4
votes
1answer
67 views

Parsimony (cladistics)

I don't understand how to sum the changes in a phylogenetic tree. Here for example: http://www.med.nyu.edu/rcr/rcr/course/phylo-cladistic.html How do you end up with 8 for the first and 9 for the ...
4
votes
2answers
57 views

Cell cycle selection

Is it possible to select from colonies only cells which are at a certain stage in the cell cycle? E.g. if I was trying to analyse expression of a number of genes during different stages of the cell ...
8
votes
1answer
10k views

What is the composition of human feces?

Are there any studies or general information on the composition of human feces? I'd specifically like to know the percentage of carbohydrates and amino acids relative to the amount that was ingested ...
4
votes
1answer
99 views

What percentage of human capillaries are located in the skin?

As in the subject line, what percentage of capillaries in a human (expressed in terms of total length, I suppose) are located in the skin, as opposed to internal organs? Google scholar has not turned ...
9
votes
3answers
4k views

Why does human facial and head hair continue to grow?

Many people can grow extremely long head hair and facial hair. Are there evolutionary theories as to why this is the case? It seems like having long hair could be a disadvantage, and extremely long ...
6
votes
1answer
84 views

Is the eyes' movement discrete?

When tired and it was dark, I noticed that if I focused on a dim light source and moved my eyes fairly rapidly sideways, the resulting images that lingered for a short while were not smoothly blurred ...
1
vote
1answer
75 views

Hearing system as in visual system: exists well also - in protecting the inner mechanical parts of both sensing systems - a similarity?

I prefer answers, not just discussing. In the mechanical part of the human eye the control system to protect for overload of the diaphragm in the iris with a strong coupling to the light intensity ...
6
votes
3answers
17k views

Do animal cells have vacuoles?

I overheard a rather heated argument about whether or not animal cells have vacuoles. One person said that they do, but they're much smaller than vacuoles in plant cells. The other person said they ...
6
votes
1answer
129 views

Can jellyfish improve Black Sea environment?

According to this study, cited by many popular science magazines, jellyfish and other, smaller animals can contribute to the vertical ocean stir as much as currents do. Black Sea chemistry and ...
2
votes
0answers
11 views

Difference between Diffuse Optical Tomography and Optical Tomography

What are there the differences between these two modalities? Diffuse Optical Tomography (DOT) Optical Tomography (OT) Are there forms of OT that are not DOT?
3
votes
2answers
52 views

Are there inherent problems in simulating marine environments, as compared to terrestrial systems?

We cultivate a number of terrestrial organisms in greenhouses and stables where they live in completely artificial environments. This seems to extend far less to marine organisms, such as fish. ...
6
votes
1answer
5k views

How long will norovirus live?

I hope this is the right place to ask. I subscribe to several Stack Exchange threads, and regard them as the best internet forum for genuine and credible answers. I spent last evening talking to ...
2
votes
1answer
69 views

Do siblings have a bias toward believing they look different from each other?

Anecdotally, I have observed (myself included) that siblings tend to think that they look less similar to each other than an unrelated observer would say. Is there any experimental data to back this ...
5
votes
1answer
91 views

Are there known minimal marine ecosystems that are stable?

A more entertaining phrasing of the question would be "what would a marine ecologist put into a perfect aquarium?" I was reading about Prochlorococcus, among other photoautotrophs, and found that ...
2
votes
2answers
813 views

Is it possible that the recipient of a heart transplant would display some of the donor's personality traits, as if the heart has memories?

I've read somewhere that after a person has a heart transplant, it is possible that his/her attitude, action or behavior would change slightly or significantly, as though he/she possesses some aspects ...
3
votes
1answer
81 views

Atomic force microscopy: depth penetration?

What depth penetration can one typically get with atomic force microscopes? (i.e. how far into the tissue can one image?). I have found numbers on acquisition times (minutes) and spatial resolutions ...
3
votes
3answers
193 views

Super-resolution imaging in vivo

Are there any microscopy modalities or techniques for in vivo imaging at higher resolutions than the diffraction limit? I was looking at this list: Super resolution microscopy, but they don't talk ...
3
votes
1answer
44 views

Lateral, axional and temporal resolutions for imaging in vivo

What are the spatial (lateral and axional), and temporal resolutions that one is expected to get with the following optical imaging techniques? Optical Bioluminiscence Imaging (BLI) Optical ...
5
votes
1answer
1k views

How much gas is exchanged in one human breath?

When we breathe, our lungs absorb a portion of the oxygen in the air, and replace it with some amount of carbon dioxide and water vapor. Typically, how much $O_2$ (in grams, milliliters, or moles for ...
4
votes
1answer
163 views

Possible to Gain More Weight than the Food You Eat

I was wondering if it's possible gain more weight than the mass of the food you eat. At a first look, this is impossible because of conversation of matter, but are there other things to take into ...
7
votes
2answers
146 views

Can allelopathy succesfully be used against algal blooms?

Algal blooms caused by man (harmful algal blooms) are a major ecological problem. An excessive amount of algae causes hypoxia and logically, most marine wildlife can't be sustained in hypoxic ...
4
votes
1answer
162 views

Evolutionary explanation to why we have such large memory capacities?

The scientific consensus is that no one ever fills up their memory capacity by learning facts and so on, even in the information age. My question is therefore, is there an evolutionary reason as to ...
2
votes
3answers
89 views

Simulating Cell differentiation

I'm a computer programmer deeply interested in Biology. I wish to write a computer simulation for cell differentiation. I understand there will be seemingly impossible challenges in doing this. But ...
3
votes
1answer
166 views

Neuroscience of temperature regulation and perception

The hypothalamus is known to be important in the regulation of body temperature, but I'm curious whether anyone knows about the neurocircuitry of perceived temperature. It seems like there could be a ...
4
votes
2answers
166 views

Is every part of a virus important for replication?

Is every component of a virus absolutely essential for its infection and replication in a host cell? Or can you just have parts of it to cause infection?
5
votes
4answers
2k views

Why Do Ruminants Require A Multi-Compartment Stomach To Digest Food?

Cows, camels, sheep, goats, etc being ruminants must chew their food repeatedly by regurgitating their food from their first stomach compartment and chewing their 'cud'. This then finer chewed ...
4
votes
1answer
3k views

How does prolonged exposure to high frequency noise affect hearing?

Is there any research showing how prolonged exposure to background noises, particularly high frequency noises, affect hearing abilities? Does constant high pitched noise cause damage even a low ...
2
votes
1answer
67 views

Historical recovery from mass extinction events

Is there a way to generally characterize how species "regrew" after the various mass extinction events happening periodically from 450 Ma to 65 Ma. Would the surviving species just start back where ...
2
votes
1answer
1k views

Does coloring affect the perception of depth?

I have a question about the mechanics of human vision which may be as much of a physics question as it is a biology/physiology question. I noticed that if I try to imagine a clear blue daytime sky ...
3
votes
1answer
346 views

How do multiple replication forks function without 'colliding', and what is the benefit of this method?

I'm currently reading a little about DNA replication, and have come accross the following statement; Replication starts from a fixed point and is bi-directional ... In Eukaryotes, there are ...
2
votes
2answers
3k views

Do T-cells express MHC molecules?

T-cells recognize the MHC molecules and body's own peptides. When it doesn't, it alarms the immune system. But do T-cells express MHC molecules ? If so, how are they using it? If not, what happens ...
3
votes
1answer
95 views

Would ovoviparous to viviparous mutation have been gradual? How would that work?

It seems unlikely that an ovoviparous ancestor of mammals long ago could have had a viviparous offspring in a sharp one-generation dividing line, but what would be the gradual steps between egg birth ...
6
votes
1answer
251 views

Why does not the host produce any immune response to antiserum antibodies?

When an antiserum is injected to a person to protect oneself from a certain disease, the antibodies in the antiserum come from another organism. The question is: Why don't the injected antibodies ...
1
vote
1answer
198 views

Cine-MRI versus MRI

Could someone explain the difference between Cine-MRI and MRI? I am reading conflicting things online, such as Cine-MRI uses ECG-gating, or that Cine-MRI takes many images of the same position of the ...
2
votes
2answers
117 views

Can a new Y-chromosome be created?

The major gene of the Y-chromosome is SRY. Would it be possible to get the X-chromosome and add SRY to create a "fuller" Y-chromosome? What advantage does the skinny Y-chromosome give an individual ...
1
vote
1answer
118 views

Interlocus Contest Evolution means suicide?

I was reading Matt Ridley's "Genome" book. I am trying to understand the Interlocus Contest Evolution in his X-Y chapter. I do not understand why the X and Y chromosome would want to kill each other. ...
2
votes
0answers
42 views

Is there an entry-level circadian model of serotonin, ghrelin, dopamine and the sense of well being?

I've long been interested in circadian rhythms and recently came across a variety of articles that appear to indicate that the following neurotransmitters, transferases and hormones are connected. ...
6
votes
2answers
802 views

Does body temperature affect human lifespan?

If a human body were somehow to be kept at a cold temperature (say 30C) for the entire life of the given individual. And somehow the brain could be fooled into thinking that this 30C feels nice and ...
2
votes
1answer
567 views

Temperature Tolerance In Relationship To Body Temperature

A humans body temperature averages at around 98.6°F A dog's body temperature averages at around 101.5°F If the temperature ...
3
votes
3answers
1k views

Why does the apex of the human heart usually point to the left?

In the majority of human beings, the apex of the heart (left ventricle) points towards the left side of the body. Sometimes however (approx. 1/12000 births), a person is born with a condition known ...
11
votes
2answers
179 views

Have any genetically altered organisms actually become abundant in a natural environment?

Most of the things that come up in Google and Google Scholar for this question have a mostly/completely speculative tone, or at best use models instead of measurements. This report describes some ...
1
vote
0answers
42 views

Can viral proteins cause infection? [duplicate]

Possible Duplicate: HIV Rapid Tests Can proteins found on the surface of RNA viruses cause infection without the presence of the actual RNA and other components used in the virus?
3
votes
1answer
366 views

Are there records of monozygotic twins in which one experiences androgen insensitivity syndrome

I have given my high school biology students the thought experiment of "What would happen if a researcher induced twinning of a female zygote and then replaced one of the X Chromosomes with a copy of ...
4
votes
1answer
111 views

Difference In Telomeres Between A Thale Cress Plant And A Methuselah Tree

From what I have read and understood telomeres cap off how many times a cell can divide before it can no longer divide and that is what causes aging. A thale cress plant apparently has a life cycle ...
19
votes
2answers
1k views

Why Is Most Life Symmetrical Externally But Not Internally?

Mammals, reptiles, arachnids, insects, etc are all as far as I am aware symmetrical in appearance. Take a human for instance, make a line from the top of our head right down the middle. However, ...
3
votes
3answers
195 views

Are there people cured of HIV by means of HAART?

I wonder if there people who were cured of HIV only by means of highly active anti retro-viral therapy (HAART) or other drugs rather than by bone marrow transplant? I know that HAART can suppress HIV ...
6
votes
2answers
172 views

Why do people feel extreme cold at different temperatures compared to other people of same body structure?

I have seen some people shivering in the room temperature of 18°C while others of similar body structure do not feel that much amount of cold. Of course the clothing of both people is similar if ...
1
vote
1answer
74 views

Can gelatine digestion make blood more thick?

Can gelatine cause blood thickening if digested?
7
votes
1answer
215 views

Why Can't A Male Mule Have Offspring?

I've read that female mules can sometimes have offspring, but that male mules are incapable of doing so. Why is that the case? Is their sperm not capable of entering the egg or is their a genetic ...
2
votes
1answer
132 views

In scuba diving, are nitrogen narcosis and high pressure nervous syndrome the same thing?

In training for scuba diving, they tell you that when you're bellow 100 ft or so you have to watch out for changes in mental state that resemble drunkenness. The cause of these mental disturbances is ...

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