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Biology > Key Knowledge 10 > Flashcards

Key Knowledge 10 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

gene pool

A

The collection of all the genes and alleles within a specific population

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2
Q

Allele frequencies

A

the proportion of a particular allele appearing at a certain gene locus in a gene pool.

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3
Q

mutation

A

responsible for introducing new alleles into a population via changes to DNA. These changes can involve the substitution, addition, or deletion of single nucleotide bases or larger blocks of DNA.

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4
Q

genotype 

A

the genetic composition of an organism at a particular gene locus

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5
Q

phenotype 

A

the physical or biochemical characteristics of an organism that are the result of gene expression and the environment

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6
Q

heritability 

A

the transmission from parent to offspring (i.e. encoded in genes)

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7
Q

germline cell 

A

a cell involved in the generation of gametes in eukaryotes

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8
Q

somatic cell 

A

any cell in an organism that is not a germline cell

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9
Q

point mutation 

A

a mutation that alters a single nucleotide in a DNA sequence

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10
Q

block mutation 

A

a mutation that affects a large chunk of DNA, or an entire gene

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11
Q

silent mutation 

A

a mutation in which a nucleotide is substituted for another, changing the codon, but still coding for the same amino acid. Therefore, there is no effect on protein structure

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12
Q

missense mutation 

A

a mutation in which a nucleotide is substituted for another, changing the codon and coding for a different amino acid. Therefore, there can potentially be an effect on protein structure

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13
Q

nonsense mutation 

A

a mutation in which a nucleotide is substituted for another, changing the codon to a stop codon, prematurely ceasing translation of the gene’s mRNA. Therefore, there is an effect on protein structure

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14
Q

frameshift mutation 

A

a mutation that involves the insertion or deletion of one or two nucleotides, altering every codon from that point forward

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15
Q

deletion

A

removal of a section of DNA

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16
Q

Duplication

A

replication of a section of DNA, lengthening the DNA

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17
Q

inversion

A

reversal of a section of DNA

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18
Q

translocation

A

switching of two sections of DNA on different chromosomes

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19
Q

four conditions of natural selection

A
  • variation
  • selection pressure
  • selective advantage
  • heritability
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20
Q

variation

A

Individuals in a population vary genetically, which leads to phenotypic differences

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21
Q

Selection pressure

A

An environmental selection pressure impacts the survivability of organisms within a population and their ability to reproduce.

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22
Q

Selective advantage

A

Individuals with phenotypes that are fitter or more advantageous under the environmental selection pressure are conferred a selective advantage, allowing them to survive and reproduce more successfully.

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23
Q

Heritability

A

The advantageous trait must be heritable, allowing it to be passed on from the parents to their offspring. Therefore, over time, the frequency of the advantageous allele will increase

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24
Q

Students can sometimes struggle to answer short answer questions on natural selection. However, in most of these questions, you simply need to apply the following four conditions of natural selection to the scenario:

A
  1. Variation – identify the variation that exists within the existing population.
  2. Selection pressure – identify the environmental selection pressures within the particular environment that are acting on the population.
  3. Selective advantage – explain the effects of the environmental selection pressure in terms of survivability and how it confers a selective advantage for the organisms with a fitter or more advantageous phenotype.
  4. Heritability – state that organisms with the fitter or more advantageous phenotype will reproduce and pass on the advantageous alleles to the next generation, increasing their frequencies.
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25
Q

The effect of selection pressures on genetic diversity

A

Environmental selection pressures can reduce the genetic diversity of a gene pool as the fitter individuals with alleles that code for advantageous phenotypes are more likely to survive and reproduce.

26
Q

Environmental selection pressures drive the adaptation of a population through the process of natural selection. It is important to note that:

A

• These environmental selection pressures determine which phenotypes are considered fitter and advantageous and, consequently, which traits are more likely to be passed on to the next generation.

• As advantageous traits become more common in a population, the allele frequencies of the population changes, with the frequency of the advantageous allele increasing.

• Due to the generational increase in the frequency of the advantageous allele, the genetic diversity of the population will also decrease as the phenotypes of the population are driven towards a specific allele.

27
Q

Darwin’s observations

A
  1. There is phenotypic variation within species.
  2. Offspring tend to inherit the traits of their parents.
  3. Species produce more offspring than required to replace themselves.
  4. There is a struggle to survive.
28
Q

Darwin’s inferences

A
  1. Individuals whose traits give them more chance to survive and reproduce leave more offspring than other individuals.
  2. The unequal chance of reproduction will lead to accumulation of favourable traits in the population over generations
29
Q

Sexual Selection

A

Reproduction is more important in natural selection than survival.
For some species, natural selection favours individuals who reproduce at the expense of survival

30
Q

Reduction of genetic diversity

A

Natural selection reduces genetic diversity by eliminating alleles that confer on individuals a selective disadvantage

31
Q

Stabilising selection

A

Most of the time, natural selection acts to stabilise allele frequencies, reducing the frequency of traits at either extreme of the range of phenotypes in a population.

32
Q

Directional selection

A

If a selection pressure changes, it can result in a selective advantage for individuals which are less common in a population

33
Q

Disruptive selection

A

Sometimes a change in selection pressures creates a selective advantage for either end of a distribution of traits, but a disadvantage for the most common phenotype.

34
Q

genetic diversity

A

the variation in genetic makeup or alleles within a
population

35
Q

genetic drift

A

a random event that dramatically alters a population’s gene pool

36
Q

bottleneck effect 

A

the reduction in genetic diversity that occurs when a large proportion of a population is removed due to a chance event

37
Q

founder effect 

A

the reduction in genetic diversity that occurs when a population is derived from a small unrepresentative sample of the original population

38
Q

unrepresentative sample 

A

a small selection of individuals from a larger group that does not reflect the characteristics of the larger group

39
Q

The consequences of the bottleneck and founder effects on genetic diversity

A

Bottleneck effect- Reduces genetic diversity through the removal of alleles due to random events (e.g. natural disaster)

Founder effect- Reduces genetic diversity through the establishment of a new population with a small unrepresentative sample of the original population

40
Q

Reductions in genetic diversity have two major risks:

A

• Inbreeding – this keeps harmful alleles in the gene pool.
• Lower adaptive potential – populations become vulnerable to new selection pressures that could challenge and potentially wipe out the entire population due to the absence of advantageous alleles

41
Q

interbreeding 

A

when two individuals living in different populations mate and have offspring

42
Q

gene flow 

A

the flow of alleles in and out of a population due to the migration or interbreeding of individuals between two populations

43
Q

immigration 

A

the movement into a population

44
Q

emigration

A

the movement out of a population

45
Q

When new alleles are brought into a population through immigration, the genetic diversity in a population increases.

A
  • This increase is more pronounced in smaller populations since they have a smaller gene pool to begin with.
  • In larger populations, the immigration of new alleles into the population does not significantly affect the gene pool.
46
Q

emigration removes alleles from a population’s gene pool, decreasing genetic diversity

A
  • Once again, the effects of emigration are more pronounced in smaller populations compared to larger populations.
47
Q

selective breeding 

A

the changing of a population’s gene pool due to humans altering the breeding behaviour of animals and plants to develop a selected trait. Also known as artificial selection

48
Q

 The requirements for selective breeding

A
  • Variation
  • Selection pressure
  • Heritability
49
Q

Variation- selective breeding

A

Individuals in a population vary genetically, which leads to phenotypic differences.

50
Q

Selection pressure- selective breeding

A

Direct human intervention places an artificial selection pressure upon a population of individuals, only allowing certain individuals with desirable traits to breed together.

51
Q

Heritability- selective breeding

A

The trait selected must be heritable, allowing it to be passed on from the parents to their offspring. Therefore, after the breeding population reproduces, the frequency of the selected allele will increase.

52
Q

A comparison between selective breeding and natural selection

A

Selective breeding:
- Artificial
-Involves human-induced selection pressures in the form of humans directly selecting desirable traits or removing particular traits from a population.

Natural selection:
- Environmental
- Involves naturally occurring environmental selection pressures such as predation, disease, and climate change, which select individuals with a selective advantage within their environment.

53
Q

The effect of selective breeding on genetic diversity

A

Selective breeding can lead to smaller gene pools and overexpression of deleterious alleles, which can reduce adaptability and fitness within a population.

54
Q

antimicrobial agent 

A

an agent that kills or slows the growth of microorganisms. Examples include antiseptics, disinfectants, antifungals, antivirals, and antibacterial agents

55
Q

antimicrobial resistance 

A

the ability of a microorganism to survive exposure to an antimicrobial agent

56
Q

When asked about the development of antibiotic-resistant bacteria, just like questions regarding the process of natural selection, you simply need to follow the same basic answer structure

A

(1) outline that variation exists
(2) identify the presence of a new selection pressure (exposure to antibiotics)
(3) identify the group that is conferred an advantage
(4) highlight the increased heritability of the antibiotic-resistant alleles.

57
Q

There are many factors which contribute to the formation of antibiotic-resistant bacteria, including the:

A

• inappropriate compliance with a treatment plan, where a course of antibiotics is prematurely stopped (e.g. when a patient feels better and believes that continued use of their prescribed antibiotics is no longer required).
• inappropriate use of antibiotics, where antibiotics are prescribed when they are not required.
• widespread use of antibiotics, where the generally increased use of antibiotics can increase the probability that an individual prescribed antibiotics will be inhabited by antibiotic-resistant bacteria.

58
Q

Viral antigenic drift and shift

A

Viruses constantly adapt and modify their surface antigens through the processes of antigenic drift and shift, thereby increasing the difficulty of forming effective vaccines and medications against viruses.

59
Q

antigenic drift 

A

small and gradual mutations in the genes encoding for viral surface antigens

60
Q

antigenic shift 

A

sudden and significant mutations in the genes encoding for viral surface antigens

61
Q

viral recombination 

A

the combination of surface antigens from two or more different strains of a virus to form a completely new virus subtype

Biology (13 decks)

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