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Questions tagged [definitions]

Questions looking for clarifications or definitions of biological terminology.

22
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6answers
34k views

Do apes and humans share 99% of DNA or 99% of genes? What is the difference?

I made an answer on the Scifi.SE that can be read here. It is about how the characters in the story Jurassic Park might have gotten DNA for all the species shown. In my answer, I said this: Apes ...
18
votes
2answers
881 views

Transitivity of Species Definitions

There are many definitions of "species" which usually take the form Two individuals are of the same species if ... An implied (rarely made explicit) property of any sensible species definition is ...
15
votes
2answers
5k views

Are 'homeothermic' and 'endothermic' synonymous?

I got this question from the comments below this answer. So, do homeothermic and poikilothermic have the same meaning as endothermic and ectothermic, respectively? A user also suggested that the ...
15
votes
2answers
22k views

Is blood regarded as an organ?

It consist approximately 7 percent of body weight. By definition organ is composed of multiple tissues. Blood is a fluid, a circulating tissue. Therefore can we call this fluid system a liquid organ?...
12
votes
3answers
1k views

What is the definition of a mutation?

There are two alleles that determine the sensitivity of a person to Coumadin (a medicine for blood thinners used to treat a stroke etc). Sometimes you encounter the terminology that one has a mutation ...
11
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4answers
2k views

What is the definition of “Natural Selection”?

Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. Natural selection, a process that results in the adaptation of an organism to its ...
8
votes
1answer
103 views

Can an organism obtaining a part of its genome via horizontal gene transfer be called a “hybrid”?

Wikipedia definition of "hybrid" offers many competing definitions. But most seem to be centered on sexual-reproduction gene transfer. Is there an official (in a textbook or widely accepted peer ...
7
votes
1answer
834 views

What does “Mutational Variance” mean?

Background The concept of mutational variance can be found in many articles including this one for example. The mutational variance of a trait number $i$ can be found in the M-matrix in position $m_{...
6
votes
3answers
607 views

Can domestic breeding be considered evolution?

Domestic breeding of animals (and plants) by humans seems to match some of the definitions of evolution I have been able to find: "a process that results in heritable changes in a population spread ...
6
votes
2answers
8k views

Are spiders part of the study of entomology?

The definition of entomology says it is the science of studying insects. I know spiders are not insects but does entomology include studying spiders as well? Otherwise is there any name to the ...
6
votes
1answer
14k views

What is the definition of a stringent/relaxed plasmid?

I have found a publication which proposes some definitions, including a definition for strict and relaxed replication. The definitions are: Relaxed control of plasmid replication. Relaxed control ...
6
votes
3answers
4k views

Polymorphism in cnidarians?

To me, the phenomenon of polymorphism in cnidarians is particularly troubling. I gather that it essentially refers to existence of various different forms or kinds of individuals, i.e. zooids and ...
6
votes
2answers
784 views

What is Environmental Robustness? Is it different from plasticity?

Hansen (2006) in his review uses the concept of environmental robustness independently of the other concepts of robustness (at pages 139 and 140) without defining ...
6
votes
2answers
6k views

How different are these terms: Phylloclade, Phyllode, Cladophyll and Cladode?

We started with Plant Morphology in class (specifically, the morphology of angiosperms). My teacher's provided us with the following terms and their definitions. Phylloclade A modified ...
5
votes
1answer
3k views

What is a tardigrade “in tun form”?

While reading this article about tardigrades that had been previously frozen, I came across some verbiage I wasn't sure of and couldn't find any real explanation given the context. The article kept ...
5
votes
1answer
368 views

How would one describe the R-factor in crystallography?

Yes, there is the wikipedia definition, but how would one explain this concept to a non structural biologist?
5
votes
1answer
319 views

Problem with an analogy (Cell Membrane)

I'm studying biology for the first time seriously. I've been reading OpenStax College's material. In the section of "The Cell Membrane", I have the following problem: Choose the answer that best ...
5
votes
1answer
3k views

Soft and Hard selection

Seems to me that these two sources (M. Whitlock, B. Wallace) use different definitions of soft and hard selection. M. Whitlock: Soft selection occurs when the relative fitness of an individual is ...
4
votes
1answer
312 views

Was Darwin aware of the difficulties behind the concept of species?

Introduction The concept of species is a very old concept that suffers from not being a natural category. There exists no single definition that would categorize living beings into groups and that ...
4
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1answer
223 views

Can an exotic species be also endemic?

While talking about the evolution and conservation of dingoes in Australia, someone asked an interesting question: Can I define the dingo as an endemic species? That question, despite apparently ...
4
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2answers
4k views

What is an organism?

The definition of an organism Wikipedia gives is An organism is any contiguous living system. I understand that these are not organisms according to this definition: A bird and a tree it's ...
4
votes
1answer
387 views

What is “Peripheral Dogma”?

The book, Introduction to Bioinformatics, by Arthur M. Lesk, 3rd edition; Oxford; low-price-edition; in its chapter-1 (introduction), page-no. 6 ; provided a paragraph, entitled "Dogmas: Central and ...
3
votes
1answer
23k views

What is a suicide plasmid?

What is a suicide plasmid? Example: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2737453/ mentions a "suicide vector". See also http://www.sci.sdsu.edu/~smaloy/MicrobialGenetics/topics/plasmids/allele-...
3
votes
3answers
8k views

What is the difference between abiogenesis and spontaneous generation?

As we all should know, abiogenesis and spontaneous generation are far from identical. For one, spontaneous generation was disproven with Pasteur, and abiogenesis seems to be a solid scientific theory. ...
3
votes
3answers
6k views

What is a gene transcript, how is it different from an allele?

Within human genetics, My current understanding of a transcript for a particular gene is that it's the exact nucleotide sequence and position of a particular instance of said gene in some individual. ...
3
votes
2answers
257 views

What is the definition for vitamins?

I have found the following definition on Wikipedia: An organic chemical compound (or related set of compounds) is called a vitamin when the organism cannot synthesize the compound in sufficient ...
3
votes
1answer
8k views

What is the definition of “dry weight” and “dry cell weight”?

As I understand it, the dry weight of something is its weight minus the weight of its water content. Is this the definition? What about dry cell weight?
3
votes
1answer
693 views

The meaning of the $\alpha$ helix and $\beta$ sheets in proteins [duplicate]

I asked this question to my Biology teacher and he, in collaboration with a Chemistry teacher, couldn't find the answer. My question is the following: "What does the $\alpha$ and $\beta$ represent in ...
3
votes
1answer
306 views

How do we call a region of low carrying capacity?

I am looking for a convenient word to define a region of the landscape where the local carrying capacity (population size) for a given species is low but different from zero. The species is still ...
2
votes
1answer
555 views

What is the difference between a cytokine, a hormone and a protein hormone?

I'm trying to figure out the difference between hormone, cytokine and protein hormone. It's clear to me that all three are biological messengers, but there seems to some ambiguity and overlap between ...
2
votes
2answers
4k views

What is a cortical circuit?

I have read about cortical circuits in the context of connectomics (e.g. any example here) and computational neuroscience (e.g. any example here), but a simple Google/Wikipedia does search not show an ...
2
votes
1answer
37 views

Is studying chemical and physical properties of chemical substances that make up organisms really a task of molecular biology?

I have read in a high school textbook that (translated into English by myself): "Branch of science that concerns itself with studying chemical and physical properties of substances that make up ...
2
votes
1answer
476 views

Introgression vs admixture

What is the difference between genetic introgression and genetic admixture ? Are these terms interchangeable ? Do they apply to different population scopes or something ? The usage seems kind of vague ...
2
votes
1answer
27 views

What do the column labels in this table mean?

This table shows the effect of sound (song and tones) on female birds. However, I'm not sure what the labels (F1 22, P and η2) mean. I've seen the labels on other tables too. (from https://www.ncbi....
2
votes
2answers
399 views

Definitions of robustness and canalization

The concepts of robustness and canalization are fashionable today in the biology literature. However, I am not sure of their definitions and I am not sure either that all authors actually use the same ...
2
votes
1answer
60 views

How do you define a gene list?

So I wrote in a chapter that I will be checking for publications with gene lists in them. I got a comment asking "How would you define a gene list and what criteria did I use". I know that gene lists ...
2
votes
1answer
431 views

Definition of Sexual Selection?

How do you define Sexual Selection (SS)? (One might want to subdivide SS into intra- and inter- SS to answer) Is SS clearly different from Natural Selection (NS)? Is SS nested within NS or are NS ...
2
votes
0answers
53 views

What function will survive evolution?

I wrote the following phrase in my scientific text: X is ubiquitous in life of Y. On some occasions X might be detrimental, resulting, for example, in so so phenomena. But is it plausible that a ...
2
votes
0answers
50 views

Majority rule definition

In this book, they talk about the majority rule. Majority rule, which retain s the edges present in more than 50% of the trees. They used that rule also in ...
1
vote
3answers
141 views

Evolution as a directed graph exploration?

First of all, I am not biologist, nor good in chemistry/physics. Secondly, I am really eager to understand. So I think of a "life" (of a certain whatever being) as a space of somewhat properties. ...
1
vote
1answer
3k views

What does pseudo-irreversible mean?

In this publication (PDF) I encountered the following word: Binding of rupatadine to histamine H1 receptors isolated from the guinea-pig cerebellum and lung was demonstrated by inhibition of 3H-...
1
vote
1answer
39 views

What does “crude” mean in this context?

Taken from Ian Freshney's Culture of Animal Cells: The enzymes used most frequently for tissue disaggregation are crude preparations of trypsin, collagenase, elastase, pronase, Dispase, DNase, ...
1
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1answer
50 views

Actual definition of cardiac output

Is cardiac output the amount of blood pumped by both ventricles in 1 minute or only by the left ventricle in 1 minute?
1
vote
1answer
251 views

Usage of “lineage” over “species”

Remi.b has suggested here: The concept of species is poorly defined and is often misleading. The concept of lineage is much more helpful. IMO, the only usefulness of this poorly defined concept ...
1
vote
2answers
99 views

What are the major differences between good study habits for biology vs mathematics? [closed]

I'm a math prof. But, I've always loved reading about biology (the paleobiology of microbes and some small animals mostly) it's my hobby but I want to learn more maybe take a course. My longer term ...
1
vote
1answer
1k views

Exact definition of 'convergent' and 'divergence' in cell signalling?

From what I understand, we refer to 'signal convergence' as being when two different ligands/stimuli lead to the same (at least in part) responses inside a single cell. This may or may not be due to ...
1
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1answer
2k views

Definitions of common and rare disease

Is there an epidimiological way to define rare and common diseases ?
1
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1answer
4k views

What is an on-line measurement? What is an off-line measurement?

See it used here: http://en.wikipedia.org/wiki/Fed-batch. In the table giving the different strategies to control growth in a fed-batch culture, one finds, for example: "on-line measurement of glucose"...
1
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1answer
53 views

What does endochorous dispersers means?

In an article (Guerrero and Tye, 2009) it talks about endochorous dispersers. Guerrero, A. M., and A. Tye. 2009. Darwin's Finches as Seed Predators and Dispersers. The Wilson Journal of Ornithology ...
1
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1answer
623 views

What is a sex-biased gene?

How do you define a male-biased gene and a female-biased gene as they are found in the abstract of this article.