3
votes
1answer
163 views

Why insects are so small compared to mammals?

I was wondering what biological limitations make the dimension of the insects small compared to the dimension of the mammals. I know in other eras insect were bigger!
3
votes
2answers
259 views

What insect is in this photo?

Found in Russia, in the kitchen. It is about 1–2 cm length.
3
votes
2answers
198 views

What is a bacterial biofilm?

Bacteria produce something called a biofilm. I have found a few definitions; some say it is a complex of live and dead bacteria and others say it is a layer on cell wall. What is it made of? What ...
3
votes
2answers
2k views

Difference between mice and rats

What is the actual biological difference between mice and rats? Are they actually the same thing with two different names depending on appearance (are they all mice for instance and we call the larger ...
3
votes
3answers
418 views

Looking for Kelly Chibale's paper on Malaria cure

From National Geographic, there has been a lot of hype on Kelly Chibale's work from University of Cape Town on the aminopyridine MMV390048. Unfortunately, this was from an announcement from an ...
3
votes
2answers
165 views

Is it possible to correctly identify presence of Y chromosome with external physical test only?

I asked a question related to the third sex, and I came to know that its always possible to categorize a human to male or female with presence of Y chromosome. Now, I have another question. Is there ...
3
votes
2answers
318 views

Can someone identify this bird?

We recently found a nest in the back garden and a little bird inside. Can you help us identify it? The nest is quite small like the bird so we are wondering whether this is the parent or a baby chick. ...
3
votes
2answers
342 views

Gene and alleles

This is a multiple choice question: Consider a gene, ABC, which codes for an enzyme involved in the metabolism of sugars. There are two known alleles of this gene, ABC1 and ABC2. Which statement ...
3
votes
4answers
125 views

Is an egg classified based on the species inside it, or by the species that laid it?

Basically what I'm asking is if an animal of species x were to lay an egg, and the animal inside that egg happened to be the first member of a genetically new ...
3
votes
2answers
81 views

How can neuronal signals faithfully be reproduced by scalp electrodes?

There is a skull barrier (and possibly other layers too) between the brain and the scalp. I have seen people trying to extract EEG signals from the scalp by connecting electrodes and interface it to ...
3
votes
1answer
116 views

What is this plant?

It was found in Eastern Pennsylvania (in the United States) in a deeply wooded area.
3
votes
2answers
397 views

How do roots obtain nutrition?

I have a city garden (see picture below) and yesterday I was nurturing it and I pulled up a small plant. I saw its root system and laid it in the sun to dry a bit and then scraped of the rest of the ...
3
votes
1answer
154 views

Before Evolution was proposed by Charles Darwin, what were the leading secular theories to explain how life developed? [closed]

Outside of evolution, what were the leading scientific schools of thought that Charles Darwin contented with when he published his evolution theory as way of natural selection in 1859?
3
votes
2answers
8k views

Possible genotypes for blood types?

If I am blood type B, what are all the possible genotypes that could be expressed by my parents? I think it might be 16 but I was reading online and saw this: Similarly, someone who is blood type ...
3
votes
1answer
311 views

What happens to the precursor protein's signal sequence after it is cleaved?

Where does this signal sequence "go" after it has been cleaved by signal peptidase and what is its next function?
3
votes
2answers
623 views

What are the major causes of mutations in DNA?

I know that point mutations can change the base sequence of a gene by altering a specific codon that codes for a particular amino acid. Are these mutations purely random events that occur when DNA is ...
3
votes
1answer
319 views

Why isn't the insertion of a single nucleotide destructive for DNA?

As far as I know proteins are built by sequentially reading triplets of nucleotides. But if at a certain point a nucleotide is inserted in the sequence, the following sequence of triplets is ...
3
votes
2answers
8k views

What causes muscles to generate heat on contraction?

I'm curious what the exact cause is of dramatic heat generation that comes along with muscle activity. Can anybody explain this in understandable language?
3
votes
2answers
418 views

How are two species with similar phenotypes identified as different?

How are two species with similar phenotypes identified as different? Have two different individuals that were thought to be different species ever been determined to be from the same species ( or ...
3
votes
3answers
4k views

Why does pH have an effect on enzymes?

I am currently studying biology and have a question about how pH affects enzymes. When the pH gets closer to the enzyme's pH optimum, the enzyme activity also increases. I would like to know why? ...
3
votes
2answers
583 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
1answer
1k views

Why are urban birds still scared of humans?

I understand that animals are naturally scared of humans because we basically slaughtered every living thing we found in our way for millennia. How long does it take for them to genetically 'forget' ...
3
votes
1answer
238 views

Are the byproducts of mammalian digestion simply depleted versions of the food or liquid consumed?

When mammals consume food and digest it or drink fluids that are then filtered by their kidneys, are the waste products generated simply depleted versions of what they consumed? Are there other ...
3
votes
1answer
390 views

Macroevolution vs. microevolution

Where is the line usually drawn between macroevolution and microevolution? I thought that, although similar processes govern both, the line was at the species level, with macroevolution being changes ...
3
votes
2answers
210 views

High sequence similarity but start codon isn't methionine

I have noticed in a particular genome sequence of a prokaryote that various regions in a sequence share similarity which is high(>80%) with known proteins. However, the start is not a methionine. Is ...
3
votes
2answers
1k views

Why does Glutamine have the symbol Q?

Spent a half hour googling this and the best I could find was this: Now for some rhymes: Arginine = R. R we having fun yet? Asparagine = N The kNights of Ne say "Ne". Glutamine is a cute ...
3
votes
2answers
4k views

Is there any complex organism that is both autotroph and heterotroph?

Possibility also include "adaptation mode" if such exist. I don't discern whether autotrophic/heterotrophic part play only minor role either.
3
votes
1answer
102 views

Color of the Fur coat of Polar bears

Recently I was playing a quiz and a question was asked about the color of the fur coat of a polar bear. To my surprise the answer was black. I thought it was yellowish white or creamy. Why so ?
3
votes
1answer
90 views

Majority of transcripts are from sense strand?

I am wondering whether majority of transcripts are transcribed from the 5'->3' strand? Because I encounter a lot of expressions like "anti-sense transcripts". Could anybody help clarify this? Thanks.
3
votes
1answer
94 views

Why is competitive inhibition reversible?

My Biochemistry book mentions that 'competitive inhibition' is a reversible form of inhibition. But given that the inhibitor is blocking the active site and prevents an enzyme-substrate complex to be ...
3
votes
1answer
221 views

Reason for the source of fetal bovine serum

What is the reason that perhaps the most commonly used serum in labs is fetal bovine derived? Is there something about fetal serum that is particularly useful over say serum just harvested ...
3
votes
2answers
2k views

What magnification do I need to see blood cells?

If I want to buy a microscope for my kids to be able to view single celled creatures and blood cells, about what magnification is required? A Celestron Pentaview digital scope claims up to 600×. Is ...
3
votes
2answers
299 views

Is organ transplantation race dependent?

I watched (IMHO canibalistic) movie "Seven Pounds" where protagonist donated many of his organs to other people and I noticed, that most recipients were black also as protagonist was. Is race really ...
3
votes
1answer
999 views

Why is the pituitary gland located in the brain?

Why is the pituitary gland located in the brain in humans, instead of elsewhere in the body? Why would this be an evolutionary beneficial adaptation?
3
votes
2answers
283 views

Why don't mosquitoes evolve towards muting themselves?

Quite certainly, muted mosquitoes would be much more effective as far as their blood-sucking pursuits are concerned, since mosquito sound is predominantly responsible for sealing their fate (between ...
3
votes
2answers
1k views

Are Whales More Intelligent Than Humans?

Are Whales smarter than Humans? Their brain size leads me to think so.
3
votes
3answers
315 views

How do we look inside the cell?

My sister is in 9th grade biology and her teacher avoided answering the question of how we actually study the inside of a cell. I haven't taken biology in a while but I'd like to give her an answer. ...
3
votes
2answers
131 views

What virus transforms full grown plants?

I read an article by a gardener describing how a virus had transmitted a negative trait to his plants. It rather shocked me, because I hadn't realized that a virus could transform an adult plant. I ...
3
votes
2answers
115 views

What does the gene name “lexA” stand for?

It is an important gene expressed in E. coli that represses the SOS response and also the expression of lambda lytic phase genes. UV light and damage to DNA is responsible for its breakdown and hence ...
3
votes
2answers
200 views

How do humans perceive time?

We can see length, and other physical quantities. We can perceive through our other senses like (temperature through thermoreceptors, weight through pressure receptors etc.). But how do we "sense" ...
3
votes
2answers
1k views

Why do humans have only two nipples?

If other animals have more than 2 nipples, then why do humans have only 2 nipples? Even my pet dog has more than 2 nipples.
3
votes
2answers
4k views

Is there a difference between polarity and hydrophobicity?

From literature the two terms seem to be interchangeable when discussing protein domains and motifs. But biochemically, what are the specific differences between these two terms? For example what is ...
3
votes
2answers
3k views

How to calculate relatedness in haplodiploid organisms (mainly full sisters and full brothers)?

I have tried to calculate the relatedness for haplodiploid organisms, but cannot understand the calculations behind full sister and full brother. (taken from Wikipedia: haplodiploidy I have managed ...
3
votes
2answers
202 views

What if a Point Mutation is seen in only half the coverage for its location?

I've been looking at some sequenced exomes and found an interesting point mutation that causes a Proline-to-Leucine amino acid change in the protein. This seems like it could have a big impact on the ...
3
votes
3answers
156 views

More entropy: Atom or Macromolecule? [closed]

A question that appeared on my last exam was : Which of the following has greater entropy A) An atom B) A macromolecule The question doesn't specify anything else(i.e. type/size of atom or ...
3
votes
4answers
6k views

Which organs do cats not eat on their prey?

My female cat is a very active hunter and brings me her prey daily. Except for shrews and birds, she always eats them entirely. This afternoon she brought me this: It was quite large (maybe ...
3
votes
3answers
189 views

What are good sources of free-to-use images and diagrams

I am looking for good image repositories for biology teaching. Photos and textbook-like diagrams. I am interested in images that can be used commercially without payment, or, at least, that require ...
3
votes
2answers
83 views

TB disease - treatment and infection

Background: I'm currently performing research in mathematical biology, specifically on the treatment dynamics of HIV and TB co-infection. Question: Can a person infected with TB disease, who are ...
3
votes
3answers
329 views

How quickly is antibiotic resistance lost?

I would imagine the bacterial genome is highly conserved and limited in its space, but maybe I am wrong. If you were to take a strain of antibiotic resistant bacteria and kept them isolated, but fed ...
3
votes
2answers
357 views

Does antibacterial soap work chemically?

Normal soap requires scrubbing, does anti-bacterial soap require scrubbing too? Since it (I assume) works chemically, can I produce the same cleansing effect without lathering with soap and using ...

15 30 50 per page