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Biology > Topic 7 - Genetics, Populations, Evolution & Ecosystems > Flashcards

Topic 7 - Genetics, Populations, Evolution & Ecosystems Flashcards

1
Q

Abiotic factors

A

The non-living aspects of an ecosystem e.g. temperature, light intensity, moisture, soil pH and oxygen levels.

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2
Q

Adaptation

A

A feature of an organism that increases its chance of survival in its environment.

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3
Q

Allele

A

A version of a gene

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4
Q

Allele frequency

A

The number of times an allele appears within a population’s gene pool.

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5
Q

Allopatric speciation

A

A form of speciation that occurs when two populations become
geographically isolated.

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6
Q

Autosomal linkage

A

When two or more genes are positioned on the same autosome. They are unlikely to be separated by crossing over during meiosis so are often inherited together.

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7
Q

Autosome

A

A chromosome that is not an X or Y chromosome.

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8
Q

Belt transect

A

A line along a sampled area, upon which quadrats are placed at certain intervals to determine the abundance and distribution of organisms in an ecosystem.

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9
Q

Biodiversity

A

The variety of genes, species and habitats within a particular area

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10
Q

Biotic factors

A

The living components of an ecosystem e.g. food availability, pathogens and predators.

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11
Q

Carrying capacity

A

The average size of a population that can be supported by an ecosystem over extended periods of time. This varies depending on biotic and abiotic factors.

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12
Q

Chi-squared test

A

A statistical test used to determine whether a pattern of inheritance is statistically significant.

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13
Q

Climax community

A

The stable community of organisms that exists at the final stage of ecological succession.

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14
Q

Codominant

A

When both alleles for a gene in a heterozygous organism equally contribute to the phenotype.

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15
Q

Community

A

All of the populations of different species living together in a habitat.

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16
Q

Conservation

A

The maintenance of ecosystems and biodiversity by humans in order to preserve the Earth’s resources. This typically involves the management of succession.

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17
Q

Degrees of freedom (X^2 test)

A

Th number of categories minus 1

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18
Q

Dihybrid inheritance

A

The inheritance of two different genes, that determine two
phenotypes, on two different chromosomes.

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19
Q

Diploid

A

Describes a cell with a nucleus containing two sets of chromosomes.

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20
Q

Directional selection

A

A type of selection that favours one extreme phenotype and selects against all other phenotypes.

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21
Q

Disruptive selection

A

A type of selection that favours individuals with extreme phenotypes and selects against those with phenotypes close to the mean.

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22
Q

Dominant

A

Describes an allele that is always expressed. Represented by a capital letter.

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23
Q

Ecosystem

A

The community of organisms (biotic) and non-living (abiotic) components of an area and their interactions. It is a dynamic system.

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24
Q
A
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25
Q

Epistasis

A

Describes a relationship between genes where the allele of one gene affects the expression of a different gene.

26
Q

Evolution

A

The gradual change in the allele frequencies within a population over time. Occurs due to natural selection.

27
Q

Gene

A

A length of DNA on a chromosome that codes for the production of one or more
polypeptide chains and functional RNA.

28
Q

Gene pool

A

All of the different versions of genes (alleles) in the individuals that make up a population.

29
Q

Genetic drift

A

Variations in allele frequencies in small populations due to chance

30
Q

Genetic variation

A

Differences in genotypes between members of a population which may occur due to mutations, meiosis, or random fertilisation.

31
Q

Genotype

A

An organism’s genetic composition. Describes all alleles.

32
Q

Habitat

A

The region where an organism normally lives.

33
Q

Hardy-Weinberg principle

A

A model that predicts that the ratio of dominant and recessive
alleles in a population will remain constant between generations if the following five conditions are met: no new mutations; no natural selection; no migration; large population; and random mating. It provides an equation for calculating the frequencies of alleles:
p^2 + 2pq + q^2 = 1.0
where p is the frequency of the dominant allele, and q is the frequency of the recessive allele.

34
Q

Herterozygous

A

When someone has two different alleles of a gene e.g. Ff

35
Q

Homozygous

A

When someone has two identical alleles of a gene e.g. ff.

36
Q

Interspecific competition

A

A type of competition that takes place between members of
different species.

37
Q

Intraspecific competition

A

A type of competition that takes place between members of the
same species.

38
Q

Locus

A

The position of a gene on a chromosome.

39
Q

Monohybrid inheritance

A

The inheritance of one gene

40
Q

Multiple alleles

A

When a gene has more than two potential alleles

41
Q

Natural selection

A

The process by which the frequency of beneficial alleles gradually increases in a population’s gene pool over time. This theory was developed by Charles Darwin.

42
Q

Niche

A

Describes how an organism ‘fits’ into an ecosystem and its role in that environment.

43
Q

Phenotype

A

An organism’s observable characteristics. Due to interactions of the genotype and the environment.

44
Q

Pioner species

A

Species that can survive in hostile environments and colonise bare rock or sand e.g. lichens

45
Q

Population

A

All organisms of the same species living with one another in a habitat at the same time.

46
Q

Predator

A

An organism that eats other organisms.

47
Q

Prey

A

An organism that is eaten by predators

48
Q

Quadrat

A

A square grid of a known area used in sampling to determine the abundance of organisms in a habitat. There are two types: point quadrats and frame quadrats.

49
Q

Random Sampling

A

A sampling technique used to avoid bias e.g. creating a square grid and generating random coordinates.

50
Q

Recessive

A

Describes an allele that is only expressed in the absence of a dominant allele. Represented by a small letter.

51
Q

Selection pressures

A

Environmental factors that drive evolution by natural selection and limit population sizes e.g. competition, predation and disease.

52
Q

Sex-linkage

A

The presence of a gene on an X or Y chromosome

53
Q

Speciation

A

The formation of new species due to the evolution of two reproductively separated populations. Two forms: allopatric and sympatric speciation.

54
Q

Species

A

A group of similar organisms that are able to breed with one another to produce living, fertile offspring.

55
Q

Stabilising selection

A

A type of selection that favours individuals with phenotypes close to the mean (average) and selects against extreme phenotypes.

56
Q

Succession

A

Describes changes in the community of organisms occupying a certain area
over time.

57
Q

Sustainable

A

The ability to maintain something for future generations.

58
Q

Sympatric speciation

A

A form of speciation that occurs when two populations within the same area become reproductively isolated.

59
Q

Systematic sampling

A

A sampling technique used to determine the abundance and
distribution of organisms along an area at periodic intervals e.g. along a belt transect. This is
commonly used in ecosystems where some form of gradual change occurs.

60
Q

Variation

A

The differences between individuals due to genes, the environment or a combination of both.

Biology (41 decks)

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