7
votes
1answer
721 views

Why do human eyes glow red on a photo and dog's eyes green?

Previous Research I know that cameras sometimes come with an anti "red eye" functionality that involves two flashes, presumably the second flash coincides with the shutter opening. Question Why do ...
7
votes
2answers
176 views

Can a single axon propagate multiple simultaneous action potentials?

I have not been able to locate any research that indicates whether a single axon of a neuron or nerve cell can conduct multiple simultaneous (i.e. spatially separate) action potentials. I am aware ...
7
votes
2answers
5k views

What determines if a gene is dominant or recessive?

Going back to my high school days we were taught about dominant and recessive genes. We were taught how to calculate the geneotype and pheneotype of potential offspring using a small table (forgotten ...
7
votes
3answers
511 views

How can you test what color different people perceive?

If I would show someone a yellow object and ask them, "is this object yellow?" That person would say "yes". But I could never know if my perception of the color yellow is the same as that other ...
6
votes
1answer
1k views

How do neurons form new connections in brain plasticity?

I've been reading about brain plasticity and how the brain can "rewire" itself. One of the things that is not clear to me - how neurons can establish new connections. Does this rewiring mean that ...
5
votes
3answers
495 views

Books for beginners [closed]

I want to study biology. I have zero previous knowledge of biology but I know Physics, Chemistry and Maths. From which book should I start? I have heard about Campbell Biology, but it is very costly ...
5
votes
1answer
100 views

enzymes that stabilize DNA loops

As a follow-up of a previous question, I would like to know what enzymes or protein complexes have been used to manipulate DNA samples into stabilizing DNA loops. I have read that cohesin is one of ...
5
votes
2answers
699 views

How is membrane capacitance related to the increased speed of saltatory conduction?

Here is the original question which inspired my question. As explained by the answers there, the reason saltatory conduction in myelinated neurons is faster than non-myelinated conduction is because ...
5
votes
1answer
208 views

Is there such thing as Animal non-verbal body language?

Have there been any studies done on the animal use of their bodies to signal, communicate or express their emotions, particularly to members of other species (ex: humans)? I've been observing a very ...
4
votes
1answer
213 views

Relationship between nerves and axons

I just wanted to get a realistic viewpoint of our nervous system. I understand arteries and veins, but I wanted to know how similar our nervous system is to that? I understand we have neurons ...
4
votes
3answers
153 views

Why are the fertility rates of large predators kept low?

Predators at the top of a food chain, like lions, seem to have a relatively low fertility rate, which fits well to the ecosystem and avoids overpredation. But what is the mechanism that keeps the ...
4
votes
1answer
682 views

Why does max heart rate decrease with age?

I have heard that max heart rate declines steadily with age, and can be approximated by the equation Max Rate = 220 - Age. What is the physiological reason for this decline, and how is it ...
4
votes
1answer
141 views

How to calculate the effective population size ($N_e$) with overlapping generations?

From this Source: If generations are overlapping, then the effective population size $N_e$ does not equal the population size $N$. I know mathematical formulations in order to find the effective ...
4
votes
2answers
199 views

Gas from bacteria that's not methane

Is gas produced by bacteria always mainly methane? Or, are there bacteria out there that produce some biogas composed mainly of hydrogen, natural gas, propane, butane?
3
votes
2answers
339 views

How are DNA segments selected in PCR?

I understand that in PCR we're able to amplify only selected portions of the DNA... however despite reading it from multiple sources, I cannot figure out how this selection actually takes place. I ...
3
votes
1answer
392 views

Will the increase in atmospheric carbon dioxide lead to larger insects?

From my understanding, the increase in atmospheric carbon dioxide will also increase oxygen levels. That makes me wonder if in the near future insects will grow larger than they are today, since their ...
3
votes
2answers
520 views

Initial population when i count backwards?

My question is dealing with how many ancestors it took to produce me: --> to produce me it took 2 people (my parents) = ($2^1$) people = 2 --> one generation further included = ($2^1 + 2^2$) people ...
3
votes
2answers
1k views

Ill effects of urea and NH₃ on metabolism

What exactly does urea do that harms our body? Does it interfere with our cellular processes or disturbs the colloidal onchotic pressure of our blood? I have heard that NH3 damages the brain. What ...
2
votes
1answer
461 views

Can DNA & RNA be considered as nature's programming language?

The final frontier of Biological Sciences could be considered understanding the effects of variation in the DNA (and RNA). If after fertilization the DNA of the zygote could be genetically ...
2
votes
1answer
80 views

Fast standing and the heart's insufficient accommodation of the increased venous return

Assume you are 45 minutes on the supine position. Furthermore: you stand all of a sudden and fast and without sympaticus activity. The venous return (smooth musculature of vessels) accommodates ...
2
votes
1answer
2k views

Ancestral Allele explanation

I'm having some trouble understanding the concept of ancestral allele. What exactly does it mean? What does it have to do with Identity by descent/state? What does it have to do(if anything) with ...
2
votes
1answer
558 views

What can cause the bloating in high protein diet of Whey proteins?

I am thinking what can cause the swelling of gastrointestinal system i.e. bloating after high protein diet of Whey proteins. Liver does breaks those proteins to branched chain amino acids (BCAA), ...
2
votes
1answer
67 views

Effective population size when the population sizes varies from season to season

Let's think of a species which has four generations per year and which population size changes from season to season so that the population size is 100 in summer, 200 in spring, 50 in autumn and 20 in ...
2
votes
2answers
172 views

Radiation and “Safe Dose”

I've read about safe doses of radiation, briefly. Why is there such a thing a safe dose? Can't any radiation give you cancer? Why is it more and more dangerous to take in larger and larger doses? Just ...
2
votes
3answers
123 views

Can antibiotic resistant bacteria compete with normal one in an antibiotic free environment?

The question is based on an intuition that antibiotic resistance can't come along. This mutation will probably make bacteria less tenacious. Is there any research how AR bacteria compete with normal ...
2
votes
1answer
2k views

What would be the best design for spike-and-recovery and linearity-of-dilution validation experiments in one 96-well ELISA plate?

I have searched in the web for a detailed explanation of doing such validation experiment, but unfortunately couldn't find a satisfactory one. I came across the following sources: Thermo ...
1
vote
1answer
70 views

Additive genetic variance with $n$ loci

The genetic variance of a quantitative trait (the quantitative trait in question is fitness) can be express as the sum of two components, the dominance and additive variance: $$\sigma_D^2 + ...
1
vote
1answer
109 views

Additive genetic variance with $n$ alleles

The genetic variance of a quantitative trait (the quantitative trait in question is fitness) can be express as the sum of two components, the dominance and additive variance: $$\sigma_D^2 + ...
1
vote
1answer
29 views

To understand clearly extraintestinal diseases

Extradistestinal disease seems to prefer to "bowel" diseases, I think this is about diseases outside gastrointestinal tract so stomach. Consider diseases ulcerative colitis and Crohn's disease ...
0
votes
2answers
138 views

What is the name of the condition where no pacemaker cells are active in the heart for a short-time?

Assume that the heart is beating, but no pacemaker cells are working for at least 15 seconds. This would be a very long compensatory pause if extrasystole started it. There may be some low frequent ...
33
votes
5answers
7k views

What does the human body use oxygen for besides the final electron acceptor in the electron transport chain?

My biology teachers never explained why animals need to breathe oxygen, just that we organisms die if we don't get oxygen for too long. Maybe one of them happened to mention that its used to make ATP. ...
24
votes
2answers
578 views

Smallest viable reproducing population

What is the smallest viable reproducing population, such as in a human population. By viable I mean a population which keeps genetic defects low (enough). A very strongly related question: what is ...
21
votes
3answers
36k views

Why do mammalian red blood cells lack a nucleus?

How did the red blood cell in humans get to lose its nucleus (and other organelles)? Does the bone marrow just not put the nucleus in, or is it stripped out at some stage in the construction of the ...
20
votes
4answers
3k views

Where does the 'C' in exhaled CO₂ mostly come from?

When a human being exhales CO₂, what is, by the numbers, the main source of carbon atoms exiting the body in this way? I mean what class of cells, or which tissues are the biggest on a pie chart of ...
18
votes
3answers
1k views

How long can I store extracted RNA?

If I extract RNA from a (leaf tissue) sample using a one-step phenol:chloroform extraction, how long can those samples be stored at -80°C? And how many times can I defrost and refreeze them before ...
17
votes
1answer
532 views

What is the lowest pressure at which plants can survive?

What is the lowest pressure at which plants can survive? How the plants behave in a Martian-type atmosphere? Is there any plant that can survive such atmosphere? Can a lichen grow at Martian ...
16
votes
5answers
1k views

Are there any examples of sudden leaps in evolution?

As far as I understand, various abilities like flying, sight, hearing etc. were caused by slow evolution, where those with a greater ability to to these things had better chance of survival. (If this ...
15
votes
1answer
885 views

How Do White Blood Cells Learn? Or Do They?

So I get the concept that a vaccine is a weakened form of a virus so that the body can "learn" to fight it and make a person immune to that disease, but how exactly does this learning take place? What ...
14
votes
4answers
3k views

Why do parasites sometimes kill their hosts?

It's bothered me for a while now. I understand why a parasitoid would do this, as it only temporarily requires the host, and that not all parasites kill their hosts. There seems to be no evolutionary ...
14
votes
1answer
630 views

Why is yawning contagious?

Why does yawning seems to be contagious? Is this similar to laughter being contagious or does it has a different reason?
13
votes
2answers
2k views

Why don't we develop immunity against common cold?

We all suffer from common cold, and that, frequently. Why have we not developed immunity against it till now? By immunity I mean immunity as a species.
13
votes
1answer
253 views

How does herpes (HSV) infection suppress HIV?

HIV compromises the human body to defend against infection. Yet people who are infected with herpes are at less risk of developing AIDS. How does this work?
12
votes
1answer
1k views

Why do neurons die so quickly (relative to other cells) when deprived of oxygen?

This question could be considered a follow-up question to Why is a lack of oxygen fatal to cells?, although the top answer there does not address why damage starts to pop in. The answer says this: ...
11
votes
1answer
80 views

What limits chromosomal length?

What are the upper and lower limits for chromosome length? Are these limits different in different species or kingdoms? If there is any limit, which cellular or molecular factors are reasons?
11
votes
1answer
2k views

How does translational coupling work in prokaryotes?

Today I heard about a phenomenon called "translational coupling", where the translation of one protein influences the translation of another protein. The messenger RNA levels don't seem influenced. ...
10
votes
3answers
781 views

The evolutionary process in bird wings, especially with regard to winglets

In this answer on aviation.SE a comparison is made between the shapes of airplanes wings and the shapes of birds wings. It concludes with the following remark: After all, no bird has winglets. Not ...
10
votes
4answers
862 views

“Same” DNA vs genes

It is often cited that humans share 99% (or 98%) of their DNA with chimpanzees. On the other hand it is stated that siblings share only half of their genes. What (if any) is the difference between ...
10
votes
1answer
2k views

How to obtain bacteria samples at home?

As the original question went from hold to closed, I thought I would write up a more appropriate question. How should one go about getting bacterial samples to look at under a microscope at home? ...
10
votes
3answers
1k views

How are our senses dimmed during sleep?

Our senses are not as sensitive during sleep compared to wake. There is an arousal threshold during sleep that only when it is overcome will it wake a person up. My question is how is this arousal ...
10
votes
4answers
6k views

How does sodium in one's diet affect blood pressure?

Due to high blood pressure, my doctor has recommended I go on a low-sodium diet. So, that got me wondering what it is about sodium that drives this recommendation? What does sodium do to a body ...

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