioned heat transfer - heat is the transfer of the kinetic energy of atoms and molecules. Heat can still be transferred (in some cases quite easily) in an ionic solid because, as you said, ions can vibrate about a mean position. When this happens they bump into their neighbors, which spreads the kinetic energy around.
In summary, ionic compounds don't conduct electricity very well because the charge carriers can't move through the crystal. They can conduct heat because the kinetic energy itself is the "heat carrier" - it can be transferred without moving ions too far from their mean positions.
The following is multiple choice question (with options) to answer.
What term is used to describe a compound that does not conduct an electric current in either aqueous solution or in the molten state? | [
"xerophyte",
"porous",
"kilocalorie",
"nonelectrolyte"
] | D | A nonelectrolyte is a compound that does not conduct an electric current in either aqueous solution or in the molten state. Many molecular compounds, such as sugar or ethanol, are nonelectrolytes. When these compounds dissolve in water, they do not produce ions. The Figure below illustrates the difference between an electrolyte and a nonelectrolyte. |
SciQ | SciQ-763 | aerospace-engineering, renewable-energy, regulations
Title: Do regulations in the United States limit the size of aerial wind turbines? What with all the work done by the FAA recently on regulating drone usage, I thought it would be nice to turn my eyes to the sky for another, less-known type of aerial denizen: the aerial wind turbine.
Wikipedia has all the relevant information, so I won't rehash it here. The most important thing here is that aerial wind turbines - and I'm mostly interested in aerostat-based designs - are free-floating, just like certain types of tethered drones, which have given the FAA headaches because they're not like most aircraft.
I did find this article, which says
Regulations and technological restrictions suggest it may not happen very soon, or at all, but some researchers believe aerial turbines will be tapping high-altitude winds for power generation sometime in our future and perhaps within the decade.
and
That said, companies currently working on the project seem very loosely formed. They are in the development phase and are aware of federal airspace restrictions.
Here's the relevant FAA page.
I suspect that FAA regulatory measures on drones cover aerial wind turbines, but I'm not positive, and I'd like to see some specific mention of them in regulations, if possible. I assume they're treated as (tethered) drones, but I haven't been able to find any direct mention.
The following is multiple choice question (with options) to answer.
Peregrine falcons made an incredible recovery after laws were passed banning the use of what? | [
"Carbaryl",
"miticide",
"Acetamiprid",
"ddt"
] | D | Government policies and laws are needed to protect biodiversity. Such actions have been shown to work in the past. For example, peregrine falcons made an incredible recovery after laws were passed banning the use of DDT. |
SciQ | SciQ-764 | cell-biology, nutrition, blood-circulation, liver
Title: How do nutrients get to the cells they need to get to? I understand the basics of digestion. I know that nutrients get absorbed by the microvilli, enter the bloodstream and travel to the liver but after all that, what is the biological mechanism that guides these nutrients to the proper receiving location? Broadly speaking, nutrients that enter the blood from the gut, and those that are released into the blood by the liver, are available to any cells that require them. So there is no "guiding to the correct location" in the sense that you suggest.
Lipids for example are present in the various lipoproteins and can be acquired from these by all cells. Iron is bound to transferrin, and any cell with transferrin receptors can internalise the transferrin and take the iron. Glucose is available in solution in the plasma, and free fatty acids are bound to serum albumin in the blood. During starvation the liver produces ketones ("ketone bodies") which are taken up by many different tissues/cell types.
The following is multiple choice question (with options) to answer.
What pathway in a plant do water and nutrients travel through from the roots to the leaves? | [
"flowers",
"stem",
"bark",
"skin"
] | B | |
SciQ | SciQ-765 | meteorology, atmosphere, wind, air-currents
Title: Where does wind come from? Wind is (according to Wikipedia) the flow of gases on a large scale.On the surface of the Earth, wind consists of the bulk movement of air.
What forces would cause such a mass movement of air? Wind is caused by pressure differences. Think of a balloon full of air; poke a hole in it and the air comes out. Why? Because the pressure in the balloon is higher than outside, and so to regain equal pressure, mass moves and that is the wind.
There is a bit more to this in the atmosphere as the Earth rotates and near the surface friction also plays a role. The equation of motion is the Navier-Stokes and in vector form in Cartesian space is:
$$\dfrac{\partial\mathbf u}{\partial t} = - \mathbf u \cdot \nabla \mathbf u -\dfrac{1}{\rho}\nabla p-2 \mathbf \Omega \times \mathbf u + \mathbf g + \mathbf F$$
In this equation, $\mathbf u$ is the vector wind, $(\mathbf u \cdot \nabla)$ is the advection operator, $\rho$ is density, $\mathbf \Omega$ is the vector rotation of the Earth, $\mathbf g$ is effective gravity and $\mathbf F$ is friction.
The LHS is the time rate of change of the wind at a point in space (as opposed to following the parcel). The RHS represent a number of factors that produce a change in the wind. From left to right:
Advection of momentum (non-linear)
Pressure gradient force (this is wind blowing from high to low pressure)
Coriolis force (this turns wind to the right in the NH and left in the SH and causes the wind to flow parallel to isobars)
gravity (provides hydrostatic balance with the PGF in the vertical)
Friction (in the boundary layer you may see this as $\nu\nabla^2\mathbf u$)
The following is multiple choice question (with options) to answer.
In the tropics what are the prevailing winds called? | [
"tradewinds",
"storm winds",
"a front",
"crosswinds"
] | A | The major wind belts push the water in the surface currents. The water moves in the direction of :. |
SciQ | SciQ-766 | 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.
How many chromosomes are in a diploid human cell? | [
"47",
"41",
"46 chromosomes",
"46.63 chromosomes"
] | C | Sperm are male gametes , or reproductive cells. When a male gamete meets a female gamete, they can form a new organism. Sperm form when certain cells in the male reproductive system divide by meiosis , resulting in cells with half the amount of DNA as a regular "body" cell. More precisely, sperm cells are haploid sex cells, having one set of chromosomes. Regular body cells are diploid, having two set of chromosomes. As there are 46 chromosomes in a diploid human cell, how many are in a human sperm cell?. |
SciQ | SciQ-767 | physical-chemistry, bond, water, atoms, molecules
Title: Why does matter have spaces between them? If you mix sugar Crystal in a glass of water and mix it well, the level of water will not rise.The reason they say is that matter have spaces between them.If matter have spaces between them , How come that empty space is not visible to our eyes.If I look at a glass of water , I see all the molecules mixed up well.Not like there are some areas where there is no H20 molecule and some they’re are.
What does it exactly mean and how does it look like and what is happening there?
My thinking:
Is it like there are intermolecular forces between H20 molecules but they are at a separation from each other and still have the bond.Why does level inc if I put my finger. Note that there is the law of mass and energy conservation, but there is no law about volume conservation.
Molecules of matter are in eternal motion. Molecules of gases move freely by flying between collisions. Nitrogen or oxygen molecules of air have an average speed of a supersonic fighter, colliding at rate typically 10 billions collisions per second, with the mean free flight distance typically 70 nm. Such motion creates space between them. ( Try to keep a sworm of vivid children in tight packed formation. )
Molecules of liquids and solids are held together by attractive forces. Loosely for the former, so they continuously separate and rejoin. Tightly for the latter, so they just vibrate.
Another reason for space between molecules is electrostatic repulsion of their electrons, if they get too close. If you hit a wall, you did not really touch it. The wall started to repulse you by the mighty electrostatic force, when your and it's electrons got too close.
If you mix 1 L of ethanol and 1 L of water and let it cool down ( because it warms up ), the total volume will not be 2 L, but about 1.96 L. It is due the fact the average energy of bonds water-ethanol (via hydrogen bonds) is greater than the average energy of bonds water-water and ethanol-ethanol. This leads to shorter average distance between molecules ( fractions of nanometre ), as stronger bonds are shorter, and to the volume contraction.
The following is multiple choice question (with options) to answer.
Motion of water molecules helps break up interactions between what? | [
"enzymes and acids",
"acids and bases",
"solid ions or molecules",
"ions or hormones"
] | C | Motion of water molecules helps break up interactions between solid ions or molecules. |
SciQ | SciQ-768 | inorganic-chemistry, molecular-orbital-theory
Below is a drawing of the five occupied orbitals where you can see that the $\sigma$ ones have become $sp$-like and that the carbon contribution is greater in the HOMO. C is on the left and N on the right.
The following is multiple choice question (with options) to answer.
Which cycle is named after the scientist melvin calvin? | [
"calvin cycle",
"melvin cycle",
"melcal cycle",
"krebs cycle"
] | A | The second stage of photosynthesis takes place in the stroma surrounding the thylakoid membranes of the chloroplast. The reactions of this stage can occur without light, so they are sometimes called light-independent or dark reactions. This stage of photosynthesis is also known as the Calvin cycle because its reactions were discovered by a scientist named Melvin Calvin. He won a Nobel Prize in 1961 for this important discovery. |
SciQ | SciQ-769 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
What is formed when a subducting plate flows under another tectonic plate? | [
"fault line",
"magma",
"volcanic arc",
"boundary plate"
] | C | As you would expect, where plates collide there are lots of intense earthquakes and volcanic eruptions. The subducting oceanic plate melts as it reenters the mantle. The magma rises and erupts. This creates a volcanic mountain range near the coast of the continent. This range is called a volcanic arc . The Andes Mountains, along the western edge of South America, are a volcanic arc ( Figure below ). |
SciQ | SciQ-770 | homework-and-exercises, friction, free-body-diagram
So $F_T$ = 170.0 N $\pm$ 59.4 N = 229.4 N or 110.6 N. How do you know which one to pick? Is there some sort of law that says the tension is always minimized?
This isn't even accounting for the fact that the real definition of static friction is $F_{fr} \le \mu F_N$, so $F_{fr}$ could be less than 59.4 N. How would that change things?
EDIT: corrected one of the numbers The answer you have found is in fact the correct one, including the range of values; the question does not give enough information to be any more exact.
Consider that you are pulling this block up the slope, and decide that you need to take a break. You know that gravity is exerting $170\text{ N}$ down the slope at all times, so you lower the tension you're exerting on the rope to that value (there's a convenient spring scale incorporated into the rope). Nothing happens, so you lower the force a bit more. Again, nothing happens, so you know that static friction is taking up some of the load. You keep on reducing the up-slope force you exert on the rope, until, at about $110\text{ N}$ applied force, the block begins to slide down-slope. Friction is doing all it can to prevent down-slope slide, and you've reached the most reduced force rest you're going to get.
After a while, you continue up the hill. You pull up harder and harder on the rope, but for a while nothing happens. You are assuming more of the up-slope force, as static friction contributes less and less. You pass $170\text{ N}$, and still nothing happens. Static friction is now acting down the slope, adding to the down-slope gravity force. Finally, at about $230\text{ N}$ applied up-force, friction reaches its limit in helping gravity, and you continue your up-hill slog...
At any time during your stopping, resting, and resuming your journey, the conditions would meet those of Part (3), and any of the forces of tension between $110\text{ N}$ and $230\text{ N}$ could be observed...
The following is multiple choice question (with options) to answer.
What force increases a slide downhill and decreases a slide uphill? | [
"gravity",
"tension",
"nuclear",
"frictional"
] | A | Discussion As might have been expected, the player slides a shorter distance by sliding uphill. Note that the problem could also have been solved in terms of the forces directly and the work energy theorem, instead of using the potential energy. This method would have required combining the normal force and force of gravity vectors, which no longer cancel each other because they point in different directions, and friction, to find the net force. You could then use the net force and the net work to find the distance d that reduces the kinetic energy to zero. By applying conservation of energy and using the potential energy instead, we need only consider the gravitational potential energy. |
SciQ | SciQ-771 | immunology, cancer, immunosuppression
Title: Normal cells and the immune system Normal or healthy cells have a natural ability to avoid being attacked by the immune system.
So if a cancer cell has all inherited 'strategies' for avoiding the immune system (that are from their earlier pre-cancerous states) does this make them hard to detect or be affected by the immune system. The development of cancer has various reasons. For example in more than 50% of tumors, p53 is mutated. p53 among other things regulates mitosis and forces the cell to arrest in a specific growth state if other systems detected a mutation in the DNA.
But in your special case we have to look at major histocompatibility complexes (MHCs) and NLRC5. There are two types of MHC, namely MHC class I and class II. MHC II presents mostly bacterial peptides to CD4+ T cells causing a immune response. However, MHC I presents viral peptides and peptides from your own body. These peptides are detected by CD8+ T cells which are cytotoxic T cells initializing apoptosis. Without these own peptides natural killer (NK) cells are activated because of a missing-self signal causing apoptosis, too.
The following is multiple choice question (with options) to answer.
Lymphoma is a cancer of a type of what type of cells, called lymphocytes? | [
"white blood cells",
"lung cells",
"red blood cells",
"brain cells"
] | A | Blood cancers affect the production and function of your blood cells. Most of these cancers start in your bone marrow where blood is produced. In most blood cancers, the normal production of blood cells is replaced by uncontrolled growth of an abnormal type of blood cell. These abnormal blood cells are cancerous cells, and prevent your blood from performing many of its functions, like fighting off infections or preventing serious bleeding. Leukemia is a cancer of the blood or bone marrow. It is characterized by an abnormal production of blood cells, usually white blood cells. Lymphoma is a cancer of a type of white blood cell called lymphocytes. There are many types of lymphoma. |
SciQ | SciQ-772 | 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 type of eggs do fully terrestrial vertebrates carry? | [
"amniotic",
"epithelial",
"amphibious",
"aqueous"
] | A | The amniotic egg is an important adaptation in fully terrestrial vertebrates. It first evolved in reptiles. The shells of reptile eggs are either hard or leathery. |
SciQ | SciQ-773 | climate-change, ice-age
Title: Was there a period of global warming before the start of the last ice age? I am curious to know if there was a period of global warming that took place before the start of the last ice age and I would like to know how long this period of global warming lasted. There was an interglacial befor the last glaciation:
glacial–interglacial cycles last ~100,000 years (middle, black line) and consist of stepwise cooling events followed by rapid warmings, as seen in this time series inferred from hydrogen isotopes in the Dome Fuji ice core from Antarctica
NOAA
The following is multiple choice question (with options) to answer.
What is the time since the beginning of the ice ages? | [
"quaternary period",
"Jurassic period",
"Paleolithic era",
"Mesozoic epocH"
] | A | The Quaternary Period is the time since the beginning of the ice ages. The climate has been cooler than it was earlier in the Cenozoic. Since the end of the Pleistocene ice ages, which are probably not entirely over, we have been in the Holocene Epoch. The Holocene is also called the Recent. |
SciQ | SciQ-774 | muscles, lungs, human-physiology
Title: Why is there smooth muscle in our bronchioles? Having muscle tissue in our bronchioles that can constrict seems like a poor choice for tissue. Why would our airway want to ever close up? Wouldn't it be more beneficial for our bronchioles to just remain open? There are at least two things to consider.
First, ability to limit airflow is a defense mechanism for animal. Imagine getting into area of some sort of toxic evaporation, e.g. CO2 cloud near volcano , then it makes sense to decrease delivery of toxin via lungs to minimum. As I understand, that is what an allergic asthma attack. (Sorry for not providing good enough source of that)
Secondly, you are incorrect in assuming that normal state is "dilated". Dilation of branchioles is sympathetic ("fight-and-fly") response of the nervous system to something like danger, that requires short-term boost in energy production. That is, by default, your airflow is limited. Probably, to limit amount of energy you effectively burn via oxygenation. But most importantly, you leave yourself a reserve in terms of oxygen supply for critical moments.
Some more information you might find here.
The following is multiple choice question (with options) to answer.
What will the contraction of smooth muscles help organs do? | [
"move joints",
"move across distances",
"carry out functions",
"fine motor movements"
] | C | Muscle tissue in the walls of internal organs such as the stomach and intestines is smooth muscle . When smooth muscle contracts, it helps the organs carry out their functions. For example, when smooth muscle in the stomach contracts, it squeezes the food inside the stomach, which helps break the food into smaller pieces. Contractions of smooth muscle are involuntary. This means they are not under conscious control. |
SciQ | SciQ-775 | everyday-chemistry, food-chemistry
Title: Is it not safe for health to finish a bottle of wine during a week People said that wine is good for health. So I take a cup (less than 100 mL) of wine every evening. (Yes, wine is cheap where I live.) So to finish a bottle of wine (750 mL), it takes me a week.
(Of course I put it in the refrigerator.) I have to say that it doesn't taste good after 3 days (but still OK).
But I don't know if it is not safe to do so. Maybe the wine begins to produce something not good for health after a few days when it is opened. So, my question is: what chemical species are formed after opening a wine bottle, making it go bad? Are they only bad for the taste, or also bad unhealthy? The bad taste left after drinking wine can be attributed a number of agents found in wine, particularly alcoholic wines.
Alcoholic wines typically contain 8-15% ethanol. When ethanol mixes with oxygen in air it gets oxidised, gradually producing acetic acid (vinegar).
Furthermore, the reaction of ethanol with urea (naturally present in wine) to form ethyl carbomate (urethane) can produce a saline, bitter taste, although probably not toxic.
The ethanol in wine is produced through the fermentation of carbohydrates by yeast. This process also results in the production of acetaldehydes which contribute to its complex set of flavours.
Ethanol itself however is tasteless. It is however toxic and a class 1 carinogen according to the International Agency for Research on Cancer (IARC).
When consumed, ethanol is oxidised by alcohol dehydrogenase (ADH) enzymes in the body to produce acetaldehyde, which is 10-30 times more toxic than alcohol and possibly carcinogenic in humans.
Recent scientific research on cancer seems to indicate even low levels of alcohol consumption (1 cup per day) 'increases the risk of cancer of oral cavity and pharynx, esophagus and female breast' Source: http://annonc.oxfordjournals.org/content/early/2012/08/21/annonc.mds337.full
So a bad taste may not be the worst thing alcohol leaves in one's mouth.
The following is multiple choice question (with options) to answer.
What is an acid that can be produced from the aerobic fermentation of wine? | [
"orange juice",
"vinegar",
"grape juice",
"soda"
] | B | Vinegar is an acid that can be produced from the aerobic fermentation of wine. In fact, vinegar is most likely the oldest known acid. It is commonly used as a food additive (to give things an acidic or sour taste) and as a mild cleaning agent. |
SciQ | SciQ-776 | geology, mineralogy, minerals, weathering
To me, supergene has a specific meaning, it may be part of the weathering process in some locations, but weathering involves the breaking down of rocks due to: reactions with atmospheric gasses, water (usually rain), changes brought on by plants, bacteria wind and temperature.
My suggestion to use the term weathering or weathered.
The following is multiple choice question (with options) to answer.
Weathering is fundamental to the creation of what, which exists as a very thin layer over solid rock? | [
"soil",
"moss",
"fungus",
"aquifers"
] | A | Without weathering, we would not have any soil on Earth. People could not live on Earth without soil! Your life and the lives of most organisms depend on soil. Soil is only a very thin layer over solid rock. Yet, it is the place where reactions between solid rock, liquid water and air take place. We get wood, paper, cotton, medicines, and even pure water from soil. So soil is a very important resource. Our precious soil needs to be carefully managed and cared for. If we don’t take care of the soil we have, we may not be able to use it in the future. |
SciQ | SciQ-777 | geology, mineralogy, minerals, weathering
To me, supergene has a specific meaning, it may be part of the weathering process in some locations, but weathering involves the breaking down of rocks due to: reactions with atmospheric gasses, water (usually rain), changes brought on by plants, bacteria wind and temperature.
My suggestion to use the term weathering or weathered.
The following is multiple choice question (with options) to answer.
What type of weathering causes the minerals in a rock to change? | [
"natural",
"chemical",
"toxic",
"artificial"
] | B | Chemical weathering is different than mechanical weathering. The minerals in the rock change. The rock changes composition and becomes a different type of rock. Most minerals form at high pressure or high temperatures deep within Earth. But at Earth's surface, temperatures and pressures are much lower. Minerals that were stable deeper in the crust are not stable at the surface. That’s why chemical weathering happens. Minerals that formed at higher temperature and pressure change into minerals that are stable at the surface. Chemical weathering is important. It starts the process of changing solid rock into soil. We need soil to grow food and create other materials we need. Chemical weathering works through chemical reactions that change the rock. |
SciQ | SciQ-778 | thermodynamics, atoms, phase-transition
But let's look at how the states change. In a solid, you have a bunch of atoms that can be thought of as masses connected by springs. As heat is added to the system, the atoms begin to vibrate in the lattice of springs. As more heat is added, they vibrate enough to break the springs. This is when the solid begins to melt and turn to a liquid.
Now you have a liquid where the atoms are all moving around but they aren't free to move wherever they want. More heat is added to the system and the atoms begin to translate faster and faster. Eventually they translate fast enough to overcome the forces that are holding them together in a liquid. Now they fly free and are a gas.
So ultimately, heat is energy that makes atoms and molecules move in some way. They may translate, rotate, vibrate, or the electrons may begin moving around depending on how much heat is there and what configuration the molecule has.
The following is multiple choice question (with options) to answer.
What is the process in which a liquid changes to a solid? | [
"melting",
"freezing",
"boiling",
"condensation"
] | B | Freezing is the process in which a liquid changes to a solid. It occurs when a liquid cools to a point at which its particles no longer have enough energy to overcome the force of attraction between them. |
SciQ | SciQ-779 | botany, ecology, digestion, climate-change
The timing of residence times and flux rates (i.e., movement from one place to another) dictate whether a reservoir acts as a source or sink.
CO2 (carbon dioxide) and CH4 (methane) are quite different in the reactions from which they are generated (see Would fewer cows mean less methane emission?), the rate at which they are generated, and ultimately in their chemistry. This last point has drastic impacts on residence times, flux rates, and ultimately their their climate warming impacts:
Both molecules differ in their residence times in the atmosphere as well as their magnitude of radiative forcing. From MIT:
methane immediately begins to trap a lot of heat—at least 100 times as much as the CO2. But the methane starts to break down and leave the atmosphere relatively quickly. As more time goes by, and as more of that original ton of methane disappears, the steady warming effect of the CO2 slowly closes the gap. Over 20 years, the methane would trap about 80 times as much heat as the CO2. Over 100 years, that original ton of methane would trap about 25 times as much heat as the ton of CO2.
Note, also, that some of the atmospheric methane will eventually be chemically converted to carbon dioxide. From here.
Methane enters the atmosphere and eventually combines with oxygen (oxidizes) to form more CO2. Methane converts to CO2 by this simple chemical reaction.
Regarding methane production of cows and rates of release of greenhouse gasses, please see my other recently-answered BIO.SE post: Would fewer cows mean less methane emission?
Regarding carbon storage:
As stated above, understanding the carbon cycle requires both an understanding of residence times and flux rates. To determine the carbon storage ability of one biome or environment vs another, we typically measure the biomass of the organic matter (with interest in determining the C:N ratio) as well as flux rates in/out of our target carbon reservoir (e.g., plants such as crops or trees). Regarding flux rates, of particular interest are rates of carbon sequestration.
Ultimately, any community of plants that is capable of sequestering more carbon into large amounts of high-C:N biomass will result in larger carbon storage. The longer-lived those plants (i.e., the less labile their carbon), the longer that community of plants acts as a carbon sink.
The following is multiple choice question (with options) to answer.
By pulling out grass by its roots and over-grazing, livestock contribute to what negative process? | [
"migration",
"evolution",
"immigration",
"erosion"
] | D | As pictured below ( Figure below ), some grazing animals, especially sheep and goats, eat grass right down to the roots. They may even pull the grass entirely out of the ground. Grazing animals can kill the grass. They may thin it out so much that it offers little protection to the soil. If animals are kept in the same place too long, the soil may become completely bare. The bare soil is easily eroded by wind and water. |
SciQ | SciQ-780 | isomers
(5) $\ce{CH3CH2CH(CH3)-O-CH3}$ :methyl sec-butyl ether
(6) $\ce{(CH3)3-C-O-CH3}$ : methyl tert-butyl ether
The following is multiple choice question (with options) to answer.
What are the three types of isomers? | [
"structural, cis-trans, Polystyrene",
"structural , chromosome - trans , enatiomers",
"structural, Polypropylene , enatiomers",
"structural, cis-trans, enatiomers"
] | D | |
SciQ | SciQ-781 | evolution, botany, photosynthesis, speculative, chloroplasts
Title: Why do plants have green leaves and not red? I know plants are green due to chlorophyll.
Surely it would be more beneficial for plants to be red than green as by being green they reflect green light and do not absorb it even though green light has more energy than red light.
Is there no alternative to chlorophyll? Or is it something else? Surely it would be even more beneficial for plants to be black instead of red or green, from an energy absorption point of view. And Solar cells are indeed pretty dark.
But, as Rory indicated, higher energy photons will only produce heat. This is because the chemical reactions powered by photosynthesis require only a certain amount of energy, and any excessive amount delivered by higher-energy photons cannot be simply used for another reaction1 but will yield heat. I don't know how much trouble that actually causes, but there is another point:
As explained, what determines the efficiency of solar energy conversion is not the energy per photon, but the amount of photons available. So you should take a look at the sunlight spectrum:
The following is multiple choice question (with options) to answer.
The chloroplasts contain a green pigment called what? | [
"chlorophyll",
"chloroplasm",
"sodium",
"melanin"
] | A | The chloroplasts contain a green pigment called chlorophyll, which captures the energy of sunlight for photosynthesis. Like plant cells, photosynthetic protists also have chloroplasts. Some bacteria also perform photosynthesis, but they do not have chloroplasts. Their photosynthetic pigments are located in the thylakoid membrane within the cell itself. |
SciQ | SciQ-782 | equilibrium, solubility
Title: Why does adding water to a saturated solution increase the number of ions present in the solution? In my book, it is stated that when some water is added to a test tube having a saturated $\ce{Ag2SO4}$ solution, with its solid at equilibrium, the number of $\ce{Ag}$ ions in the solution increases.
I don't understand it. If $\ce{Ag2SO4}$ solution is saturated, it means that no more solute can dissolve, and if we add water, the amount of dissolved solute should not change.
Also, if the amount of dissolved $\ce{Ag}$ increases, would the $K_\mathrm{sp}$ value also increase? Consider a saturated solution of $\ce{Ag2SO4}$. The following equilibrium is attained.
$$ \ce{Ag2SO4 <=> 2Ag+ + SO4^2-}$$
Adding water accounts to increasing the volume of the solution. Hence more amount of solute can be dissolved since solubility of a salt depends on the amount of salt dissolved per unit volume. Therefore, there is an increase in the no. of ions produced in the solution. But as Avnish Kabaj mentioned, $[\ce{Ag+}]$ remains the same.
Also as MollyCooL said, $\pu{K_{sp}}$ doesn't change as it is a constant at a particular temperature.
The following is multiple choice question (with options) to answer.
What state occurs when the amount of solute dissolved exceeds the solubility? | [
"supersaturation",
"polymerisation",
"density",
"alkalinity"
] | A | supersaturated : When the amount of solute dissolved exceeds the solubility. Occurs when a solution is saturated and the temperature slowly drops. |
SciQ | SciQ-783 | development
Title: How detachment/separation works in biology? It might be a strange question, but I'm interested in the mechanics of separation/detachment during asexual reproduction, for example when an organism reproduces by budding (I don't mean cellular budding like baker's yeast). When the newly formed body is fully matured it detaches itself from the parent / original body.
It might not be caused by a specific tissue, as animals with not so differentiated bodies are (also) capable of such, but I could easily be wrong. Is this (the detachment) triggered by changes in the cell membrane? I can't really think of other explanations. Reproductive budding and what you call 'cellular budding' are really highly related processes. Budding as a form of reproduction essentially partitions protein aggregates and damaged cellular components into the host or mother and builds fresh or 'young' cells on the opposite side of a partition. To begin understanding this look at Saccharomyces cerevisiae (budding yeast) which forms protein rings (from the septin proteins) at the membrane, around the bud neck which separates the mother and daughter cells Hartwell 1971. This ring acts a partition that in part, withholds protein aggregates and certain proteins from diffusing from the mother to the daughter. This protein ring is an example of how cells limit diffusion of proteins and cellular components to the daughter cell. Another good example that comes to mind is Linder 2007, though it is done in E Coli, not budding yeast, where mother cells maintain protein aggregates and age, while the daughter cells are given fresh components and are therefore more fresh and 'young'.
Now like you mention, imagine this process in a multicellular organism to be fundamentally the same. At some point the multicellular organism will start an outgrowth of cells, while restricting what materials are given to the daughter cells to maintain their youth. And eventually a new organism will have been created. Some of the details will be different, but the fundamental process is is quite similar. In that you start with an old cell that creates a new cell from scratch, but rather than splitting all cellular components equally between mother and daughter, the daughter cells is made in peak condition while the mother cell retains much of the cell 'junk' like protein aggregates.
Hopefully that starts to answer your question.
The following is multiple choice question (with options) to answer.
What occurs when spores from two parents fuse and form a zygospore? | [
"asexual reproduction",
"sexual reproduction",
"twins",
"internal reproduction"
] | B | The majority of fungi can reproduce both asexually and sexually. This allows them to adjust to conditions in the environment. Yeast reproduce asexually by budding. Other fungi reproduce asexually by producing spores. Sexual reproduction occurs when spores from two parents fuse and form a zygospore. |
SciQ | SciQ-784 | rna-seq, r, deseq2, networks
Title: What are the ways to process a list of differentially expressed genes? We are studying six different human macrophage/dendritic cell types isolated from healthy skin. They all differ from each other in a few cell surface markers.
We are interested in the characteristics of each cell type ("marker" genes or biological processes), the differences between them (especially cell surface proteins), and their relations (e.g. "which are the closest relatives?") as can be inferred from the transcriptome, from an immunological point of view. The wider context is HIV-infection, thus HIV infection-related differences (and similarities) are of particular interest.
One naive approach is to contrast two of the most similar cell types (as inferred from previous knowledge, the sorting strategy and the PCA plot), and produce a list of differentially expressed (DE) genes.
I have now a list of ~500 DE genes between two cell types, together with fold changes, expression means etc., produced with DESeq2 on bulk RNA-seq data.
What are the best practices to process this list to answer some of the above?
I've found PPI analysis on NetworkAnalyst, and GO and pathway analysis on InnateDB useful.
What other options are available?
I'm particularly interested in approaches using R. You originally had asked a very broad question, so I'll try to demonstrate why that is such a hard question to answer. I've done two fairly large differential analysis studies (and a few smaller ones) covering very different areas of research, and the approaches that other researchers used subsequent to my differential expression calculations were unsurprisingly also very different.
The following is multiple choice question (with options) to answer.
Macrophages and dendritic cells are types of what" | [
"amoena cells",
"mast cells",
"phagocytic cells",
"supercapacitor cells"
] | C | |
SciQ | SciQ-785 | optics, atmospheric-science
Title: Why do mountains disappear into the distance? Traveling south on CA 99 we noticed that atmospheric conditions were exceptionally clear and played a little game attempting to determine how far away we could identify Shasta. As we got further and further away it got smaller, greyer, and harder to locate. I took to using these closer (green) low hills that were nearly aligned with it to locate it. As expected, the low hills went down below the horizon.
Yet proceeding south I managed to reacquire it (partially using Lassen as a reference point), and manage to mostly hold it for quite some time. As we were coming up on Chico, it started to get close to disappearing below the horizon. But that never happened. Just north of Chico, Shasta disappeared into blue sky while I was looking right at it. It did not go below the horizon. It was not occluded by any cloud or smoke or smog, nor by trees for that matter. There was no indication of an atmospheric disturbance. I didn't lose its location and fail to require it.
So why might Shasta have disappeared? What limit did I exceed that I could no longer see it?
(safety note: I was not the one driving, so I could indeed turn and look straight backwards for minutes at a time) The reason it disappeared is the same as why the sky is blue: Rayleigh scattering of light from air and small particles in it. When you're close to the mountain its light only travels a short distance through air, so you see it sharply. The further you go away from it the more of its light is scattered. Additionally the light of the mountain is mixed up with light from the sun. If sunlight is scattered towards you at a location of the path between the mountain and your eye it looks like it comes from the mountain (see drawing). The reason why it looks like the mountain becomes mixed with blue is the $\propto \lambda^{-4}$ efficiency of Rayleigh scattering.
The following is multiple choice question (with options) to answer.
What side of a mountain does the rainshadow effect occur on? | [
"due north",
"the leeward side",
"windward",
"starboard"
] | B | Rainshadow effect occurs on the leeward side of a mountain range. |
SciQ | SciQ-786 | cell-biology, organelle
Title: Why is sedimentation rate significant for a ribsome When we take a look at biology textbooks (Campbell, Pearson etc), they will only mention the difference between eukaryotic and prokaryotic ribosome sedimentation rates. Why is sedimentation rate numerically important for ribosomes and not for other organelles like the mitochondria or the nucleus? Summary
Ultracentrifugation was necessary to identify and ribosomes, and characterize them on the basis of their size. The method does not allow an absolute measurement of molecular mass, but uses a relative quantitation as sedimentation coefficient, expressed in Svedberg Units (S).
Nuclei and mitochondria were characterized by light microscopy and, being much larger than ribosomes, sediment at speeds which do not require an ultracentrifuge and would not be resolved in an ultracentrifuge.
Nuclei and mitochondria vary in size, so their size is not a defining property for them. Ribosomes from one source all have the same size, which may differ from that of ribosomes from other sources in a definitive manner.
Ribosomes are composed of smaller subunits, which are assembled from precursor particles of a different size. They occur in larger complexes on mRNA (polysomes). These forms of different but specific size can be separated and characterized by on the basis of size in the ultracentrifuge — i.e. by their sedimentation coefficient.
Amplification and examples
The following is multiple choice question (with options) to answer.
Centrioles are a very important part of what? | [
"centrosomes",
"enterocytes",
"centricles",
"tubercles"
] | A | Centrioles are a very important part of centrosomes, which are involved in organizing microtubules in the cytoplasm. Centrosomes are associated with the nuclear membrane during prophase of the mitosis. In mitosis, the nuclear membrane breaks down and the microtubule organizing center (MTOC) of the centrosome arranges microtubules such that they interact with the chromosomes to build the mitotic spindle. |
SciQ | SciQ-787 | physical-chemistry, gas-laws
Title: What volume does one mole of an ideal gas occupy? This has been bugging me for a while now...
Obviously, to calculate the volume/space occupied by a mole of (an ideal) gas, you'll have to specify temperature ($T$) and pressure ($P$), find the gas constant ($R$) value with the right units and plug them all in the ideal gas equation $$PV = nRT.$$
The problem? It seems to be some sort of common "wisdom" all over the Internet, that one mole of gas occupies $22.4$ liters of space. But the standard conditions (STP, NTP, or SATP) mentioned lack consistency over multiple sites/books. Common claims: A mole of gas occupies,
$\pu{22.4 L}$ at STP
$\pu{22.4 L}$ at NTP
$\pu{22.4 L}$ at SATP
$\pu{22.4 L}$ at both STP and NTP
Even Chem.SE is rife with the "fact" that a mole of ideal gas occupies $\pu{22.4 L}$, or some extension thereof.
Being so utterly frustrated with this situation, I decided to calculate the volumes occupied by a mole of ideal gas (based on the ideal gas equation) for each of the three standard conditions; namely: Standard Temperature and Pressure (STP), Normal Temperature and Pressure (NTP) and Standard Ambient Temperature and Pressure (SATP).
Knowing that,
STP: $\pu{0 ^\circ C}$ and $\pu{1 bar}$
NTP: $\pu{20 ^\circ C}$ and $\pu{1 atm}$
SATP: $\pu{25 ^\circ C}$ and $\pu{1 bar}$
And using the equation, $$V = \frac {nRT}{P},$$
where $n = \pu{1 mol}$, by default (since we're talking about one mole of gas).
I'll draw appropriate values of the gas constant $R$ from this Wikipedia table:
The volume occupied by a mole of gas should be:
The following is multiple choice question (with options) to answer.
What is the volume of the molecules of an ideal gas? | [
"zero",
"three",
"two",
"one"
] | A | Because the molecules of an ideal gas are assumed to have zero volume, the volume available to them for motion is always the same as the volume of the container. In contrast, the molecules of a real gas have small but measurable volumes. At low pressures, the gaseous molecules are relatively far apart, but as the pressure of the gas increases, the intermolecular distances become smaller and smaller (Figure 10.23 "The Effect of Nonzero Volume of Gas Particles on the Behavior of Gases at Low and High Pressures"). As a result, the volume occupied by the molecules becomes significant compared with the volume of the container. Consequently, the total volume occupied by the gas is greater than the volume predicted by the ideal gas law. Thus at very high pressures, the experimentally measured value of PV/nRT is greater than the value predicted by the ideal gas law. Figure 10.23 The Effect of Nonzero Volume of Gas Particles on the Behavior of Gases at Low and High Pressures. |
SciQ | SciQ-788 | cell-biology, cell, eggs, reproductive-biology, chickens
Title: Why are hard boiled eggs so homogeneous? A eukaryotic animal cell is a complicated piece of biological machinery. Some major structures inside of the cell (see the image below) include: the nucleus, mitochondria, Golgi vesicles, and various tubular structures. Why then is the single-celled, unfertilized chicken egg so homogeneous when it is cooked (or before)? The only major structure I can recognize is the cell nucleus.
*Image Credit: "Animal cell structure en" by LadyofHats (Mariana Ruiz) - Own work using Adobe Illustrator. Image renamed from Image:Animal cell structure.svg. Licensed under Public domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Animal_cell_structure_en.svg#mediaviewer/File:Animal_cell_structure_en.svg Disclaimer: This is my understanding of the egg anatomy as a general biologist. There is most certainly better references and sources out there to explain this (please add better references if you know of any).
If I understand you correctly, your question is why we do not see cell organelles in a cracked or boiled egg. If so, your question seems to stem from a misunderstanding of what the egg white and egg yolk represents. A chicken egg is not simply an enlarged cell, and the egg yolk is not the cell nucleus.
When an oocyte matures in the chicken ovary, it stores yolk inside the cell and therefore enlarges. The yolk is therefore part of the oocyte cytoplasm. However, as it enlarges, the yolk is separated from the germinal disc, which holds all the other cell organelles (including the nucleus). The germinal disc is seen as a small white area on the egg yolk. Eventually, when the oocyte has accumulated enought yolk, it disattaches from the ovary (ovulation) and goes into the hens oviduct. This process is happening continuously, and oocytes of different stages of maturation are present on the ovary, which can be seen in this image:
The following is multiple choice question (with options) to answer.
What part of the body are eggs formed in? | [
"ovaries",
"pancreas",
"intestine",
"brain"
] | A | Eggs form in the ovaries. After puberty, an egg is released from an ovary each month in the process of ovulation. The egg passes through the fallopian tube where fertilization may take place. |
SciQ | SciQ-789 | cell-biology, nutrition, blood-circulation, liver
Title: How do nutrients get to the cells they need to get to? I understand the basics of digestion. I know that nutrients get absorbed by the microvilli, enter the bloodstream and travel to the liver but after all that, what is the biological mechanism that guides these nutrients to the proper receiving location? Broadly speaking, nutrients that enter the blood from the gut, and those that are released into the blood by the liver, are available to any cells that require them. So there is no "guiding to the correct location" in the sense that you suggest.
Lipids for example are present in the various lipoproteins and can be acquired from these by all cells. Iron is bound to transferrin, and any cell with transferrin receptors can internalise the transferrin and take the iron. Glucose is available in solution in the plasma, and free fatty acids are bound to serum albumin in the blood. During starvation the liver produces ketones ("ketone bodies") which are taken up by many different tissues/cell types.
The following is multiple choice question (with options) to answer.
What is the first digestive organ that food enters? | [
"digestive system",
"intestine",
"kidneys",
"mouth"
] | D | The mouth is the first organ that food enters. But digestion may start even before you put the first bite of food into your mouth. Just seeing or smelling food can cause the release of saliva and digestive enzymes in your mouth. |
SciQ | SciQ-790 | equilibrium, aqueous-solution, solubility, gas-laws, food-chemistry
Title: How much carbonation is in one liter of commercial fountain Coca-Cola From what I understand generally Coke is carbonated to roughly 6.2 g per liter in bottles and cans, or 3.1 volumes of CO2. I was watching this video because I was curious about how fountain soda machines worked.
https://www.youtube.com/watch?v=RRHNt67xbMs
By the end of the video they suggest that the soda is carbonated to around 5 volumes of carbonation. Which as I understand would be somewhere in the realm of 11 g of CO2 per liter, almost twice that of the normal soda. I imagine there are a couple other factors involved, like they are dispensing more CO2 than is actually dissolved in the soda as a consequence of trying to instantly carbonate. According to everything I know about carbonation I know from beer making they are carbonating almost 20 times higher than a forced beer carbonation technique in home brewing. Can anyone help me better understand this? I would think that the carbonation level difference between bottled and fountain soda would be something highly controlled by beverage companies for the sake of product consistency.
I did some additional reading and found that the correct maintenance levels on soda fountains with chilled water to roughly 40 degrees F is 75 psi if that helps. For 3.1 volumes of carbonation as I understand equilibrium would be just like 5 psig. I know I missing something big.
I can only assume that the rate of carbonation loss is inversely exponential as the carbonation approaches closer to equilibrium for the environmental pressure. Would 5 volumes rapidly decarbonate to 2-3 volumes but not get much lower very quickly? If the soda is not distributed, the rate of loss of $\ce{CO2}$ would be an exponential decay. So changing from 5 volumes to 3 volumes is faster than from 3 to 1 volumes.
A can of soda with 3 volumes of $\ce{CO2}$ has about 15 psi of extra pressure inside the can. If it was increased to 25 psi (5 volumes, like the fountain sodas), the can would need to be thicker to ensure it doesn't rupture, which would increase the cost of the can. There is a balance of the amount of $\ce{CO2}$ and the cost for the drink.
The following is multiple choice question (with options) to answer.
Soda fizzes when what common gas comes out of solution? | [
"carbon monoxide",
"helium",
"carbon dioxide",
"nitrous oxide"
] | C | Soda fizzes when carbon dioxide comes out of solution. Which do you think will fizz more, warm soda or cold soda?. |
SciQ | SciQ-791 | electric-circuits, electric-current, capacitance, voltage, electronics
Title: Phases of current and voltage Why $u(t)$ and $i(t)$ are in the same phase in a resistor, but in a condensator $i(t)$ is ahead of $u(t)$ by $\pi/2$, and vice versa in a coil?
Note: I need physical explanation, like main reason of this act. No need for mathematical reasons like
$$ i(t) = C \frac{du}{dt} $$
When $u(t)=U\sqrt{2}\sin\omega t$, then $i(t)=C\omega\cdot U\sqrt{2}\sin(\omega t+\pi/2)$.
This case is for condensator as you know. In a resistor current flow directly causes a voltage drop so the voltage and current vary together with no lag: eg. if there is a step function of current there is a step function of voltage with no delay between the steps.
In a capacitor being supplied with a current, the current supplies the capacitor with a flow of electrons which it accumulates (integrates as a function of time) and the voltage across the capacitor is a function of its accumulated charge, or total charge.
eg. if there is a step function of current there is a linear ramp function of voltage instead of a step function.
It is this integration, or accumulation, as a function of time that causes the phase difference between the voltages across the resistor and the capacitor. eg. if the current into the capacitor is a sine wave, the voltage on the capacitor will be a cosine wave--the integral of the sine wave. Hence the pi/2 lagging phase difference.
Similarly for an inductor except the integral becomes a derivative and the phase difference becomes leading.
The following is multiple choice question (with options) to answer.
The voltage and current are exactly in phase in a what? | [
"resistor",
"capacitor",
"harmonic",
"battery"
] | A | Resistors in an AC Circuit Just as a reminder, consider Figure 23.47, which shows an AC voltage applied to a resistor and a graph of voltage and current versus time. The voltage and current are exactly in phase in a resistor. There is no frequency dependence to the behavior of plain resistance in a circuit:. |
SciQ | SciQ-792 | electrochemistry, redox, equilibrium, ph, concentration
Therefore, if you link two Standard Hydrogen Electrodes, you won't be able to measure a voltage.
If you don't intend to have standard conditions however, the reduction will indeed take place in the more acedic half-cell (simply spoken). This is also indicated by the electrode potential you calculated: -0,059V * pH. The reduction takes place in the half-cell with the higher potential and the potential you calculated increases with lower pH (more acedic solution).
The following is multiple choice question (with options) to answer.
Combining the voltages of the oxidation and reduction half reactions helps to determine what? | [
"magnetic",
"voltage",
"moisture",
"slimy"
] | B | To determine the overall voltage of a particular voltaic cell, simply combine the voltages of the oxidation and reduction half reactions. Even if you need to take a multiple of a half reaction for the electrons to cancel, do not take the multiple of the E1/2. Use the values directly as is from - ball-ch14_s03_t01. Spontaneous redox reactions have positive overall voltages. If the voltage of the reaction as written is negative, it is not spontaneous in that direction. Rather, the reverse reaction is the spontaneous redox reaction. |
SciQ | SciQ-793 | elements, radioactivity
Title: Why radioactive elements emit alpha beta and gamma rays I am confused about this that why radioactive elements emits alpha beta and gamma rays WHILE other elements can't do so. The stability of nuclei is really a sophisticated topic in theoretical quantum mechanics. But there is a simple way to think about what is happening that doesn't get too intense with the quantum mechanical theory.
Nuclei are made from two particles: protons and neutrons. But protons are positively charged and repel each other. The electromagnetic force is very strong and therefore this force is very large. So the first mystery is why all nuclei don't just fly apart.
The reason they don't is that there are two very short-range but very strong forces that bind the nucleus together: the strong and weak nuclear forces. Without getting into mind-bending topics in theoretical physics we can understand something about their net effect like this.
The interaction of the electromagnetic force and the two nuclear forces has some structure (it's quantum stuff, just accept it). Some combinations of protons and neutrons are more stable than others. Each combination has an energy level and some combinations have lower energy than others. Nuclei with even numbers of protons and neutrons are more stable than odd-odd combinations and nuclei with wildly unbalanced neutron to proton ratios are less stable. Neutrons act a little like a glue, helping protons stick together (this is an oversimplification as too many neutrons is also a source of instability: this is a consequence of a complicated interplay of several forces). But bigger nuclei are less stable and need a higher ratio of neutrons. And some large nuclei are just too large for the forces to keep them together so beyond a certain point all nuclei are unstable.
Some nuclei can be transformed into a more stable (lower energy) nucleus by various forms of radioactive decay. Nuclei with too many neutrons can emit a beta particle (this decay mode converts a neutron into a proton); elements with too many protons can emit a positron (converting a proton into a neutron). Bigger nuclei can become more stable by kicking out an alpha particle (which makes the nucleus significantly smaller, moving it towards the stable zone). Gamma radiation is associated with some of these modes: the high energy photons "mop up" the excess energy (I'm simplifying a lot).
The following is multiple choice question (with options) to answer.
What occurs when an unstable nucleus emits a beta particle and energy? | [
"methane decay",
"beta decay",
"nucleus decay",
"alpha decay"
] | B | Beta decay occurs when an unstable nucleus emits a beta particle and energy. A beta particle is an electron. It has a charge of -1. In nuclear equations, a beta particle is represented by the symbol . The subscript -1 represents the particle’s charge, and the superscript 0 shows that the particle has virtually no mass. Nuclei contain only protons and neutrons, so how can a nucleus emit an electron? A neutron first breaks down into a proton and an electron (see Figure below ). Then the electron is emitted from the nucleus, while the proton stays inside the nucleus. The proton increases the atomic number by one, thus changing one element into another. |
SciQ | SciQ-794 | acid-base
Title: What makes protons give the property of acidity? Brønsted Lowry definition of an acid says that an acid gives away protons.
What I don't understand is what makes dissolved protons grant the property of acidity? Like, why would dissolved protons eat up materials?
My question applies to bases too, I suppose. And I guess you could include Lewis-acids and bases in your argumentation...
It's a question that has been bothering me for long. By the way I am not chemist(nor do I study chemistry). Whether something is a Brønsted acid is defined by its pH.
$$pH = -log_{10}[H^+]$$
In other words, the better a substance is at releasing protons, the higher the concentration of protons [H+], and correspondingly the lower its pH.
Whereas for Lewis acid, it is the ability for it to strip electrons from anything it attacks (electrophilicity). There is no direct measurement for the strength of Lewis acidity, as many factors have to be taken into consideration, such as enthalpy change, steric factors. In fact, many substances can act as Lewis acids can also act as Lewis bases, such as water, ammonia, and even some alkanes.
Ultimately, what makes acids and bases so corrosive is its ability act as an oxidant or reductant.
Oxidation: Lose electrons/Gain hydrogen.
Reduction: Gain electrons/Lose hydrogen.
The following is multiple choice question (with options) to answer.
A chemical property describes the ability of a substance to undergo a specific what? | [
"radiation change",
"weight Change",
"chemical change",
"liquid change"
] | C | A chemical property describes the ability of a substance to undergo a specific chemical change. A chemical property of iron is that it is capable of combining with oxygen to form iron oxide, the chemical name of rust. The more general term for rusting and other similar processes is corrosion. Other terms that are commonly used in descriptions of chemical changes are burn, rot, explode, decompose, and ferment. Chemical properties are very useful in identifying substances. However, unlike physical properties, chemical properties can only be observed as the substance is in the process of being changed into a different substance. |
SciQ | SciQ-795 | thermodynamics, visible-light, perpetual-motion
Needless to say, perpetual motion of an untouched body is useless in terms of extraction of mechanical energy.
The following is multiple choice question (with options) to answer.
When energy is captured or transformed, it inevitably degrades and becomes what less useful form of energy? | [
"temperature",
"heat",
"chemical",
"motion"
] | B | Physics also tells us that, although energy can be captured or transformed, it inevitably degrades, becoming heat, a less useful form of energy. This is why organisms require a constant input of energy; the work they must do uses up the energy they take in. Energy, unlike materials, cannot be recycled. The story of life is a story of energy flow – its capture, transformation, use for work, and loss as heat. |
SciQ | SciQ-796 | python, template, tkinter, gui, factory-method
Title: Python - Tkinter - periodic table of chemical elements Inspired by a question on StackOverflow I decided to code a GUI that is simple, efficent and can be used in other projects as well. I wanted to share this code since it probably is usefull to other people as well. You may want to share some practical hints how to make this code even better.
The code produces a table of frames and shows the information, I did gather for about 5 hours from wikipedia, in the final output. The frames are made clickable to make the usecase wider then without. I hope you enjoy this bit of code.
Database:
symbols = ['H','He','Li','Be','B','C','N','O','F','Ne',
'Na','Mg','Al','Si','P','S','Cl','Ar','K', 'Ca',
'Sc', 'Ti', 'V','Cr', 'Mn', 'Fe', 'Co', 'Ni',
'Cu', 'Zn', 'Ga', 'Ge', 'As', 'Se', 'Br', 'Kr',
'Rb', 'Sr', 'Y', 'Zr', 'Nb', 'Mo', 'Tc', 'Ru',
'Rh', 'Pd', 'Ag', 'Cd', 'In', 'Sn', 'Sb', 'Te',
'I', 'Xe','Cs', 'Ba','La', 'Ce', 'Pr', 'Nd', 'Pm',
'Sm', 'Eu', 'Gd', 'Tb', 'Dy', 'Ho', 'Er', 'Tm',
'Yb', 'Lu', 'Hf', 'Ta', 'W', 'Re', 'Os', 'Ir',
'Pt', 'Au', 'Hg', 'Tl', 'Pb', 'Bi', 'Po', 'At', 'Rn',
The following is multiple choice question (with options) to answer.
The periodic table is one of the cornerstones of chemistry because it organizes all the known elements on the basis of their what? | [
"chemical properties",
"acid properties",
"liquid properties",
"size properties"
] | A | The periodic table is one of the cornerstones of chemistry because it organizes all the known elements on the basis of their chemical properties. A modern version is shown in Figure 2.7 "A Modern Periodic Table". Most periodic tables provide additional data (such as atomic mass) in a box that contains each element’s symbol. The elements are listed in order of atomic number. |
SciQ | SciQ-797 | 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 filter wastes from blood so they can be excreted from the body? | [
"pancreas",
"liver",
"lungs",
"kidneys"
] | D | Vertebrates have an excretory system that includes a pair of kidneys. Kidneys are organs that filter wastes from blood so they can be excreted from the body. |
SciQ | SciQ-798 | star, black-hole, cosmology, supermassive-black-hole
In case, the trajectory passes sufficiently close to the BH and the object is rather big and fluffy, like (some) stars, the tidal forces may not merely distort the object, but rip it apart.
Such tidal disruption of stars must happen if a star passes close to a supermassive BH. This can hardly be directly observed, but the it is thought that some of the stellar matter forms an accretion disc around the BH and produces a characteristic light curve. An observed light curve in agreement with this model is often interpreted as circumstantial evidence for a stellar disruption event.
The following is multiple choice question (with options) to answer.
The tidal forces near what celestial phenomena are so great they can actually tear matter from a companion star? | [
"black holes",
"large holes",
"dwarf star",
"wormholes"
] | A | Tides are not unique to Earth but occur in many astronomical systems. The most extreme tides occur where the gravitational force is the strongest and varies most rapidly, such as near black holes (see Figure 6.26). A few likely candidates for black holes have been observed in our galaxy. These have masses greater than the Sun but have diameters only a few kilometers across. The tidal forces near them are so great that they can actually tear matter from a companion star. |
SciQ | SciQ-799 | 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.
What are female gonads normally called? | [
"ovaries",
"glands",
"tubules",
"testes"
] | A | Animals often have gonads , organs that produce eggs or sperm. The male gonads are the testes , and the female gonads are the ovaries . Testes produce sperm; ovaries produce eggs. Sperm and egg, the two sex cells, are known as gametes , and can combine two different ways, both of which combine the genetic material from the two parents. Gametes have half the amount of the genetic material of a regular body cell; they are haploid cells. In humans, gametes have one set of 23 chromosomes. Gametes are produced through a special type of cell division known as meiosis . Normal human cells have 46 chromosomes. They are diploid cells, with two sets of 23 chromosomes (23 pairs). |
SciQ | SciQ-800 | human-biology, biochemistry, metabolism, food
Which seem to go in different, rather contradictory directions.
Also, Studies partially supporting either viewpoint can be found:
Study considering hemoglobin A1c levels
Study considering peak glucose levels
Study considering snacking
Which leaves the non-biologist asking themselves which is the "major effect" (certainly, there will be some truth to each position, but the question is which one(s) got the "main point"), and if there are any other important effects to be considered, hence this broad question here, so I understand, from a biological standpoint, what happens to the carbohydrates when I eat them, so I can conclude for myself how to adapt my diet for "optimal" health. Scope of Answer
The original poster provided ample context for his question, which related to health considerations. It was perhaps for this reason, among others, that the question had not received an answer at the time of writing: questions relating to medical or health advice are off-topic here. However, his actual question is primarily biochemical:
What are the biological differences between the digestion of sugar and
different types of carbs as constituents of different types of food in
humans?
Although this might be answered with a little internet search, I felt it would be hospitable if someone offered him an answer to this — and this only.
Definitions
The basic sugar unit is a mono-saccharide, those of relevance to this question being hexoses or pentoses, having six or five carbon atoms, respectively.
What in non-technical language is called sugar, refers to a specific molecule, sucrose, which is a disaccharide of covalently-bonded glucose and fructose.
What in non-technical language are referred to as dietary carbohydrates generally refers to the storage polysaccharide of plants such as potato and other root vegetables, rice, and other cereal crops used to make bread. This is a homo-polymer composed solely of glucose units.
Summary of the differences in metabolism
Arising from these definitions, the following differences in metabolism emerge:
Different enzymes (amylase for these polysaccharides, sucrase for saccharose) are used to catalyse the hydrolysis of the linkages between the monomeric units.
Absorption in the gut is different for glucose and fructose, as is transport into cells.
The following is multiple choice question (with options) to answer.
Starch and glycogen, as well as simple sugars like glucose and fructose, can all be categorized broadly as what? | [
"acids",
"impurities",
"carbohydrates",
"vegetables"
] | C | Of the four major macromolecular groups (carbohydrates, lipids, proteins, and nucleic acids) that are processed by digestion, carbohydrates are considered the most common source of energy to fuel the body. They take the form of either complex carbohydrates, polysaccharides like starch and glycogen, or simple sugars (monosaccharides) like glucose and fructose. Sugar catabolism breaks polysaccharides down into their individual monosaccharides. Among the monosaccharides, glucose is the most common fuel for ATP production in cells, and as such, there are a number of endocrine control mechanisms to regulate glucose concentration in the bloodstream. Excess glucose is either stored as an energy reserve in the liver and skeletal muscles as the complex polymer glycogen, or it is converted into fat (triglyceride) in adipose cells (adipocytes). Among the lipids (fats), triglycerides are most often used for energy via a metabolic process called β-oxidation. About onehalf of excess fat is stored in adipocytes that accumulate in the subcutaneous tissue under the skin, whereas the rest is stored in adipocytes in other tissues and organs. Proteins, which are polymers, can be broken down into their monomers, individual amino acids. Amino acids can be used as building blocks of new proteins or broken down further for the production of ATP. When one is chronically starving, this use of amino acids for energy production can lead to a wasting away of the body, as more and more proteins are broken down. Nucleic acids are present in most of the foods you eat. During digestion, nucleic acids including DNA and various RNAs are broken down into their constituent nucleotides. These nucleotides are readily absorbed and transported throughout the body to be used by individual cells during nucleic acid metabolism. |
SciQ | SciQ-801 | cell-biology, molecular-biology
Title: Intracellular lipid transport I know that lipids are carried around the body in the blood either as micelles or by lipid-binding proteins which allow them to be solved.
Lipids can't always be integrated in a membrane though, the phospholipids used in membranes have to be synthesised somewhere from a precursor which will also by hydrophobic.
Consequently, at some point there will have to be transport of lipids within the cell where the lipids will need to be in solution. How is this facilitated? Like in the blood, intracellular lipid trafficking is facilitated by vesicular transport and lipid carriers like fatty acid binding proteins. In addition, intracellular membranes are densely packed and they can exchange lipids by collision and transient hemifusion. If you have access to Cell, a good review is from Prinz W. 2010 Lipid Trafficking sans vesicles, Where, Why, How?
The following is multiple choice question (with options) to answer.
Lipids are biochemical compounds such as fats and? | [
"minerals",
"vegetables",
"oils",
"salts"
] | C | Lipids are biochemical compounds such as fats and oils. Organisms use lipids to store energy. In addition to carbon and hydrogen, lipids contain oxygen. |
SciQ | SciQ-802 | nutrition, hematology, metabolism
Title: How does a glucose molecule enter the cell from blood vessel? The transporters in the plasma membrane of the cells promote the entry of glucose molecules from the extracellular matrix to the cytosol of the cell. Could someone explain how does the nutrient molecule enter the extracellular space from the blood vessel?
For instance, in the context of the pancreas, the walls of the blood vessel is fenestrated. The literature also provides evidence for the presence of connexon in the endothelium of the capillaries.
My doubt is, the nutrient molecule that diffuses from the blood vessel reaches the cytosol of the cell through
Diffusing through connexon ?(or)
Does it reach the interstitial matrix(the fluid surrounding the cells) and then uptaken by the transporters present in the plasma membrane of the cell? I think I understand your question, Natasha. In short, your own answer #2 is correct.
There are 3 spaces, and 2 pathways for glucose to pass from one to the next:
intracapillary plasma
extracellular fluid
the cytosol.
Ways glucose gets into the cell:
(2->3) To get from the ECF to the cytosol , glucose always needs a transport protein. These are the GLUTs. In two cases, the small intestine and kidney, these are part of a secondary active transport system based on the Na/K-ATPase. In the pancreas, it's GLUT2.
(1->2) To get from the capillary plasma to the ECF requires filtration, the process of applying hydrostatic pressure to the plasma and literally squeezing it like a sponge. The boundary of the "blood sponge" is the basement membrane. The membrane holds in the proteins, and lets anything dissolved in the watery serum (like glucose) through.
The Filtration Constant Kf is proportional to the percentage of the BM that is exposed in a given capillary, which varies by the type and other factors like histamine release.
The following is multiple choice question (with options) to answer.
What is the process of small molecules passing through the plasma membrane called? | [
"convection",
"permeation",
"absorption",
"diffusion"
] | D | Small molecules can pass through the plasma membrane through a process called diffusion. Diffusion is the movement of molecules from an area where there is a higher concentration (larger amount) of the substance to an area where there is a lower concentration (lower amount) of the substance ( Figure below ). The amount of a substance in relation to the total volume is the concentration . During diffusion, molecules are said to flow down their concentration gradient , flowing from an area of high concentration to an area of low concentration. Molecules flowing down a concentration gradient is a natural process and does not require energy. |
SciQ | SciQ-803 | thermodynamics, physical-chemistry
Title: Change of heat capacity fluid when you add solvent I am considering a liquid for which I know $C_p$ or $C_v$. I am wondering how this changes when you add a (minor) amount of solvent to the liquid. Is there a general theory around describing how a random liquid's heat capacity changes when you add a random solvent? Or is it a very specific process for the particular liquid and solvent one considers? References to literature would be very much appreciated! If I understand You correctly, by solvent You mean any liquid different than Your 'main' liquid. If so, it is pretty straightforward, since it is a simple mixture of two liquids. If the heat capacity of main fluid is defined as 'energy required to change the temperature of a mass unit of an object by 1 K', then the heat capacity of the mixture is mass fraction-averaged:
$C_m$ = $g_1 * C_1 + g_2 * C_2$
If it is defined as 'energy required to change the temperature of one mole of an object by 1 K', i.e. it is molar heat capacity, then the molar heat capacity of the mixture is mole fraction-averaged:
$C_m$ = $x_1 * C_1 + x_2 * C_2$
$g$ and $x$ are mass and mole fractions of the components.
The following is multiple choice question (with options) to answer.
What change the physical properties of solvents? | [
"molecules",
"cells",
"solutes",
"chemical reactions"
] | C | Solutes change the physical properties of solvents. They lower the freezing point and raise the boiling point of solvents. |
SciQ | SciQ-804 | neuroscience
Title: Nervous system : Nerve signals If the electrical signals from all the various organs throughout the body eventually connect to the nerves in the spinal column traveling up to the brain, how does the brain differentiate the different signals. Is the nerve in the spinal column like an electrical conduit with many wires inside? Yes is the simple answer. A nerve will go up to a specific part of the brain which the brain knows corresponds to a certain region of the body. It isn't perfect though e.g. pain in the diaphragm confuses the brain which doesn't recognise that pain must be coming from there so instead tells the body there is shoulder pain, however this is useful in medicine. Another infamous example is pain from heart disease (angina) which causes pain in the jaw and arm. Perhaps even more interestingly, if a nerve is cut and then grows back linking to the wrong nerve it may lead to the completely wrong part of the body being identified when touched. Also if the brain itself is stimulated in these corresponding areas, a person will feel he or she is indeed being touched in a certain part of the body.
The following is multiple choice question (with options) to answer.
Which human body system is a complex network of nervous tissue that carries electrical messages throughout the body? | [
"the lymph system",
"the localized system",
"the bacterial system",
"the nervous system"
] | D | The nervous system is a complex network of nervous tissue that carries electrical messages throughout the body. Its functions include controlling muscles, maintaining balance, sensing internal and external environments, controlling body systems to maintain homeostasis, preparing the body for emergencies, and allowing higher mental functions such as thinking. |
SciQ | SciQ-805 | evolution, zoology, anatomy
Title: Are the transverse septum in sharks and the diaphragm in mammals homologous structures? Are the transverse septum in sharks and the diaphragm in mammals homologous structures?
I have searched on Google Scholar and Web of Science, but haven't found substantial evidence to prove or falsify the claim. A beginning of answer here below, I hope. Please first consider that many structures are involved in the question here, the diaphragm (UBERON:0001103), the diaphragmaticus muscle (UBERON:0036071) and the septum transversum (UBERON:0004161). At Bgee (bgee.org) we aim annotating relations of similarity between anatomical structures, please have a look at our GitHub
https://github.com/BgeeDB/anatomical-similarity-annotations
We already annotated 'diaphragm' as a mammalian structure, not homologous in Amniota (please see https://raw.githubusercontent.com/BgeeDB/anatomical-similarity-annotations/master/release/similarity.tsv). In our next release, you will see the annotation for the 'diaphragmaticus muscle' which is an analog organ in Crocodylians (and Turtles) but not homologous to the mammalian diaphragm either. See here for more details about this new Uberon class:
https://github.com/obophenotype/uberon/issues/1229.
Based on the comments here above, I would say that currently we can argue that there is no evidence for a homologous relationship between the 'septum transversum' in sharks and the mammalian diaphragm. Please note that UBERON:0004161 septum transversum describes the (mammalian) embryonic structure that will give rise to the central tendon of the diaphragm, while here you are talking about a adult structure closer to a 'diaphragmaticus muscle'-like septum, as far as I understand.
But anyway thank you for your interesting question that points out a very exciting and rapidly evolving evo-devo field, as this recent paper also suggests
The following is multiple choice question (with options) to answer.
What is a sheet of muscle that spreads across the bottom of the rib cage? | [
"diaphragm",
"cartilage",
"diagram",
"thorax"
] | A | The diaphragm is a sheet of muscle that spreads across the bottom of the rib cage. When the diaphragm contracts, the chest volume gets larger, and the lungs take in air. When the diaphragm relaxes, the chest volume gets smaller, and air is pushed out of the lungs. |
SciQ | SciQ-806 | bond, intermolecular-forces, electronegativity, dipole, hydrogen-bond
Title: Bending of water and methanol towards a charged objects I just had a question about why does water, methanol or any other polar substances tend to bend towards the charged object.
I think it is because of a slight dipole dipole movement between the charged object and the polar substance, but not sure if that's the reason. As you state, in an electric field, a polar molecule such as methanol or water, having an uneven charge distribution, is attracted (or repelled) by an electric field. This orients the molecule, but is not primarily responsible for the attraction of the bulk substance.
An electric field causes a force on even a nonpolar molecule such as methane or sulfur, though. You can pick up powdered sulfur with a charged piece of plastic because of electrostatic induction, which moves electrons in the bulk material.
This induced charge is similar to the effect of moon (and sun) on tides, pulling the water underneath the moon more strongly than it pulls on the more distant core of the earth, and on the core more strongly than on the ocean on the opposite side of the planet, causing uneven distribution of the water. In a similar way, an external field causes an uneven distribution of charge.
The following is multiple choice question (with options) to answer.
What creates charged regions in a water molecule? | [
"ionic bonds",
"noncovalent bonds",
"nonpolar bonds",
"polar covalent bonds"
] | D | |
SciQ | SciQ-807 | inorganic-chemistry, solubility, allotropes
Title: Solubility of white phosphorus Why is white phosphorus soluble in $\ce{CS2}$ but red phosphorus not? Is it something in relation with the structures of both? Please explain. White phosphorus has P4 molecules packed into a crystal,these dissolve readily in Carbon Disulfide.
Whereas Red phosphorus is polymeric in nature. It is a derivative of white phosphorus where one P-P bond is broken and an addtional bond is formed with neighboring tetrahedron molecule resulting in a chain like structure .
Like all long chain polymers this will lower its ability to dissolve and its solubility in solvents
The following is multiple choice question (with options) to answer.
Phosphorus exists as several allotropes, the most common being red, black, and what? | [
"white phosphorus",
"purple phosphorus",
"green phosphorus",
"yellow phosphorous"
] | A | Phosphorus exists as several allotropes, the most common being red, black, and white phosphorus. White phosphorus consists of tetrahedral P4 molecules and melts at 44.15°C; it is converted to red phosphorus by heating at 400°C for several hours. The chemical differences between red and white phosphorus are considerable: white phosphorus burns in air, whereas red phosphorus is stable; white phosphorus is soluble in organic compounds, whereas red phosphorus is not; white phosphorus melts at 44.15°C, whereas red phosphorus melts at 597°C. If the enthalpy of fusion of white phosphorus is 0.659 kJ/mol, what is its ΔS? Black phosphorus is even less reactive than red. Based on this information, which allotrope would you predict to have the highest entropy? the lowest? Why?. |
SciQ | SciQ-808 | cancer, mutations
Here is another great paper that specifically addresses your question, linking increased cell division with the accumulation of both significant and insignificant mutations, which over time, lead to an accumulation of mutations needed for cancer to develop.
The following is multiple choice question (with options) to answer.
What is the term for environmental causes of mutations? | [
"mutagens",
"pollutants",
"carcinogens",
"catalysts"
] | A | A mutation is a change in the base sequence of DNA or RNA. Environmental causes of mutations are called mutagens. The effects of a mutation depend on the type of mutation and whether it occurs in a gamete or body cell. |
SciQ | SciQ-809 | geology, rocks, sedimentology, geomorphology, terminology
Title: What do you call boulders of non sedimentary rock that were lithified into sandstone? I'm convinced there is a word for this. I was in the Hoodoos at Writing on Stone this weekend and kept noticing what looked like reddish quartzite boulders laying around in the sand, or sometimes sticking partially out of the hoodoos.
When a non-sedimentary rock gets washed out into silt which later lithifies, what's it called? It's kind of like a conglomerate, except there's only a couple of really big rocks, which eventually fall out out the rock because all the sandstone around them eroded away. The technical term for a sedimentary rock that has a lithified fine-grained sediment with larger pieces of rocks suspended in it upon lithification is a conglomerate. The fine-grained interstitial part is called the matrix, and the large pieces suspended in it are called clasts. Clasts can range from gravel- to boulder-size. These are technical terms used by sedimentologists.
It is tempting to refer to these fragments as xenoliths but as that word has a very specific meaning in igneous petrology, it is best to avoid it to remove any confusion.
The following is multiple choice question (with options) to answer.
How are classic sedimentary rocks group? | [
"size of sediment",
"density",
"particle depth",
"color"
] | A | Clastic sedimentary rocks are grouped by the size of the sediment they contain. Conglomerate and breccia are made of individual stones that have been cemented together. In conglomerate, the stones are rounded. In breccia, the stones are angular. Sandstone is made of sand-sized particles. Siltstone is made of smaller particles. Silt is smaller than sand but larger than clay. Shale has the smallest grain size. Shale is made mostly of clay-sized particles and hardened mud. |
SciQ | SciQ-810 | physiology, herpetology, poison, amphibians
+
0.002 mg/L will fatally damage the sensitive skin on tadpoles, frogs, salamanders and other amphibians.
another source:
Free chlorine (Cl2) is a greenish gas that is well known for its
highly toxic properties as can be attested to by the thousands of
soldiers that died and were severely injured from chlorine exposure
during World War I. In water, chlorine is the most toxic substance
that we will discuss. Ironically for the amphibian keeper, it is this
toxic nature of chlorine and its ability to denature proteins, which
makes its encounter inevitable. Chlorine is generally used as an
antibacterial agent in municipal water supplies and may be present in
concentrations of over 9 mg/1 in some tap water (measured in Houston,
Texas as an example, although levels were generally lower). The
concentration of chlorine in municipal water supplies can vary greatly
from day to day, or even hour to hour, depending on conditions at the
water treatment facilities. Concentrations as low as 0.0034 mg/1 have
been noted to reduce reproduction in fathead minnows with 72 hour
LC100 (lethal concentration for 100% kill) at 0.15 mg/1 (Arthur and
Eaton,1971). LC50 (96 hour) for the shiners (Notemigonus chrysoleucas)
was as low as 0.19 mg/1 (Esvelt et al., 1971). The concentrations
found in municipal water supplies are many times greater than the
minimum lethal concentrations for many aquatic life forms.
Thus, the well being of the frog in the water of the swimming pool depends on the time the frog spends in the water. Eventually, with extended exposure the chlorine concentration will exceed the one compatible will life and the frog will die. This time is multifactorial variable, thus cannot be assessed easily - the weight and the skin surface area and skin permeability will affect the frog survival in a great degree.
The following is multiple choice question (with options) to answer.
How many eyelid membranes do frogs have? | [
"one",
"three",
"two",
"four"
] | B | In order to live on land and in water, frogs have three eyelid membranes: one is see-through to protect the eyes underwater, and the two other ones let them see on land. Frogs also have a tympanum , which acts like a simple ear. They are found on each side of the head. In some species, the tympanum is covered by skin. |
SciQ | SciQ-811 | organic-chemistry, nomenclature, hydrocarbons
Title: Preferred IUPAC names for branched unsaturated hydrocarbons (polyenes)?
What are the preferred IUPAC names for the following three compounds?
Compound 1 is 3-ethenylhexa-1,5-diene. 2 is 3-methylidenehexa-1,5-diene.
But I am still not sure about 3. I have narrowed it down to two choices: 3-ethylidenehexa-1,5-diene or 4-ethenylhexa-1,4-diene.
How do I decide which two of the three double bonds should be in the parent chain, considering that both choices of parent chain have the same number of complex and double bonds?
The information I used is from the following Q&As:
How is a side-group that contains a double bond named?
How do you name an alkene using IUPAC rules if the longest carbon chain in this alkene does not include the double bond? According to the general methodology described in the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), a double bond is expressed by changing the ending ‘ane’ of the name of the corresponding saturated parent structure to ‘ene’.
P-31.1.1.1 The presence of one or more double or triple bonds in an otherwise saturated parent hydride (…) is denoted by changing the ending ‘ane’ of the name of a saturated parent hydride to ‘ene’ or ‘yne’. Locants as low as possible are given to multiple bonds as a set, even though this may at times give ‘yne’ endings lower locants than ‘ene’ endings. If a choice remains, preference for low locants is given to the double bonds. In names, the ending ‘ene’ always precedes ‘yne’, with elision of the final letter ‘e’ in ‘ene’. Only the lower locant for a multiple bond is cited, except when the numerical difference between the two locants is greater than one, in which case the higher locant is enclosed in parentheses.
(…)
For example:
The following is multiple choice question (with options) to answer.
What is another word for saturated hydrocarbons? | [
"alkanes",
"aldehydes",
"catalysts",
"enzymes"
] | A | Saturated hydrocarbons contain only single bonds between carbon atoms. They are also called alkanes. They may form straight-chain, branched-chain, or cyclic molecules. Compounds with the same number of atoms but different shapes are called isomers. |
SciQ | SciQ-812 | pressure, fluid-statics, atmospheric-science, buoyancy, gas
Title: Math behind helium balloons lifting objects to (almost) space So I've seen those big helium balloons that are not even filled all the way up, but they still manage to reach heights of up to 30 km. I think they're mainly used for research and etc. Furthermore, I also have noticed that because of the lower pressure higher in the atmosphere helium expands and balloon seems filled up. How do you actually find maximum volume of the balloon according to the height that it has to reach and temperature at that height? And how much helium do you need according to the mass that the balloon has to carry? Take a look at the ideal gas law and Archimedes' principle.
How do you actually find maximum volume of the balloon according to the height that it has to reach and temperature at that height?
The ideal gas law describes how the volume of a gas varies with amount, in mol, of gas particles, pressure, and temperature. You should be able to calculate the volume of helium at high and low altitudes by searching for the pressures and temperatures at those locations. Note that the gas pressure is of the helium in the balloon. This is only slightly larger than the surrounding air (atmospheric) pressure due to any surface tension in the balloon, so we can take the two to be roughly equal.
And how much helium do you need according to the mass that the balloon has to carry?
Archimedes' principle allows you to calculate the upthrust on an object in a fluid (a liquid or gas).
The upthrust is determined by the volume of the object (in this case the volume of the air balloon), and the density of the fluid (here the density of the air at different altitudes).
In order for the balloon to be able to float, the upthrust must be at least as large as the weight of the balloon (the combined mass of the gas and the load).
The following is multiple choice question (with options) to answer.
Where is the pressure of gases in the atmosphere at its greatest? | [
"stratosphere",
"sea level",
"core",
"mountain ranges"
] | B | The pressure of gases in the atmosphere is greatest at sea level and decreases rapidly as altitude increases. |
SciQ | SciQ-813 | geology, fossil-fuel, petroleum
For some transport applications, the energy density is still a winning attribute of hydrocarbons: most notably, powered flight for freight and travel.
We already have two routes to non-fossil hydrocarbons: biological sources, and direct chemical synthesis. Each involves capturing atmospheric CO2, and combining with water, to generate a blend of hydrocarbons.
Now, we already have means of creating hydrocarbons suitable for flight (e.g. Jet-A and Jet-A1 fuels). And there are already demonstration plants that have closed-loop generation of synthetic hydrocarbons, for use in electricity-grid-balancing, by using surplus electricity to synthesise methane, which is then burnt in gas turbines when required. Similarly, Tony Marmont's team have been synthesising petrol (gasoline) from air, water, and electricity.
However, none of those things mean that hydrocarbons necessarily have much of a future, beyond plastics production. Because hydrocarbon-powered aviation has a lot of environmental problems beyond just CO2 emissions, in particular it makes other contributions to exacerbating global warming. And there are lots of options for energy storage within the electricity supply chain.
The following is multiple choice question (with options) to answer.
What strong and lightweight manmade material is derived from hydrocarbons and used in ropes, tents and parachutes? | [
"cellophane",
"aluminum",
"styrofoam",
"nylon"
] | D | nylon: Human-made fabric. Material is made from hydrocarbons found in petroleum products. It is found in a number of plastic utensils. Taking advantages of its strength and light weight, nylon is a component of ropes, fishing nets, tents, and parachutes. |
SciQ | SciQ-814 | homework, reproduction, embryology
Title: Which process is needed to complete male reproductive development? In order to properly complete male reproductive development:
A. primordial germ cells must begin Meiosis I in utero.
B. Sertoli cells must produce testosterone.
C. Dihydrotestosterone must masculinize Wolffian duct derivatives
D. the paramesonephric ducts must degenerate
E. the metanephros must form the genital epithelium
My attempt: I think the answer is C because testosterone turns into DHT which then masculinzing the wolffian duct. Other people I am studying with claim the answer is D (which is true) except that I dont think the loss of the paramesonephric duct is needed to complete male repro development. Regarding option C:
Although it is correct that testosterone is converted into DHT, it is the former, not the latter, which is responsible for differentiation of the mesonephric (a.k.a. Wolffian) ducts:
Between 8 and 12 weeks, the initial secretion of testosterone stimulates mesonephric ducts to transform into a system of organs—the epididymis, vas deferens, and seminal vesicle—that connect the testes with the urethra.*
DHT (dihydrotestosterone) is produced in the Leydig cells by the 5α-Reductase enzyme. It is required for induction of the external male genitalia (urethra, penis, and scrotum) and prostate from the embryonic ureteral groove, and for testicular descent into scrotum.
Regarding option D:
Sertoli cells secrete Anti Müllerian Hormone (AMH), which causes degeneration of the müllerian (a.k.a. paramesonephric) ducts between weeks 8 and 10. It is normal to speak about degeneration of the müllerian ducts as a defining aspect of male embryology, and thus I believe answer D is correct. Your point is taken, however:
Nevertheless, small müllerian duct remnants can be detected in the adult male, including a small cap of tissue associated with the testis, called the appendix testis, and an expansion of the prostatic urethra, called the prostatic utricle.*
The following is multiple choice question (with options) to answer.
What is the third male reprodutive structure after the penis and testes? | [
"clitoris",
"scrotum",
"anus",
"epididymis"
] | D | Male reproductive structures include the penis, testes, and epididymis. |
SciQ | SciQ-815 | biochemistry, plant-physiology, plant-anatomy
Title: Why do plants store energy as carbohydrates and not as fats? In my introductory biology class, we are learning about biomolecules. The textbook says fats are a more efficient energy store than carbohydrates.
So my question is - why would plants store their energy as carbohydrates and not as fats, if fats are a more efficient energy store? There are quite some reasons for why plants prefer carbohydrates for energy storage rather than fats. I will reach some of them one at a time.
The following is multiple choice question (with options) to answer.
What are considered solid lipids that animals use to store energy? | [
"sugars",
"fats",
"acids",
"proteins"
] | B | Fats are solid lipids that animals use to store energy. Examples of fats include butter and the fat in meat. |
SciQ | SciQ-816 | zoology, organs, vestigial
Title: Is the appendix a vestigial structure in all vertebrates? In humans the Appendix is a vestigial organ. Does it serve no apparent purpose in all the vertebrates that have one? Smith et al. (2009) provide a survey of the morphology of the cecal appendix. One current hypothesis is that the appendix provides "safe harbor" for symbiotic gut bacteria. Among mammals, there is a vast array of cecal appendices:
In summary:
A comparative anatomical approach reveals three apparent morphotypes
of the cecal appendix, as well as appendix-like structures in some
species that lack a true cecal appendix. Cladistic analyses indicate
that the appendix has evolved independently at least twice (at least
once in diprotodont marsupials and at least once in Euarchontoglires),
shows a highly significant (P < 0.0001) phylogenetic signal in its
distribution, and has been maintained in mammalian evolution for 80
million years or longer.
The following is multiple choice question (with options) to answer.
The small, egg-shaped organs that lie on either side of the uterus are called? | [
"ovaries",
"lungs",
"glands",
"kidneys"
] | A | The two ovaries are small, egg-shaped organs that lie on either side of the uterus. They produce eggs and secrete estrogen. Each egg is located inside a structure called a follicle . Cells in the follicle protect the egg and help it mature. |
SciQ | SciQ-817 | sexual-reproduction
So when it's not maintained -- when there's no selection pressure on two populations -- inevitably there will be genetic drift that will randomly disrupt this fine-tuned system. If a population of, say, voles is isolated on an island, they will continue to have pressure to be able to interbreed with other voles on the island, but if they can't interbreed with those on the mainland there won't be any consequences, and so over long enough time they'll drift and lose that ability -- just as many apes, not suffering any consequences from not synthesizing vitamin C, gradually lost that ability from random drift.
There's another side to it. Two populations in the same location may be positively selected to not be able to interbreed. Think about two groups of finches, one with small fine beaks that eat tiny seeds deep inside pine cones, and one with heavy beaks that crush and eat thick-shelled nuts. They each do fine, but they can interbreed and produce offspring that have intermediate beaks -- too thick to reach the fine seeds that one parent eats, but too delicate to crush the nuts that the other parent eats. Those intermediate offspring will die off, and both parents will have wasted their resources raising them. Both parents would be better off not breeding with each other, but only breeding with their own kind to produce specialized and efficient offspring. There is now selection pressure on the birds to recognize their own kind (perhaps through songs or mating displays) and ultimately to be inter-sterile, so they never waste resources on the un-fit offspring. There's a gradation of separation over time, in which the different populations become more and more distinct. Eventually, at some arbitrary point, humans start calling them "species", but that's just us, not biology.
"Species" is an important concept, but it's not special in evolution; speciation is just one aspect of natural selection, there's nothing magical about it.
The following is multiple choice question (with options) to answer.
Which competition leads to one species going extinct or both becoming more specialized? | [
"intraspecific",
"interspecific",
"beneficial",
"mimicry"
] | B | Interspecific competition occurs between members of different species. It may lead to one species going extinct or both becoming more specialized. |
SciQ | SciQ-818 | galaxy-cluster, x-ray
Here's a fun article/interview on the collision between the Milky Way and Andromeda, though I think Roeland van der Marel might be exaggerating the new star formation a bit if we're to believe Wikipedia where it says there won't be much free gas.
As for the speed of our collision, Andromeda is currently heading towards us (or, we're heading towards it, whichever you prefer) at about 110 km/s source. and it's currently about 2.5 million light years away. Source.
Covering 2.5 million light years (about 24 million trillion km) in 4 billion years (126 million billion seconds), works out to an average speed of 190 km/s, so we can roughly estimate that the speed of impact between our two galaxies will reach a peak somewhere around 270 or so km/s. But (see video you also have to take into account the rotation speed and it appears (video above) the rotations will be going in opposite directions when the galaxies collide. We orbit the Milky way at about 250 km/s and Andromeda, being larger, probably a bit faster orbit speed. Adding the 2 velocities together, in our neck of the woods, we might see some relative velocity and some gas & dust collisions at (guessing here, cause I don't know if the rotations will slow down as the galaxies approach), but lets say 500 to 600 km/s or so. For any close bright stars from Andromeda, that could be fast enough for visible changes to a few near-by Andromeda stars in constellations over a single human lifetime.
Perhaps, we'll pass through an oort cloud of another star every few thousand years or so, perhaps even the occasional kuiper belt equivalent, every ten or 50 million years - er, maybe. We could see some very impressive meteor showers and perhaps an occasional, slightly more frequent, dinosaur killing level comet or meteor impact - but I'm just speculating. There might be lots of interesting things to see between 4 and 5 billion years from now.
The following is multiple choice question (with options) to answer.
Who discovered that the andromeda nebula is over 2 million light years away | [
"mills hubble",
"edwin hubble",
"smith hubble",
"richter hubble"
] | B | The universe contains all the matter and energy that exists and all of space and time. We are always learning more about the universe. In the early 20th century, Edwin Hubble used powerful telescopes to show that some distant specks of light seen through telescopes are actually other galaxies. ( Figure below ) Hubble discovered that the Andromeda Nebula is over 2 million light years away. This is many times farther than the farthest distances we had measured before. He realized that galaxies were collections of millions or billions of stars. Hubble also measured the distances to hundreds of galaxies. Today, we know that the universe contains about a hundred billion galaxies. |
SciQ | SciQ-819 | star, observational-astronomy, amateur-observing, asteroids
Title: Do objects that are invisible to the naked eye occlude much of the stars to Earth based observers? I was looking at a star recently and some other object that appeared to be stationary in relation to the star was occluding the light to only one of my eyes. This is why it caught my attention.
I was able to move my head around this shadow and see the star but there was a definite tiny area where the star was clearly hidden. The object hiding the star also appeared to be a similar size to the tiny point of light of the star. Is this common to observe?
For the last few days I have been asking myself how many objects could be hidden like this (though most with shadows that engulf the earth); How thick are asteroid belts etc, that are between our eyes and the rest of the stars.
Is most of it hidden? From your description, an object that blocks out light from a star in only one location cannot be an astronomical object.
Occultations by asteroids are fairly common. You can see a list at http://www.asteroidoccultation.com/. When a star is being occluded by an asteroid there will be a fairly narrow strip from which the star will be hidden. But it is still about 50km wide. The star appears to rapidly fade, and it remains hidden for at most a few seconds, then reappears. Your description of "only hidden to one of my eyes" doesn't fit an asteroid occultation.
The object hiding the star must, therefore, have been local, and not moving. It would be speculation to suggest what it could be.
There are may objects that are hidden in visible light, not by asteroids, but by interstellar dust clouds. We can see them by using other wavelengths.
The following is multiple choice question (with options) to answer.
What does every star emit that humans cannot see? | [
"dust",
"radiation",
"sound",
"light"
] | B | Visible light is only a small part of the electromagnetic spectrum. There are parts of the electromagnetic spectrum that humans cannot see. This radiation exists all around you. You just can’t see it! Every star, including our Sun, emits radiation of many wavelengths. Astronomers can learn a lot from studying the details of the spectrum of radiation from a star. |
SciQ | SciQ-820 | geology, mineralogy
There is an adage amongst some geologists that states "gold is where you find it". There is no altitude preferable for finding gold deposits. It's found in mountains, in deserts, in forests, under salt lakes, even dissolved in the oceans. The oceans contain the largest quantities of gold, but it is uneconomic to extract it from sea water because the concentration are so low.
Biological indicators, such a vegetation may work for some base metals, such as copper, but not necessarily for gold.
Also, gold can occur as a deposit of just gold, but it can also occur in association with other metals in the form of polymetallic deposits which contain gold, silver, copper, lead or zinc, even uranium.
Finally, not all deposits of minerals, gold included, are reserves. To be classified as a reserve and an orebody, a deposit of mineralization must be economic to mine.
The following is multiple choice question (with options) to answer.
What type pf mining is used to obtain mineral ores that are near the surface? | [
"surface mining",
"function mining",
"core mining",
"multi-layered mining"
] | A | Surface mining is used to obtain mineral ores that are near the surface. Blasting breaks up the soil and rocks that contain the ore. Enormous trucks haul the broken rocks to locations where the ores can be removed. Surface mining includes open-pit mining, quarrying, and strip mining. |
SciQ | SciQ-821 | 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 external female reproductive structures are referred to collectively as what? | [
"the vulva",
"the Fallopian tube",
"the uterus",
"the cervix"
] | A | The external female reproductive structures are referred to collectively as the vulva. They include the labia (singular, labium), which are the “lips” of the vulva. The labia protect the vagina and urethra, both of which have openings in the vulva. |
SciQ | SciQ-822 | inorganic-chemistry, acid-base, everyday-chemistry
$$\ce{H2O + CO2(aq) <=> H2CO3}$$
and the protolysis of true $\ce{H2CO3}$
$$\ce{H2CO3 <=> H+ + HCO3-}$$
For a weak acid
$$\begin{align}
\log[\ce{H+}]&\approx\frac12\left(\log K_\mathrm a+\log[\ce{H2CO3^*}]\right)\\
&=\frac12\left(-6.3-5.0\right)\\
&=-5.65\\
\mathrm{pH}&=5.65
\end{align}$$
Thus, pure rain in equilibrium with the atmosphere has about $\mathrm{pH}=5.65$. Any acid rain with lower $\mathrm{pH}$ would be caused by additional acids.
The following is multiple choice question (with options) to answer.
Acid rain may be caused by what? | [
"water pollution",
"volcanos",
"hurricanes",
"air pollution"
] | D | Air pollution may also cause acid rain. This is rain that is more acidic (has a lower pH) than normal rain. Acids form in the atmosphere when nitrogen and sulfur oxides mix with water in air. Nitrogen and sulfur oxides come mainly from motor vehicle exhaust and coal burning. |
SciQ | SciQ-823 | organic-chemistry
Title: What are the minimal chemical requirements for a food which we all can eat? I've been puzzled by the following though experiment for the past few days:
I want to make my own food from scratch, but I do not know where to start from.
I want to be 100% sure that what I eat will never contains something that can damage my body. For example: If you buy something from the local market you can not be 100% sure that it's safe to eat. (99.9 % maybe... but that's not 100%)
I want to ask you to tell me, how can I make a food that I can eat, or should I say - live on it, for the rest of my life, that's 100% safe, I can control every aspect of it's creation and has many combinations of taste because I love diversity.
Thank you for your time : )
Edit:
Because I realized my question is very broad and indeed is a little... too much scientific I want to close it. But before I do so, here's what I had in mind:
I wanted to take some chemical elements, put them in a jar, run some electricity, heat, whatever through it, filter it, do some additional processing and eat it.
I wanted to know if the stomach can take it, because I was going to eat food that's not hard to digest. Considering the three basic biomolecules used by the body are carbohydrates, lipids, and proteins, you would need to consume these three molecules only. Now we can choose three substances.
Glucose, one of the most basic carbohydrates, is needed for ATP production, so that would be a food choice there.
Any oil or butter will provide lipids.
Protein comes from a variety of sources. Meat is typically though of as the best, but nuts are a pretty good source too.
Since nuts satisfy proteins and lipids, I'd say honey roasted peanuts are the most basic food you could live off of, if you replace pure glucose for the honey.
The following is multiple choice question (with options) to answer.
What process is used to chemically and mechanically break down the food you eat into smaller parts? | [
"absorption",
"digestion",
"filtration",
"regression"
] | B | Digestion and Absorption Digestion is the mechanical and chemical break down of food into small organic fragments. It is important to break down macromolecules into smaller fragments that are of suitable size for absorption across the digestive epithelium. Large, complex molecules of proteins, polysaccharides, and lipids must be reduced to simpler particles such as simple sugar before they can be absorbed by the digestive epithelial cells. Different organs play specific roles in the digestive process. |
SciQ | SciQ-824 | physical-chemistry, phase-transition, states-of-matter, matter
What phases are available to what material is studied in materials science and there are books of tables on the topic. As you might guess by now, one can get arbitrarily detailed...
By the way, Helium also has more than two phases, as there is also a superfluid phase. All other materials can be made solid at appropriately low temperatures with potentially higher-than average pressure.
Finally, compound materials such as wood usually are not considered to make phase transitions as a whole, since the different materials that wood is made of might behave very differently at different temperatures/pressures.
The following is multiple choice question (with options) to answer.
What is the study of matter and the changes that material substances undergo. | [
"biology",
"geology",
"physiology",
"chemistry"
] | D | Chemistry is the study of matter and the changes that material substances undergo. Of all the scientific disciplines, it is perhaps the most extensively connected to other fields of study. Geologists who want to locate new mineral or oil deposits use chemical techniques to analyze and identify rock samples. Oceanographers use chemistry to track ocean currents, determine the flux of nutrients into the sea, and measure the rate of exchange of nutrients between ocean layers. Engineers consider the relationships between the structures and the properties of substances when they specify materials for various uses. Physicists take advantage of the properties of substances to detect new subatomic particles. Astronomers use chemical signatures to determine the age and distance of stars and thus answer questions about how stars form and how old the universe is. The entire subject of environmental science depends on chemistry to explain the origin and impacts of phenomena such as air pollution, ozone layer depletion, and global warming. The disciplines that focus on living organisms and their interactions with the physical world rely heavily on biochemistry, the application of chemistry to the study of biological processes. A living cell contains a large collection of complex molecules that carry out thousands of chemical reactions, including those that are necessary for. |
SciQ | SciQ-825 | reproduction
To understand oscillatory phenomenon in general, you need to understand that a lot of the processes in biology are driven by the chaotic (used in the formal since) vibrating or shaking of molecules and fluid microcurrents. This means that we can not know (regardless of how sensitive we measure) the conditions specific enough to create the specific path. These things are not tied to genes or to the person in general (perhaps exuding of mutations/disorders that effect the morphology of sperm or egg). Rather it is specific to any single fertilization reaction simple because of chance/chaos.
The following is multiple choice question (with options) to answer.
What occurs when the presence or absence of a specific behavior prevents reproduction from taking place? | [
"spontaneous mutation",
"primary speciation",
"natural selection",
"behavioral isolation"
] | D | Behavioral isolation occurs when the presence or absence of a specific behavior prevents reproduction from taking place. For example, male fireflies use specific light patterns to attract females. Various species of fireflies display their lights differently. If a male of one species tried to attract the female of another, she would not recognize the light pattern and would not mate with the male. Other prezygotic barriers work when differences in their gamete cells (eggs and sperm) prevent fertilization from taking place; this is called a gametic barrier. Similarly, in some cases closely related organisms try to mate, but their reproductive structures simply do not fit together. For example, damselfly males of different species have differently shaped reproductive organs. If one species tries to mate with the female of another, their body parts simply do not fit together. (Figure 18.19). |
SciQ | SciQ-826 | hydrology, rivers, dams
Title: Do dams reduce the flow of river downstream? There is a conflict between Egypt and Ethiopia, because the latter wants to build a dam on the Nile river. Citing this article:
[Egypt] fears the Nile dam will reduce its share of the river and leave the
country with dwindling options as it seeks to protect its main source
of fresh water.
What do they mean by "reduce its share of the river"? As far as I understand, the dam will create a reservoir, which will initially divert some water to be filled, but once that is done, the flow of the river should be the same. Is Egypt worried about this initial reduction, or do dams somehow reduce the flow of a river?
If so, what is the mechanism? I would guess that this is due to increased evaporation from the river, since the reservoir has a bigger surface than the usual river, but then again, it also collects more rain. Once a dam has been constructed in a river, the natural flow of water will be disrupted.
You correctly state that initially there will be a period required for the dam to fill. Until then, little of no water will flow beyond the dam.
Dams are created for one or more of three reasons:
To supply potable water to a population of humans for domestic or
industrial purposes.
For agricultural purposes.
To generate hydro-electricity.
The following is multiple choice question (with options) to answer.
Why have rivers in arid regions been reduced to trickles? | [
"emigration",
"diversion of water",
"global warming",
"rainforest destruction"
] | B | |
SciQ | SciQ-827 | molecular-genetics, gene-expression, chromosome
Title: Why is aneuploidy usually lethal? So, I was reading about aneuploidy and how a zygote with one extra or less chromosome usually would not survive to full term. I suppose this happens because aneuploidy leads to some kind of protein imbalance. So, in case of monosomy we would have a shortage of proteins, and in case of trisomy we would have an excess of proteins.
On the other hand, a conventional argument for having two copies of each gene is that, if one gene gets corrupted because of some kind of mutation, we still have another copy that produces the correct protein. So, in case of a recessive genetic disorder, the zygote can survive even with half the amount of protein.
My question is then, why can't monosomic aneuploidy be looked at the same way? Moreover, I read that monosomic aneuploidy is almost always fatal, while trisomic aneuploidy is sometimes tolarated. What causes zygotic termination in aneuploidy often isn't an issue with proteins or other gene products i.e. being "too sick" to live. It's that the zygote is basically "self error checking" and if it encounters a serious genetic error (e.g. aneuploidy) it self-terminates, as it would likely not survive anyway. Sometimes this self-termination fails, and the zygote develops. Depending on the specific aneuploidy, it may not make it to term, or perhaps it will, and you will have a child born, albeit the child will usually have a decreased quality of life/life-span.
A similar mechanism works in your somatic (non-reproductive) cells everyday when they replicate and divide - if they detect and error in their DNA that cannot be repaired, the cells SHOULD kill themselves. Sometimes this fails, and can give rise to cancer.
The following is multiple choice question (with options) to answer.
Having extra chromosomes or damaged chromosomes can cause what? | [
"deformities",
"problems",
"diseases",
"disorders"
] | D | Some children are born with genetic defects that are not carried by a single gene. Instead, an error in a larger part of the chromosome or even in an entire chromosome causes the disorder. Usually the error happens when the egg or sperm is forming. Having extra chromosomes or damaged chromosomes can cause disorders. |
SciQ | SciQ-828 | mechanical-engineering, structural-engineering, control-engineering
For example, if I wanted to setup such a facility, who would I have to consult?
You either find a consulting engineering firm with a lot of experience in designing and planning (and building!) such a plant. Or you find anexperienced hydroponics expert (the first bullet point) and a consulting firm with experience in a relevant field like wastewater.
Alternativly, you find a company specialized in building and selling hydroponics farms. This will give you less choice over the final plant - the company will want to work with their preferred components and concepts, and crucially they will want to reuse as much egnineering work from previous projects as they can.
The following is multiple choice question (with options) to answer.
What do farmers use greenhouses for? | [
"to extend the growing season",
"to decrease the growing season",
"to predict the growing season",
"to allow the growing season"
] | A | Farmers use greenhouses to extend the growing season. A greenhouse traps heat. Days that are too cool for a growing plant can be made to be just right. Similar to a greenhouse, greenhouse gases in the atmosphere keep Earth warm. |
SciQ | SciQ-829 | quantum-mechanics, potential-energy, measurement-problem, quantum-tunneling
So there is a way to do this in the classical way, using evanescent wave coupling.
Especially in optics, evanescent-wave coupling refers to the coupling between two waves due to physical overlap of what would otherwise be described as the evanescent fields corresponding to the propagating waves.[7]
One classical example is frustrated total internal reflection in which the evanescent field very close (see graph) to the surface of a dense medium at which a wave normally undergoes total internal reflection overlaps another dense medium in the vicinity. This disrupts the totality of the reflection, diverting some power into the second medium.
https://en.wikipedia.org/wiki/Evanescent_field#Evanescent-wave_coupling
The following is multiple choice question (with options) to answer.
What is it called when two waves in the same medium pass one another? | [
"frequency",
"accumulation",
"synchrony",
"interference"
] | D | Any two waves in the same medium undergo wave interference as they pass each other. At the location where the two waves collide, the result is essentially a summation of the two waves. In some places, a wave crest from one source will overlap a wave crest from the other source. Since both waves are lifting the medium, the combined wave crest will be twice as high as the original crests. Nearby, a wave trough will overlap another wave trough and the new trough will be twice as deep as the original. This is called constructive interference because the resultant wave is larger than the original waves. Within the interference pattern, the amplitude will be twice the original amplitude. Once the waves pass through each other and are alone again, their amplitudes return to their original values. |
SciQ | SciQ-830 | paleoclimatology
Has trees, i.e., long-lived woody plants that are capable of growing at least ten meters tall and that grow both upward by extending new branches and outward by widening of the trunk. Amongst other things, this rules out times before ~380 million years ago, which was when the first trees formed.
Has sufficient trees so as to constitute a forest, which I'll define as a largish area where trees grow sufficiently dense so as to form a more or less closed canopy. This distinguishes forests from areas with only a few trees such as savannas and krummholz.
Has very harsh winters, with at least one month where the average temperature is well below freezing, and temperatures of -40° C are not rare. This distinguishes boreal forests from cold oceanic forests such as the Magellanic subpolar forests in southern Chile and Argentina.
Has mild summers, with only a few months where the average temperature exceeds 10° C. This distinguishes boreal forests from hemiboreal and temperate forests. Note that some scientists do not make this distinction, classifying Köppen climate zone Dfb as boreal.
Is extensive. This distinguishes large boreal forests from high altitude subalpine forests that would locally pass the above tests. Subalpine forests can occur at any latitude, including Australia's Snow Mountains, New Zealand's Southern Alps, and parts of the Andes. This is not a clear-cut boundary. As a climate cools, subalpine forests may spread to the valleys between mountains and then spread out beyond the mountains. At some point, such montane forests becomes boreal forests.
The following is multiple choice question (with options) to answer.
Which forests are found throughout the ocean in temperate and arctic climates? | [
"coral reefs",
"mangrove",
"kelp",
"cedar"
] | C | Multicellular seaweeds called kelp may grow as large as trees. They are the food base of ecosystems called kelp forests (see Figure below ). Kelp forests are found throughout the ocean in temperate and arctic climates. They are highly productive ecosystems. |
SciQ | SciQ-831 | immunology, cancer, immunosuppression
Title: Normal cells and the immune system Normal or healthy cells have a natural ability to avoid being attacked by the immune system.
So if a cancer cell has all inherited 'strategies' for avoiding the immune system (that are from their earlier pre-cancerous states) does this make them hard to detect or be affected by the immune system. The development of cancer has various reasons. For example in more than 50% of tumors, p53 is mutated. p53 among other things regulates mitosis and forces the cell to arrest in a specific growth state if other systems detected a mutation in the DNA.
But in your special case we have to look at major histocompatibility complexes (MHCs) and NLRC5. There are two types of MHC, namely MHC class I and class II. MHC II presents mostly bacterial peptides to CD4+ T cells causing a immune response. However, MHC I presents viral peptides and peptides from your own body. These peptides are detected by CD8+ T cells which are cytotoxic T cells initializing apoptosis. Without these own peptides natural killer (NK) cells are activated because of a missing-self signal causing apoptosis, too.
The following is multiple choice question (with options) to answer.
What is the type of cancer in which bone marrow produces abnormal white blood cells that cannot fight infections? | [
"pneumonia",
"lymphedema",
"leukemia",
"melanoma"
] | C | type of cancer in which bone marrow produces abnormal white blood cells that cannot fight infections. |
SciQ | SciQ-832 | newtonian-mechanics, classical-mechanics, angular-velocity, rotational-kinematics
$$
The rotational energy of the system is the sum of rotational energies of the particles:
$$
E_\text{rot} = \sum_i \frac{\;\; L_i^2}{2J_i}
$$
There are two translational energies:
The following is multiple choice question (with options) to answer.
Mechanical energy can also usually be expressed as the sum of kinetic energy and what other kind of energy? | [
"potential energy",
"directional energy",
"reflective energy",
"partial energy"
] | A | Kinetic and potential energy add up to mechanical energy. |
SciQ | SciQ-833 | bond, ions, metal
Title: Can we picture metallic bonding as an equilibrium between electrons and cations? Can we picture metallic bonding as an equilibrium between electrons and cations?
Suppose:
$$\ce{Al^3+ + 3e- <=> Al}$$ In metals, electrons are non-localized, forming a "sea" of electrons, rather than having them localized, as in the $\ce{Na+Cl-}$ lattice of crystalline salt. See Metallic bonding for a more complete description.
It is, of course, a matter of degree, as covalent, ionic and metallic bonding can "blend" from one to the other. A bond can be considered partially ionic and covalent, for example; see these helpful graphics
The following is multiple choice question (with options) to answer.
What kind of bonds are forces of attraction between positive metal ions and the valence electrons that are constantly moving around them? | [
"ionized bonds",
"neutron bonds",
"metallic bonds",
"liquid bonds"
] | C | Metallic bonds are forces of attraction between positive metal ions and the valence electrons that are constantly moving around them (see the Figure below ). The valence electrons include their own and those of other, nearby ions of the same metal. The valence electrons of metals move freely in this way because metals have relatively low electronegativity, or attraction to electrons. The positive metal ions form a lattice-like structure held together by all the metallic bonds. For an animated version of metallic bonding, go to this URL:. |
SciQ | SciQ-834 | organic-chemistry, reaction-mechanism, redox
Aldehydes are very easily oxidized to carboxylic acids, and thus the aldehydes formed in the cleavage reaction do not survive. They are rapidly transformed into carboxylic acid groups, by a complex reaction whose mechanism you need not worry about.
Now, if the alkene had not had any hydrogens attached, the product in that case would have been a ketone
rather than an aldehyde. Ketones are not easily oxidized further, and the reaction would have stopped at that
stage.
If one of the alkene carbons had a hydrogen substituent, while the other did not, then we would get both acid
and ketone groups in our product, as shown below.
The following is multiple choice question (with options) to answer.
Aldehydes and ketones can work weak hydrogen bonds with water through what atom? | [
"carbon carbon atom",
"basalt oxygen atom",
"pyridinium oxygen atom",
"carbonyl oxygen atom"
] | D | Aldehydes and ketones can work weak hydrogen bonds with water through the carbonyl oxygen atom. The lower members of both series (3 carbons or fewer) are soluble in water in all proportions. As the length of the carbon chain increases, water solubility decreases. Similar to ethers, neither aldehydes nor ketones can hydrogen bond with themselves. As a result, their boiling points are generally lower than those of alcohols. Unlike alkanes however, aldehydes and ketones are polar molecules due to the more electronegative oxygen atom. The dipole-dipole interactions are stronger than the dispersion forces present in alkanes. The boiling points of aldehydes and ketones are intermediate between those of alkanes and alcohols. For example, the boiling point of ethane is -89°C, ethanal is 20°C, and ethanol is 78°C. |
SciQ | SciQ-835 | reproduction, asexual-reproduction
Title: can self-fertilization in flowers be called asexual reproduction? Suppose a flower having both male and female reproductive parts is self-fertilized then can this be called asexual reproduction...?I'm quite confused cause in this case the fusion of male and female gametes do take place but again the gametes are from the same parent....please help. According to this article from Berkeley, asexual reproduction is:
Any reproductive process that does not involve meiosis or syngamy
Using this definition of asexual reproduction and knowing self-fertilization involves meiosis and syngamy, it is not asexual.
The following is multiple choice question (with options) to answer.
Asexual reproduction in plants is typically an extension of the capacity for what? | [
"indeterminate growth",
"blooming growth",
"extracellular growth",
"substrate growth"
] | A | |
SciQ | SciQ-836 | 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.
A type of what in a cow's gut enables the animal to digest grass? | [
"virus",
"algae",
"bacteria",
"pests"
] | C | Kevin Walsh. Cows are able to digest grass with the help of the bacteria methanogens in their gut . CC BY 2.0. |
SciQ | SciQ-837 | 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.
What basic structures are called the building blocks of life and comprise all living things? | [
"seeds",
"lipids",
"pigments",
"cells"
] | D | Cells may be small in size, but they are extremely important to life. Like all other living things, you are made of cells. Cells are the basis of life, and without cells, life as we know it would not exist. You will learn more about these amazing building blocks of life when you read this chapter. |
SciQ | SciQ-838 | neuroscience, brain, neuroanatomy, neurology
Title: Why do humans alone have the capability to have religious/spiritual experiences? What is it in our brain that makes having such experiences possible? I assume other species don't have these. Sure there are instances in the natural world where you can see individuals of the species gather around the dead one. Sometime even the alpha male in the group allows the kin/relatives of the dead individual to approach it (for whatever reason).
The kind of thing I don't see in the wild-life kingdom is an individual becoming "enlightened" or the likes.
Sure our cerebrum is highly developed and all. But "what" is it in our brain that makes it capable for humans to have such experiences?
I've read articles saying we have identified such regions in the brain. Just want to know what these structures are. Did such research establish that such structures also exist in other species too? Its not clear that this is true.
Working with animals has been a little disconcerting over the past 50-60 years. In the distant past, I think most evolutionary anthropologists and their like bought into the idea that humans were completely uniquely intelligent and spiritual. But the more we try to define human sensibilities apart from other animals, the more we find its difficult to see animals as being completely incapable of human feelings and even thoughts.
I refer you to this question which describes the shift in intelligence theories over the years: Why have humans evolved conciousness?
The above reference is just to say that every definition of intelligence that is fairly broad has been overturned by animals (thumbs, socialization, tool use, self awareness, communication and language).
If you want to say 'I know we're special, but I just can't say how' you are in lots of good company... it's become pretty hard to lay down a definition that includes all human beings and excludes animals.
The following is multiple choice question (with options) to answer.
What kind of behavior occurs only after experience or practice and describes most human behaviors? | [
"learned behavior",
"practiced behavior",
"inherited behavior",
"innate behavior"
] | A | Other than infant reflexes, human behaviors are mainly learned rather than innate behaviors. Learned behavior is behavior that occurs only after experience or practice. Did you ever teach a dog to sit on command? That’s an example of a learned behavior. The dog wasn’t born knowing that it should sit when it hears the word sit. The dog had to learn the behavior. |
SciQ | SciQ-839 | computability, turing-machines, physics
Title: Can normal physics laws be simulated in Digital physics? Physics is defined as the study of an object {matter or energy} with its interaction with other objects:
Physics is the study of matter, energy, and the interaction between them.
On the other hand, Digital physics is based on computations and information.
Digital physics is a collection of theoretical perspectives based on the premise that the universe is, at heart, describable by information, and is therefore computable.
The following is multiple choice question (with options) to answer.
What is the study of the interaction between matter and energy called? | [
"climatology",
"astronomy",
"chemistry",
"geology"
] | C | Chemistry is the study of matter and energy and how they interact, mainly at the level of atoms and molecules. Basic concepts in chemistry include chemicals, which are specific types of matter, and chemical reactions. In a chemical reaction, atoms or molecules of certain types of matter combine chemically to form other types of matter. All chemical reactions involve energy. |
SciQ | SciQ-840 | physiology, cell-membrane, blood-sugar, antihistamines
So I think the tiredness of antihistamines is because of the increased amount of active fast mechanisms of insulin secretion, while less very fast mechanisms.
To carry the raw food mass in the intestines also require much energy.
What is the physiological mechanism behind the tiredness of excess antihistamines? Thanks to studies on animal behavior and on histamine dection in the Central Nervous System, researchers found out the "histaminergic system".
It's thought that histamine-containing neurons regulate sleep-wake cyrcle, immunity, memory, body temperature, drinking, feeding rhythms. By the way, knockout rats who lack of histamine system don't show big defects in any function.
H1-Receptors for Histamine are distributed in the CNS and in the rest of the body. H1-antagonists (such as Promethazine, Chlorcyclizine, Loratadine...) have different effects on CNS, depending on dose. At conventional doses central depression appears and patients are sedated. They can even experience an antihistamine "hangover" in the morning, even if they take these drugs at bedtime. By the way, antihistamine overdose typically shows with convulsions.
The "non-sedating" H1-antagonists, or "second generation" have a lot less effects on CNS. They have polar chemical structure: they can not cross the blood-brain barrier.
By the way, a lot of typical and atypical anti-psychotic drugs have H1-antagonism effects on the brain (with H2 and H4 antagonism): their main goal is sedation to stop the patient from hurting himself (or others) during manic episodes.
So I think the last two sentences explain that sedation is almost a totally CNS-mediated side effect of antihistamine drugs.
H1-antagonists don't suppress gastic secretion, do not inhibit salivary, lacrimal or other exocrine secretions. Older H1-antagonists have an anti-colinergic effect on muscarinic receptors: they may reduce ACh-mediated secretions, typically in mouth and in the respiratory tree.
The following is multiple choice question (with options) to answer.
Prescribed to treat allergies, antihistamines and corticosteroids help control what system that attacks allergens? | [
"nervous system",
"cardiovascular",
"immune system",
"reproductive system"
] | C | Most allergies can be treated with medicines. Medicines used to treat allergies include antihistamines and corticosteroids. These medicines help control the immune system when it attacks an allergen. Sometimes, allergies cause severe symptoms, a condition known as anaphylaxis. For example, they may cause the throat to swell so it is hard to breathe. Severe allergies may be life threatening. They require emergency medical care. |
SciQ | SciQ-841 | biochemistry
Title: Food which does not produce urea My professor of bioengineering said that all foods produce urea. Do foods exist which does not produce urea?
Thank you very much. Food doesn't produce urea, your body produces urea from the nitrogen content of the food you eat (mostly comes from proteins). So you can eat e.g honey, which contains minimal, if any, amount of nitrogen.
The following is multiple choice question (with options) to answer.
The main advantage of urea is its very low what? | [
"temperature",
"toxicity",
"cost",
"energy requirement"
] | B | |
SciQ | SciQ-842 | hematology, cardiology, blood-circulation, red-blood-cell, veins
Veins are not like impermeable rubber tubes, they are 'living' structures requiring, like all cells, Oxygen and glucose to survive. Smaller veins get the O2 from diffusion, while the larger veins need help from vasa vasorum, small blood bessels that bring blood to the walls of the veins.
The innermost cells lining veins are epithelial cells. They also line valves.
In the picture you posted, blood is not circulating well behind valves. The cause of hypoxia is that epithelial cells are continually removing O2 from the blood.
When enough O2 is removed to cause hypoxia, the endothelial cells may become damaged by the lack of O2, causing inflammation and (possibly) potentiating clot formation.
Activation of endothelial cells by hypoxia or possibly inflammatory stimuli would lead to surface expression of adhesion receptors that facilitate the binding of circulating leukocytes and microvesicles. Subsequent activation of the leukocytes induces expression of the potent procoagulant protein tissue factor that triggers thrombosis.
Mackman N. (2012). New insights into the mechanisms of venous thrombosis. The Journal of clinical investigation, 122(7), 2331–2336. doi:10.1172/JCI60229
The following is multiple choice question (with options) to answer.
What type of blood cells transport oxygen to the tissues so they can function? | [
"depleted blood cells",
"white blood cells",
"red blood cells",
"mutated blood cells"
] | C | Red blood cells transport oxygen to the tissues so they can function. In the absence of oxygen, cells cannot carry out their biochemical responsibilities. Oxygen moves to the cells attached to hemoglobin, a protein found in the red cells. In cases of carbon monoxide poisoning, CO binds much more strongly to the hemoglobin, blocking oxygen attachment and lowering the amount of oxygen reaching the cells. Treatment involves the patient breathing pure oxygen to displace the carbon monoxide. The equilibrium reaction shown below illustrates the shift toward the right when excess oxygen is added to the system:. |
SciQ | SciQ-843 | human-anatomy
Atraumatic dislocation.
This occurs when the shoulder dislocates with minimal force such as reaching up for an object or turning over in bed. Usually it will 'pop' back in itself or with a little help. Normally this type of dislocation does not need reducing in A&E. It can occur regularly throughout the day and will be associated with certain positions the arm is placed into. This type of dislocation is associated with people that have 'lax' joints, for example people who hyper-extend their knees and elbows and can get the palms of both hands onto the floor with ease. This joint laxity is normal for these people and the onset of dislocation can be associated with a change in how the muscles around the shoulder are interacting with each other or a change in posture/ position of the arm. This can produce an imbalance in the control of the joint. Referral for appropriate physiotherapy is the initial form of management. The physiotherapist should look at the way in which the muscles and shoulder joint is moving and posture aiming to restore the balance. Treatment can 'cure' the problem as long as the exercises and advice is continued, but in some cases there is only minimal or nil benefit. At this point surgical intervention is indicated.
Positional Non-traumatic dislocations.
This group of people can dislocate their shoulders without any form or history of trauma. Some may have started out dislocating their shoulder as a party trick; others may have always had shoulders that just 'fall' out of joint. This type of dislocation is usually painless and can be put back in easily. Both shoulders are typically involved. The cause of this type of dislocation is usually a result of what we call 'abnormal muscle patterning' which means the strong muscles around the shoulder joint are not working in the correct order causing them to pull the shoulder out of joint with active movement in the particular direction such as lifting the arm forward above the head or out to the side and above the head. The main treatment for this is physiotherapy that looks at re-sequencing the muscles in order to prevent further dislocations. Occasionaly surgery in the form of thermal capsular shrinkage or plication may be neccessary.
The following is multiple choice question (with options) to answer.
What title is used to describe health professionals who use nonsurgical techniques to help patients with musculoskeletal system problems that involve the bones, muscles, ligaments, tendons, or nervous system? | [
"chiropractor chiropractors",
"podiatrist",
"dentist",
"physical therapist"
] | A | Chiropractor Chiropractors are health professionals who use nonsurgical techniques to help patients with musculoskeletal system problems that involve the bones, muscles, ligaments, tendons, or nervous system. They treat problems such as neck pain, back pain, joint pain, or headaches. Chiropractors focus on the patient’s overall health and can also provide counseling related to lifestyle issues, such as diet, exercise, or sleep problems. If needed, they will refer the patient to other medical specialists. Chiropractors use a drug-free, hands-on approach for patient diagnosis and treatment. They will perform a physical exam, assess the patient’s posture and spine, and may perform additional diagnostic tests, including taking X-ray images. They primarily use manual techniques, such as spinal manipulation, to adjust the patient’s spine or other joints. They can recommend therapeutic or rehabilitative exercises, and some also include acupuncture, massage therapy, or ultrasound as part of the treatment program. In addition to those in general practice, some chiropractors specialize in sport injuries, neurology, orthopaedics, pediatrics, nutrition, internal disorders, or diagnostic imaging. To become a chiropractor, students must have 3–4 years of undergraduate education, attend an accredited, four-year Doctor of Chiropractic (D. ) degree program, and pass a licensure examination to be licensed for practice in their state. With the aging of the baby-boom generation, employment for chiropractors is expected to increase. |
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