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A Level Biology > Genetics Population And Ecosystems > Flashcards

Genetics Population And Ecosystems Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is the genotype?

A

The genetic constitution of an organism.

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2
Q

What is the phenotype?

A

The expression of the genetic constitution and its interaction with the environment.

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3
Q

What is an allele?

A

One of a number of alternative forms of a gene.

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4
Q

What does a locus represent?

A

The location of a gene on a chromosome.

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5
Q

What does ‘diploid’ mean?

A

Cells with nuclei containing two sets of chromosomes.

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6
Q

What does ‘haploid’ mean?

A

Cells with a single copy of each chromosome, e.g., gametes.

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7
Q

What is a dominant allele?

A

An allele that is always expressed in the phenotype.

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8
Q

What is a recessive allele?

A

An allele expressed in the phenotype only when both alleles are recessive.

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9
Q

What does codominance mean?

A

When both alleles are expressed in the phenotype.

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10
Q

What does homozygous mean?

A

Having identical alleles for a particular gene.

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11
Q

What does heterozygous mean?

A

Having different alleles for a particular gene.

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12
Q

What is the principle of the Hardy-Weinberg equation?

A

It predicts allele frequencies in a population will remain constant if certain conditions are met.

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13
Q

What is a monohybrid cross?

A

A genetic cross involving one gene.

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14
Q

What is a dihybrid cross?

A

A genetic cross involving two genes.

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15
Q

What is autosomal linkage?

A

Two genes located on the same chromosome, reducing their likelihood of being separated during crossing over.

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16
Q

What is sex linkage?

A

A gene’s locus being on a sex chromosome, often the X chromosome.

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17
Q

What is epistasis?

A

When one gene affects the expression of another gene at a different locus.

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18
Q

How can the chi-squared test be used in inheritance?

A

To compare observed and expected phenotypic ratios.

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19
Q

What is the gene pool?

A

The total number of all alleles in a population.

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20
Q

What is genetic drift?

A

Random changes in allele frequency, particularly impactful in small populations.

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21
Q

What is natural selection?

A

The process where alleles providing selective advantages increase in frequency within a population.

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22
Q

What are the conditions required for Hardy-Weinberg equilibrium?

A

Random mating, no natural selection, large population size, no mutations, and no migration.

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23
Q

What is allopatric speciation?

A

The formation of a new species due to geographical isolation followed by reproductive isolation.

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24
Q

What is sympatric speciation?

A

The formation of a new species within the same geographical area due to reproductive isolation.

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25
Q

What is a carrying capacity?

A

The maximum population size of a species an ecosystem can support, determined by biotic and abiotic factors.

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26
Q

What is the difference between intraspecific and interspecific competition?

A

Intraspecific competition occurs within a species, while interspecific competition occurs between different species.

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27
Q

What is primary succession?

A

The colonization of bare ground by pioneer species leading to a climax community.

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28
Q

What is secondary succession?

A

The recolonization of a damaged ecosystem where soil is already present.

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29
Q

Why is genetic diversity important?

A

It allows populations to adapt and survive changes in environmental pressures.

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30
Q

What is the significance of a large gene pool?

A

It indicates high genetic diversity, providing stability and adaptability to the population.”Question

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31
Q

What is a phenotype influenced by?

A

The genotype and interaction with the environment.

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32
Q

What does ‘multiple alleles’ mean?

A

More than two alleles exist for a gene, though only two are present in a diploid organism.

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33
Q

What is the expected phenotypic ratio in a monohybrid cross between two heterozygous organisms?

A

3:1 (dominant:recessive).

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34
Q

What is the expected phenotypic ratio in a dihybrid cross between two heterozygous organisms?

A

9:3:3:1 (unless linked genes or epistasis).

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35
Q

How does codominance affect the phenotype?

A

Both alleles are expressed, resulting in a phenotype that shows characteristics of both alleles.

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36
Q

What are the three alleles in human blood groups?

A

IA, IB, IO.

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37
Q

Which blood group alleles are codominant?

A

IA and IB.

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38
Q

What is the genotype of a person with blood group AB?

A

IAIB.

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39
Q

What does the Hardy-Weinberg equation calculate?

A

The allele frequency or number of carriers in a population.

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40
Q

What is the equation for Hardy-Weinberg equilibrium?

A

p² + 2pq + q² = 1, where p and q are allele frequencies.

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41
Q

What is the definition of genetic drift?

A

Random changes in allele frequency, particularly significant in small populations.

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42
Q

What are two types of genetic drift?

A

Founder effect and genetic bottleneck.

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43
Q

What is the founder effect?

A

When a small number of individuals start a new population, leading to reduced genetic diversity.

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44
Q

What is a genetic bottleneck?

A

A sharp reduction in population size due to events like disasters, reducing genetic diversity.

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45
Q

Why are small populations more affected by genetic drift?

A

Rare alleles are more likely to be lost by chance.

46
Q

What is the difference between allopatric and sympatric speciation?

A

Allopatric involves geographical isolation; sympatric occurs without geographical barriers.

47
Q

What causes sympatric speciation?

A

Reproductive isolation due to factors like mutations or behavioral changes.

48
Q

What is stabilizing selection?

A

A type of natural selection that favors the average phenotype, reducing variation.

49
Q

What is directional selection?

A

A type of natural selection that favors one extreme phenotype, shifting the population mean.

50
Q

What is disruptive selection?

A

A type of natural selection favoring both extreme phenotypes over the average, potentially leading to speciation.

51
Q

What are abiotic factors?

A

Non-living factors like temperature, light intensity, and pH that influence ecosystems.

52
Q

What are biotic factors?

A

Living factors like competition, predation, and disease that influence ecosystems.

53
Q

What is a niche?

A

The role of a species within its ecosystem, including its interactions and use of resources.

54
Q

What does the mark-release-recapture method estimate?

A

The population size of motile species.

55
Q

What are key assumptions in the mark-release-recapture method?

A

No immigration/emigration, marks do not affect survival, and enough time is allowed for mixing.

56
Q

What is primary succession?

A

The colonization of bare ground by pioneer species leading to soil formation and biodiversity increase.

57
Q

What is secondary succession?

A

Recolonization of a disturbed ecosystem, starting with soil and resulting in a climax community.

58
Q

What is a climax community?

A

The final, stable community in an ecosystem, characterized by high biodiversity and complex food webs.

59
Q

What is the purpose of the chi-squared test in genetics?

A

To determine if observed phenotypic ratios differ significantly from expected ratios.

60
Q

How is the null hypothesis used in chi-squared tests?

A

It states there is no significant difference between observed and expected frequencies.

61
Q

What is epistasis?

A

When one gene masks or modifies the expression of another gene.

62
Q

What is autosomal linkage?

A

When two genes are located on the same chromosome and tend to be inherited together.

63
Q

Why does autosomal linkage affect phenotypic ratios?

A

Linked genes reduce the chance of recombination, altering expected ratios.

64
Q

What is sex linkage?

A

A gene located on a sex chromosome, usually the X chromosome.

65
Q

Why do males often exhibit recessive sex-linked traits?

A

Males have only one X chromosome, so recessive alleles on it are expressed.

66
Q

What is the definition of a gene pool?

A

The total collection of alleles in a population.

67
Q

How do selection pressures affect allele frequencies?

A

They favor certain alleles, increasing their frequency while reducing others.

68
Q

What is conservation?

A

The active management of ecosystems to maintain biodiversity and prevent species extinction.

69
Q

Why is managing succession important for conservation?

A

To maintain habitats for species that may be outcompeted in a climax community.

70
Q

What factors can change carrying capacity in an ecosystem?

A

Abiotic factors like temperature and biotic factors like new predators or diseases.”Question

71
Q

What is the definition of a species?

A

A group of organisms that can interbreed to produce fertile offspring.

72
Q

What is a population?

A

A group of organisms of the same species occupying a specific area at the same time.

73
Q

What is a community?

A

Populations of different species living in the same area.

74
Q

What is an ecosystem?

A

A community and the non-living components of its environment.

75
Q

What is a habitat?

A

A specific part of an ecosystem where a population lives.

76
Q

What does primary succession start with?

A

Bare ground or surfaces like rock, sand, or water.

77
Q

What do pioneer species do in succession?

A

They colonize hostile environments, improve soil quality, and make the environment less hostile for other species.

78
Q

What characterizes the climax community in succession?

A

Stable populations, high biodiversity, and complex interactions.

79
Q

What is the effect of interspecific competition?

A

It reduces resource availability between different species.

80
Q

What is the effect of intraspecific competition?

A

It regulates population size within a species by competition for resources.

81
Q

How can quadrats be used to estimate population size?

A

By dividing the area into sections, randomly sampling, and calculating averages.

82
Q

What are examples of abiotic factors affecting ecosystems?

A

Light intensity, temperature, pH, and water availability.

83
Q

What are examples of biotic factors affecting ecosystems?

A

Predators, competition, disease, and availability of mates.

84
Q

What is the formula for estimating population size using mark-release-recapture?

A

Population size = (number in first sample × number in second sample) / number of marked individuals recaptured.

85
Q

What are assumptions of the Hardy-Weinberg principle?

A

Random mating, no selection, large population, no mutation, no migration.

86
Q

What is genetic variation caused by?

A

Mutations, meiosis (crossing over and independent segregation), and random fertilization.

87
Q

How does the bottleneck effect reduce genetic diversity?

A

A significant population reduction causes loss of alleles by chance.

88
Q

What is directional selection?

A

A form of natural selection favoring one extreme phenotype, shifting allele frequencies.

89
Q

What is disruptive selection?

A

A form of natural selection favoring extreme phenotypes over intermediate ones, potentially leading to speciation.

90
Q

What does ‘null hypothesis’ state in chi-squared tests?

A

There is no significant difference between observed and expected results.

91
Q

What is the role of degrees of freedom in chi-squared tests?

A

It determines the critical value, calculated as the number of phenotypes minus one.

92
Q

What is the critical value in chi-squared tests for p < 0.05?

A

7.815 when degrees of freedom is 3.

93
Q

What does a significant chi-squared result indicate?

A

The null hypothesis is rejected; observed differences are not due to chance.

94
Q

What is the role of random sampling in population studies?

A

It removes bias and ensures representative data.

95
Q

Why is a large sample size important in biological studies?

A

It increases reliability and reduces the impact of anomalies.

96
Q

What is the role of conservation in managing ecosystems?

A

To maintain biodiversity and prevent extinction by managing succession and human impact.

97
Q

What is the founder effect?

A

When a new population is started by a few individuals, leading to reduced genetic diversity.

98
Q

What is the importance of genetic diversity in populations?

A

It allows adaptation to environmental changes and survival under selection pressures.

99
Q

What is an example of stabilizing selection?

A

Human birth weight, where average weights have higher survival rates.

100
Q

How do you calculate percentage change in biology experiments?

A

Percentage change = (change / original value) × 100.

101
Q

What is the purpose of controls in experiments?

A

To ensure that only the independent variable affects the results.

102
Q

What is epistasis, and how does it influence phenotypes?

A

Interaction between genes where one gene masks or modifies another’s expression.

103
Q

How does crossing over during meiosis affect inheritance?

A

It increases genetic variation by exchanging DNA between homologous chromosomes.

104
Q

What is the phenotype ratio for a dihybrid cross of heterozygous parents?

A

9:3:3:1, unless linked genes or epistasis are involved.

105
Q

What is the effect of linked genes on inheritance ratios?

A

They are inherited together more often, altering expected phenotypic ratios.

106
Q

What is the interaction of abiotic and biotic factors in niches?

A

Species adapt their roles based on resource use, predation, and competition.

107
Q

What are examples of human activities that affect carrying capacity?

A

Deforestation, pollution, introduction of invasive species, and overhunting.

108
Q

Why do species in the same habitat occupy different niches?

A

To reduce competition by specializing in different resources or times.

109
Q

What is a correlation coefficient used for in biology?

A

To measure the strength and direction of a relationship between two variables.

110
Q

How is the p-value interpreted in statistical tests?

A

A p-value < 0.05 indicates results are statistically significant.

A Level Biology (12 decks)

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