source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-944 | 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.
Mutations that lead to cancer usually occur in genes that control the cell cycle. these include tumor-suppressor genes and what? | [
"Darkness Oncogenes",
"apparition - oncogenes",
"extinction - oncogenes",
"proto-oncogenes"
] | D | Mutations that lead to cancer usually occur in genes that control the cell cycle. These include tumor-suppressor genes and proto-oncogenes. |
SciQ | SciQ-945 | endocrinology, glucose, homeostasis, insulin, hypothalamus
Title: Role of the Hypothalmus in the control of Blood Sugar In homeostatic regulation of blood glucose, the receptor and effector is the Pancreas, but how does the control centre — the Hypothalamus — connect and link into this process? Your question doesn’t make it clear whether you think that the pancreas must be under the control of the hypothalmus, or whether you are asking whether it has an influence on the pancreas in relation to the secretion of insulin and glucagon, which control the concentration of blood glucose.
First, it has been long known that secretion of insulin can be influenced by the concentration of glucose in isolated pancreatic islets in vitro, so it can not be true that the effects must involve the hypothalmus. This is implicit in most book or general information articles you might find on the web, but for an original reference a review by W.J. Malaisse in Diabetologia 9, 167–173 (1973) seems highly cited.
I know almost nothing about physiology, but on searching the web for the role of the hypothalmus in glucose homeostasis, found a most readable prize-winning postgraduate essay on the topic by Syed Hussein of Imperial College London. I trust that it is in order to append an edited extract of this:
The following is multiple choice question (with options) to answer.
What type of environment is maintained in homeostasis? | [
"constant internal",
"fluid internal",
"noisy internal",
"stable external"
] | A | Homeostasis is maintaining a constant internal environment. |
SciQ | SciQ-946 | newtonian-mechanics, vectors, collision, rigid-body-dynamics
So the impulse vector through the contact point has the following effect in the motion of each body
$$ \begin{aligned}
\Delta \boldsymbol{v}_1 & = -\tfrac{1}{m_1} \boldsymbol{n} J & \Delta \boldsymbol{v}_2 & = \tfrac{1}{m_2} \boldsymbol{n} J \\
\Delta \boldsymbol{\omega}_1 &= -\mathbf{I}_1^{-1} ( \boldsymbol{r}_c-\boldsymbol{r}_1) \times \boldsymbol{n} J & \Delta \boldsymbol{\omega}_2 &= \mathbf{I}_2^{-1} ( \boldsymbol{r}_c-\boldsymbol{r}_2) \times \boldsymbol{n} J
\end{aligned} \tag{2} $$
where $\Delta \boldsymbol{v}_i$ is the vector change of body's center of mass, and $\Delta \boldsymbol{\omega}_i$ the vector change of the body's rotational velocity.
And the kinematics of the contact point before impact are
$$ \begin{aligned}
\boldsymbol{v}_{1c}^\text{before} & = \boldsymbol{v}_1 + \boldsymbol{\omega}_1 \times (\boldsymbol{r}_c - \boldsymbol{r}_1) \\ \boldsymbol{v}_{2c}^\text{before} & = \boldsymbol{v}_2 + \boldsymbol{\omega}_2 \times (\boldsymbol{r}_c - \boldsymbol{r}_2) \\
\end{aligned} \tag{3} $$
and after impact
$$ \begin{aligned}
The following is multiple choice question (with options) to answer.
When calculating impulse, consider the change in _______ of one of the objects in the collision? | [
"momentum",
"sound",
"potential energy",
"velocity"
] | A | the initial momentum of an object. When calculating impulse, consider the change in momentum of one of the objects in the collision. |
SciQ | SciQ-947 | metabolism, human-anatomy, pharmacology, liver
For drugs introduced through an injection, for example, metabolism occurs throughout the circulatory system and in the liver. Remember that it's all the same blood supply, but the first-pass effect just refers to the blood that goes to the liver before entering the systemic circulation (by which it can travel to its target).
The following is multiple choice question (with options) to answer.
What word describes any chemical that affects the body’s structure or function? | [
"toxin",
"drug",
"treatment",
"gift"
] | B | A drug is any chemical that affects the body’s structure or function. Many drugs, including both legal and illegal drugs, are psychoactive drugs . This means that they affect the central nervous system, generally by influencing the transmission of nerve impulses. For example, some psychoactive drugs mimic neurotransmitters. At the link below, you can watch an animation showing how psychoactive drugs affect the brain. http://www. thirteen. org/closetohome/animation/neuron-main. html. |
SciQ | SciQ-948 | biochemistry, proteins, enzymes, digestive-system, digestion
Title: Betaine HCl stomach pH It seems betaine HCL is often recommended for those suffering from "low stomach acid" -- which, as I understand, is having too high stomach pH for proper digestion (especially for proteolysis via pepsin). However, I have a few questions then -- though I'm not sure if my reasoning is correct here:
Understandably, one wouldn't want to drink pure or highly concentrated HCl by itself to increase stomach acid! But then, what role does the betaine play?
I'm guessing betaine HCl probably does not dissolve in water to give the same pH as just straight (or concentrated) hydrochloric acid -- since then it would seem just as dangerous as drinking plain HCl!
In that case, if it doesn't decrease the pH as much, making it safe for oral consumption, what value does it bring for "lowering stomach pH" anyway? I mean, one could just drink a little vinegar or citric acid for the same effect?
Or, perhaps, is betaine-HCl just a means of some "delayed release" of HCl to lower stomach pH without hurting the mouth and esophagus during its initial consumption? Betaine may just be a useful carrier here, given it's quaternary ammonium and carboxylic acid groups (e.g., a zwitterionic carrier)
Alternatively, could the value of betaine HCl simply be in providing a source of Cl- anions, possibly for increased pepsin activity? (I'm not sure if pepsin requires merely low pH or specifically also needs Cl- anions as well) Betaine-HCl does seem to be often formulated with additional pepsin enzyme(s) as well... Betaine HCl (trimethylglycine) was present in over the counter "stomach acidifiers" but the US FDA says there is no evidence for its efficacy and has banned its use for this indication (source: US FDA) - it may be freely available elsewhere, I am unaware of the regulatory status in other jurisdictions.
The following is multiple choice question (with options) to answer.
The entry of acidic chyme into the duodenum stimulates the release of what? | [
"oxygen",
"gastrin",
"secretin",
"progesterone"
] | C | Pancreatic Secretion Regulation of pancreatic secretion is the job of hormones and the parasympathetic nervous system. The entry of acidic chyme into the duodenum stimulates the release of secretin, which in turn causes the duct cells to release bicarbonaterich pancreatic juice. The presence of proteins and fats in the duodenum stimulates the secretion of CCK, which then stimulates the acini to secrete enzyme-rich pancreatic juice and enhances the activity of secretin. Parasympathetic regulation occurs mainly during the cephalic and gastric phases of gastric secretion, when vagal stimulation prompts the secretion of pancreatic juice. Usually, the pancreas secretes just enough bicarbonate to counterbalance the amount of HCl produced in the stomach. Hydrogen ions enter the blood when bicarbonate is secreted by the pancreas. Thus, the acidic blood draining from the pancreas neutralizes the alkaline blood draining from the stomach, maintaining the pH of the venous blood that flows to the liver. |
SciQ | SciQ-949 | Arrange 6 adults and 12 children in 5 rooms, with at least 1 adult in each room
Problem: How many ways can you arrange 6 adults and 12 children in 5 rooms of max 4 people such that there is at least 1 adult per room. Every person and room is distinguishable.
My take from the problem is the following:
1. There are 2 distinct ways to place 18 people in room of 4: $\{4, 4, 4, 4, 2\}$ and $\{4,4,4,3,3\}$
2. For the first sequence, I can start by fixing all the adults in every room in the following manner: $\binom{6}{2} \times \binom{4}{1} \times \binom{3}{1} \times \binom{2}{1} \times \binom{1}{1}$
3. Now there are 2 cases:
1. The room with 2 adults is the one with 2 people $\binom{12}{0} \times \binom{12}{3} \times \binom{9}{3} \times \binom{6}{3} \times \binom{3}{3}$
2. The room where 2 adults is among one that contains 4 people $\binom{12}{2} \times \binom{10}{3} \times \binom{7}{3} \times \binom{4}{3} \times \binom{1}{1}$
4. There are $5!$ ways to shuffle the rooms around since they are distinguishable
Adding the 2 cases in (3) and multiplying it with (2) and (4) should in my opinion give me the answer with the sequence $\{4, 4, 4, 4, 2\}$. Is there anything wrong with my reasoning?
• Your reasoning is correct. – N. F. Taussig Mar 23 '18 at 10:03
Just for fun let's look at how we might solve this with generating functions.
The following is multiple choice question (with options) to answer.
Adulthood is divided into how many stages? | [
"two",
"three",
"five",
"four"
] | B | Adulthood is divided into the stages of early, middle, and late adulthood. |
SciQ | SciQ-950 | human-biology, anatomy
The proportions of diagrams and cross sections of the nasal cavity all seem wildly different. Some of them are just blatantly wrong, depicting, for example, the Eustachian tubes coming from the roof of the nasal cavity instead of the sides. It has been very difficult to find good information on any of this. I am not even sure if I am referring to the region correctly. By nasal cavity, I mean everything between the back of the throat and the posterior nares, although I am aware the nasal cavity includes the region all the way up to the anterior nares as well.
This is the only picture I can find that shows the nasal septum.
This is a better diagram of the rest of the structures. The pharyngeal tonsils are the adenoids. I'm impressed to stumble upon someone who can do that with his tongue. And mainly because I can do that myself!
Looking at the images and feeling with my tongue, this rugged area you mention is definitely too close to the nose to be the adenoids.
So I googled a bit (well, more like a lot) and I found this cool webpage which details that area.
http://www.theodora.com/anatomy/the_pharynx.html
and I found this snippet of text:
Above the pharyngeal tonsil, in the middle line, an irregular
flask-shaped depression of the mucous membrane sometimes extends up as
far as the basilar process of the occipital bone; it is known as the
pharyngeal bursa.
I've found stones in my tonsils but never in my adenoids. What I've sometimes found was dried mucus adhered to it when waking up in the morning.
I believe those stones might be rests of food (which can't really get up there).
Maybe this green mucus you found was just dried mucus? Maybe a little infection on a particular day?
I hope you get the answer, since it's passed a quite long time since you asked :)
The following is multiple choice question (with options) to answer.
What is the single bone that forms the posterior skull and posterior base of the cranial cavity? | [
"occipital bone",
"maxilla",
"limbic bone",
"radiating bone"
] | A | Occipital Bone The occipital bone is the single bone that forms the posterior skull and posterior base of the cranial cavity (Figure 7.9; see also Figure 7.8). On its outside surface, at the posterior midline, is a small protrusion called the external occipital protuberance, which serves as an attachment site for a ligament of the posterior neck. Lateral to either side of this bump is a superior nuchal line (nuchal = “nape” or “posterior neck”). The nuchal lines represent the most superior point at which muscles of the neck attach to the skull, with only the scalp covering the skull above these lines. On the base of the skull, the occipital bone contains the large opening of the foramen magnum, which allows for passage of the spinal cord as it exits the skull. On either side of the foramen magnum is an oval-shaped occipital condyle. These condyles form joints with the first cervical vertebra and thus support the skull on top of the vertebral column. |
SciQ | SciQ-951 | genetics, botany, seeds
Title: What DNA does a self-fertile plant's seedling have? Some plants are said to be self-fertile. An example is Prunus tomentosa.
Assuming that no cross-pollination happened with other plants, if a self-fertile plant such as prunus tomentosa produces a seedling, what DNA will the seedling have? Is the seedling's DNA an exact copy of the parent plant's DNA, or do the genes get rearranged? Selfing (aka self-fertilizing) differs from cloning. When selfing occurs, the offspring is not an exact copy of the parent. When cloning occurs, the offspring is an exact copy (except for a few mutations) of the parent.
Selfing implies that an individual will produce two gametes (typically a spermatozoid and an ovule but that might be a bit more complicated) and these two gametes are fusing to give the zygote (egg or offspring if you prefer).
As a consequence, when selfing, meiosis is occurring (and therefore segregation and recombination) so that the offspring is not an exact clone of the parent but rather some kind of a rearrangement of the parent genome (with a few mutations of course).
The following is multiple choice question (with options) to answer.
Is the progeny produced by asexual reproduction stronger or weaker than seedlings produced by sexual reproduction? | [
"the same",
"lighter",
"weaker",
"stronger"
] | D | |
SciQ | SciQ-952 | aqueous-solution, solubility, solvents, solutions
Title: Does removing solution affect a supersaturated solution Given a mixture of: a saturated solution of a solute in a solvent together with excess of the solute compound as crystalline material.
If one were to change the bulk composition of the mixture by removing some of the solution could this cause dissolution or precipitation of the solid in the remaining mixture, or the concentration of the remaining solution?
Presumably one should expect some crystallisation in the portion of the solution that is removed from the mixture?
If one were to change the bulk composition of the mixture by removing some of the solution [...]
This does not change the composition of the solution above the solid. Since the concentration of the solute remains constant, I do not expect a change.
Presumably one should expect some crystallisation in the portion of the solution that is removed from the mixture?
It still is a saturated solution. Unless you evaporate the solvent (= increase the concentration of the solute) or change the temperature, nothing will change.
The following is multiple choice question (with options) to answer.
Supersaturated solutions of most solids in water are prepared by cooling what? | [
"plasma solutions",
"mineral solutions",
"saturated solutions",
"dense solutions"
] | C | (b) Write a balanced chemical equation showing the products of the dissolution of Fe(NO3)3. Compare the processes that occur when methanol (CH3OH), hydrogen chloride (HCl), and sodium hydroxide (NaOH) dissolve in water. Write equations and prepare sketches showing the form in which each of these compounds is present in its respective solution. What is the expected electrical conductivity of the following solutions? (a) NaOH(aq) (b) HCl(aq) (c) C6H12O6(aq) (glucose) (d) NH3(l) 14. Why are most solid ionic compounds electrically nonconductive, whereas aqueous solutions of ionic compounds are good conductors? Would you expect a liquid (molten) ionic compound to be electrically conductive or nonconductive? Explain. Indicate the most important type of intermolecular attraction responsible for solvation in each of the following solutions: (a) the solutions in Figure 11.8 (b) methanol, CH3OH, dissolved in ethanol, C2H5OH (c) methane, CH4, dissolved in benzene, C6H6 (d) the polar halocarbon CF2Cl2 dissolved in the polar halocarbon CF2ClCFCl2 (e) O2(l) in N2(l) 11.3 Solubility 16. Suppose you are presented with a clear solution of sodium thiosulfate, Na2S2O3. How could you determine whether the solution is unsaturated, saturated, or supersaturated? 17. Supersaturated solutions of most solids in water are prepared by cooling saturated solutions. Supersaturated solutions of most gases in water are prepared by heating saturated solutions. Explain the reasons for the difference in the two procedures. Suggest an explanation for the observations that ethanol, C2H5OH, is completely miscible with water and that ethanethiol, C2H5SH, is soluble only to the extent of 1.5 g per 100 mL of water. Calculate the percent by mass of KBr in a saturated solution of KBr in water at 10 °C. See Figure 11.17 for useful data, and report the computed percentage to one significant digit. Which of the following gases is expected to be most soluble in water? Explain your reasoning. (a) CH4 (b) CCl4. |
SciQ | SciQ-953 | human-biology, cell-biology, bacteriology, cell-membrane
Title: Can general soap kill bacteria? I have read that general soap can kill bacteria by opening holes in the bacterial membrane.
http://questions.sci-toys.com/node/90
However, I found some articles as well saying that it cannot.
http://goaskalice.columbia.edu/answered-questions/does-soap-kill-germs
There seems split answers among experts,
so I would like to know which one is correct.
Could anyone advise me?
Thanks. Soap kills nearly all the bacteria it comes into contact with by dissolving the bacterial membrane. Some viruses with protein coats can resist soap, but many viruses have similar membranous coats (like HIV) and are usually disrupted by soap. I'm sure it washes some away too, but to say they don't kill bacteria is misleading. In the end, though, they are gone.
Antibacterial soap with triclosan does not kill bacteria on contact and are no more effective than if they had no triclosan at all. That's actually a good thing since really using an antibiotic would probably accelerate antibiotic resistant bacteria which is a serious - probably catastrophic public health failure. A recent study showed that killing bacteria by soaking with triclosan took 9 hours to start showing an effect.
To achieve full sterility, surgeons bathe their gloves in iodine (see details in the comments below) and their instruments will be sterilized by heating them beyond the boiling point in an autoclave under pressure. That's useful when you are breaching the skin in surgery, but the skin needs some bacteria to be healthy long term and works well to fend off bacterial infections.
Your confusion seems to come from finding a page full of errors. Alice didn't really do her homework.
The following is multiple choice question (with options) to answer.
Bacterial stis usually can be cured with what? | [
"pesticides",
"antiviral drugs",
"antibiotics",
"antioxidants"
] | C | Bacterial STIs usually can be cured with antibiotics. |
SciQ | SciQ-954 | electromagnetic-radiation, thermal-radiation, intensity
Title: Doubt in the definition of intensity So I know that radiant intensity is defined as "power transferred per unit solid angle per unit area which is perpendicular to the direction of propagation of energy". So now I have a very small (first) doubt, if we have an area that is emitting energy and we want to calculate the "rate of energy intercepted" by another area (not perpendicular to the direction of propagation), then do we take the perpendicular component of the area where we need the energy intercepted ($a_2$) or the perpendicular component of the area which is emitting energy E ($a_1$)?
I think the answer stays same, but I am asking this just for conceptual clarity.
Now, I also have another doubt. Intensity is always measured perpendicular to the energy propagation direction, and diffused emitter (emitting diffusely) is an emitter whose intensity emitted is independent of the direction (please correct me if I am wrong).
So the question is as follows :
A small surface (area ${10}^{-3} m^2$) emits diffusively, and measurements indicate that the total intensity associated with emission in the normal direction I = 7000 $\frac{W}{{metre}^2 sr}$. The emitted radiation is intercepted by two surfaces, $a_1$ (perpendicular to energy direction), $a_2$ (vertical) where, area of each is ${10}^{-3} m^2$. What is the power intercepted by $a_1$ and $a_2$?(assume the direction of energy propagation is constant over the full area)
The following is multiple choice question (with options) to answer.
Intensity is defined to be the power per unit area carried by a what? | [
"filament",
"wire",
"wave",
"shift"
] | C | Intensity is defined to be the power per unit area carried by a wave. Power is the rate at which energy is transferred by the wave. In equation form, intensity I is. |
SciQ | SciQ-955 | human-biology, physiology, proteins, amino-acids, diet
Title: Amino Acid requirement + intake in relation to diet + meat type I was arguing with a friend:
I said: The Yulin festivals cannot be condemned by western culture, as we also kill animals in equally cruel ways.
She said: It isn't just that the killing is cruel, but it doesn't help us, as humans do not derive the same essential amino acids from consuming these less traditional meats (e.g. dogs, cats, etc) like they would from consuming more traditional meats (e.g. cow, pig, goat, etc) She cites her father, a geneticist, as her source.
Question one:
Are my friend and her father correct? Does the consumption of a less traditional meat (e.g. cats, dogs, etc) provide fewer essential amino acids than the consumption of traditional meats (e.g. cows, pigs, chickens, etc)?
Question two:
My friend also made a comment about veganism and vegetarianism (I am a vegetarian), stating that for the same reason as her and her father's above comment, people who exclude meat from their diet need to use supplements. Is this correct, or would it also be possible to just vary diet to obtain these essential amino acids? There is a difference between animals in their requirements for amino acids. For example, cats need high amounts of taurine (and can't make it) and when fed diets lacking enough can go blind. This is why vegans trying to feed vegan diets to their pets can be very bad for the pet. Animal proteins have sufficient taurine for the cat.
However, the meat of a cat or dog is just as a complete source of protein for humans as any other meat. All essential amino acids are there in sufficient ratios. Suggesting otherwise by her father suggests some confusion between the dietary needs of cat vs. the nutritional value of the cat to another predator.
Your second question is easily answered by looking up essential amino acids. Wiki is plenty sufficient to get the gist Wiki Link. In short, most plants don't contain the full complement of amino acids that humans require (and can't make on their own). So to get this full complement, it requires eating multiple plant products that together contain the required amino acids.
From Harvard School of Public Health
The following is multiple choice question (with options) to answer.
Trophic level 4 = tertiary consumers that eat what kind of consumers? | [
"herbivores",
"insects",
"secondary consumers",
"primary consumers"
] | C | Trophic level 4 = tertiary consumers that eat secondary consumers. |
SciQ | SciQ-956 | Is it 10% from each dimension or from the volume? Hard to figure out from the problem.
Why? The problems says "The dimension of each container is decreased by 10 percent". That tells you precisely which is intended
If from the each dimension then:
V 1= 50x 60x 120 = 360000 cm3 = 360 litres
V2=45 x 54 x 108 = 262440 cm3 = 262.4 liltres
V 3 = 40.5 x 48.6 x 97.2 = 191.3litres
V4 = 36.45 x 43.74 x 87.48 =139.4 litres
V5 = 32.81 x 39.37 x 78.74 = 101.7 litres
V6 = 29.61 x 35.47 x 70.94 =74.5 litres
I need some feedback.
4. Hello, terminator!
A hardware supplier has designed a series of six plastic containers with lids
. . where each container (after the first) can be placed into the next larger one.
The containers are rectangular boxes.
. . The dimensions of the largest one are 120 cm by 60 cm by 50 cm.
The dimensions of each container are decreased by 10 percent
. . with respect to the next larger one.
(a) Determine the volume of each container.
(b) Determine the volume of all the containers.
Write your answers in litres (one litre = 1000 cubic cm).
The original box has dimensions $L,\,W,\,H$
. . Its volume is: . $L\!\cdot\!W\!\cdot\!H\text{ cm}^3$
The next box has dimensions: $0.9L,\,0.9W,\,0.9H$
. . Its volume is: . $(0.9L)(0.9W)(0.9H) \:=\:0.729(LWH)$
That is, each box is 0.729 of the volime of the next larger box.
The first box has volume: . $120\cdot60\cdot50 \:=\:360,\!000\text{ cm}^3$
. . That is: . $V_1 \:=\:360\text{ liters.}$
The following is multiple choice question (with options) to answer.
What takes the shape of the container they are placed in and have a definite volume? | [
"gases",
"solids",
"loads",
"liquids"
] | D | |
SciQ | SciQ-957 | analytical-chemistry, titration, color
Title: Titrating iodine starch solution with sodium thiosulphate - Colour change I investigated two mixtures with different solvents, one with water and one with n-heptane. Both contained iodine $\ce{I2}$ as a solute. To both solutions I added a bit of starch.
As I remember this resulted in a colourchange. So the solution turned from yellowish to dark blue (if I remember correctly!).
Now according to wikipedia starch and iodine indeed form a structure which has a dark blue colour. But it only forms in the presence of $\ce{I^-}$.
This leaves me wondering, why do I remeber the solution to be dark blue, eventhough I think there was no $\ce{I^-}$ present? Could it be the solution turned dark blue only after I added some sodium thiosulfate? Because in the next step I did a titration with $\ce{Na2S2O3}$.
In this case I don't see which reaction could have produced the $\ce{I^-}$ though. I thought only $\ce{NaI}$ is produced after adding the sodium thiosulfate.
$$\ce{I_2 + 2Na_2S_2O_3 -> 2NaI + Na_2S_4O_6} \tag{1}$$
So at which point did the solution turn dark blue and where did the $\ce{I^-}$ come from, that was needed for the formation of the starch-iodine-compound? Could it be there is an intermediate step to (1) in which $\ce{I^-}$ is formed and this $\ce{I^-}$ was used to produce the dark blue starch-iodine compound? I don't think your memory is serving you right. That is why we write everything in the notebook, especially color changes.
I think you are doing distribution experiments where iodine is distributed between aqueous layer and an organic layer. When we add indicator for titration, it is not a solid starch but starch which is boiled in water. So when you added starch $solution$ to heptane which contained iodine, I would not be surprised if the starch solution turned blue.
The following is multiple choice question (with options) to answer.
What is produced when a colorless solution of lead nitrate is added to a colorless solution of potassium iodide? | [
"brown solid precipitate",
"yellow solid precipitate",
"purple solid precipitate",
"blue solid precipitate"
] | B | When a colorless solution of lead(II) nitrate is added to a colorless solution of potassium iodide, a yellow solid called a precipitate is instantly produced ( Figure below ). A precipitate is a solid product that forms from a reaction and settles out of a liquid mixture. The formation of a precipitate may also indicate the occurrence of a chemical reaction. |
SciQ | SciQ-958 | 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.
Due to the difference in the distribution of charge, water is what type of molecule? | [
"crooked",
"ionic",
"polar",
"uneven"
] | C | Due to the difference in the distribution of charge, water is a polar molecule. |
SciQ | SciQ-959 | ## Ch112
The aorta carries blood away from the heart at a speed of about 39 cm/s and has a radius of approximately 1.0 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.072 cm/s, and the radius is about 6.2 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
• solve in the same approach...
The aorta carries blood away from the heart at a speed of about 44 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.071 cm/s, and the radius is about 6.4 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Solution:
The volume has to be the same, so:
44cm/s * 1.44pi cm^2 = 199.05 cm^3/s
so x(.071cm/s * pi*.00064^2) = 199.05cm^3/s
x = (44 * 1.44pi)/(.071 * pi * .00064^2) = 2.17869718 * 10^9 capillaries
• The aorta carries blood away from the heart at a speed of about 37 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.069 cm/s, and the radius is about 6.3 x 10^-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Flow rate = Cross sectional area * speed
Blood flow from the aorta = (pi)(1.2)^2(37) = 167.38 cm^3/sec.
The following is multiple choice question (with options) to answer.
What do we call the major artery carrying recently oxygenated blood away from the heart? | [
"muscular artery",
"aorta",
"capillary",
"arteriole"
] | B | Arterial Supply The major artery carrying recently oxygenated blood away from the heart is the aorta. The very first branches off the aorta supply the heart with nutrients and oxygen. The next branches give rise to the common carotid arteries, which further branch into the internal carotid arteries. The external carotid arteries supply blood to the tissues on the surface of the cranium. The bases of the common carotids contain stretch receptors that immediately respond to the drop in blood pressure upon standing. The orthostatic reflex is a reaction to this change in body position, so that blood pressure is maintained against the increasing effect of gravity (orthostatic means “standing up”). Heart rate increases—a reflex of the sympathetic division of the autonomic nervous system—and this raises blood pressure. |
SciQ | SciQ-960 | biochemistry, transition-metals, oxidation-state, proteins
15. Goddard, W. A., III; Olafson, B. D. Ozone Model for Bonding of an O2 to Heme in Oxyhemoglobin. Proc. Natl. Acad. Sci. 1975, 72 (6), 2335–2339. DOI: http://10.1073/pnas.72.6.2335.
16. Chen, H.; Ikeda-Saito, M.; Shaik, S. Nature of the Fe−O2 Bonding in Oxy-Myoglobin: Effect of the Protein. J. Am. Chem. Soc. 2008, 130 (44), 14778–14790. DOI: 10.1021/ja805434m.
17. Grinstaff, M. W.; Hill, M. G.; Labinger, J. A.; Gray, H. B. Mechanism of catalytic oxygenation of alkanes by halogenated iron porphyrins. Science 1994, 264 (5163), 1311–1313. DOI: 10.1126/science.8191283.
18. Wilson, S. A.; Kroll, T.; Decreau, R. A.; Hocking, R. K.; Lundberg, M.; Hedman, B.; Hodgson, K. O.; Solomon, E. I. Iron L-Edge X-ray Absorption Spectroscopy of Oxy-Picket Fence Porphyrin: Experimental Insight into Fe–O2 Bonding. J. Am. Chem. Soc. 2013, 135 (3), 1124–1136. DOI: 10.1021/ja3103583
19. Wilson, S. A.; Green, E.; Mathews, I. I.; Benfatto, M.; Hodgson, K. O.; Hedman, B.; Sarangi, R. X-ray absorption spectroscopic investigation of the electronic structure differences in solution and crystalline oxyhemoglobin. Proc. Natl. Acad. Sci. 2013, 110 (41), 16333–16338. DOI: 10.1073/pnas.1315734110.
The following is multiple choice question (with options) to answer.
In a model of a hemoglobin molecule, the purple part indicates the presence of what element? | [
"silver",
"gold",
"iron",
"helium"
] | C | Hemoglobin Molecule. This model represents the protein hemoglobin. The purple part of the molecule contains iron. The iron binds with oxygen molecules. |
SciQ | SciQ-961 | everyday-chemistry, metal, transition-metals, smell
Also, it turns out that $\ce{Fe^{2+}}$ ions (but not $\ce{Fe^{3+}}$) are capable of oxidizing substances present in oils produced by the skin, namely lipid peroxides. A small amount of $\ce{Fe^{2+}}$ ions are produced when iron comes into contact with acids in sweat. These then decompose the oils releasing a mixture of ketones and aldehydes with carbon chains between 6 and 10 atoms long. In particular, most of the smell of metal comes from the unsaturated ketone 1-octen-3-one, which has a fungal/metallic odour even in concentrations as low as $1\ \mu g\ m^{-3}$ . In short:
Sweaty skin corrodes iron metal to form reactive $\ce{Fe^{2+}}$ ions that are oxidized within seconds to $\ce{Fe^{3+}}$ ions while simultaneously reducing and decomposing existing skin lipid peroxides to odorous carbonyl hydrocarbons that are perceived as a metallic odor.
In the supporting information for the article (also free-access), the authors describe experiments performed with other metals, including copper:
The following is multiple choice question (with options) to answer.
What kind of gland produces an oily substance that waterproofs the hair and skin? | [
"nail gland",
"mucous gland",
"secretion gland",
"sebaceous gland"
] | D | oily substance produced in the dermis by a sebaceous gland that waterproofs the hair and skin. |
SciQ | SciQ-962 | acid-base
Title: Is the conjugate base of every polyprotic acid amphoteric? Since all compounds with an accessable free lone pair can act as a Brønsted-Lowry base, I was wondering if there was any specific example of a substance that when it loses a proton, it cannot accept a proton but can donate another proton.
Please note that I am not considering something like sulfuric acid which is a strong diprotic acid, as $\ce{HSO^{-}_{4}}$ still accepts a proton even if its to a limited extent. The conjugate base of sulfuric acid, bisulfate ion, shows little amphoteric character in water solution. Unless you drop the pH to about 2 or below, it is only an acid, and a moderately strong one at that.
The following is multiple choice question (with options) to answer.
Which type of substance is considered a proton donor in a reaction? | [
"acid",
"base",
"carbon",
"oxygen"
] | A | The Arrhenius definition of acids and bases is somewhat limited. There are some compounds whose properties suggest that they are either acidic or basic, but which do not qualify according to the Arrhenius definition. An example is ammonia (NH 3 ). Its aqueous solution turns litmus blue, it reacts with acids, and displays all the other properties of a base. However, it does not contain the hydroxide ion. In 1923, a broader definition of acids and bases was independently proposed by Danish chemist Johannes Brønsted (1879-1947) and English chemist Thomas Lowry (1874-1936). A Brønsted-Lowry acid is a molecule or ion that donates a hydrogen ion in a reaction. A Brønsted-Lowry base is a molecule or ion that accepts a hydrogen ion in a reaction. A hydrogen ion is commonly referred to as a proton, and so acids and bases are proton donors and proton acceptors respectively according to the Brønsted-Lowry definition. All substances that are categorized as acids and bases under the Arrhenius definition are also defined as such under the Brønsted-Lowry definition. The new definition, however, includes some substances that are left out according to the Arrhenius definition. |
SciQ | SciQ-963 | 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 are materials that are good conductors of thermal energy called? | [
"thermal conductors",
"atmospheric conductors",
"geospatial conductors",
"reflective conductors"
] | A | Conduction is usually faster in liquids and certain solids than in gases. Materials that are good conductors of thermal energy are called thermal conductors . Metals are excellent thermal conductors. They have freely moving electrons that can transfer energy quickly and easily. That’s why the metal pot in Figure above soon gets hot all over, even though it gains thermal energy from the fire only at the bottom of the pot. In Figure below , the metal heating element of the curling iron heats up almost instantly and quickly transfers energy to the strands of hair that it touches. |
SciQ | SciQ-964 | newtonian-mechanics, forces, mass, inertia
Title: Proof behind inertia increases with mass? My book starts off by giving an example that if we kick a football it flies away but if we kick a stone of the same size with equal force then it stays at rest. It says that from this series of events we may conclude that inertia increases with mass.
But can't there be several other reasons why the stone didn't move?
For example considering the fact that the stone has greater mass, maybe when we kick the stone with the same amount of force used to kick the football, the stone does start to move with lesser acceleration than the football but is subsequently stopped by friction?
On top of that since the stone weighs more, the friction is also more. Maybe that stops from it flying away? You are completely right: the stone, due to its higher inertia (because of its higher mass), accelerates less but is still moving. That’s the essence of $F=ma$. So the example in your book is indeed not accurate.
An accurate experiment would take place in more controlled context, e.g. letting the probes of different mass hang from a long string. That’s what Newton did AFAIK.
The following is multiple choice question (with options) to answer.
Why do players with more mass often have a larger impact in football? | [
"momentum is larger",
"potential energy is lower",
"kinetic energy is lower",
"Velocity is larger"
] | A | Figure 28.18 Momentum is an important concept for these football players from the University of California at Berkeley and the University of California at Davis. Players with more mass often have a larger impact because their momentum is larger. For objects moving at relativistic speeds, the effect is even greater. (credit: John Martinez Pavliga). |
SciQ | SciQ-965 | ichthyology, vertebrates
Title: If an organism is supported only by cartilage, does it have an endoskeleton? Lamprey and sharks lack bones, but does this mean they are not classified as having an endoskelton? Does an organism need bone to be considered as having an endoskeleton? From wikipedia
An endoskeleton (From Greek ἔνδον, éndon = "within", "inner" + σκελετός, skeletos = "skeleton") is an internal support structure of an animal, composed of mineralized tissue.
Cartilage is a mineralized tissue so it counts as a skeleton from this definition. A bit further in the wikipedia article it says
The vertebrate endoskeleton is basically made up of two types of tissues (bone and cartilage)
The following is multiple choice question (with options) to answer.
Corals build hard exoskeletons that grow to become what? | [
"algae",
"fungi",
"stability reefs",
"coral reefs"
] | D | |
SciQ | SciQ-966 | homework-and-exercises, newtonian-mechanics, forces, newtonian-gravity, potential-energy
Title: Calculate magnitude of force acting on some area by falling object I have simple question: is it possible to calculate magnitude of force acting on some area by falling object?
Let's say I have an object with mass $5\text{ kg}$. I drop that object in height 1 meter. It potential energy was
$$\begin{align}
E_p &= hmg \\
E_p &= 5(9.81) \\
E_p &= 49.05 \text{ J}
\end{align}$$
Near the ground, kinetic energy of object is
$$E_k = E_p$$
So the velocity is
$$\begin{align}
E_k &= \sqrt{2\frac{E_p}{5}} \\
E_k &= \sqrt {19.62} = 4.429 \frac{\mathrm{m}}{\mathrm{s}}
\end{align}$$
Is there any way how to calculate force of object against ground when it falls on it? If not, what something (against ground) can be calculated for this problem?
EDIT: Let's say that ground is from glass, thickness $10\text{ cm}$. What properties would be affected? Your data is not enough. You need some data on the ground material (such as modulus of elasticity), body material and shape, etc. For example, if the ground is not hard, the force will be small.
EDIT (06/10/2013): As I said, you need more input data. I don't have time to give you a detailed analysis. You may wish to look at https://www.endevco.com/news/archivednews/2009/2009_02/tp321.pdf to get an idea about the essential factors of the problem.
The following is multiple choice question (with options) to answer.
What property is the result of force acting on a given area? | [
"vaccuum",
"pull",
"resistance",
"pressure"
] | D | Pressure is the result of force acting on a given area. It can be represented by the equation:. |
SciQ | SciQ-967 | biochemistry, neuroscience, brain, neuroanatomy
Title: The human brain in numbers I: neurons Even though knowing the number of neurons in a functional unit or with the same function is not of main importance, it may be interesting to know their orders of magnitude, especially in the human brain. For example:
|------------------|------------------|
| cerebellum | 100,000,000,000 |
| cortex | 20,000,000,000 |
| telencephalon | 10,000,000,000 |
| brainstem | 1,000,000,000 |
| sensory neurons | |
| haptic | 500,000,000 |
| visual | 100,000,000 |
| auditory | 2,000 |
| limbic system | |
| amygdala | 10,000,000 |
|------------------|------------------|
The following is multiple choice question (with options) to answer.
Nervous tissue consists of just two basic types of nerve cells: neurons and? | [
"glial cells",
"red blood cells",
"white blood cells",
"mammalian cells"
] | A | Although the nervous system is very complex, nervous tissue consists of just two basic types of nerve cells: neurons and glial cells. Neurons are the structural and functional units of the nervous system. They transmit electrical signals, called nerve impulses. Glial cells provide support for neurons. For example, they provide neurons with nutrients and other materials. |
SciQ | SciQ-968 | molecular-biology, neurotransmitter, muscles, receptor
Is the membrane continuous along these tubules, or does the tubule just end somewhere inside the muscle fiber?
The membranes are continuous.
When the muscle is twitching... is this neurological of nature, or is it related to a molecular cause in the muscle itself?
Most things you'd call a muscle twitch are at the whole-muscle-group scale, involving the coordinated contraction of many individual motor units, so it's basically neurological.
When the muscle is cramping... I'm almost certain this arises in the muscle. What causes it? A malfunction with regard to the calcium ions?
A muscle cramp is a colloquialism for a couple of things that are quite different from each other. Overall, as with the previous question, if someone's experiencing a muscle cramp that means it's a fairly macroscopic phenomenon and it likely involves a whole group of muscle filaments, so it's neurological. Most spasms and cramps are neurologically mediated.
The connections with electrolyte balances (cramps from low sodium, potassium, magnesium, or calcium) also hint at the neurological basis because neurons act on each other (and on muscles) by forming or dissipating ion gradients. You may know that low dietary calcium can lead to muscle cramps; if this was relevant to the calcium release within the myocyte (from the sarcoplasmic reticulum) then the calcium-starved muscles wouldn't be expected to chronically contract (which requires calcium) but to chronically relax.
That being said, there's a lot of room for feedback mechanisms. So, let's say a person experiences a muscle tear; the tear is small enough that it doesn't compromise the function of the entire muscle group. In this case it's adaptive for the local damage to 'signal' to the rest of the muscle group to initiate spasm so as to stabilize the damaged structures as they're repaired. In this scenario the local damage would 'inform' a neurological (and/or endocrine) response that actually effects the spasm.
Lastly, and on a slightly different subject, what are the microlesions in the muscles that occur during strength training, and what is the overcompensation that happens?
The following is multiple choice question (with options) to answer.
The plasma membrane of a skeletal muscle fiber is called the what? | [
"sheath",
"soleus",
"annulata",
"sarcolemma"
] | D | Skeletal Muscle Fiber Structure Each skeletal muscle fiber is a skeletal muscle cell. These cells are incredibly large, with diameters of up to 100 µm and lengths of up to 30 cm. The plasma membrane of a skeletal muscle fiber is called the sarcolemma. The sarcolemma is the site of action potential conduction, which triggers muscle contraction. Within each muscle fiber are myofibrils—long cylindrical structures that lie parallel to the muscle fiber. Myofibrils run the entire length of the muscle fiber, and because they are only approximately 1.2 µm in diameter, hundreds to thousands can be found inside one muscle fiber. They attach to the sarcolemma at their ends, so that as myofibrils shorten, the entire muscle cell contracts (Figure 38.34). |
SciQ | SciQ-969 | newtonian-mechanics, forces, newtonian-gravity, free-body-diagram, string
Title: How does a weight connected to a string over a pulley pulling a cart apply force onto the cart? How does the mass hanging down on the bottom (Assuming frictionless environment) apply a pull force to the car? How does the weight of the object transfer to the string (tension force and maybe the pulley does something?) which pulls the car? I wonder if the following diagram is helpful:
There is a force from the pulley on the string - that is what allows the tension to "turn the corner" so the force from the weight (which is downwards) is turned into a horizontal force (tension that can pull the cart).
The following is multiple choice question (with options) to answer.
What is the force pulling an object downward called? | [
"density",
"weight",
"magnetism",
"momentum"
] | B | The weight of an object is the force pulling the object downward. On Earth, this would be the gravitational force of the Earth on the object. On the moon, this would be the gravitational force of the moon on the object. The gravitational force of the moon is one-sixth the magnitude of the gravitational force of the Earth; the weight of the moon rock on the moon will be one-sixth the weight of the moon rock on the Earth’s surface. Weight is measured in force units—newtons—by a calibrated spring scale as shown here. |
SciQ | SciQ-970 | 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.
Which part of all mammals have the same basic bone structure? | [
"knees",
"necks",
"forelimbs",
"ankles"
] | C | The forelimbs of all mammals have the same basic bone structure. |
SciQ | SciQ-971 | formal-languages, notation
Title: What does ({a,b}*)² mean? Pretty much just the title. Is it all possible combinations of a and b that have 2 letters ? It’s not a standard way to specify a regular or any other language, so any answer would be a guess. Most likely candidates:
A string in (a, b)*, followed by another string in (a, b)*
A string in (a, b)*, followed by the same string again.
Ask whoever gave this specification for a language.
The following is multiple choice question (with options) to answer.
The symbol for each what is usually the first letter or two of its name? | [
"element",
"property",
"state",
"material"
] | A | |
SciQ | SciQ-972 | newtonian-mechanics, mass
Title: Why is there no effect in the mass of the bob on the period of the simple pendulum? Why is there no effect in the mass of the bob on the period of the simple pendulum?
I have found out many different explanations. However, I wasn't able to find a scientific explanation for my research proposal. TLDR: Restoring force (force of gravity) is dependent on mass, so mass cancels out in $F=ma$.
We know that force due to gravity $F_g=mg$, and so the part of acceleration contributed by the gravitational force, which is $g$, stays the same. The only other force is the tension by the rod/string, which depends linearly on the mass (Net force $T-mg=\frac{mv^2}{r}$, so $T=mg+\frac{mv^2}{r}$), and so if you also apply $F=ma$, the mass divides out. (Note: from now on everything loses dependence on mass, so answer could technically stop here. But OP specifically requested for period, so I'll go on.) If the acceleration stays the same, if the length and the angle stays the same, then the magnitude and direction of acceleration do not change. Therefore, doesn't matter what mass it is, the initial acceleration is the same, and the acceleration changes with time in the same way, as a function $a(t)$. Therefore, if the acceleration at all times is the same, regardless of the mass, the period $T=f(\theta)\cdot2\pi \sqrt{\frac{l}{g}} $, will not depend on the mass.
The following is multiple choice question (with options) to answer.
The only things that affect the period of a simple pendulum are its length and the acceleration due to gravity. the period is completely independent of other factors, such as this? | [
"rate",
"speed",
"size",
"mass"
] | D | for the period of a simple pendulum. This result is interesting because of its simplicity. The only things that affect the period of a simple pendulum are its length and the acceleration due to gravity. The period is completely independent of other factors, such as mass. As with simple harmonic oscillators, the period T for a pendulum is nearly independent of amplitude, especially if θ is less than about. |
SciQ | SciQ-973 | biochemistry, hydrogen-bond, amino-acids
Title: Why there is hydrogen bonding involved in salt bridge formation between glutamic acid and lysine? I saw this figure on Wikipedia:
After seeing this image I got really confused about the difference between these two, or maybe the similarities. Of course, I understand that a hydrogen bond can be seen as +/- interaction (because of the dipole). However, I don't understand why this Lys + Glu interaction would also make a hydrogen bond. If it would, I would expect the hydrogen bond between the double bounded oxygen and the $\ce{N}$ atom from the $\ce{NH3+}.$
I hope someone can explain me what this figure means in respect to both of the interactions shown. An electrostatic interaction is one between a centre of positive charge and a centre of negative charge. In your example, instead of a primary ammonium cation ($\ce{H3\overset{+}{N}R}$) you could also consider the fully methylated quarternary ammonium cation $\ce{Me3\overset{+}{N}R}$ which would still be able to build up an electrostatic interaction with the acid anion. The centre of positive charge is somewhere between the three ammonium hydrogens and the centre of negative charge somewhere between the two carboxylic oxygens.
A hydrogen bond, on the other hand, is a directional interaction of the type $\ce{X-H\bond{....}Y}$, where $\ce{X}$ and $\ce{Y}$ are electronegative elements and $\ce{Y}$ must feature a lone pair. Thus, hydrogen bonds always contain three atoms and only those three. One one of the three ammonium hydrogens can form a hydrogen bond with only one of the two oxygen atoms.
The following is multiple choice question (with options) to answer.
What is the amide bond that occurs between the amino nitrogen of one amino acid and the carboxyl carbon of another amino acid? | [
"a magnetite bond",
"a amino bond",
"a peptide bond",
"a covalent bond"
] | C | A peptide bond is the amide bond that occurs between the amino nitrogen of one amino acid and the carboxyl carbon of another amino acid. The resulting molecule is called a dipeptide. Notice that the particular side chains of each amino acid are irrelevant since the R groups are not involved in the peptide bond. |
SciQ | SciQ-974 | cell-biology
Title: Structure of Cell Are cells spheres or ovals/circles bound by phospholipidbilayer?
If they are spherical how are we able to see the nucleus through the phospholipid bilayer under a microscope? Not exactly. That is a stereotype of cells. Muscle cells are not round nor oval, but rather elongated rods. If you were to look up epithelia cells, you can quickly see that cells are grouped based on their physical characteristics; simple (round/oval & single layer), columnar, and cuboidal to name a few. Cells come in many shapes and sizes. As Hans stated, stains are vital in viewing cellular components. There is a diverse amount of stains used - which all carry a purpose and benefit in a specific application.
The following is multiple choice question (with options) to answer.
What encloses the border of animal cells? | [
"cells membrane",
"Jacket membrane",
"plasma membrane",
"dust membrane"
] | C | 3.4 | The Cell Membrane By the end of this section, you will be able to: • Understand the fluid mosaic model of membranes • Describe the functions of phospholipids, proteins, and carbohydrates in membranes A cell’s plasma membrane defines the boundary of the cell and determines the nature of its contact with the environment. Cells exclude some substances, take in others, and excrete still others, all in controlled quantities. Plasma membranes enclose the borders of cells, but rather than being a static bag, they are dynamic and constantly in flux. The plasma membrane must be sufficiently flexible to allow certain cells, such as red blood cells and white blood cells, to change shape as they pass through narrow capillaries. These are the more obvious functions of a plasma membrane. In addition, the surface of the plasma membrane carries markers that allow cells to recognize one another, which is vital as tissues and organs form during early development, and which later plays a role in the “self” versus “non-self” distinction of the immune response. The plasma membrane also carries receptors, which are attachment sites for specific substances that interact with the cell. Each receptor is structured to bind with a specific substance. For example, surface receptors of the membrane create changes in the interior, such as changes in enzymes of metabolic pathways. These metabolic pathways might be vital for providing the cell with energy, making specific substances for the cell, or breaking down cellular waste or toxins for disposal. Receptors on the plasma membrane’s exterior surface interact with hormones or neurotransmitters, and allow their messages to be transmitted into the cell. Some recognition sites are used by viruses as attachment points. Although they are highly specific, pathogens like viruses may evolve to exploit receptors to gain entry to a cell by mimicking the specific substance that the receptor is meant to bind. This specificity helps to explain why human immunodeficiency virus (HIV) or any of the five types of hepatitis viruses invade only specific cells. |
SciQ | SciQ-975 | 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.
Heterotrophic organisms use organic compounds, usually from other organisms, as a source of what basic element of life? | [
"carbon",
"oxygen",
"hydrogen",
"monoxide"
] | A | Heterotrophic organisms use organic compounds, usually from other organisms, as carbon sources. |
SciQ | SciQ-976 | electrons, energy-conservation, atomic-physics, orbitals
Title: The unanswered question: Where do electrons get their ever-lasting circulating energy? This question has been asked by many others like me, and in so many forums as well as here, and answered by many as well, and I still do not find the answer. The question is "Where do electrons get their ever-lasting circulating energy?". All answers somehow start explaining about the descreet energy levels of the electrons (BUT not how these emerged at the first place), the theories about why electrons do not crash into the nucleus, and the uncertainty principle etc. But no one so far really answers the main question - where the electrons get their initial energy from, the energy they need to start operating at all? Is it the energy they got at the beginning, by the proposed Big Bang of the Universe, or how? Is this a question that is still unanswered by science? Well, we don't know how the universe got started, so a valid answer would just be that there's some amount of energy available and distributed throughout all physical systems, and we can't say where it came from.
(If we take into account the expansion of the universe then the total energy isn't constant, but it changes in a predictable way.)
However, for the specific case of an atom I can be a bit more useful: an electron in an atom has less energy than an electron by itself. This makes sense: things generally tend towards a state of lower energy, so if an atom had positive energy (instead of negative) it would break apart. If you start with a proton and an electron separated from each other, they will attract thanks to the electromagnetic force, and end up together in a state of lower energy. The difference will be radiated away as electromagnetic waves, and will disperse through the universe.
The following is multiple choice question (with options) to answer.
Electrons always result in what? | [
"an contraposition that is larger than the parent atom",
"an anion that is larger than the parent atom",
"an dissociative that is larger than the parent atom",
"A HYPER-PIGMENTATION THAT IS LARGER THAN THE PARENT ATOM"
] | B | The addition of electrons always results in an anion that is larger than the parent atom. When the electrons outnumber the protons, the overall attractive force that the protons have for the electrons is decreased. The electron cloud also spreads out because more electrons results in greater electron-electron repulsions. Notice that the group 16 ions are larger than the group 17 ions. The group 16 elements each add two electrons while the group 17 elements add one electron per atom for form the anions. |
SciQ | SciQ-977 | diffusion
The reverse process is also happening with molecules diffusing from right to left at a rate proportional to their concentration in the right side solution. As the concentration on the right side increases to be equal to the concentration on the left, so the diffusion rates become equal and there is zero nett diffusion and the system approaches equilibrium.
Note that this assumes a "perfect" system where there is no chemical reaction occurring between the solutes or between the solutes and the membrane. In practice this means that either the interaction between solutes A and B is the same as the interaction between the solutes and the solvent or that the solute molecules are so greatly outnumbered by the solvent molecules that the solute-solute interactions are not significant.
The rate of diffusion of solute A may be different from B (i.e. the proportionality constant between rate and concentration may be different). This means that before reaching equilibrium the relative concentrations of A and B may change but at equilibrium, the relative concentration will be the same as initially.
If we define "reaching equilibrium" as having some fraction (say 99.99%) of the final concentration then increasing the initial global concentration will increase the lag for both solutes equally and will not change their relative concentrations.
The following is multiple choice question (with options) to answer.
The diffusion of water across a membrane because of a difference in concentration is called? | [
"hemostasis",
"osmosis",
"diffusion",
"absorption"
] | B | The diffusion of water across a membrane because of a difference in concentration is called osmosis . Let's explore three different situations and analyze the flow of water. |
SciQ | SciQ-978 | species-identification, theoretical-biology, taxonomy, literature, bioluminescence
Title: Looking for the closest example of life forms similar to some mathematical patterns
Caveat: this is my first question here, it is quite interdisciplinary, but I hope to be in the correct place to ask. I am a user of Mathematics Stack Exchange since some years ago, and this question is related with some questions there (here, here whose general formula is discussed here and here).
Context: I am preparing a mathematical paper regarding a new family of dynamical systems (if you are not familiar with the concept, simplifying the idea it is a mathematical formula in which starting from a initial value, once applied to the formula the resulting value is again applied to the formula, and so on, finally the values are plotted and eventually a -sometimes interesting- pattern emerges) whose attractors (plotted patterns) in the present case seem to have unexpected pareidolic properties.
Basically some of the patterns generated by these systems show similarities with some structures of invertebrate life forms, specially insects, marine jellyfish, and zooplancton and also due to the patterns of the accumulation of points, also with life forms presenting bioluminescence properties.
For each interesting pattern so far I have tried to find the closest life form example, to compare both the model and the life form patterns.
So my target is including in the paper the closest life form similar to each mathematical pattern. Initially it is just a pareidolic coincidence, but it might be interesting if the mathematical formula can resemble models of some organic structures.
These are the ones I have been able to gather, both the model and the closest life form I found. The pictures I am using at the right side of and below the images are just for the sake of completeness (they belong to their respective owners, I do not own them, if there is any problem I will remove them, so just please let me know). The formula can be verified at the MSE links I have added at the beginning of the question and the Python code to generate them is in this link (please feel free to use it and modify it). The questions are after the examples (click to enlarge):
Patterns similar to thorax and abdomen of Bembicini wasp, head and body of Turritopsis dohrnii (inmortal jellyfish) and Tardigrade limbs:
Patters similar to Drain fly:
The following is multiple choice question (with options) to answer.
Bioluminescence is an example of what type of activity that is carried out by a cell and is precisely coordinated and controlled? | [
"respiration",
"metabolic",
"reproduction",
"growth"
] | B | |
SciQ | SciQ-979 | neuroscience, physiology, human-physiology, reflexes
Title: Are there neuron mediated reactions faster than reflexes? I'm interested in how fast the human body can respond to a stimulus. I know the fastest reflex, the blink reflex, operates around 100ms from stimulus to reaction. I also know that the blink reflex is known as the fastest reflex in the human body. My interest is in the fastest responses to stimuli I can find in the body.
Are there any faster responses to stimuli within the human body which use neurons but are not categorized as a reflex (due to some technicality), meaning they could be faster than the fastest reflex? To the best of my understanding a reflex is defined by the use of neurons to convey the information, I'm just wondering if there are any grey areas which don't qualify as a reflex but may be faster. I don't want to potentially write off an entire class of neurological behavior in my research simply because I stopped at the blink reflex. A reflex as fast as the blink in a neural circuit:
I would consider suppression of outer hair cells in the cochlea to be a reflex; the faster component of this reflex is about the same as the blink reflex, around 100 ms. The hair cells themselves aren't considered neurons, but the pathway that suppresses their motility certainly is.
A much much faster non-neuronal "reflex":
That said, the outer hair cells themselves also dance along quite fast in response to sensory input, even faster than the typical hearing range for humans, faster than 20kHz! In some ways, this is a reflex because you are taking sensory (specifically, auditory) information and turning it into a motor response, but all the "action" is taking place within one cell, and it isn't a neuron.
A more classical reflex that is substantially faster than 100 ms
Reflexes in the periphery can be much faster than 100 ms. The myotatic reflex, or stretch reflex, can be as fast as 30 ms in the knee - this is the reflex that is tested when a physician smacks you on the knee with a hammer (used as a test of spinal and peripheral nerve function, not as a punishment). It's likely there are other stretch reflexes that are faster just because distances to the spinal cord are shorter, but these might be more difficult to test (in this paper they report latencies as fast as 20 ms).
The following is multiple choice question (with options) to answer.
What reflex is commonly tested in newborn infants to establish the presence of neuromuscular function? | [
"phalanges",
"plantar",
"glandular",
"renal"
] | B | Approximate colors are shown, along with pKin values and the pH range over which the color changes. It is important to be aware that an indicator does not change color abruptly at a particular pH value; instead, it actually undergoes a pH titration just like any other acid or base. As the concentration of HIn decreases and the concentration of In− increases, the color of the solution slowly changes from the characteristic color of HIn to that of In−. As we will see in Section 16.6 "Buffers", the [In−]/[HIn] ratio changes from 0.1 at a pH one unit below pKin to 10 at a pH one unit above pKin. Thus most indicators change color over a pH range of about two pH units. We have stated that a good indicator should have a pKin value that is close to the expected pH at the equivalence point. For a strong acid–strong base titration, the choice of the indicator is not especially critical due to the very large change in pH that occurs around the equivalence point. In contrast, using the Saylor URL: http://www. saylor. org/books. |
SciQ | SciQ-980 | ionic-compounds, oxidation-state, terminology
Something like the oxalate anion $\ce{C2O4^2-}$ is a multinuclear anion. Its ionic charge is $2-$, as evident by the superscript. However, you cannot always determine the constituent elements’ oxidation states a priori — the only thing you do know is that the sum of the oxidation states must equal the charge number. In oxalate, carbon has $\mathrm{+III}$ as you correctly mentioned and oxygen has $\mathrm{-II}$, as it should be of no surprise to you. Added up, this leaves us with:
$$2 \times (+3) + 4 \times (-2) = +6 + -8 = -2$$
And $2-$ is the ionic charge as we already know. This rule goes both ways, so you can use the (known) ionic charge of a multinuclear ion to determine an element’s oxidation state if the other oxidation states are known: in $\ce{SO3^2-}$ oxygen has $\mathrm{-II}$, so sulphur can only have $\mathrm{+IV}$.
The following is multiple choice question (with options) to answer.
All of the monatomic ions have oxidation numbers equal to their? | [
"atomic number",
"charges",
"shape",
"atomic weight"
] | B | There are 6 elements in this reaction. All of the monatomic ions have oxidation numbers equal to their charges. Additionally, we can assign an oxidation state of -2 to each oxygen atom and +1 to each hydrogen atom. Now, we just need to assign the oxidation states of manganese in MnO 4 - , nitrogen in the nitrite and nitrate ions, and sulfur in the sulfate ion. These can be determined by choosing a value for which all of the oxidation states in the ion add up to its overall charge. For example, in the nitrite ion:. |
SciQ | SciQ-981 | 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.
Unlike plants, animal species rely almost exclusively on what type of reproduction? | [
"multiplication",
"pollination",
"regeneration",
"sexual reproduction"
] | D | Introduction Plants have evolved different reproductive strategies for the continuation of their species. Some plants reproduce sexually, and others asexually, in contrast to animal species, which rely almost exclusively on sexual reproduction. Plant sexual reproduction usually depends on pollinating agents, while asexual reproduction is independent of these agents. Flowers are often the showiest or most strongly scented part of plants. With their bright colors, fragrances, and interesting shapes and sizes, flowers attract insects, birds, and animals to serve their pollination needs. Other plants pollinate via wind or water; still others self-pollinate. |
SciQ | SciQ-982 | life, extremophiles
Title: How close to Earth's core can organisms live? We don't to know much about organisms living deep below the Earth's crust. Recently a team led by S. Giovanni discovered some microbes 300 m below the ocean floor. The microbes were found to be a completley new and exotic species and apparently they feed off hydrocarbons like methane and benzene. Scientists speculate that life may exist in our Solar System far below the surface of some planets or moons. This raises some questions:
What is the theoretical minimum distance from Earth's core where life can still exist. Please explain how you came up with this number. For example, there are temperature-imposed limits on many biochemical processes.
Is there the potential to discover some truly alien life forms in the Earth's mantle (by this I mean, life which is not carbon based, or life which gets its energy in ways we have not seen before, or non DNA-based life, or something along these lines)?
What is the greatest distance below the Earth's crust that life has been discovered? I believe it is the 300 m I cited above, but I am not 100% sure. There's a lot we don't know about life in deep caves, but we can bound the deepest living organism to at least 3.5 kilometers down, and probably not more than 30 kilometers down.
The worms recovered from deep mining boreholes are not particularly specifically adapted to live that far down: they have similar oxygen/temperature requirements as surface nematodes.
The Tau Tona mine is about 3.5 kilometers deep and about 60˚ C at the bottom. Hydrothermal vent life does just fine up to about 80˚C, and the crust gets warmer at "about" 25˚C per kilometer. It's entirely reasonable to expect life to about 5 kilometers down, but further than that is speculation.
Increasing pressure helps to stabilize biological molecules that would otherwise disintegrate at those temperatures, so it's not impossible there could be life even deeper. It may even be likely, given that the Tau Tona life breathes oxygen.
I am certain no life we might recognize as life exists in the upper mantle.
The following is multiple choice question (with options) to answer.
Give an example of benthos that live near vents on the deep ocean floor. | [
"amphipods",
"tubeworms",
"crustaceans",
"arthropods"
] | B | Some benthos live near vents on the deep ocean floor. Tubeworms are an example ( Figure below ). Scalding hot water pours out of the vents. The hot water contains chemicals that some specialized bacteria can use to make food. Tubeworms have the bacteria living inside them. The bacteria get protection and the tubeworms get some of the food. |
SciQ | SciQ-983 | dna, chromosome
Title: Are the complementary base pairs known as genes? In my text book ,it is written that a chromosome has 1000s of genes and it is distributed throughout the chromatids except in the centromere. But we know that the chromosomes have DNAs inside them which have complementary base pairs. Then are these base pairs known as genes?? Don't assume a chromosome to be some X-shaped box that contains DNA inside it and DNA as a container of genes.
DNA, genes, Chromatid, Chromosomes are just different names at different levels of the same thing.
In molecular biology, you'll find multiple definitions of certain terms because as new insights are gained by any researcher, the definition gets modified. So one has to always make their concept clear so that they don't get confused between the same yet uniquely different terms.
So, Let's first look at how different their definitions can be:
DNA is a molecule inside cells that contains the genetic information responsible for the development and function of an organism. DNA molecules allow this information to be passed from one generation to the next. DNA is made up of a double-stranded helix held together by weak hydrogen bonds between purine-pyrimidine nucleotide base pairs: adenine (A) paired with thymine (T), and guanine (G) paired with cytosine (C). Also called deoxyribonucleic acid.
GENE, For many years the HGNC has maintained the definition of a gene as “a DNA segment that contributes to phenotype/function. In the absence of demonstrated function a gene may be characterized by sequence, transcription, or homology”. As there is still no universally agreed alternative we continue to use this definition.
Chromosome is a highly coiled structure of DNA molecule. Often observed in X-shaped only. Along with DNA, some proteins are also make up chromosomes.
The following is multiple choice question (with options) to answer.
What is the distinctive shape of the molecule that contains genetic information? | [
"cylindrical",
"cube",
"spiral",
"conical"
] | C | The spiral structure in the picture is a large organic molecule. Can you guess what it is? Here’s a hint: molecules like this one determine who you are. They contain genetic information that controls your characteristics. They determine your eye color, facial features, and other physical attributes. What molecule is it?. |
SciQ | SciQ-984 | species-identification, botany, ecology, trees
Title: Identifying a shrub with unusual "many shoots" growth behavior While recently hiking in the southern mountains of New Hampshire, we came across a plant, and some of them were exhibiting what we interpreted to be a disease, or least unusual growth. On some of the nodes, there were a large number of extra stalks:
On each plant, the number and locations of these things varied, and not all of them had it. And we first assumed it was some ivy, or parasite, or separate plant, but it seemed pretty clear to us that it was coming right from the same branch.
We soon saw there were dead versions of this plant, and all of them had this "extra shoot" variation:
So we reasoned that no matter what this thing was -- natural variation or some kind of disease -- it was killing the plants.
Google image search was no help. It possibly identified the plant as a "viburnum", but was unable to help with the growth.
Anyone know what plant this is, or what this growth behavior is the result of? Possibly an example of a "Witch's Broom."
Witch's Broom is a deformity in plants (typically woody species) which typically causes dense patches of stems/shoots to grow from a single point on the plant. The name comes from the broom-like appearance of the stems.1
Witch's broom may be caused by many different types of organisms, including fungi, oomycetes, insects, mistletoe, dwarf mistletoes, mites, nematodes, phytoplasmas, or viruses.2
Sources:
1. Wikipedia
2. Book of the British Countryside. Pub. London : Drive Publications, (1973). p. 519
Image1. Gardeningknowhow.com
Image2. Iowa state University
The following is multiple choice question (with options) to answer.
What is a bread mold and research organism that also grows in the wild on burned vegetation | [
"nemophora",
"whey",
"penicillin",
"neurospora"
] | D | |
SciQ | SciQ-985 | genetics, cell-biology, embryology, meiosis, gamete
Title: Fertilization of the human egg- where does our centrosome come from? Is there a centrosome in a human egg cell? Is the reason why the egg cell remains paused before meiosis 2 because there isn't a centrosome, and it only divides when the sperm fertilizes it thus it can have a centrosome? If this is so, then how did oogenesis happen? ? To answer the first part of your question. The sperm actually introduces two centrosomes. The centrosome then nucleates the new microtubule assembly to form the sperm aster — a step essential for successful fertilization. You can visit these sites Simerly, et al as well as Paweltz, et al
The following is multiple choice question (with options) to answer.
How do most echinoderms reproduce? | [
"asexually",
"sexually",
"grafting",
"flowering"
] | B | Some echinoderms can reproduce asexually by fission, but most echinoderms reproduce sexually. They generally have separate sexes and external fertilization. Eggs hatch into free-swimming larvae. The larvae undergo metamorphosis to change into the adult form. During metamorphosis, their bilateral symmetry changes to radial symmetry. |
SciQ | SciQ-986 | genetics, dna
Title: How do mutations come to be shared by all cells? It's my understanding that various hazards can damage the DNA in our cells, causing mutations.
But whenever I picture this, I see the damage being done to one of our tissues (for example, our lungs due to smoking, or our skin due to UV rays).
When I think about this, I see that... many cells in a smoker's lungs, or many cells on the back of a beach-goer's neck, may have mutations in their DNA. But only the cells in that tissue have these mutations... the other cells in our body would not have the same mutations.
In particular, sperm and egg cells would not have the same mutations, so the mutations due to smoking and UV rays shouldn't pass on to children.
Are there instances where mutations that occur over the course of our life are spread to every cell, including sperm and egg cells, so that every cell reflects the mutation, and the mutation is passed onto our offspring? Goods question! Only mutations that occurred when we were in the early stages of development will affect all cells. That's why pregnant mothers shouldn't smoke. The reason for this is that one cell goes on to divide and become all our cells so any mutations in that cell are passed on to cells formed when it divides. That same principle explains your smoker example. In the lung we have two types of cells which are called Type 1 and Type 2. Type 1 cells are constantly dying as they get old and they get replaced by type 2 cells whose job it is to divide continuously to replace Type 1 cells. So we have lots of type 1 and few type 2. When type 2 divide they make one type 1 cell and one type 2 cell, so type 2 cells never run out. If smoke causes a mutation in type 1 cells generally they're okay because they'll die before enough mutations occur. Of course something that causes lots of mutations could make it cancerous before it dies but that's rare. Now if it occurs in Type 2 cells every subsequent type 1 or type 2 cell that cell makes is mutated.
The following is multiple choice question (with options) to answer.
What do all cells have in common? | [
"small size",
"same shape",
"life span",
"same function"
] | A | Cells with different functions often vary in shape. They may also vary in size. However, all cells are very small. Even the largest organisms have microscopic cells. Cells are so small that their diameter is measured in micrometers. A micrometer is just one-millionth of a meter. Use the sliding scale at the following link to see how small cells and cell parts are compared with other objects. |
SciQ | SciQ-987 | thermodynamics, energy, electricity, efficient-energy-use
Title: Cutting down on power by bypassing mechanical to electrical conversions: Why not? The only answer to this I can think of is energy portability issues.
Another modern-world insanity is converting mechanical energy to electrical, only to turn it back into mechanical. The example I like to use is a refrigerator's reciprocating compressor.
If we directly attach a steam turbine's axle to the crankshaft of the compressor, we will not need to suffer losses in heat in our conversion of mechanical to electrical (at the power plant) then back to mechanical energy (in our appliance). Long ago, a primitive factory used one big engine or turbine or water wheel to rotate a set of overhead shafts, from which leather belts were suspended at intervals to power small pieces of machinery scattered throughout the factory. This arrangement was inflexible in that when the single big engine stopped, so did the entire factory, and when electricity came into common use, this overhead shafting arrangement fell quickly out of favor.
The power losses in long-distance electrical power transmission are more than made up for by the ease with which it is performed and the flexibility it affords. This makes "local power generation" as you describe it impractical because a hundred small steam turbines are much more wasteful of heat energy than one large turbine.
The only practical exception is integrated co-generation in which a small engine running on, for example, natural gas powers a generator while also spinning the shaft of a heat pump. The waste heat from the engine's cooling system makes residential hot water, the waste heat from its exhaust goes through a heat exchanger to provide hot air for space heating, the heat pump furnishes air conditioning (or pulls heat from outside the dwelling) and the electricity from the generator powers up your small appliances in the home while also charging a set of batteries.
Overall thermodynamic efficiency of such a device can exceed 95%, and examples of this technology are just now coming onto the market.
The following is multiple choice question (with options) to answer.
What do electric motors use to change electrical energy into kinetic? | [
"fans",
"resonances",
"electromagnets",
"generators"
] | C | Many common electric devices, such as doorbells, contain electromagnets. If they have moving parts, they are likely to have an electric motor. An electric motor is a device that uses an electromagnet to change electrical energy to kinetic energy. |
SciQ | SciQ-988 | bacteriology
Saier, MH. & Bogdanov, V. (2013) Membranous Organelles in Bacteria. JOURNAL OF MOLECULAR MICROBIOLOGY AND BIOTECHNOLOGY 23: 5-12 DOI: 10.1159/000346496
Free full text here.
The language used in this review seems to support the existence of mesosomes as some sort of intermediate in the formation of intracellular membranes in prokaryotes. This review is a polemic in favour of the idea that prokaryotes do indeed contain intracellular membrane-bounded compartments. It has no abstract, but the first paragraph gives a flavour of its stance:
The traditional view of life on Earth divides the living world into two major groups, prokaryotes and eukaryotes. These two groups were originally suggested to differ in very basic respects. While eukaryotes had complex cell structures including a cytoskeleton and intracellular membrane-bounded organelles, prokaryotes were believed to lack them. In fact, numerous textbooks and current sources still note this distinction and hold it to be true. For example, in Campbell’s Biology [Campbell, 1993, p. 515] it is stated without equivocation: ‘Prokaryotic cells lack membrane-enclosed organelles.’ In ‘Functional Anatomy of Prokaryotic and Eukaryotic Cells’ [Tortora et al., 2009, chapt. 4] it is similarly claimed that ‘Prokaryotes lack membrane-enclosed organelles, specialized structures that carry on various activities’. In the current Wikipedia, under ‘Prokaryote’ the following statement can be found: ‘The prokaryotes are a group of organisms whose cells lack a cell nucleus (karyon) or any other membrane-bounded organelles’. In the same online compendium under ‘Organelle’, one can read: ‘whilst prokaryotes do not possess organelles per se, some do contain protein-based microcompartments’. Proteinceous microcompartments will be the subject of a forthcoming Journal of Molecular Microbiology and Biotechnology written symposium, but this one will show that these generalizations, suggesting a lack of subcellular compartmentalization in prokaryotes, are blatantly in error [Murat et al., 2010a].
The following is multiple choice question (with options) to answer.
What are prokaryotic cells filled with? | [
"rna",
"protein",
"cytoplasm",
"chlorophyll"
] | C | cytoplasm. Like all other cells, prokaryotic cells are filled with cytoplasm. It includes watery cytosol and other structures. |
SciQ | SciQ-989 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
What is the name of plant-like protists? | [
"sponge",
"bacteria",
"algae",
"arthropod"
] | C | Plant-like protists are called algae (singular, alga). They are a large and diverse group. Some algae, diatoms, are single-celled. Others, such as seaweed, are multicellular (see Figure below ). |
SciQ | SciQ-990 | zoology
Title: What is right below skin? I was skinning a gopher so my cat can eat it (it was a pest and we didn't want to waste it). I thought its organs would fall out and make a mess, but that didn't happen. There was this sticky, transparent substance that surrounded its insides. What is this casing called? My dad said it was mucus but that isn't specific enough since there is mucus inside the stomach so I don't think they are the same.
I think this casing is found in all multicellular animals but I couldn't be sure. Based on your reference to organs falling out and the overall description, I presume you're thinking of the abdominal cavity primarily, so there you'd be looking at the peritoneum or possibly the serous membranes of other organs (e.g., pleura, pericardium). These are membranous (in the general sense, not as a cell membrane) connective tissues covering the organs found in the abdomen and chest.
Other things you'll find underneath skin would include layers of fat, other connective tissues, muscle.
Here's a labeled image of a mouse dissection from Friedrich, L., Schuster, M., de Celis, M. F. R., Berger, I., Bornstein, S. R., & Steenblock, C. (2021). Isolation and in vitro cultivation of adrenal cells from mice. STAR protocols, 2(4), 100999.:
You might also look for dissections of fetal pigs or cats, which are commonly used in laboratory demonstrations for students (more often cats longer ago, more often fetal pigs these days).
The following is multiple choice question (with options) to answer.
A sticky, moist secretion that covers mucous membranes is called what? | [
"mucus",
"sweat",
"saliva",
"pus"
] | A | One way mucous membranes protect the body is by producing mucus. Mucus is a sticky, moist secretion that covers mucous membranes. The mucus traps pathogens and particles so they can’t enter the body. |
SciQ | SciQ-991 | entomology
Title: The death of Earthworm In rainy season when children sprinkle salt on earthworm ,it dies.But salt is not dangerous.We use it daily.Then why earthworm dies? It's because on the earth worm skin's special mucous. Acording to this article: Why do earthworms die when salt is sprinkled on them? the mucous makes moist to the worm's skin, which is vital for their survival. Moreover, the worms don't have a respiratory organs, like lungs, gills, etc. This means that Carbon Dioxide and other characterized as "dump" gases can not be exchanged with the Oxygen. But worms breath through their skin, with the help of these special mucous that are developed on its skin. If their skin dries out the result will be death, because the gas exchange will not last without the mucous help. Similarly, the circulatory system won't function, because its main role is to trade gasses with the cells via red blood cells.
What about salinity?
Salinity is a very important factor for the earthworms health, because high salinity destroy their valunable and sensitive skin and kills the mucous that in fact help the worm to "breathe". Low salt concentrations are very beneficial for the worm, because not only their mortarity level is increaced, there are size changes to the worm's body (noticeable bigger size).
Here are and some photos of a worm that its enviroment has low salinity and high salinity:
High salinity:
Low-to-medium salinity
Source: Why do earthworms die when salt is sprinkled on them?.
The following is multiple choice question (with options) to answer.
What system lets flatworms maintain a proper balance of water and salts? | [
"excretory",
"digestive",
"homeostasis",
"nervous"
] | A | Flatworms reflect several major evolutionary advances in invertebrates. They have three embryonic cell layers, including mesoderm. The mesoderm layer allows them to develop organ systems. For example, they have muscular and excretory systems. The muscular system allows them to move from place to place over solid surfaces. The excretory system lets them maintain a proper balance of water and salts. Flatworms also show cephalization and bilateral symmetry. |
SciQ | SciQ-992 | geochemistry, paleoclimatology, clathrates
Title: Release mechanism for methane clathrate at the PETM The Paleocene-Eocene Thermal Maximum (PETM) is a well-studied warming event near the Paleocene-Eocene boundary.
It is characterized by its extreme warming rate: from onset to recovery the event lasted ca. 100 kyrs, and the global temperature is thought to have increased by ~6 °C in barely 20 kyrs.
This event is of particular interest not only for its $\delta^{18}\rm O$ but also a sharp negative excursion in the $\delta^{13}\rm C$, implying a strong input of $^{13}\rm C$-depleted carbon into the system.
Simplified and redrawn after Zachos et al. 2001
One frequently invoked hypothesis to explain this input is the leakage of methane from clathrates trapped in seafloor sediments.
Being a paleontologist and not a geochemist, I struggle to understand the actual chemical mechanism involved.
I was thus wondering if someone could explain the mechanisms allowing the destabilization of methane clathrates at the same time on a global scale.
If it's just linked to a temperature threshold, how come it wasn't reach prior to that (warmer temperature were reached during the Cretaceous)? There seems to be some uncertainty as to the cause and mechanism for the PETM. In the Science Daily article Methane may be answer to 56-million-year question: Ocean could have contained enough methane to cause drastic climate change (2011) reporting research from Rice University, they claim that the seafloor was already warmer, thus according to their models:
if the oceans were warmer, they would contain less dissolved oxygen and the kinetics for methane formation would have been faster.
With less oxygen to consume organic matter on the way down, more sank to the ocean floor, Gu said, and there, with seafloor temperatures higher than they are today, microbes that turn organic matter into methane work faster.
Thus, they claim, the amount methane in the form of clathrates would have been approximately the same amount as today, but in a thinner stability zone. They are not clear about what caused the destabilisation, but made the analogy of a charging-discharging capacitor (shown below, from the same source):
The following is multiple choice question (with options) to answer.
What gas associated with global warming is released when limestone is heated during the production of cement? | [
"carbon dioxide",
"oxygen",
"carbon monoxide",
"hydrogen"
] | A | Carbon dioxide is released when limestone is heated during the production of cement. |
SciQ | SciQ-993 | 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.
Because their embryos are surrounded by a thin membrane, reptiles are considered what? | [
"lineages",
"amniotes",
"vertebrates",
"carnivorous"
] | B | Reptiles are also amniotes, which means their embryos are surrounded by a thin membrane. |
SciQ | SciQ-994 | 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 type of energy is clean and does not release greenhouse gases? | [
"natural gas",
"lithosphere energy",
"coal",
"geothermal energy"
] | D | Geothermal energy is clean and does not release greenhouse gases. |
SciQ | SciQ-995 | isomers, cis-trans-isomerism
Title: How many geometrical isomers will be formed here?
Can someone help me calculate the number of geometrical isomers in this compound? According to me there should be 3 isomers here but according to my teacher, there are 4.I believe that both EZ and ZE cases will be same here. A possible reason you are being led astray is related to the way the substituents on the right side of the tri-substituted double bond are drawn in a linear fashion. However, when the hydrogen and the n-propyl group are drawn with the proper hybridization, only four isomers are possible, as napstablook has stated in a Comment.
In trienes 1 and 2 the tri-substituted double bond is stereogenic with the (Z)-designation in the former and the (E)-designation in the latter. The (Z)-propenyl group has priority over the (E)-propenyl group. The tri-substituted double bond in trienes 3 and 4 is non-stereogenic owing to the presence of identical groups at one end of the tri-substituted double bond.
The following is multiple choice question (with options) to answer.
Physical and chemical properties of geometric isomers are generally what? | [
"different",
"similar",
"difficult",
"round"
] | A | Physical and chemical properties of geometric isomers are generally different. While cis -2-butene is a polar molecule, trans -2-butene is nonpolar. Heat or irradiation with light can be used to bring about the conversion of one geometric isomer to another. The input of energy must be large enough to break the pi bond between the two carbon atoms, which is weaker than the sigma bond. At that point, the now single bond is free to rotate and the isomers can interconvert. |
SciQ | SciQ-996 | cell-biology
Title: Are there human cells, apart from red blood cells and platelets, without a nucleus? I know that blood platelets and erythrocytes do not have a nucleus. Are there more cells in the human body without a nucleus, such as pancreas, cartilage, or lung cells? Short answer
As far as I know, red blood cells and blood platelets are the only human cells in our body without a nucleus.
Background
Erythrocytes and thrombocytes are the only human cells without a nucleus, as far as I know. However, if you count the gut as being part of the human body (in essence it is a continuation of the skin and as such it can be considered to be on our outside), then we are loaded with cells lacking a nucleus, namely all the bacteria that live in our intestines such as E. coli. Bacteria, being prokaryotes, lack a nucleus. In fact, there are ten times more bacteria than human cells in our gut (Wenner, 2007).
Reference
Wenner, Sci Am 2007
The following is multiple choice question (with options) to answer.
What type of cell has a singular chromosome, no nucleus, and few other organelles? | [
"graphic",
"trophic",
"prokaryotic",
"monophyletic"
] | C | Cell division is simpler in prokaryotes than eukaryotes because prokaryotic cells themselves are simpler. Prokaryotic cells have a single circular chromosome, no nucleus, and few other organelles. Eukaryotic cells, in contrast, have multiple chromosomes contained within a nucleus and many other organelles. All of these cell parts must be duplicated and then separated when the cell divides. |
SciQ | SciQ-997 | cell-biology, microbiology
Title: Are there any organisms that are made of more than one (~5-12) cell? Prokaryotes and eukaryotes are unicellular, made of one cell. Great. Eukaryotes are unicellular or multicellular. But the typical examples of multicellular eukaryotes we have are made of, often, trillions of cells, like us humans. Ants must still be made of many millions of cells. Are there known eukaryotes with very few cells that make them up? Like, 5, or something? Or maybe a dozen cells making up the whole organism in its fully developed state? There's Trichoplax adhaerens, a Placozoa, made of a few thousand cells. Then there is Dicyema japonicum, a simple mesozoan, made up of 9 to 41 cells. Arguably, the simplest multicellular organism is the algae Tetrabaena socialis, whose body consists of 4 cells. Then, there's the parasitic Myxozoa which have 7 cells.
The following is multiple choice question (with options) to answer.
Protists, fungi, animals, and plants all consist of what kind of cells? | [
"enzymes",
"eukaryotic",
"parenchyma",
"xylem"
] | B | |
SciQ | SciQ-998 | geology, volcanology, mineralogy, minerals
Title: Where can obsidian be found? Where is obsidian found?
Is it typically found on the surface or underground?
If underground, how far under (meters or feet would be perfect)?
Also, is it found everywhere on Earth, or just in areas where volcanic activity is (or was recently) high? Obsidian is formed when a rhyolitic (or felsic) lava flows cool rapidly. This must mean that it's mostly available on the surface (and I think if you go near volcanos you can find pieces of Obsidian on the ground) because molten rock cools much faster above ground than it does below, allowing the melt to cool with small crystals (as opposed to intrusive rocks which have larger crystals). This means that Obsidian is an extrusive igneous rock.
I am betting that Obsidian is very common around most active volcanos around the world!
The following is multiple choice question (with options) to answer.
What does magma that cools underground form? | [
"plates",
"cracks",
"intrusions",
"anomalies"
] | C | Magma that cools underground forms intrusions ( Figure below ). Usually this magma is very viscous felsic magma. This magma does not rise easily and so cools slowly underground. Intrusions become land formations if they are exposed at the surface by uplift and erosion. |
SciQ | SciQ-999 | Would there ever be a reason where one is justified in reporting an uncertainty with more than one significant figure? For example, 7.3 ± 1.3 cm?
• What is the application? The reason I'm asking is because in different science and engineering fields there could be specific standards and common practices for measurement error reporting and handling. May 11, 2015 at 20:30
• I asked the question in the context of very simple measurements (lengths of pencils) just so that we'd have something specific to talk about.I would like to know these rules in order to apply them in the sciences. May 12, 2015 at 19:21
• There's no firm rule in physics: both $7.3\pm 1.3$ and $7\pm 1$ will be Ok. Something like $7.3415687464\pm 0.06813513846$ will not fly. May 12, 2015 at 19:58
• I recommend looking at this: QUAM:2012.P1 (EURACHEM/CITAC Guide, “Quantifying Uncertainty in Analytical Measurement”, 3rd Ed., 2012.) You can easily find it online, for free, and it is all about quantifying uncertainties in measurements, though with an obvious focus on analytical chemistry-related measurements.
– Ed V
Sep 2, 2019 at 16:22
Your pencil example is peculiar. You'll see why when I describe how this precision thing works in a typical case.
Say, you're measuring a room with a measuring tape that has 1 mm ticks. You get 10033 mm measurement. The way to report this is 10033$\pm$0.5 mm. You usually take the half the tick as an a priori uncertainty $\sigma=0.5$.
To increase precision you measure the room several times: 10033, 10041, 10031. Now you can calculate the standard deviation $\sigma_3\approx 5.3$ mm, so you can throw out the a priori uncertainty, and report $10035\pm 5$. You see how $\sigma_3>\sigma$.
The following is multiple choice question (with options) to answer.
What is used to report the results of scientific measurements? | [
"latin units",
"si units",
"los units",
"bi units"
] | B | The number in the measurement can be represented in different ways, including decimal form and scientific notation. (Scientific notation is also known as exponential notation; a review of this topic can be found in Appendix B. ) For example, the maximum takeoff weight of a Boeing 777-200ER airliner is 298,000 kilograms, which can also be written as 2.98 × 105 kg. The mass of the average mosquito is about 0.0000025 kilograms, which can be written as 2.5 × 10−6 kg. Units, such as liters, pounds, and centimeters, are standards of comparison for measurements. When we buy a 2-liter bottle of a soft drink, we expect that the volume of the drink was measured, so it is two times larger than the volume that everyone agrees to be 1 liter. The meat used to prepare a 0.25-pound hamburger is measured so it weighs onefourth as much as 1 pound. Without units, a number can be meaningless, confusing, or possibly life threatening. Suppose a doctor prescribes phenobarbital to control a patient’s seizures and states a dosage of “100” without specifying units. Not only will this be confusing to the medical professional giving the dose, but the consequences can be dire: 100 mg given three times per day can be effective as an anticonvulsant, but a single dose of 100 g is more than 10 times the lethal amount. We usually report the results of scientific measurements in SI units, an updated version of the metric system, using the units listed in Table 1.2. Other units can be derived from these base units. The standards for these units are fixed by international agreement, and they are called the International System of Units or SI Units (from the French, Le Système International d’Unités). SI units have been used by the United States National Institute of Standards and Technology (NIST) since 1964. Base Units of the SI System Property Measured. |
SciQ | SciQ-1000 | 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? | [
"mouth",
"stomach",
"esophagus",
"tongue"
] | A | The mouth is the first digestive organ that food enters. The sight, smell, or taste of food stimulates the release of saliva and digestive enzymes by salivary glands inside the mouth. Saliva wets the food, which makes it easier to break up and swallow. The enzyme amylase in saliva begins the chemical digestion of starches to sugars. |
SciQ | SciQ-1001 | organic-chemistry, bond, covalent-compounds
Title: The difference between peptide bonds and the bonds between polypeptides? I was doing some tests for the multiple-choice final we've got ahead. And it was on me to count the peptide bonds in an Insulin hormone with 51 aminoacids arranged in two polypeptides with 30 and 21 aminoacids. (these are not true in reality) the number of bonds were 49, not 50, and that means the bond between two polypeptides doesn't count as a peptide bond. Additionally, I know that polypeptide bonds make the proteins' molecular structure, as it is now. (just look at that shape.) PEPTIDE COVALENT BONDS CAN NEVER cause that kind of 3d orientation in space. So there must be some fundamental difference between those bonds. What is it?
My research couldn't find any results as simple things have jammed the internet. Aside from covalent bonds (amide and disulfide), the sturcture of a protein is determined by hydrogen bonds, salt bridges, and less specific interactions such as hydrophobic and hydrophilic effects. Hydrophobic portions of the protein chain tend toward the interior of the folded protein and hydrophilic regions to the exterior, in aqueous solution.
The following is multiple choice question (with options) to answer.
Insulin is made up of how many polypeptide chains? | [
"two",
"twelve",
"three",
"four"
] | A | |
SciQ | SciQ-1002 | newtonian-mechanics, energy, work, definition
Note that I wrote "the amount of a body's kinetic energy" rather than just "a body's kinetic energy". To say that the work done on the body (even with my amendments above) is the kinetic energy that it acquires doesn't give you much of an idea as to what kinetic energy IS. Your (2) gives you a better idea.
The following is multiple choice question (with options) to answer.
What is the term for the energy of movement? | [
"potential energy",
"molecular energy",
"mechanical energy",
"intrinsic energy"
] | C | 1. Mechanical energy is the energy of movement. It is found in objects that are moving or have the potential to move. |
SciQ | SciQ-1003 | evolution, species
Title: Parents that eat their own children I am told that there are some species, like fish or rabbits, that if let, will eat their own children. If this is true, how does a species like this exist? Shouldn't the fact that they kill their own lineage make them nonviable? Yes, it is true.
Prairie dogs
Prairie dogs for example are known for frequent infanticides.
Many other species kill their babies too
But of course, such behaviour also exists in other lineages such as grey langurs, gerbilles, lions, giant water bugs and Bottlenose dolphins (just to cite a few examples).
How does that evolve
It will be impossible to provide a complete universal explanation to this behaviour because the evolutionary processes causing this behaviour varies from lineage to lineage. For examples, in lions, only males kill young of the females that are still nursing and they do so when taking over a new harem only. In prairie dogs, mothers cause infanticide preferentially on others' babies but also on their own babies.
Going into the details of how such behaviour evolves in every specific lineage would probably require writing an intro on kin selection and other fields of evolutionary biology which is way too much for a single post. You may want to have a look at the wikipedia article infanticide for a start.
Shouldn't the fact that they kill their own lineage make them nonviable?
Of course, they don't kill all the babies. Only a fraction of them!
The following is multiple choice question (with options) to answer.
What type of organisms are helpless at birth and require lots of help from their parents? | [
"precocial organisms",
"altricial organisms",
"multicellular organisms",
"Microorganisms"
] | B | Organisms can use different strategies to increase their reproduction rate. Altricial organisms are helpless at birth, and their parents give them a lot of care. This care is often seen in bird species. ( Figure below ). Altricial birds are usually born blind and without feathers. Compared to precocial organisms, altricial organisms have a longer period of development before they reach maturity. Precocial organisms, such as the geese shown below, can take care of themselves at birth and do not require help from their parents ( Figure below ). In order to reproduce as much as possible, altricial and precocial organisms must use very different strategies. |
SciQ | SciQ-1004 | 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.
Metallic bonds allow metals to do what, in the manner of a willow tree? | [
"break easily",
"bend without breaking",
"stand tall",
"grow"
] | B | The thick, rigid trunk of the oak tree on the left might crack and break in a strong wind. The slim, flexible trunk of the willow tree on the right might bend without breaking. In one way, metals are like willow trees. They can bend without breaking. That’s because metals form special bonds called metallic bonds. |
SciQ | SciQ-1005 | organic-chemistry, mixtures
Title: Would Oxygen Gas and Ozone be a pure substance together? If I have oxygen gas and ozone ($\ce{O2 + O3}$) together would it be considered a pure substance or a mixture?
And would pure substances always have the same molecular structure? Ozone is highly reactive and unstable, while dioxygen is stable. There do not combine to form a compound. So, clearly it is a mixture.
To answer the second part of the question, "And would pure substances always have the same molecular structure?", first a Wikipedia definition on substances, to quote:
A chemical substance is a form of matter having constant chemical composition and characteristic properties.[1][2]...
Chemical substances can be simple substances[4], chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint.[4]
Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water...
However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical.
And further:
A chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[5] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[6] The chemical substance index published by CAS also includes several alloys of uncertain composition.[7] Non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature".[8]
The following is multiple choice question (with options) to answer.
What is a substance that can not be broken down any further into other substances? | [
"pure molecule",
"pure substance",
"unbreakable substance",
"pure material"
] | B | pure substance that cannot be broken down into other types of substances. |
SciQ | SciQ-1006 | waves
Title: Is wave motion the combined motion of the disturbance and the medium? Using a textbook slinky as an example, if the disturbance propagates through the slinky from left to right and the particles of the slinky vibrate up and down, does that mean 'wave motion' is also associated with the medium? Since the motion of the wave that we perceive is the combined motion of the disturbance and the medium? This answer is maybe not the most straightforward satisfactory answer to your stated question, but I think it anticipates ways of thinking that are used in more advanced areas of physics.
There are two pictures of what a wave is.
A wave is coherent motion in a medium; as time progresses energy moves through the medium and vibrations occur in different locations.
A wave is a propagating disturbance. It is not made of anything, the word "wave" refers a disturbance which propagates energy from one place to another.
Your question kind of implies that a wave is some combination of 1 and 2. I would say that either 1 or 2 are valid pictures, but you should treat them as distinct pictures of the same physical phenomenon and not reason about both simultaneously.
The advantage of the first picture is that it gives you a clear mechanical model of what is going on at a fundamental level; if you zoom in there are particles in the material, and the particles are oscillating back and forth in tandem -- that coherent motion is a wave. However, the disadvantage is that wave phenomena occur in many circumstances, and there are features of any particular example that will not generalize and can lead you astray if you take them too seriously. For example, light traveling in vacuum cannot be accurately visualized as motion of particles.
The advantage of the second picture is that it is more abstract and general -- wave phenomena occur in all kinds of materials, and so there is no need to specify which specific material you are thinking of, because we can make very general statements about waves that apply to any material. The disadvantage is that it can be hard to wrap your head around a disturbance without a medium, and also sometimes trying to be too general means you miss special aspects of the particular situation you might be interested in (for example, cool behavior like solitons can occur in water but not in light propagating in vacuum).
The following is multiple choice question (with options) to answer.
What three characteristics do waves have? | [
"theory , refraction and deflection",
"reflection, refraction and deflection",
"structure , refraction and deflection",
"spin, refraction, and deflection"
] | B | Most waves approach the shore at an angle. The part of the wave that is nearer the shore reaches shallow water sooner than the part that is farther out. The shallow part of the wave "feels" the bottom first. This slows down the inshore part of the wave and makes the wave "bend. " This bending is called refraction . |
SciQ | SciQ-1007 | human-biology, physiology, digestive-system, liver, bile
Both solid lines are subsets of bile acids, measured in the serum of cholecystectomized patients in a classic 1978 study. The shaded areas represent control (not cholecystectomized) patients. These measurements suggest that enterohepatic circulation still follows a pulsatile pattern after cholecystectomy.
The following is multiple choice question (with options) to answer.
What organ creates bile? | [
"liver",
"heart",
"kidney",
"pancreas"
] | A | The liver is an organ of both digestion and excretion. It produces a fluid called bile , which is secreted into the duodenum. Some bile also goes to the gall bladder , a sac-like organ that stores and concentrates bile and then secretes it into the small intestine. In the duodenum, bile breaks up large globules of lipids into smaller globules that are easier for enzymes to break down. Bile also reduces the acidity of food entering from the highly acidic stomach. This is important because digestive enzymes that work in the duodenum need a neutral environment. The pancreas contributes to the neutral environment by secreting bicarbonate, a basic substance that neutralizes acid. |
SciQ | SciQ-1008 | particle-physics, astrophysics, education
Title: Are leptons, baryons and energy the only products of radioactive decay? I recently visited my child's elementary school to speak to a science classroom about rocks and minerals. While trying to explain what a crystal is, I got sloppy and mis-spoke that an atom was the smallest possible piece of matter (rather than an element!) I was quickly stopped and corrected by a 9-year-old that told me in fact atoms can be split into leptons and baryons. I told her she was right, and explained that if an atom of an element is divided it becomes a different element (overlooking isotopes!).
My knowledge of particle physics is limited and later I began wonder what I might be leaving out, that should not be left out, when talking of the types of 'ordinary matter' in nature. What happens in high-energy physics experiments aside. I know that there are other elementary particles besides leptons and baryons, photons are obviously everywhere.
But if we restrict the discussion to radioactive decay, fusion in stars, cosmic rays, is everything a lepton, baryon, or a photon? Your
What happens in high-energy physics experiments aside
partially contradicts your final question
But if we restrict the discussion to radioactive decay, fusion in stars, cosmic rays, is everything a lepton, baryon, or a photon?
Radioctive decay has as end products photons, leptons and baryons.
Fusion and cosmic rays are the realm of elementary particle physics, the energies involved much higher than the ones in natural radiaoctivity.
The reality of what "everything is made up of" depends on the energy with which you look at "everything". The answer is that everything is made up by the elementary particles, following the rules of the standard model, nuclear models, atomic models as the energies involved in "looking" at everything diminish. It is a compositeness built up consecutively. You might be interested in this answer to a similar question.
These are the elementary particles out of which all matter is formed. Every day matter involve mainly the first column and the last column . The two middle ones have been found in cosmic rays to start with and in accelerator experiments that led to the discovery of the standard model. They are particles that cannot come out from nuclear decays or fissions, i.e. "naturally" but need excess energy to materialize.
The following is multiple choice question (with options) to answer.
What is the smallest and most fundamental unit of matter, consisting of a nucleus surrounded by electrons? | [
"atom",
"proton",
"neutron",
"molecule"
] | A | Levels of Organization of Living Things Living things are highly organized and structured, following a hierarchy that can be examined on a scale from small to large. The atom is the smallest and most fundamental unit of matter. It consists of a nucleus surrounded by electrons. Atoms form molecules. A molecule is a chemical structure consisting of at least two atoms held together by one or more chemical bonds. Many molecules that are biologically important are macromolecules, large molecules that are typically formed by polymerization (a polymer is a large molecule that is made by combining smaller units called monomers, which are simpler than macromolecules). An example of a macromolecule is deoxyribonucleic acid (DNA) (Figure 1.15), which contains the instructions for the structure and functioning of all living organisms. |
SciQ | SciQ-1009 | genetics, molecular-biology, cell-biology, cancer, mutations
Title: Question about proto-oncogenes and oncogenes? My textbook says:
Growth-promoting genes are called proto-oncogenes. Some can be changed into oncogenes by a point mutation that alters the ability of the proto-oncogene to be switched off. They remain permanently switched on. Oncogenes promote unregulated cell division. Such cell division leads to a tumour.
Does this mean that the change from proto-oncogene to oncogene is not a mutation in the exon, but rather in the intron?
I hope I used these terms correctly. Thank you for any help :) I am going to add to @MattDMo 's answer a bit.
Proto-oncogenes Function, Developmental Program, and Regulation
Proto-oncogenes are normally functioning genes that are more often than not in the pathways that lead to mitosis and cellular replication. They have important roles in the development, growth, and maintenance of the organism. Proto-oncogene is an accurate description of the genes, but I unfortunately think that sometimes people think that the genes themselves are bad and that isn't the case.
Growth and development in multicellular organisms are highly regulated processes with many checks and balances. Certain cells need to grow in certain places at certain times, and then they need to go into and remain in interphase. If they don't, or they do things at the incorrect times, the multicellular organism will not develop properly or will develop conditions such as cancer.
It is often these points of regulation that become dysregulated when a proto-oncogene becomes oncogenic. If there are regions of allostery that are affected by a mutation in the coding sequence (exon) and a control molecule that represses the activity of the enzyme through conformation change can no longer bind, then that enzyme can remain active, always turned on.
You can also have a situation where you have transcriptional regulators of proto-oncogenes that can be effected making the gene product oncogenic. If there is a mutation in an enhancer (intronic) of the gene that affects the binding kinetics of enhancers leading to a great increase in transcription, this concentrational difference can lead to uncontrolled grown and tumor formation.
The following is multiple choice question (with options) to answer.
Mutation of beneficial proto-oncogenes is a prime culprit in what disease? | [
"heart disease",
"obesity",
"cancer",
"diabetes"
] | C | The products of proto-oncogenes are required for normal growth, repair and homeostasis. However, when these genes are mutated, they turn into oncogenes and play a role in the development of cancer. Proto-oncogenes may be growth factors, transcription factors, or other proteins involved in regulation. A very common oncogene, ras , is normally a regulatory GTPase that switches a signal transduction chain on and off. Ras and Ras-related proteins are products of oncogenes found in 20% to 30% of human tumors. The transcription factor myc is an oncogene often seen mutated in Burkitt’s lymphoma, a rare type of lymphoma, a cancer of the lymphocytes. |
SciQ | SciQ-1010 | electromagnetism, electrostatics, acceleration, coulombs-law
Title: Can we apply Coulomb's law for accelerating point charges when they are at rest? Can we apply Coulomb's law for accelerating point charges at the instant when they are at rest? Not in general, accelerated charge produces different electric field than the Coulomb field. There is acceleration field, which has non-zero curl and thus is not a conservative field like the Coulomb field.
Only if the particle acceleration is small enough and we are interested in field close enough to the particle, then we can ignore the acceleration field component, because the Coulomb field is dominant. But in large enough distances the acceleration field always becomes dominant.
The following is multiple choice question (with options) to answer.
What happens to charges whenever they are accelerated? | [
"they radiate",
"they die",
"they fuse",
"they darken"
] | A | Receiving Electromagnetic Waves Electromagnetic waves carry energy away from their source, similar to a sound wave carrying energy away from a standing wave on a guitar string. An antenna for receiving EM signals works in reverse. And like antennas that produce EM waves, receiver antennas are specially designed to resonate at particular frequencies. An incoming electromagnetic wave accelerates electrons in the antenna, setting up a standing wave. If the radio or TV is switched on, electrical components pick up and amplify the signal formed by the accelerating electrons. The signal is then converted to audio and/or video format. Sometimes big receiver dishes are used to focus the signal onto an antenna. In fact, charges radiate whenever they are accelerated. When designing circuits, we often assume that energy does not quickly escape AC circuits, and mostly this is true. A broadcast antenna is specially designed to enhance the rate of electromagnetic radiation, and shielding is necessary to keep the radiation close to zero. Some familiar phenomena are based on the production of electromagnetic waves by varying currents. Your microwave oven, for example, sends electromagnetic waves, called microwaves, from a concealed antenna that has an oscillating current imposed on it. |
SciQ | SciQ-1011 | immunology, organs, transplantation, hla
GVHD is increasing due to the increasing number of allogeneic hematopoietic cell transplantations (HCT). More than 25,000 allogeneic transplantations performed annually. Given current trends, the number of transplants from unrelated donors is expected to double within the next five years, significantly increasing the population of patients with GVHD.[4] Yet the major complication, GVHD, remains lethal and limits the use of this important therapy.
Long-term immunosuppressants are usually the treatment regimen for chronic GVHD. Fungal, bacterial, and viral infections are a major risk with this treatment since the immune system will be suppressed for a very long time.[5]
[1] Transplant rejection
[2] Graft-versus-host disease
[3] Graft Versus Host Disease
[4] Graft-versus-Host Disease
[5] Graft vs Host Disease: An Overview in Bone Marrow Transplant
The following is multiple choice question (with options) to answer.
What is it in bone marrow transplants that may cause a graft versus host reaction? | [
"cancer",
"tumors",
"neutrophils",
"lymphocytes"
] | D | |
SciQ | SciQ-1012 | human-biology, physiology, bacteriology, microbiome
Title: Where do the bacteria within the vagina originate from? I understand that it's feasible the bacteria within the gastrointestinal tract originate from the food we eat and air we breath, but where does this population of microbes originate from? Most of the initial colonisation is said to be coincidental ('happenstance' as the textbook puts it!) exposure.
It's then fairly predictable depending on:
type of delivery (as Larry commented);
feeding; and
receipt of antibiotics.
In terms of feeding, there are differences in flora between babies fed human milk and those that are given cow's milk.
There's a section called 'Establishment and Composition of Normal Flora' in chapter 187 of Principles and Practice of Pediatric Infectious Diseases (3rd ed) by Long which discusses the above.
It's also said that hormones may influence indigenous flora. For example, premenarcheal and postmenopausal vaginal flora are very different to those present during the childbearing period.[1].
Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. 2009. Churchill Livingstone.
The following is multiple choice question (with options) to answer.
The vagina starts at the vulva and ends where? | [
"testicle",
"pelvic brim",
"the uterus",
"clitoris"
] | C | The vagina is a tube-like structure about 9 centimeters (3.5 inches) long. It begins at the vulva and extends upward to the uterus. It has muscular walls lined with mucous membranes. The vagina has two major reproductive functions. It receives sperm during sexual intercourse, and it provides a passageway for a baby to leave the mother’s body during birth. |
SciQ | SciQ-1013 | genetics, homework
Title: "structural and regulatory elements of genes" Can anyone please explain a little about these two elements of genes? My main problem is with "which ‘switch on’ instructions".
genes have structural elements (which code for a particular protein) and regulatory elements (which ‘switch on’ instructions) The expression of protein coding genes happens by the process of transcription. So promoters facilitate access of the RNA polymerase complex to DNA to begin transcribing a locus on the genome. The promoter of a gene often contains sequences that bind proteins called transcription factors, which play a role in various parts of the transcriptional process as well as components of RNA polymerase themselves (Such as a Pribnow box in prokaryotes, or a TATA box or an initiator element in animals).
So whether a gene is turned on and if so, how much it is turned on, is a property of how many transcription factor binding sites exist in the promoter, the nature of the transcription factors themselves in terms of their influence on transcription, and in eukaryotes and some archaea, epigenetic processes that control the access of transcriptional machinery to the locus being transcribed.
So when you think about the two elements in a gene, think of a light (the bit of a gene that codes for proteins) and a dimmer (which controls how much RNA is made by the protein-coding bit)
The following is multiple choice question (with options) to answer.
Regulatory proteins bind to regulatory elements to control what? | [
"growth",
"differentiation",
"mutation",
"transcription"
] | D | Regulation of Transcription. Regulatory proteins bind to regulatory elements to control transcription. The regulatory elements are embedded within the DNA. |
SciQ | SciQ-1014 | bacteriology
Saier, MH. & Bogdanov, V. (2013) Membranous Organelles in Bacteria. JOURNAL OF MOLECULAR MICROBIOLOGY AND BIOTECHNOLOGY 23: 5-12 DOI: 10.1159/000346496
Free full text here.
The language used in this review seems to support the existence of mesosomes as some sort of intermediate in the formation of intracellular membranes in prokaryotes. This review is a polemic in favour of the idea that prokaryotes do indeed contain intracellular membrane-bounded compartments. It has no abstract, but the first paragraph gives a flavour of its stance:
The traditional view of life on Earth divides the living world into two major groups, prokaryotes and eukaryotes. These two groups were originally suggested to differ in very basic respects. While eukaryotes had complex cell structures including a cytoskeleton and intracellular membrane-bounded organelles, prokaryotes were believed to lack them. In fact, numerous textbooks and current sources still note this distinction and hold it to be true. For example, in Campbell’s Biology [Campbell, 1993, p. 515] it is stated without equivocation: ‘Prokaryotic cells lack membrane-enclosed organelles.’ In ‘Functional Anatomy of Prokaryotic and Eukaryotic Cells’ [Tortora et al., 2009, chapt. 4] it is similarly claimed that ‘Prokaryotes lack membrane-enclosed organelles, specialized structures that carry on various activities’. In the current Wikipedia, under ‘Prokaryote’ the following statement can be found: ‘The prokaryotes are a group of organisms whose cells lack a cell nucleus (karyon) or any other membrane-bounded organelles’. In the same online compendium under ‘Organelle’, one can read: ‘whilst prokaryotes do not possess organelles per se, some do contain protein-based microcompartments’. Proteinceous microcompartments will be the subject of a forthcoming Journal of Molecular Microbiology and Biotechnology written symposium, but this one will show that these generalizations, suggesting a lack of subcellular compartmentalization in prokaryotes, are blatantly in error [Murat et al., 2010a].
The following is multiple choice question (with options) to answer.
Microfilaments are mostly concentrated just beneath what? | [
"the cell membrane",
"the nucleus",
"the cell wall",
"the cytoplasm"
] | A | Microfilaments , shown as (b) in Figure below , are made of two thin actin chains that are twisted around one another. Microfilaments are mostly concentrated just beneath the cell membrane, where they support the cell and help the cell keep its shape. Microfilaments form cytoplasmatic extentions, such as pseudopodia and microvilli , which allow certain cells to move. The actin of the microfilaments interacts with the protein myosin to cause contraction in muscle cells. Microfilaments are found in almost every cell, and are numerous in muscle cells and in cells that move by changing shape, such as phagocytes (white blood cells that search the body for bacteria and other invaders). |
SciQ | SciQ-1015 | quantum-mechanics, atomic-physics
Title: Quantum Mechanical Meaning of Atomic Orbitals According to quantum mechanics, for multi-electron atoms, a single electron around the nuclei can be in the state of linear combination of different eigen energy states. In that case, even the energy of the electron is not one of the eigen energies.
In chemistry, we often say that an electron is in an orbital (such as 1s, 2s), another electron is in another orbital, etc. How does it make sense if an electron is in a linear combination state? While it's possible for the atom to be in a superposition on energy states, the superposition collapses to an eigenstate as soon as we observe it. Therefore every atom we observe will have a distinct electronic configuration.
Incidentally, note that for a multi electron atom the assignment of electrons to the atomic orbitals 1s, 2s, etc, is an approximation. The electron correlation mixes up the atomic orbitals so strictly speaking we don't have separate atomic orbitals, just a single wavefunction for the atom. However, in most cases using atomic orbitals is an excellent approximation.
The following is multiple choice question (with options) to answer.
What term is used for any combination of two or more atoms? | [
"element",
"molecule",
"synthesis",
"nucleus"
] | B | A molecule is any combination of two or more atoms. The oxygen in the air we breathe is two oxygen atoms connected by a chemical bond to form O 2 , or molecular oxygen. A carbon dioxide molecule is a combination of one carbon atom and two oxygen atoms, CO 2 . Because carbon dioxide includes two different elements, it is a compound as well as a molecule. |
SciQ | SciQ-1016 | kinetics, energy, food-chemistry, fuel
Title: Is it possible to turn food into fuel for a combustion engine? According to McDonald's Nutrition Calculator page, the following order would contain 2480 kilocalories (or 10376 kilojoules):
1 x Double Bacon Smokehouse Burger
1 x Large Chocolate Shake
1 x Large World Famous Fries®
Would it be possible to somehow extract/convert that energy and use it to power a car engine? If so, what would be the involved chemical processes, equations and byproducts?
Note that this question is entirely motivated by curiosity and by an ingenuous notion of Lavoisier's principle of mass conservation. You can combust all you have and obtain 10376 kJ (human will obtain less energy, because we are not campfires to burn everything indiscriminately). But, instead, you can be a little bit more smart and combust fats of the same mass, which give 38 kJ per gram (proteins and carbohydrates give less than half of it). This idea allows you to use less fuel for same productivity. Actually, the idea is already widely used - check for biodiesel. Source below gives detailed basic-level insight.
Biodiesel are produced through a simple technology called trans-esterification reaction. Degummed oil free of all forms of impurities is reacted with a reasonable alcohol (ethanol, methanol, butanol etc.).
Citation source:
Biodiesel: Fuel for the Future (A Brief Review). Owolabi R. U., Adejumo A. L., Aderibigbe A. F. International Journal of Energy Engineering 2012; 2(5): 223-231.
DOI: 10.5923/j.ijee.20120205.06
The following is multiple choice question (with options) to answer.
What is biomass made into fuel called? | [
"renewable fuel",
"bio fuel",
"benign fuel",
"toxic fuel"
] | B | More recently, people have learned to process biomass to make fuel. This is called biofuel . Biofuel is created from crops, such as corn or algae. Biofuel is unique among renewable energy sources. This is because it is liquid. Unlike solar energy, for example, biofuels can be used in a car ( Figure below ). Biofuels burn more cleanly than fossil fuels. They create less pollution and less carbon dioxide. Biofuels, such as ethanol, are added to gasoline. This cuts down the amount of fossil fuels that are used. |
SciQ | SciQ-1017 | volcanology, geomorphology
Title: Why doesn't the whole volcanic cone appear black? Cooled lava looks black, but why the whole volcano, even near crater, doesn't always appear black like cooled lava? The cooled lava might be covered by ashes. So depending of the amount of ashes and the wind you might have a black volcano or a gray volcano. Many volcanoes are formed by layers of lava and ash.
https://en.wikipedia.org/wiki/Volcano#/media/File:Volcano_scheme.svg
The following is multiple choice question (with options) to answer.
What type of thin lava forms shapes and tubes as it flows? | [
"spicule",
"xerophyte",
"xeric",
"pāhoehoe"
] | D | Pāhoehoe lava is thinner than a'a, and flows more readily. Its surface looks more wrinkly and smooth. Pāhoehoe lava flows in a series of lobes that form strange twisted shapes and natural rock sculptures ( Figure below ). Pāhoehoe lava can form lava tubes. The outer layer of the lava flow cools and solidifies. The inner part of the flow remains fluid. The fluid lava flows through and leaves behind a tube ( Figure below ). |
SciQ | SciQ-1018 | cell-biology
Title: Are ribosomes assembled in rough ER and Golgi body, or in the nucleolus? I mean all the components, such as ribosomal RNA (rRNA) are synthesized in the nucleolus, but is the whole ribosome structure assembled in the nucleolus or is it also done in the rough endoplasmic reticulum and Golgi apparatus? Ribosome assembly starts in the nucleolus (of eukaryotes) and finishes in the cytoplasm. However, in the cytoplasm the Golgi apparatus is certainly not involved, and, as some cells have little rough endoplasmic reticulum, assembly does not require that. Thus, the abstract of a review by Fromont-Racine et al. in Gene (2003) vol 313 pp. 17–42 starts with the statement:
Ribosome synthesis is a highly complex and coordinated process that occurs not only in the nucleolus but also in the nucleoplasm and the cytoplasm of eukaryotic cells.
In the 26 pages of this review there is not a single mention of the words ‘endoplasmic reticulum’ or ‘Golgi’.
A more recent (and freely available) review by Thomson et al. in Journal of Cell Science (2013) vol 126 pp. 4815-4820 is in accord with this. It has a pretty poster insert which presents the assembly as a succession of events, starting in the nucleolus, proceeding to the nucleoplasm, and with some final polishing in the cytoplasm.
The following is multiple choice question (with options) to answer.
The nucleolus, which makes ribosomes, is located within what cell structure? | [
"epidermis",
"mitochondria",
"nucleus",
"Golgi apparatus"
] | C | The nucleolus, which makes ribosomes, is also within the nucleus. |
SciQ | SciQ-1019 | electrochemistry
Title: What causes the flow of electrons from anode to cathode in a Daniell cell? In a standard galvanic cell, I understand that electrons flow from the anode to the cathode. For example, in a Daniell cell, electrons flow from the Zn anode to the Cu cathode. Before the two half-cells are connected (open circuit), they are each in chemical equilibrium:
$$\require{mhchem} \ce{Zn(s) ⇌ Zn^2+(aq) + 2e^-}$$
$$\require{mhchem} \ce{Cu(s) ⇌ Cu^2+(aq) + 2e^-}$$
This means that in open circuit conditions each electrode will contain a surplus of negative charge. However, the zinc electrode will be more negatively charged because it oxidizes more easily. When the cells are connected via a wire and salt bridge, the electrons will flow from the zinc anode to the copper cathode as they attempt to re-establish new equilibrium positions.
Here is my uncertainty:
When connected, it appears that electrons are flowing from a more negatively charged area (Zn) to a less negatively charged area (Cu). Can the less negatively charged Zn be considered "positive" in relation to the more negative Zn? It seems that instead of a positively charged ion attracting them into the cathode, they travel there because the electron density is less. Is there an error in my logic?
The following is multiple choice question (with options) to answer.
Electrons flow through the electrolyte from the ________ to __________ electrode. | [
"negative; neutral",
"negative; positive",
"neutral; negative",
"positive; negative"
] | B | Both dry and wet cells work the same basic way. The electrodes react chemically with the electrolyte, causing one electrode to give up electrons and the other electrode to accept electrons. In the case of zinc and carbon electrodes, the zinc electrode attracts electrons and becomes negatively charged, while the carbon electrode gives up electrons and becomes positively charged. Electrons flow through the electrolyte from the negative to positive electrode. If wires are used to connect the two electrodes at their terminal ends, electric current will flow through the wires and can be used to power a light bulb or other electric device. |
SciQ | SciQ-1020 | botany, terminology, fruit
Title: What is the name of this part in plants, fruits, vegetables? What is the name of this part of the plant, fruit, vegetable? The thing that the plant is connected with the tree and gets nutrients with? The part we usually cut out when eat fruit.
Examples below
Papaya
Banana
Mango 'Stalk' or 'pedicel' would be an appropriate term (see, for example, this paper or this one). Specifically, you could say 'terminal part of the stalk/pedicel', though I don't know if there is a word for that.
Note that the term pedicel is commonly used for the stalk of a flower; it makes sense to use it for fruits too as they are derived from flowers.
The following is multiple choice question (with options) to answer.
What is the name of the part that connects the vagina with the uterus? | [
"ovary",
"cervix",
"urethra",
"vulva"
] | B | The uterus is a hollow organ with muscular walls. The part that connects the vagina with the uterus is called the cervix . The uterus is where a baby develops until birth. The walls of the uterus grow bigger as the baby grows. The muscular walls of the uterus push the baby out during birth. |
SciQ | SciQ-1021 | agriculture
Title: What does "permanent field" mean in agriculture? I am reading a book that in a paragraph talks about the agricultural methods used in prehistoric Finland.
The further north and east, the more extensive the amount of
burn-beat cultivation, which was a far from primitive form of
agriculture. The yield was many times higher (twenty- to thirty-fold)
than on permanent fields (five- to ten-fold), and there were multiple
varieties of the technique
A history of Finland by Henrik Meinander.
One of them is burn-beating. Like I understand, in burn-beating people cut down the trees in the forests and burn the topsoil. This way they can use that soil for 3 to 6 years for cultivation.
The other method is permanent field. I have searched the internet and the result I got was "permanent crops", like here. In which case people planted trees once in a field and harvested them multiple times.
But in another research about prehistoric Finland it was saying:
The site of Orijärvi shows that permanent field cultivation, with
hulled barley as the main crop was conducted from approximately cal AD 600 onwards.
The following is multiple choice question (with options) to answer.
No-till farming is one effort to combat what, caused by typical farming practices? | [
"soil erosion",
"drought",
"habitat destruction",
"pollution"
] | A | The photos in Figure below show how farming practices can increase soil erosion. Plant roots penetrate the soil and keep it from eroding. Plowing turns over bare soil and cuts through plant roots. Bare soil is exposed to wind and water. In the past, farmers always plowed fields before planting. Some farmers now use no-till farming, which does not disturb the soil as much. |
SciQ | SciQ-1022 | geothermal-heat
Title: What Keeps the Earth Cooking? If radioactive decay supplies only about half the Earth’s heat, what are the remaining sources of heat?
If radioactive decay supplies only about half the Earth’s heat, what are the remaining sources of heat?
Mostly it is residual heat energy from when the Earth was very young. The biggest source came from the kinetic energy of all the bodies, big and small, that collided to form the Earth being converted to heat. The differentiation of the Earth added even more heat energy to the Earth.
In addition to radioactive decay, the on-going freezing of the outer core material onto to the inner core adds a bit more heat to the system, but neither one compensates for heat transported through the mantle and crust and then out into space. Note that this heating from below is but a tiny portion of the overall energy budget for the Earth's surface.
Even the Earth's surface was very hot shortly after the formation and differentiation of the Earth. While the surface cooled quickly (geologically speaking), the interior has not. The key reason is that 2,890 km of rock makes for a fairly thick blanket.
The following is multiple choice question (with options) to answer.
Geysers are created when what is heated beneath the earth's surface? | [
"water",
"gases",
"air",
"magma"
] | A | Geysers are also created by water that is heated beneath the Earth’s surface. The water may become superheated by magma. It becomes trapped in a narrow passageway. The heat and pressure build as more water is added. When the pressure is too much, the superheated water bursts out onto the surface. This is a geyser . |
SciQ | SciQ-1023 | electric-circuits, voltage
Title: Unsatisfactory explanation for the EMF measurement of a battery Experimentally, I have seen how hooking up a battery to a simple circuit just with a high-resistance voltmeter raises the voltage reading (allegedly to a level equal to the EMF of the battery).
However, I find the explanation for why the reading rises, much less to an EMF, very unconvincing. We were told that the internal resistance and the necessary potential drop is ignored, because there is no current in the said circuit, hence why the voltmeter measures an EMF. How can this make sense? There clearly must be some current, albeit very little, flowing, for the high-resistance voltmeter to even have a reading, and that little current will still experience resistive forces from the internal resistance of the cell - so the EMF should not be attainable. Or is there a mechanism by which, when there is very little current, resistors are ignored, hence no work has to be done to traverse them?
Clearly I am wrong, as experimentally I saw the voltage rise in that super simple cell. My point of view suggests that there shouldn't be a difference between the reading in said circuit and the potential difference in a circuit consisting of 3 resistors (the voltmeter in this case measures the drop between these 3 resistors, note there is no other significant source of resistance other than the internal resistance). Really, in my theoretical understanding they should produce an equal reading, but they don't.
So, to be honest, not only do I believe that the reading we saw shouldn't have been the EMF, but not even any different from the reading in a normal circuit, as described (the latter belief clearly conflicts with reality).
I an eager to know what I am thinking wrongly about. Please ask if I can help clarify anything!
Thank you very much :)! You're quite correct that there will be some current flowing, so there must be a voltage drop due to the internal resistance of the battery. The EMF measured by any voltmeter will always be less than the true EMF.
If the internal resistance of the battery is $R_b$ and the resistance of your voltmeter is $R_m$ then the voltage you measure will be:
$$ V = \frac{R_m}{R_m + R_b} E $$
The following is multiple choice question (with options) to answer.
Increasing voltage with a higher-volt battery does what to the current? | [
"decreases it",
"stops it",
"increases it",
"blocks it"
] | C | Ohm’s law may be easier to understand with an analogy. Current flowing through a wire is like water flowing through a hose. Increasing voltage with a higher-volt battery increases the current. This is like opening the tap wider so more water flows through the hose. Increasing resistance reduces the current. This is like stepping on the hose so less water can flow through it. If you still aren’t sure about the relationships among current, voltage, and resistance, watch the video at this URL: http://www. youtube. com/watch?v=KvVTh3ak5dQ. |
SciQ | SciQ-1024 | inorganic-chemistry, decomposition
Title: Why doesn't CaO decompose into Ca and O2? Many metal oxides decompose into the free metal and oxygen gas at high temperatures, but why doesn't $\ce{CaO}$ do that? What happens to $\ce{CaO}$ at high temperatures?
This is from problem 2 of the 2011 USNCO local exam:
Oxygen gas can be produced by the decomposition of all
of the following substances EXCEPT
(A) calcium oxide. (B) hydrogen peroxide.
(C) mercury(II) oxide. (D) ozone.
The following is multiple choice question (with options) to answer.
Hydrogen peroxide will decompose over time to produce _______ gas. | [
"water and oxygen",
"hydrogen and helium",
"methane",
"water and carbon dioxide"
] | A | Again, substances in all states of matter commonly participate in decomposition reactions. For example, hydrogen peroxide will decompose over time to produce water and oxygen gas according to the following equation:. |
SciQ | SciQ-1025 | analytical-chemistry, terminology, equipment, teaching-lab
In short, is there a STANDARD way in which these terms (TD, TC, IN, EX, Blow-out, Serologic, etc) are used? Is there a standard definition regulated by some sort of organization, or at least generally agreed upon? If you think that there is, could you please provide trustworthy sources? Thanks a lot.
This probably seems like a silly question (it is =D) but it kind of bugs me not to know something so basic as "what are the different kinds of graduated pipettes?"... It seemed like something that would be quite easy to settle when I started looking into it... guess I was wrong. Since you are explicitly asking for standards, you might want to start with ISO 4787 Laboratory glassware – Volumetric instruments – Methods for testing of capacity and for use. This international standard provides methods for testing as well as for use of various volumetric instruments made from glass. Further requirements for individual volumetric instruments can be found in
The following is multiple choice question (with options) to answer.
What kind of pipettes are suitable for measuring very small amounts of liquids? | [
"macropipettes",
"clutch pipettes",
"micropipettes",
"frozen pipettes"
] | C | Pipettes are small, but important tools in many biology labs. Micropipettes, such as the ones shown here, are calibrated to measure very small amounts of liquids. For example, 100 microliters (100 µL) is about half the volume of your little finger tip; or even 1 µL, which is much smaller than a drop of water. |
SciQ | SciQ-1026 | newtonian-mechanics, forces, newtonian-gravity, free-body-diagram, string
Title: How does a weight connected to a string over a pulley pulling a cart apply force onto the cart? How does the mass hanging down on the bottom (Assuming frictionless environment) apply a pull force to the car? How does the weight of the object transfer to the string (tension force and maybe the pulley does something?) which pulls the car? I wonder if the following diagram is helpful:
There is a force from the pulley on the string - that is what allows the tension to "turn the corner" so the force from the weight (which is downwards) is turned into a horizontal force (tension that can pull the cart).
The following is multiple choice question (with options) to answer.
What is the measure of the force of gravity pulling down on an object called? | [
"mass",
"weight",
"volume",
"factor"
] | B | Weight is a measure of the force of gravity pulling down on an object. Buoyant force pushes up on an object. Weight and buoyant force together determine whether an object sinks or floats. This is illustrated in Figure below . |
SciQ | SciQ-1027 | boiling-point
Title: Why is boiling point of hydrogen greater than of helium? If we compare the boiling point of hydrogen and helium using molecular weight criteria (both have London dispersion forces as intermolecular forces of attraction because both are non polar then the one which have which have higher molecular weight will have higher intermolecular attraction forces) then helium should have greater boiling point, but if we see the boiling point data for H2 and helium then we found that H2 have its boiling point as approximately 20 Kelvin while He will have approx 4.3 Kelvin. Higher molecular weight is not the determining factor. Rather the number of electrons that could be polarized and the volume of space over which they may be polarized are the key factors in dispersion forces.
For species with similar structures higher molecular weight goes along with more or larger atoms, thus more electrons and greater polarizability; but "monatomic" and "diatomic" are not really similar structures. Compared with helium, hydrogen has as many electrons (two), and the presence of two atoms instead of one allows an opportunity for polarization over more volume. So hydrogen will have more dispersion forces.
The following is multiple choice question (with options) to answer.
Boiling points increase with which kind of mass? | [
"universal mass",
"protons mass",
"molar mass",
"lipid mass"
] | C | Carboxylic acids have high boiling points compared to other substances of comparable molar mass. Boiling points increase with molar mass. |
SciQ | SciQ-1028 | visible-light, photons, atoms, spectroscopy
Title: photon absorption by atoms causes heat? I have came up with a weird doubt: photon absorption by atoms causes heat? I mean, I was always told that if the photon's frequency is the magic one, the atoms absorbs the photon and goes to an excited state. So I have to suppose that heating (increasing in kinetic energy) happens when the frequency is outside the set of permitted transitions. Is it correct? This is true. If for example you subject Hydrogen gas to a perfectly monochromatic 121.57 nm laser, then all that will happen is that the gas will scatter the light in all directions, glowing without increasing the temperature.
Otherwise there are many different phenomena that are involved in the heat transfer of energy by radiation. For example in solids, photons are absorbed and turn into phonons which are waves that when they are numerous lead to thermalization, and for molecules you have photon absorption that leads to molecular vibration which again increases the root mean square speed, etc...
The following is multiple choice question (with options) to answer.
The largest absorption of heat comes during the vaporization of what? | [
"ice",
"carbon dioxide",
"magma",
"liquid water"
] | D | The total heat absorbed as the ice at -30°C is heated to steam at 140°C is 113.4 kJ. The largest absorption of heat comes during the vaporization of the liquid water. |
SciQ | SciQ-1029 | 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 do fungi absorb to get their nutrition? | [
"water",
"organic compounds from other organisms",
"air",
"soil"
] | B | Most fungi grow on moist soil or rotting vegetation such as dead logs. Some fungi live in water. Others live in or on other organisms. Fungi get their nutrition by absorbing organic compounds from other organisms. The other organisms may be dead or alive, depending on the fungus. |
SciQ | SciQ-1030 | frequency, wavelength
Title: Relationship between frequency and wavelength I am currently writing up a report for science class on the relationship between frequency and wavelength. And so I was wondering if anyone knew where I could find published results (literature value) and I would like to know if it is a theory or a law (presumably) and who's theory/law it is?
Thanks. You won't find published results because this is elementary physics and is covered in any physics textbook. Velocity = frequency times wavelength:
$$ v = f\lambda $$
This is particularly useful for light, where the velocity is the speed of light, because then you have the relationships between the two:
$$ f = \frac{c}{\lambda} $$
$$ \lambda = \frac{c}{f} $$
I'd guess your teacher intends your report to explore this relationship and explain why it's true. Some creative Googling should help.
The following is multiple choice question (with options) to answer.
The variable is the speed of light. for the relationship to hold mathematically, if the speed of light is used in m/s, the wavelength must be in meters and the frequency in what? | [
"miles",
"hertz",
"gigawatts",
"centimeters"
] | B | The variable is the speed of light. For the relationship to hold mathematically, if the speed of light is used in m/s, the wavelength must be in meters and the frequency in Hertz. |
SciQ | SciQ-1031 | homework, embryology
Title: Why are Birds and Reptiles with abundant yolk sac polyspermic? I was given an explanation that birds and reptiles are polyspermic because they have an abundant yolk sac. But how does it explain the thing?
Chicken as an adult is not using in my opinion yolk as an energy source.
Yolk is used during embryogenesis as the primary energy source with blastula and gastrula -stages and during organogenesis, since the embryo needs proteins and energy somewhere.
How does abundant yolk sac make birds and reptiles polyspermic? My professor says that
The yolk sac is not connected to the mechanism of polyspermy or
monospermy. [Amount of yolk inside the oocyte is then again.] The
oocytes of reptiles and birds are yolk rich - polylecithal for instance.
where
lecithal = yolk containing and some pieces of information about here.
The following is multiple choice question (with options) to answer.
A yolk sac replaces what structure for nourishing a marsupial embryo? | [
"glucose",
"uterus",
"Stomach",
"placenta"
] | D | The marsupial embryo is nourished inside the uterus with food from a yolk sac instead of through a placenta. The yolk sac stores enough food for the short period of time the embryo remains in the uterus. After the embryo is born, it moves into the mother’s pouch, where it clings to a nipple. It remains inside the pouch for several months while it continues to grow and develop. Even after the offspring is big enough to leave the pouch, it may often return to the pouch for warmth and nourishment ( Figure below ). Eventually, the offspring is mature enough to remain outside the pouch on its own. |
SciQ | SciQ-1032 | physical-chemistry, solutions
Title: What is the differences between partial pressure and vapour pressure? Was looking at Henry's law and Raoult's law
constants and there seemto be lots of
equations involved.
Henry's law involves partial pressure and the latter involves the vapor pressure.
Wondering what the difference is?
In a mixture of gases, each gas has a partial pressure which is the hypothetical pressure of that gas if it alone occupied the volume of the mixture at the same temperature.
What does this mean? For example, if we have a mixture of gases $A$, $B$ and $C$ in an isolated room, then, according to Dalton's law, the pressure exerted by the gases will be the sum of their partial pressures :
$$P = p_A + p_B + p_C$$
where $p_A$, $p_B$ and $p_C$ are the partial pressures of each gas. Also, if we have a moles of $A$, b moles of $B$ and c moles of $C$, we can express the partial pressure of each gas as below:
$$p_A = \frac{a}{a+b+c} P$$
$$p_B = \frac{b}{a+b+c} P$$
$$p_B = \frac{c}{a+b+c} P$$
Vapor pressure or equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system.
The following is multiple choice question (with options) to answer.
What is the pressure of gas in a gas mixture termed? | [
"partial pressure",
"gaseous energy",
"gaseous pressure",
"partial energy"
] | A | The pressure of a gas in a gas mixture is termed the partial pressure. |
SciQ | SciQ-1033 | 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.
Making ups about 50 percent of the modern american diet, what food group can be classified according to the number of monomers they contain of simple sugars and/or complex sugars? | [
"fats",
"proteins",
"carbohydrates",
"grains"
] | C | Carbohydrate Digestion The average American diet is about 50 percent carbohydrates, which may be classified according to the number of monomers they contain of simple sugars (monosaccharides and disaccharides) and/or complex sugars (polysaccharides). Glucose, galactose, and fructose are the three monosaccharides that are commonly consumed and are readily absorbed. Your digestive system is also able to break down the disaccharide sucrose (regular table sugar: glucose + fructose), lactose (milk sugar: glucose + galactose), and maltose (grain sugar: glucose + glucose), and the polysaccharides glycogen and starch (chains of monosaccharides). Your bodies do not produce enzymes that can break down most fibrous polysaccharides, such as cellulose. While indigestible polysaccharides do not provide any nutritional value, they do provide dietary fiber, which helps propel food through the alimentary canal. The chemical digestion of starches begins in the mouth and has been reviewed above. In the small intestine, pancreatic amylase does the ‘heavy lifting’ for starch and carbohydrate digestion (Figure 23.29). After amylases break down starch into smaller fragments, the brush border enzyme α-dextrinase starts working on αdextrin, breaking off one glucose unit at a time. Three brush border enzymes hydrolyze sucrose, lactose, and maltose into monosaccharides. Sucrase splits sucrose into one molecule of fructose and one molecule of glucose; maltase breaks down maltose and maltotriose into two and three glucose molecules, respectively; and lactase breaks down lactose into one molecule of glucose and one molecule of galactose. Insufficient lactase can lead to lactose intolerance. |
SciQ | SciQ-1034 | embryology
Title: What is a zygote? During fertilization, the nuclear membrane of the pro-nucleus of the ovum and sperm degenerate. Is the cell is stage called a zygote?
After the dissolution, mitosis occurs and two cells are formed.Or is the cell is stage called a zygote?
I'm confused as i knew a zygote was single-celled. Conventionally, a zygote is considered to be formed the moment that a spermatozoum, penetrates the cell membrane of the ovum and yields its genetic material into the ovum. Effectually, however, there is a lag between the instant of fertilization and the fusion of the male and female pronuclei. In mammals, the duration of this lag period is ~12 hours. There are also additional actions that must be completed before the first mitosis as in most mammals, including humans, the ovum is actually in the second metaphase of meiosis at the time of fertilization.
The following is multiple choice question (with options) to answer.
What is the process of the fusion of a sperm and an egg called? | [
"fertilization",
"stimulation",
"embryo",
"Sperm"
] | A | Fertilization The fusion of a sperm and an egg is a process called fertilization. This can occur either inside ( internal fertilization) or outside ( external fertilization) the body of the female. Humans provide an example of the former, whereas frog reproduction is an example of the latter. |
SciQ | SciQ-1035 | homework-and-exercises, acceleration, rotational-kinematics
Title: How to treat an exercise about the rotational acceleration during a throw? Because I am studying on my own, I don't have anyone to talk to about this when I don't understand, and I was wondering if someone could help me with a concept in rotational kinematics:
At the start of your throw of a $2.7\:\mathrm{kg}$ bowling ball, your arm is straight behind you and horizontal. Determine the rotational acceleration of your arm if the muscle is replaced. Your arm is $0.64\:\mathrm{m}$ long, has a rotational inertia of $0.48\:\mathrm{kg\:m^2}$, and has a mass of $3.5\:\mathrm{kg}$ with its center of mass $0.28\:\mathrm{m}$ from your shoulder joint.
The following is multiple choice question (with options) to answer.
What is the motion that moves the forearm from the supinated position to the pronated position? | [
"supination",
"pronation",
"flexion",
"extension"
] | B | Supination and Pronation Supination and pronation are movements of the forearm. In the anatomical position, the upper limb is held next to the body with the palm facing forward. This is the supinated position of the forearm. In this position, the radius and ulna are parallel to each other. When the palm of the hand faces backward, the forearm is in the pronated position, and the radius and ulna form an X-shape. Supination and pronation are the movements of the forearm that go between these two positions. Pronation is the motion that moves the forearm from the supinated (anatomical) position to the pronated (palm backward) position. This motion is produced by rotation of the radius at the proximal radioulnar joint, accompanied by movement of the radius at the distal radioulnar joint. The proximal radioulnar joint is a pivot joint that allows for rotation of the head of the radius. Because of the slight curvature of the shaft of the radius, this rotation causes the distal end of the radius to cross over the distal ulna at. |
SciQ | SciQ-1036 | human-anatomy
Title: Why is a penis an organ? According to Wikipedia an "An organ is a group of tissues with similar functions". I don't know anything about anatomy but it doesn't seem to me that a penis can be delimited somewhere to form a "group". Therefore I do not understand why a penis is considered an organ.
Can you explain it to me ? Frankly, that's a terrible definition by Wikipedia.
Merriam-Webster defines an organ as:
a differentiated structure (such as a heart, kidney, leaf, or stem) consisting of cells and tissues and performing some specific function in an organism
or
bodily parts performing a function or cooperating in an activity
The important defining feature of an organ is not that the tissues have similar functions but that, together, the tissues comprise a functional whole that achieves some end goal.
For the penis, it consists of multiple tissues with different functions:
(from https://www.ncbi.nlm.nih.gov/books/NBK525966/figure/article-20668.image.f1/ - original from Gray's Anatomy)
The different tissues pictured here: the fibrous envelope, the corpora cavernosa, the septum pectiniforme, the urethra and blood vessels, the nervous tissue in the skin: all of these tissues have different individual functions: structural, erectile, carrying urine or semen, etc.
The key that unifies them into an organ is that the functions of the penis at the organism level (principally sexual function) are not served by any of these tissues alone, but rather by their combination in a full structure: an organ.
Ultimately, organ definitions are somewhat opinion-based: people are lumpers and splitters, so you might find conflicting definitions for which groupings of tissues reflect distinct organs, but I think by most standards you would find the penis to be considered a distinct organ, affiliated with but distinct from the primary sex organs and associated glands.
The following is multiple choice question (with options) to answer.
What organ system consists of the skin, nails and hair? | [
"digestive system",
"endocrine system",
"integumentary system",
"nervous system"
] | C | The skin is the major organ of the integumentary system , which also includes the nails and hair. In fact, the skin is the body’s largest organ, and a remarkable one at that. Consider these skin facts. The average square inch (6.5 cm 2 ) of skin has 20 blood vessels, 650 sweat glands, and more than a thousand nerve endings. It also has an incredible 60,000 pigment-producing cells. All of these structures are packed into a stack of cells that is just 2 mm thick, or about as thick as the cover of a book. |
SciQ | SciQ-1037 | evolution, embryology, chromosome, polyploidy
Polyploidy is an important evolutionary mechanism which was and is probably responsible for a great deal of biological diversity.
Polyploidy arises easily in both animals and plants, but reproductive strategies might prevent it from propagating in certain circumstances, rather than any reduction in fitness resulting from the genome duplication.
Polyploidy may be more prevalent in animals than previously expected, and the imbalance in data arises from the fact that cytogenetics (i.e. chromosome counting) of large populations of wild specimens is a very common practise in botany, and very uncommon in zoology.
In addition, there are now several new suspected factors involved in ploidy which are currently being investigated:
The following is multiple choice question (with options) to answer.
What does it mean to be a diploid organism? | [
"micelles have two copies of each gene",
"organism has two copies of each gene",
"taproot has two copies of each gene",
"yolk has two copies of each gene"
] | B | Early land plants also evolved a dominant sporophyte generation. Sporophytes are diploid, so they have two copies of each gene. This gives them a "back-up" copy in case of mutation. This was important for coping with the strong solar radiation and higher risk of mutations on land. |
SciQ | SciQ-1038 | biochemistry
Another important difference with respect to resulting polymers formed from these bonds - polysaccharides, in contrast to proteins and nucleic acids, form branched as well as linear polymers
α-Amylose is a linear polymer of several thousand glucose residues linked by α(1 >4) bonds. Note that although α-amylose is an isomer of cellulose, it has very different structural properties. This is because cellulose’s β-glycosidic linkages cause each successive glucose residue to flip 180° with respect to the preceding residue, so that the polymer assumes an easily packed, fully extended conformation.
Peptide bond
The resulting linkage formed when α-amino acids polymerize, through the elimination of a water molecule is known as a peptide bond (sometimes called an amide bond):
Peptide bond (shown in red)
Glycosidic bonds between monosaccharide units are the basis for the formation of oligosaccharides and polysaccharides.
The glycosidic bond is therefore the carbohydrate analog of the peptide bond in proteins. (The bond in a nucleoside linking its ribose residue to its base is also a glycosidic bond)
The following is multiple choice question (with options) to answer.
What do you call the carbohydrate formed when two monosaccharides bond together? | [
"calcite",
"glucose",
"hydroxyl",
"disaccharide"
] | D | If two monosaccharides bond together, they form a carbohydrate called a disaccharide . An example of a disaccharide is sucrose (table sugar), which consists of the monosaccharides glucose and fructose ( Figure above ). Monosaccharides and disaccharides are also called simple sugars . They provide the major source of energy to living cells. |
SciQ | SciQ-1039 | fusion, renewable-energy
An energy "breakthrough" would be a loaded development. We already use lots of energy, and if we found it economic to use more we probably would. The last breakthrough shift in our ability to exploit energy resources rocketed the entire planet into a new geological era, the Anthropocene. We called this change the industrial revolution. Some obscure project that ARPA-E funded with $500,000 could cause the next industrial revolution. The implications of such a change would probably be beyond any of our imaginations.
The following is multiple choice question (with options) to answer.
What is the term for a resource that is used in a way that meets the needs of the present without keeping future generations from meeting their needs? | [
"tolerable",
"sustainable",
"structural",
"innovative"
] | B | A resource is renewable if it is remade by natural processes at the same rate that humans use it up. Sunlight and wind are renewable resources because they will not be used up ( Figure below ). The rising and falling of ocean tides is another example of a resource in unlimited supply. A sustainable resource is a resource that is used in a way that meets the needs of the present without keeping future generations from meeting their needs. People can sustainably harvest wood, cork, and bamboo. Farmers can also grow crops sustainably by not planting the same crop in their soil year after year. Planting the same crop each year can remove nutrients from the soil. This means that wood, cork, bamboo, and crops can be sustainable resources. |
SciQ | SciQ-1040 | genetics, molecular-biology, cell-biology, cancer, mutations
Title: Question about proto-oncogenes and oncogenes? My textbook says:
Growth-promoting genes are called proto-oncogenes. Some can be changed into oncogenes by a point mutation that alters the ability of the proto-oncogene to be switched off. They remain permanently switched on. Oncogenes promote unregulated cell division. Such cell division leads to a tumour.
Does this mean that the change from proto-oncogene to oncogene is not a mutation in the exon, but rather in the intron?
I hope I used these terms correctly. Thank you for any help :) I am going to add to @MattDMo 's answer a bit.
Proto-oncogenes Function, Developmental Program, and Regulation
Proto-oncogenes are normally functioning genes that are more often than not in the pathways that lead to mitosis and cellular replication. They have important roles in the development, growth, and maintenance of the organism. Proto-oncogene is an accurate description of the genes, but I unfortunately think that sometimes people think that the genes themselves are bad and that isn't the case.
Growth and development in multicellular organisms are highly regulated processes with many checks and balances. Certain cells need to grow in certain places at certain times, and then they need to go into and remain in interphase. If they don't, or they do things at the incorrect times, the multicellular organism will not develop properly or will develop conditions such as cancer.
It is often these points of regulation that become dysregulated when a proto-oncogene becomes oncogenic. If there are regions of allostery that are affected by a mutation in the coding sequence (exon) and a control molecule that represses the activity of the enzyme through conformation change can no longer bind, then that enzyme can remain active, always turned on.
You can also have a situation where you have transcriptional regulators of proto-oncogenes that can be effected making the gene product oncogenic. If there is a mutation in an enhancer (intronic) of the gene that affects the binding kinetics of enhancers leading to a great increase in transcription, this concentrational difference can lead to uncontrolled grown and tumor formation.
The following is multiple choice question (with options) to answer.
The genes that code for the positive cell cycle regulators are called what? | [
"primary genes",
"proto-oncogenes",
"stem cell genes",
"ribosomes"
] | B | Proto-oncogenes The genes that code for the positive cell cycle regulators are called proto-oncogenes. Proto-oncogenes are normal genes that, when mutated in certain ways, become oncogenes, genes that cause a cell to become cancerous. Consider what might happen to the cell cycle in a cell with a recently acquired oncogene. In most instances, the alteration of the DNA sequence will result in a less functional (or non-functional) protein. The result is detrimental to the cell and will likely prevent the cell from completing the cell cycle; however, the organism is not harmed because the mutation will not be carried forward. If a cell cannot reproduce, the mutation is not propagated and the damage is minimal. Occasionally, however, a gene mutation causes a change that increases the activity of a positive regulator. For example, a mutation that allows Cdk to be activated without being partnered with cyclin could push the cell cycle past a checkpoint before all of the required conditions are met. If the resulting daughter cells are too damaged to undergo further cell divisions, the mutation would not be propagated and no harm would come to the organism. However, if the atypical daughter cells are able to undergo further cell divisions, subsequent generations of cells will probably accumulate even more mutations, some possibly in additional genes that regulate the cell cycle. The Cdk gene in the above example is only one of many genes that are considered proto-oncogenes. In addition to the cell cycle regulatory proteins, any protein that influences the cycle can be altered in such a way as to override cell cycle checkpoints. An oncogene is any gene that, when altered, leads to an increase in the rate of cell cycle progression. |
SciQ | SciQ-1041 | botany, virus
Title: What virus transforms full grown plants? I read an article by a gardener describing how a virus had transmitted a negative trait to his plants. It rather shocked me, because I hadn't realized that a virus could transform an adult plant. I was aware of dipping arabadopsis flowers in agrobacterium tumefaciens, but the concept of non-reproductive structures being transformed seems fascinating. What kind of virus is capable of that? These are just a couple of short examples, but Witch's broom structures in trees can sometimes be caused by viruses - see Wikipedia: Witch's broom (fungi is maybe the most common cause though). In rose species you also have the similar Rose rosette disease (also called witches’-broom of rose), which is caused by a virus. The same webpage from Missouri Botanical Garden also includes a list of other plant viruses that you might find interesting.
Plant viruses that infect non-reproductive structures are common though - a overview can be found here: The American Phytopathological Society: Introduction to Plant Viruses, the Invisible Foe. More indepth information can be found in Plant Pathology (Agrios, 2012) (see ch. 12: "Plant diseases caused by viruses").
The following is multiple choice question (with options) to answer.
What are essential for pollination, but can spread disease and destroy crops? | [
"insects",
"fruits",
"mice",
"spiders"
] | A | Insects spread disease and destroy crops. However, they are essential for pollinating flowering plants. |
SciQ | SciQ-1042 | “Stepping Stone” system. I implement the ecological model in an eco-evolutionary context with connected predator-prey adaptive radiations as emergent model outputs 20,34. x0(t) = a x(t) b x(t) y(t) y0(t) = c y(t) + d x(t) y(t) Now convert our model to a matrix - vector system. Parameter avlue Interpretation a 1. DYNAMICS OF A MODEL THREE SPECIES PREDATOR-PREY SYSTEM WITH CHOICE by Douglas Magomo A Dissertation Submitted to the Graduate Studies Office of The University of Southern Mississippi in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Approved: August 2007 Reproduced with permission of the copyright owner. Set the solver type to SSA to perform stochastic simulations, and set the stop time to 3. Detect events during solution of ODE. , how predators affect prey populations, and vice-versa. It is called the Lotka-Volterra model. For this model the fit is lower than previous because of the complexity of the model when the number of prey is assumed as finite; when the number of parameters increases, the estimation process becomes more complex. α = exponential growth in population – used for preys,. Matlab program to plot a phase portrait of the Lotka-Volterra Predator Prey model. The system considers the effects of anomalous diffusion and generalized Michaelis–Menten-type reactions. The quadratic cross term accounts for the interactions between the species. View Notes - lecture3b-predator from MAE m20 at University of California, Los Angeles. 17 Predator-Prey Models The logistic growth model (Chapter 11) focused on a single population. Predation rate is simulated using the Holling's "disc equation" of functional response:. Some examples of predator-prey relationships are lion-cape buffalo, tiger-deer, snake-frog, python-rabbit, bear-fish and cheetah-gazelle. In a team effort, we created a system of closed differential equations for a predator-prey model where we were then able to generate numerical simulations through MATLAB to visualize the data. The predator-dependent model is more suitable for prey predator interactions in which predation involves the search process. a discrete time predator prey model specified by Neubert et al[9] which utilises the Ricker model to simulate prey growth. Predator prey offers this graphic user interface
The following is multiple choice question (with options) to answer.
Branching food chains and complex trophic interactions form what? | [
"food maps",
"food trees",
"food fields",
"food webs"
] | D | |
SciQ | SciQ-1043 | inorganic-chemistry
Title: Why do metals tend to lose electrons, as opposed to maintaining electric neutrality? Metals tend to lose electrons to obtain the stable noble gas configuration of 8 valence electrons.
Why do they want to obtain this configuration, and how does the strength of their "desire" to obtain this configuration compare with the "desire" to maintain neutral charge. If the answer depends on the chemical, I'm happy for you to provide some examples.
Thanks. Firstly, atoms "want" to achieve the noble gas configuration of 8 valence electrons because it is the most stable form. All that means is that it doesn't tend to react under normal conditions that we experience on Earth, therefore it will stay in that configuration for quite a while and are less likely to react. There is a more complex quantum physical answer for that but you'll have to go elsewhere for than.
The main force that keeps electrons in atoms is the electrical attraction between the electrons and the protons in the nucleus and so, if it is more energetically favourable to lose that electron in order to form a bond, then that is what will happen.
Focusing on the Alkali metals as an example, as you move down the group, they get more and more reactive. This is because of two main reasons that are a result of the electrons being further away from the nucleus:
Because they're further away, the attraction between the protons and the outer most electron is less
Secondly, taking Rubidium as an example, it has 37 electrons and 37 protons. From the perspective of the outer-most electron, there are 36 electrons repelling it, and 37 protons attracting it, therefore acting as a net charge of 1. However, if you take into account the first point, the repulsion of the closer electrons is stronger than the attraction of the protons so it could even be less than one
The following is multiple choice question (with options) to answer.
The chemical behavior of elements can largely be explained by what? | [
"chemical configuration",
"electron configurations",
"neutron configuration",
"proton configuration"
] | B | The chemical behavior of elements can largely be explained by electron configurations. |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.