All Questions
28
votes
4answers
2k views
Why 20 amino acids instead of 64?
This question got me thinking about amino acids and the ambiguity in the genetic code. With 4 nucleotides in RNA and 3 per codon, there are 64 codons. However, these 64 codons only code for 20 amino ...
18
votes
3answers
531 views
Is it necessary to conduct a power analysis before beginning an experiment?
I know that power analysis is the statistically valid way to ensure you use the correct numer of samples or repeats in an experiment. But I have never seen any biologist actually conduct a power ...
22
votes
3answers
3k views
How does the brain's energy consumption depend on mental activity?
What is the impact of mental activity on the energy consumption of the human brain?
I am most interested in intellectually demanding tasks (e.g., chess matches, solving a puzzle, taking a difficult ...
21
votes
1answer
256 views
How long will a vegetable live for after being harvested?
I understand this might depend on the types of vegetables, but is there an average or studied specifics? Does it die immediately? Is there a way to precisely diagnose death in plants? If so, what are ...
13
votes
1answer
208 views
Do trees age on a microscopic level?
Most animals age via at least two mechinisms:
at a "macroscopic" level, basically wear and tear to the point where (on evolutionary time scales) it's more genetically advantageous to optimize for ...
8
votes
1answer
514 views
Why can hair grow without limit while eyebrow cannot?
I cut my eyebrow and it grows until reach a certain length. Hair can grow without limit.
Why can hair grow without limit while eyebrow cannot?
5
votes
3answers
236 views
How does “be altruist to those who are similar to you” evolve?
There are many cases when people commit altruism. One is relationship. I am willing to die for 2 of my children or 8 nieces, say an evolutionary psychologist. Another is reciprocal altruism, which is ...
24
votes
4answers
320 views
Why are amino acids in biology homochiral?
Why are nearly all amino acids in organisms left-handed (exception is glycine which has no isomer) when abiotic samples typical have an even mix of left- and right-handed molecules?
14
votes
4answers
1k views
How many genes do we share with our mother?
Somewhere I have read we share more than 99% of our genes with every other other person and 98% of our genes with chimpanzees. What does this mean? Don't we share 50% of our genes with our mother and ...
8
votes
3answers
399 views
What is the evolutionary advantage of death?
I know death and cancer doesn't hurt humans' reproductive success. It's not helping either.
Why do we die? Why dying humans (all of us) are common? What's the point of dying?
13
votes
2answers
241 views
How is temperature sensed?
Can anyone summarize the mechanism by which when an object of a given temperature is placed in contact with, say, the skin on a human fingertip, the average speed of the particles of the object is ...
10
votes
3answers
433 views
What implications has the missing 2'-OH on the capability of DNA to form 3D structures?
The chemical difference between RNA and DNA is the missing 2'-hydroxyl group in the nucleotides that build DNA. The major effect of that change that I know of is the higher stability of DNA compared ...
7
votes
1answer
111 views
Why is maintaining a circadian rhythm important?
What are the real consequences of never maintaining a circadian rhythm?
How is circadian rhythm important for health and function? Where did it arise in evolution?
4
votes
1answer
107 views
Which sex has higher variance of reproductive rate in modern societies - male or females?
Who has a more varied reproduction rate in modern western societies - men or women? The average rate is the same of course, but I wonder which sex have higher variance - higher variance means that ...
3
votes
2answers
163 views
Short-term Lamarckism in asexual single cell organisms
I was reading through the Karr et al. (2012) whole-cell computational model. One of the things they did was to induce single-gene disruptions in their model. They observed several to be fatal, but:
...
19
votes
5answers
439 views
Why do we age? or Do we have a theory of senescence?
There seem to be a number of ideas about why we age. Hypotheses include the gradual accumulation of cell metabolic products affecting organism function and the reduction of telomere length during cell ...
30
votes
4answers
1k views
Why do plants have green leaves and not red?
I know plants are green due to chlorophyll.
Surely it would be more beneficial for plants to be red than green as by being green they reflect green light and do not absorb it even though green light ...
10
votes
5answers
1k views
How did the first self replicating organism come into existence?
When people try to explain evolution, they tell me that evolution is a cumulative result of mutations & natural section of the more superior individuals of a particular species. I think I'm fairly ...
20
votes
3answers
2k views
Is there any advantage to one blood type over another?
All humans can be grouped into ABO and Rh+/- blood groups (at a minimum). Is there any advantage at all to one group or the other? This article hints that there are some pathogens that display a ...
17
votes
4answers
2k views
Death because of distilled water consumption
One of my friends said that I would die if I drank distilled water (we were using it in a chemistry experiment) I gave it a go and surprisingly did not die.
I did a bit of Googling and found this
...
16
votes
2answers
363 views
Can rats pass on memories of a maze to their offspring?
A friend of mine told me once about a documentary movie he saw some years ago. On this movie he saw scientists talking about particular experiment. This experiment involved rats and probably ...
15
votes
4answers
347 views
How do trees manage to grow equally in all directions?
I was walking down a road with these beautifully huge trees when this question occurred to me.
Large trees with many thick branches have to grow equally in all directions, or they would tip over. Is ...
4
votes
1answer
125 views
If fever is a natural immune defense, why do people take drugs to lower it?
If fever is a natural defense against pathogens, why do sick people take NSAIDs to reduce the fever?
11
votes
2answers
315 views
Are there neurons that can sense light shining in your ears?
I know someone who bought earphones that shine light in you ears. According to what he was told, there are neurons that sense light and then make you feel wide awake when activated, which seemed like ...
10
votes
1answer
329 views
Do large animals often evolve into smaller animals?
There are several examples where the largest animals were killed off preferentially due to a major ecological shift:
The KT extinction event
The Holocene extinction, as well as the major megafauna ...
10
votes
2answers
156 views
Under what conditions do dendritic spines form?
I'm looking for resources or any information about the formation of dendritic spines and synaptogenesis, especially in relation to how new connections are formed on a daily basis.
Does the ...
9
votes
2answers
280 views
Do insects with compound eyes have depth perception?
Do insects with compound eyes have depth perception? They fly as if they do, but their eyes are so close together it seems like the image would be 2 dimensional.
8
votes
3answers
222 views
Long-term-potentiation and memory. Where do we stand?
I was reading the answers to the question: How and where, in the human brain, are memories stored? and, as expected, LTP and LTD came out.
Every time I read about LTP/LTD there is always something ...
6
votes
1answer
88 views
Macromolecule levels in daughter cells after fission
When a prokaryote undergoes binary fission, how are the non-DNA macromolecules distributed between the two daughter cells? This is motivated by comments on a previous question and a G+ discussion. I ...
4
votes
1answer
194 views
What gives things their colour?
My 6 year old daughter asked me 2 biology-related questions yesterday and I tried my best to answer them with the aid of YouTube videos. One of the questions (I may post the other one too) was
...
0
votes
1answer
138 views
Why have humans evolved conciousness?
Why did humans/animals evolve to become self-aware of their own thoughts. That is, why don't humans act and compute like a machine, or walking zombie. In my mind, such creatures would still be as ...
20
votes
3answers
270 views
Is telomere length a reliable measure of health/lifespan?
Several companies are commercializing tests for telomere length such as this one here. I understand the basic mechanism for why telomeres shorten during DNA replication, but how good is the evidence ...
16
votes
2answers
234 views
Can an adult without genetic lactase persistence still develop a tolerance for dairy foods?
While investigating the rise of adult lactose tolerance, I came across the news that China has been encouraging its citizens to drink more milk, even though most of the Asian population lacks the SNP ...
14
votes
2answers
938 views
What actually happens when my leg 'falls asleep'?
Most people have experienced the temporary loss of feeling and tingling in their leg resulting from sitting in an abnormal position for a short while. Usually you get a loss of feeling in your leg ...
13
votes
4answers
648 views
Can two humans with 44 chromosomes produce viable offspring?
It is known that there are very few individuals having 44 chromosomes, not the usual 46 chromosomes.
One example is a male in China: the first article, the second article.
The other is a female in ...
11
votes
1answer
563 views
What is the smallest number of amino acids required for life?
Is there any hypothesis on the minimum number of amino acids required for life?
10
votes
1answer
652 views
Why do we grow so much hair on our heads compared to our bodies?
I've been wondering about head hair, facial hair in particular. Human males can grow very extensive beards should they choose to not shave - however you do not really see this in our chimpanzee ...
9
votes
2answers
354 views
Will humans and animals be harmed by frequencies outside their hearing range?
The human ear (for example) is sensitive to frequencies from 20Hz to 20kHz. Any sound beyond that limit would not be heard by us naturally.
Will it harm us (effect our ability to hear) when we hear ...
9
votes
1answer
79 views
Which patterns do I have to avoid when modifying the 3'-UTR?
I want to change a pre-miRNA sequence (in my case the pre-miRNA is encoding in a 3'UTR of a gene) and then put it in a lentivirus to see if it is still processed.
After modification (permutation of ...
8
votes
1answer
155 views
Does DNA react in all of the ways most other acids do?
As I understand it from my basic chemistry, there are some fundamental reactions that exist between any acid and other substances for example acid-base reactions that form a salt, and the existence of ...
8
votes
6answers
522 views
Human evolution: Where *exactly* did the first human come from, whose parents were not?
Layman here. So I have never really quite understood this facet of human evolution, (or any other for that matter), in that, I understand the evolutionary process, but I get lost on the 'border' ...
8
votes
1answer
461 views
How to DIY preserve pet DNA today so that it can be used in 20 years
I know that there are companies that offer a kit+storage of your pet DNA for around $2k.
My question is if there is any other option for doing this yourself with a thought in mind that in 20+ years ...
8
votes
1answer
275 views
How does laser surgery correct accommodation problems?
When someone undergoes laser surgery to improve eyesight, how does it correct accommodation problems?
Why does it not help presbyopia?
6
votes
1answer
407 views
Does extracted DNA degrade after a certain time period?
For direct use as template in PCR runs. Chelex 100 5-10% w/v extraction. Without listing the whole protocol, in the end the supernate is decanted off and then stored at 4°C. I was under the impression ...
5
votes
2answers
120 views
HIV Rapid Tests
The hiv antigens that are used in the oral rapid tests, are they infectious? The tests do not contain any actual virus but I am curious if the antigens themselves could somehow create the virus on ...
4
votes
2answers
170 views
Pipetting damage on cells
I'm curious how much damage is potentially inflicted by shear stress by pipetting. I know that with syringes for stem cell injection cause a lot of damage. However, to what extend does this happen ...
4
votes
1answer
845 views
What are differences between formation of embryonic disc in chick and mammal embryo?
Exam question which got lowest average points in my university: 1/5 average.
No markscheme available so my attempt below.
I assume that embryonic disk prefers to germ disk such that Formation prefers ...
32
votes
3answers
749 views
Why did the process of sleep evolve in many animals? What is its evolutionary advantage?
The process of sleep seems to be very disadvantageous to an organism as it is extremely vulnerable to predation for several hours at a time. Why is sleep necessary in so many animals? What advantage ...
29
votes
4answers
1k views
Life without DNA?
I'm by no means an expert in the field, merely a curious visitor, but I've been thinking about this and Google isn't of much help. Do we know of any lifeforms that don't have the conventional ...
28
votes
4answers
688 views
Can scientists create totally synthetic life?
This particular question has been of a great deal of interest to me, especially since it dives at the heart of abiogenesis.
