14
votes
Accepted
What is the definition of "Natural Selection"?
Official definition
Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly?
I don't think there is such a concept as an "...
- 68k
11
votes
Accepted
Was Darwin aware of the difficulties behind the concept of species?
The whole point of Darwin's theory was that transition from one species to another is extremely slow and gradual. There are plenty of quotes in "Origin of Species" stating this, and also affirming ...
- 421
9
votes
Accepted
Can domestic breeding be considered evolution?
Yes, selective breeding results in evolution.
Definitions of evolution
I don't understand why you say that for 3 of the definitions you found, selective breeding would not be considered as evolution....
- 68k
8
votes
Accepted
Are 'homeothermic' and 'endothermic' synonymous?
[D]o homeothermic and poikilothermic have the same meaning as endothermic and ectothermic respectively[?]
No. Once you are referring to the source of the heat, while the other time you are referring ...
- 68k
8
votes
What is the difference between a cytokine, a hormone and a protein hormone?
Parts of the answer are in the text that you provide yourself. But I shall try to add where i can.
What do each of these three terms [hormone, cytokine and protein hormone] mean and how are they ...
- 533
8
votes
What is the definition of "Natural Selection"?
I've adapted your definitions to another process that I think will be less controversial to you.
Eating is the intake of food by taking into the mouth, chewing, and swallowing.
Eating, the process ...
- 44.1k
7
votes
What is the exact definition of a "gene"?
I found a dedicated paper about the definition of what is a gene. Their short definition is:
“a gene is a discrete genomic region whose transcription is regulated
by one or more promoters and distal ...
- 1,597
6
votes
Accepted
What is a tardigrade "in tun form"?
From Illinois Wesleyan University:
One way in which tardigrades have adapted to various types of
environments, has been to reversibly suspend their metabolism. This
state is known as ...
- 52.3k
6
votes
What is the definition of a mutation?
Good question!
The term mutation can be used with two different meanings. Each definition can further be split into two different more detailed definitions. The reason for this slight mess is mainly ...
- 68k
6
votes
Evolution as a directed graph exploration?
But in order to find shortest path, which is known well from algorithmic theory, you have to be as broad as possible. You try to explore as many vertices, as possible, which means you're creating ...
- 3,245
6
votes
About the definition of ketogenic amino acid
The fundamental 'problem' with acetyl-CoA is that it cannot be converted to glucose via the tricarboxylic acid (TCA) cycle: a two-carbon compound (acetyl-CoA) enters the TCA cycle, but two carbons are ...
- 4,678
5
votes
Accepted
Introgression vs admixture
The difference is referring to the directionality of gene flow.
We talk about genetic introgression when there is some gene flow from one population (say, population A) to the other (say, population ...
- 68k
5
votes
Accepted
Is studying chemical and physical properties of chemical substances that make up organisms really a task of molecular biology?
If you look at the Google ngram for the term ‘Molecular Biology’ you will see that it first appears just before 1960, and it is relevant that the Journal of Molecular Biology was founded in 1959. It ...
- 24.4k
5
votes
Accepted
What is the exact definition of a "gene"?
Folks were identifying genes for 75 years before we understood the role of DNA in heredity. Originally genes were defined as the unit of heredity from back when Mendel posited that the mechanism of ...
- 3,313
4
votes
Accepted
Problem with an analogy (Cell Membrane)
Osmosis is the diffusion of water. Pinocytosis is the endocytosis of liquid/water.
- 54
4
votes
Accepted
What does pseudo-irreversible mean?
it seems to mean persistent or long-lived. Is that correct...?
Yes, it's correct, but how persistent the effect is is related to the rate of dissociation or rate of turnover of the receptor. It is ...
- 24.7k
4
votes
Do apes and humans share 99% of DNA or 99% of genes? What is the difference?
Most of the answers here focus on the difference between the concepts of 'DNA' and 'genes' very well. However, the sequence identity between humans and chimpanzees is not covered as rigorously and ...
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4
votes
Can domestic breeding be considered evolution?
The answer is "yes". Evolution is defined as a change in heritable characteristics of a population over generations, and to me, there is no reason not to define domestic animals as populations.
The ...
- 272
4
votes
Evolution as a directed graph exploration?
Your theory is based on many false assumptions.
Evolution becomes nothing but a finding a shortest path in that
unbelievably huge directed graph.
What makes you think that evolution followed the ...
- 421
4
votes
Accepted
What do the column labels in this table mean?
F(1,22) is the result of an F-test with degrees of freedom 1 and 22, in this context most likely this is an F-test in the context of ANOVA; for the meaning of those degrees of freedom I would suggest ...
- 44.1k
3
votes
Accepted
Can an exotic species be also endemic?
I think this partially depends on the timeframe. Endemism is usually divided into paleoendemism and neoendemism (see e.g. Kier er al in PNAS for use of both terms). Here, neoendemism is referring to ...
- 16.7k
3
votes
What is the philosophical definition of life?
There is no difference along the lines of philosophy vs. science. However, there are broader and narrower definitions in biology.
The broadest I know of is "a self-replicating, chemical system (...
- 14.3k
3
votes
What is the philosophical definition of life?
They ask different questions. Philosophy may ask what is life, is there a purpose behind it, etc. Biology asks how does it work, chemistry what are the chemical reactions that drive it, physics maybe ...
- 621
3
votes
What is a gene transcript, how is it different from an allele?
No.
A gene is a unit of the genome stored in the form of DNA. It can be transcribed into mRNA (the transcript) to be used as a template in protein synthesis.
A gene can come in many different ...
- 556
3
votes
What is the definition for vitamins?
Generally speaking, bulk essential nutrients (e.g. amino acids, fatty acids) are used stoichiometrically to form macro cellular structures and are 'baked in' to the structures or compounds they are ...
- 116
3
votes
What is the difference between abiogenesis and spontaneous generation?
What truly differentiates abiogenesis from spontaneous generation?
There are three differences.
Frequency
Abiogenesis occurs very infrequently. Perhaps only once in all of earth's 4.5 billion year ...
- 2,916
3
votes
What is the definition of a mutation?
What I was taught by people in genomics is that "variation" is preferred for an allele that was not private to just one individual or family, but was found in pretty much unrelated individuals, while "...
- 5,175
3
votes
Accepted
Usage of "lineage" over "species"
Lineages have many levels, it is like using the word groups in some ways, they are stacked inside each other like the worlds biggest branching Russian nesting doll. All vertebrates is a lineage, all ...
- 14.3k
3
votes
What is a section in botany based upon?
Taxonomic rankings above the species level are arbitrary—that is, they are created just to be a useful handle, much the way one might call the plants in one’s study “my study plants” and the plants in ...
- 109
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