This tag is for questions about the general biological features of human beings (as opposed to the biology of non-humans).

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Does the change in eye color (melanin concentration) affect the iris pattern?

In cases of acquired heterochromia, is there a quantifiable change in the iris pattern; the clefts , furrows, etc. If yes, what changes are observed? And if no, are there any diseases or acquired ...
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1answer
60 views

If our skin is burned by the sun what causes the red color of the skin?

Mostly it is not a good sign we are burned because too much UV light has damaged our skin and increases skincancers. But the red color we get after a few ours, what is the exact cause of it and why ...
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21 views

Anaerobic nutrient expenditure

Doing some research into different forms of exercise and energy systems and I realized something odd about the way we talk about energy. When we eat, we take on macronutrients that are broken down ...
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1answer
37 views

the evolution of the human brain size [closed]

I was thinking, as I know, sometimes the process of producing DNA did not work well(correct me if I'm wrong), so it gives us some changes in the object we gonna ...
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2answers
182 views

Can viruses be toxic?

Bacteria can produce toxins like endotoxins and exotoxins. In diseases like cholera or tetanus they can harm infected people due to these toxins. Now, although viruses are much smaller and are ...
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1answer
132 views

Does our immune system react on all bacteria?

In our body we carry a lot of bacteria. Some of them are bad for our health, but others are beneficial. For example bacteria may protect us against other pathogenic bacteria. But is our immune ...
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1answer
956 views

I don't want to know what bacteria is called but if the bacteria from unborn babies have benifits on health? [duplicate]

This question is not the same as the duplicate. I was told that when babies are born they are born with bacteria in their stomach. When a child takes antibiotics are there unique bacteria destroyed ...
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1answer
45 views

Does a zygote express all genes?

If a zygote has all the cytoplasmic determinants and all the specific transcription factors, does that mean that all genes in the genome are expressed?
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41 views

Is the zygote the only totipotent cell?

I’ve been told that the unfertilized egg contains cytoplasmic determinants (e.g. proteins, transcription factors, mRNAs) that are divided unevenly during the early stages of cell division in an embryo....
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56 views

Are high sounds worse for your hearing than low sounds?

From about 80 dB it is possible to suffer loss hearing after a couple of hours. But does it make a difference what frequencies those sound waves are or is it just the volume of the sound in dB that ...
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136 views

What will happen when humans are injected with plant growth hormones

Will plant growth hormones (PGHs), (let us consider auxins for example) poison our body or not? I do realise that when you eat a shoot, auxins get digested and are less likely to be poisonous but when ...
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70 views

What Would Happen To a Human Who Died In Space And Stayed There For a Prolonged Period of Time? [closed]

Last night I was watching a documentary regarding the Apollo space program, and it spoke about how Apollo 8 orbited the moon 10 times then came back to Earth. It said that while the ship was in orbit ...
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2answers
81 views

Do babies conceived naturally or artificially have any differences in long-term health?

Are there any long-term differences in children conceived via artificial insemination or sexual intercourse, pending that the mother successfully delivers the child?
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0answers
39 views

Do both the Sperm and Egg must be at exactly 7.4 pH for fertilization?

I suddenly came across this article and it says that for human conception to occur both the sperm and egg must be at exactly 7.4 pH - not 7.0, nor 7.7 but 7.4. If conception depended on such exact ...
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0answers
39 views

Are all genes transcribed in differentiated cells?

My textbook tells me that it’s specific transcription factors that allow for a different set of genes to be expressed in different cells (differential gene expression). My book gives the example of ...
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2answers
2k views

Why is it advised that infants are fed mother's milk?

I have heard that mother's milk is preferred over other baby foods, because it contains immunoglobulines (secretory IgA), and other essential nutrients. But why is mother's milk so special? Any ...
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1answer
61 views

Is Zika suspected of causing birth defects only if contracted during pregnancy?

There seems to be growing evidence that a recently spreading strain of Zika virus is in fact linked to microencephaly and other birth defects in newborns (see here, here, and here for examples). I ...
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1answer
106 views

Why is it always Sodium that we talk of in blood pressure?

Why is that we emphasize so much on sodium in blood pressure? I understand that it is a major extracellular ion, but, it also is tightly regulated. So when something is that tightly regulated, won't ...
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39 views

Why are oral cells (or tissues) more heat resistant? [closed]

When we are having meals, such as enjoying hot pot and drinking hot water, we only have a sense of "warm" in our mouth, or even along the organs in alimentary canal. But when we put our fingers into ...
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1answer
98 views

Identifying an Unknown Blood Type [closed]

The following case study has a student working with blood samples to identify their blood types (A, B, AB, and O). Consider the situation and answer the questions. A student is given eight ...
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0answers
18 views

Why do kupffer cells not attack sporozoites of malaria?

During malaria, why don't kuppfer cells (hepatic macrophages) attack the plasmodium and stop schizogony, thus saving us from the disease?
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0answers
87 views

Is natural selection still at work in humans in the 21st century? [duplicate]

There has been some disussion on this site about some aspects (e.g. evolution of eye sight, or height, or the effect of medicine, or evolution the past $\sim10000$ years). My question is really more ...
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155 views

Are Young Girls Stronger than Young Boys?

According to "common wisdom" the average man has, as a proportion of his body weight, 50% more muscle mass than the average woman. This is in addition to how the average man is several inches taller ...
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Can humans extract calories from all roots? [closed]

Roots are used for storing plants' energy, which suggests that humans could extract the calories by consuming them. However, I have been unable to find any substantial sources on consuming the roots ...
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Is the amount of blood same in the pulmonary and systemic foetal circulation?

We learn that the stroke volume is the same for the right and left side of the heart. So the amount of blood in either circulations should also be the same. (is it? I myself doubt this statement. As ...
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1answer
30 views

What is the name of the property of viruses can activate a second time, with different symptoms?

The Varicella zoster virus causes chickenpox in children and shingles in adults. It appears after the initial infection, it can go dormant in the nerve, and reactivate itself decades later. In ...
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Variation of human body temperature during physical exercises [closed]

I'm currently doing a research on "Variation of human body temperature during physical exercises". I have to study about Heat equation in 1-D , 2-D and 3-D. Are there any good resources that I can ...
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49 views

What is the name of the category of viruses that affect only one side of the body?

The Varicella zoster virus causes chickenpox in children and shingles in adults. When the virus attacks as shingles, one of its distinguishing characteristics is that it only affects one side of the ...
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1answer
41 views

What is the name of the property of viruses that can go dormant in the host for 30 years?

The Varicella zoster virus causes chickenpox in children and shingles in adults. It appears after the initial infection, it can go dormant in the nerve, and reactivate itself decades later. My ...
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1answer
80 views

Is a bone marrow transplant limited by sex?

Can a female patient get transplanted with bone marrow of a male donor and vice versa?
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1answer
45 views

Lookup for transporter locations in humans

I am interested in several transporters and cotransporters (eg SLC12A1/2 and many others), more precicely, in (human) organism that are made of cells containing those transporters. So does anyone know ...
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1answer
89 views

Can a Turner syndrome patient develop male characteristics artificially?

From an answer to the question Can stem cells from male convert to cells of female-only organs, and vice versa? Y chromosome is the sex determining chromosome with SRY gene that determines testes ...
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3answers
531 views

At what temperature do human bones disintegrate?

I know, the human skin can get damaged as quickly as 2 seconds, when exposed to temperature above 80 Celsius. However, what about human bones, say the skull? For example, when you cook a meal, at ...
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43 views

Does variation in human gut length vary predictably with diet of ancestors?

Background: Numerous online searches, textbooks and other sources seem to pin the average length of the human gut from mouth to anus (oroanal) between about 5-10m in length. To pick a reputable ...
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51 views

Real Wine and Real Bread Superfoods? [closed]

On NPR news on the Fm Radio a doctor said wine and bread is the best 2 things you can eat together? A practice observed to this day by Christianity although the bread and wine are badly stripped of ...
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55 views

How would a human brain change if it existed in isolation? [closed]

How would a human brain change if it didn't receive any signals for a longer period of time (e.g. 1 month)?
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37 views

how to build a PPI network? [closed]

I would like to know how to visualise a cluster of several proteins lets say I have a list of proteins ...
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81 views

Do animals have different taste preferences within the same species?

Humans (especially children...) seem to dislike certain foods or drinks, that other humans seem to like. Common examples are coffee, french cheeses, olives, milk, fish and cabbage. Are there examples ...
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1answer
27 views

Irradiation positive effect on humans?

In research paper Euphytica 135: 187–204, 2004 it is written that: 434 mutant varieties of rice have been released with improved characters such as semi-dwarf height, early maturity, improved ...
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25 views

How many species of mites live on the human body?

How many known species of mites regularly live on the human body? I've always heard that most people have eyebrow mites. This source mentions 2 species of face mites, Demodex folliculorum and D. ...
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26 views

What are the most efficient sources of nutrition to add lean mass? [closed]

In conjunction with an exercise routine, what sources of nutrition will best help increase lean body mass. Most non-hormonal exercise supplements risk causing liver damage and gout due to excess urea ...
3
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1answer
102 views

Does our brain contain an innate function about closing only one eye?

I wasn't sure where to post this, but biology seemed fitting for me. Sorry if I'm wrong. I was wondering why, when we close both our eyes and look at light, it is clear we can see the light even ...
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2answers
5k views

Is it possible that by mutation a human could see infrared or other 'colours'?

Incoming light reacts with the several types of cone cells in the eye. In humans, there are three types of cones sensitive to three different spectra, resulting in trichromatic color vision. Each ...
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2answers
80 views

Metabolic activity postmortem

I read some papers about studies on metabolism in post-mortem tissues in human, but I do not exactly the reason about why our brain continues to have activity after death.
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1answer
269 views

What biological functions does crying serve?

Tears suddenly start flowing out of our eyes when we find our long lost friend or when someone unexpectedly decides to break up with us. Do tears really save us from harm? Or are they just the reflex ...
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1answer
43 views

How fast is the patellar reflex?

I have found a lot of content on the patellar reflex, but I cannot find any studies on how fast the reflex is, from onset of stimulus to innervation of muscles. Does anyone know of either a study or ...
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1answer
75 views

What were the main discoveries in Biology? [closed]

What were the greatest achievements in Biology? Can you please provide a short list of discoveries that you would consider as being the most important discoveries of the history of Biology.
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2answers
120 views

Are humans evolving since their first appearance? [duplicate]

Is the evolution a very prolonged progress, or are we going to witness further evolution of the human species? If so, in which direction? Are there any widely predicted changes for humans?
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1answer
71 views

What is the correlation between hand and neck flexibility? [closed]

I am trying to understand this statement in the book, Mudras, Yoga in your Hands by Gertrud Hirschi: There is a direct relationship between the hands and the neck since the nerve paths run through ...
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1answer
44 views

What's the mixture of plasma and haemoglobin called [closed]

I know of oxyhaemoglobin but the mixture of plasma and haemoglobin in the blood gives what?