All Questions
43
votes
2answers
552 views
How many times did life emerge from the ocean?
Evolution is often mistakenly depicted as linear in popular culture. One main feature of this depiction in popular culture, but even in science popularisation, is that some ocean-dwelling animal sheds ...
37
votes
3answers
566 views
Is there a reason why human eyesight and plants make use of the same wavelength of light?
The accepted range for the wavelengths of light that the human eye can detect is roughly between 400nm and 700nm. Is it a co-incidence that these wavelengths are identical to those in the ...
33
votes
3answers
7k views
Why is uracil used in RNA rather than thymine?
What is the advantage gained by the substitution of thymine with uracil? I have read previously that it is due to thymine being "better protected" and therefore more suited to the storage role of ...
32
votes
3answers
748 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 ...
31
votes
1answer
542 views
Is there any evidence that sexual selection may lead to extinction of species?
Darwin suggested that sexual selection, especially by female choice, may counter natural selection. Theoretical models, such as a Fisherian runaway process, suggest that evolution of preference and ...
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 ...
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
687 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.
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 ...
26
votes
1answer
2k views
Why Does Salt Water Help Sore Throats?
I am having some trouble understanding how salt water, a simple solution, could so effectively remove the pains of a sore throat.
I do believe that the answer is closely related to hypo/hyper-tonic ...
25
votes
2answers
497 views
How do cockroaches resist the effects of ionizing radiation?
Cockroaches are very hardy insects. It is known that, among other things, they are able to withstand bursts of ionizing radiation that would kill a human being.
The explanations of this observed ...
25
votes
1answer
1k views
Is the “Great Pacific Garbage Patch” beneficial for marine wildlife?
A study was just released by researchers at Scripps Institute of Oceanography revealing a drastic increase in the amount of plastic adrift in the Pacific Ocean. According to the paper, the amount of ...
25
votes
3answers
869 views
Why is polyploidy lethal for some organisms while for others is not?
Polyploidy is the multiplication of number of chromosomal sets from 2n to 3n (triploidy), 4n (tetraploidy) and so on. It is quite common in plants, for example many crops like wheat or Brassica forms. ...
24
votes
4answers
319 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?
24
votes
4answers
353 views
How does the sensitive plant detect vibrations?
The sensitive plant (Mimosa pudica) is a remarkable little plant whose characteristic feature is its ability to droop its leaves when disturbed:
Apparently, this ability to droop rests on the cells ...
24
votes
1answer
4k views
Why do Humans not produce Vitamin C like other mammals?
Why do most mammals produce their own Vitamin C?
Why do Humans not?
24
votes
4answers
587 views
Human perception of time depending on age
From what I can tell and what thus far all people with whom I discussed this subject confirmed is that time appears to "accelerate" as we age.
Digging a little, most explanations I found basically ...
23
votes
6answers
1k views
How should I ship plasmids?
I shipped 10 µL of my vector miniprep to a collaborator in a 1.5 mL eppendorf parafilmed shut and stuffed into a 50 mL conical with some paper-towel padding. However, something happened on the way ...
23
votes
2answers
296 views
What are the trajectories of flying insects?
Many flying insects tend to have very jagged trajectories. For moves of a fruit fly looks like a random walk.
Is there any research on the properties of trajectories (e.g. their fractal dimension or ...
23
votes
3answers
1k views
How long does antibiotic-dosed LB maintain good selection?
Various people in our lab will prepare a liter or so of LB, add kanamycin to 25-37 mg/L for selection, and store it at 4 °C for minipreps or other small cultures (where dosing straight LB with a 1000X ...
23
votes
1answer
364 views
What is itching?
What exactly at the molecular level is itching? What physiological function does itching serve, if any? I cant remember the reference but a PLCb3 null mice lost the itch phenotype, so presumably it is ...
22
votes
6answers
270 views
Has there been any observation of species adapting the evolution process?
I am very interested in the evolution of the evolution process itself. There are of course a lot of things that influence how evolution will work, but for this question, I am interested in things that ...
22
votes
3answers
2k views
Why do eukaryotic organisms have introns in their DNA?
We touched on introns and exons in my bio class, but unfortunately we didn't really talk about why Eukaryotes have introns. It would seem they would have to have some purpose since prokaryotes do not ...
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
4answers
249 views
How are the boundaries of a gene determined?
What statistical processes and methods are used by geneticists/molecular biologists to know where one gene starts and one ends?
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 ...
21
votes
2answers
238 views
How do biological communities at deep-ocean hydrothermal vents migrate between vents?
Much interest in the astrobiology community has been generated by the discovery of biological communities populating deep-ocean hydrothermal vents (i.e. "black smokers"). (1) These ecosystems rely on ...
20
votes
4answers
758 views
What exactly are computers used for in DNA sequencing?
I've thoroughly read the Wikipedia article on DNA sequencing and can't get one thing.
There's some hardcore chemistry involved in the process that somehow splits the DNA and then isolates its parts.
...
20
votes
4answers
963 views
Do plants produce any heat?
Many plants (e.g. roses, palms) can be protected from frost during the winter if shielded with an appropriate coat that can be bought in garden shops. Do plants produce any heat that can be kept ...
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 ...
20
votes
3answers
269 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 ...
20
votes
4answers
511 views
Why do men have nipples?
I'd be tempted to call nipples in men vestigial, but that suggests they have no modern function. They do have a function, of course, but only in women. So why do men (and all male mammals) have them?
...
20
votes
1answer
225 views
How does a cell know its size?
Cells come in all sorts of sizes. How do they regulate their cell size to the point where similar cell types have a fairly mono-disperse size distribution?
Reasked from ...
19
votes
2answers
257 views
Is there evidence that some non-human species perform sexual selection based primarily on intelligence? How do they do this?
I'm a biology amateur, but it seems like sexual selection is almost always performed based on physical characteristics, the outcome of physical contests, or some sort elaborate courtship. But do any ...
19
votes
2answers
350 views
Why don't teeth glow?
Hydroxyapatite is the main component of tooth enamel. It contains phosphorus in the form of phosphates, pyrophosphates etc. that are found to exhibit the the property of phosphorescence. But why don't ...
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 ...
19
votes
1answer
193 views
Regulation of chromatin structure
Recently, I reviewed the different levels of chromatin structure. The primary level is nucleosomes, where DNA is bound to histones, and has structural similarity to "beads on a string." The secondary ...
19
votes
1answer
183 views
Evolutionary origin and exogenous cues of ~28 day infradian rhythm?
The most obvious example of an approximately monthly biological cycle is the human menstrual cycle. My questions are the following:
Is it known when and where this cycle or one like it arose?
What ...
18
votes
3answers
529 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 ...
18
votes
2answers
3k views
If a human takes antibiotics are all bacteria in the body killed?
From my basic understanding, antibiotics kill living things, bacteria for example.
Do the antibiotics consumed by a human-being distinguish between what they kill? Or do they just kill every bacteria ...
18
votes
2answers
215 views
Why is rabies incurable?
I'm still not sure about the mechanics that lead to rabies being incurable. I know that it can be treated before any symptoms show up, but why is it that once symptoms show the person is a dead man ...
18
votes
1answer
330 views
Are lymphocyte sizes clustered in two groups?
Tortora writes in Principles of Anatomy and Physiology:
Lymphocytes may be as small as 6–9 μm in diameter or as large as 10–14 μm in diameter.
Those ranges are quite close to each others. Should ...
17
votes
4answers
795 views
Do trees really get a large share of their mass from the carbon in the air?
I remember hearing that trees and other plants actually obtain a large amount of their mass from the carbon floating in the air, not the ground beneath them. Does the makeup of air actually contain ...
17
votes
3answers
298 views
Good source that explains the evolution of single-celled organisms “from scratch”
Are there any books or sites that detail, step-by-step, the evolution of the first single-celled organisms (bacteria, archaea) from a Miller-Urey-like beginning? That is, assumes only amino acids, ...
17
votes
3answers
420 views
How many times did endosymbiosis occur?
According to the endosymbiont theory, mitochondria and chloroplasts originated as bacteria which were engulfed by larger cells. How many times is it estimated that this occurred in the past? Are there ...
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
...
17
votes
3answers
468 views
How is RNAse contamination in RNA based experiments prevented?
Does anyone have any suggestions to prevent RNAse contamination when working with RNA?
I tend to have issues with degradation regardless of whether I use DEPC treated / RNAse free water and filtered ...
17
votes
2answers
241 views
How does the microbial environment in your gut initiate?
Clearly, a zygote does not harbor any microbes. As it develops, and the alimentary canal tissue is differentiated, I logically assume that there is still no microbial activity in the fetus's gut. I'm ...
17
votes
2answers
211 views
How do fairy rings propagate?
It was somewhat new to me that mushrooms usually aren't individual organisms, but are merely the visible bodies of a bunch of fungi living in the soil. I know that mushrooms emit spores to reproduce, ...
17
votes
3answers
133 views
How crowded is the bacterial cell?
I was wondering what is the protein concentration in an E. coli cell. When studying enzyme kinetics and activity in vitro, I would argue that the substrate and enzyme concentrations resemble those in ...
