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AH Biology > Unit 2.2a > Flashcards

Unit 2.2a Flashcards

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1
Q

What is evolution?

A

Evolution is the change over time in the proportion of individuals in a population, differing in one or more inherited traits

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2
Q

What causes changes in the allele frequency during evolution?

A

Natural selection, sexual selection, genetic drift

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3
Q

Is natural selection random, or non-random?

A

Non-random

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4
Q

Is sexual selection random, or non-random?

A

Non-random

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5
Q

Is genetic drift random, or non-random?

A

Random

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6
Q

What does natural selection act on?

A

A population is genetic variation

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7
Q

Why does variation arise in a population?

A

It arises due to mutations

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8
Q

What are mutations?

A

They are the original source of new sequences of DNA in an organism

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9
Q

Mutations can be 1 or 2, but in rare cases, they may be 3 to the fitness of an individual

A
  1. Harmful
  2. Neutral
  3. Beneficial
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10
Q

What happens when a population produces more offspring in the environment can support?

A

Selection pressures occur

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11
Q

How do you beneficial alleles get passed on to future generations?

A

Individuals that have variation better suited to the environment survive long enough to produce offspring, passing on advantageous alleles

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12
Q

What does selection result in?

A

The non-random increase in the frequency of advantageous alleles, and the non-random decrease in the frequency of deleterious alleles

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13
Q

What is sexual selection?

A

Process involving the selection of alleles that increase the individuals chance of mating and producing offspring

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14
Q

What can sexual selection cause?

A

Sexual dimorphism

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15
Q

What is sexual dimorphism?

A

It is when 2 sexes of the same species exhibit different characteristics i.e. peacocks

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16
Q

What are the two types of sexual selection?

A

Male-male rivalry
Female choice

17
Q

How does male-male rivalry work?

A

Males that are larger or that have better weaponry win in conflicts against other males and therefore gain more access to female. This allows them to pass on these advantageous alleles.

18
Q

How does female choice work?

A

This is when females assess the fitness of males.
This can result in males attempting to attract females through elaborate displays.

19
Q

When does genetic drift occur?

A

When chance events cause unpredictable fluctuations in allele frequencies from one generation to the next

20
Q

Where is genetic drift most likely to occur?

A

It’s most likely to occur in small populations, as alleles are more likely to be lost from the gene pool

21
Q

What are the two effects that enable genetic drift?

A

Bottleneck effect
Founder effect

22
Q

What is the bottleneck effect?

A

It’s when a population is reduced for at least one generation, causing it to have low genetic diversity

23
Q

What is the founder effect?

A

It’s when a few members of a large population become isolated. The new smaller population have a small gene pool that is not representative of the original.

24
Q

How does genetic drift alter a gene pool?

A

It causes alleles to become underrepresented or overrepresented, and so allele frequencies change

25
Q

What increases the rate of evolution?

A

Selection pressures

26
Q

What influences the alleles passed down in a population?

A

Environmental factors, that act as selection pressures

27
Q

What are the two types of selection pressures?

A

Abiotic
(Soil pH, temperature, light etc.)
Biotic
(Competition, predation, disease, etc.)

28
Q

What is the Hardy-Weinberg principle?

A

It states that in the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over the generations

29
Q

What are the necessary conditions to maintain the Hardy-Weinberg principle?

A
  • No natural selection
  • No mutations
  • No migration in or out (no gene flow)
  • Random mating
  • Large population size
30
Q

What does the hardy Weinberg principle determine?

A

What are the changes an allele frequency are occurring in a population, which suggests whether or not evolution is occurring

31
Q

What is the hardy?-Weinberg principle calculation?

A

p² + 2pq + q ² = 1

32
Q

What does the p stand for in p ² + 2pq + q² = 1?

A

Frequency of dominant allele

33
Q

What does the p² stand for in p ² + 2pq + q² = 1?

A

Frequency of homozygous dominant genotype

34
Q

What does the 2pq stand for in p ² + 2pq + q² = 1?

A

Frequency of heterozygous genotype

35
Q

What does the q² stand for in p ² + 2pq + q² = 1?

A

Frequency of homozygous recessive genotype

36
Q

What does the q stand for in p ² + 2pq + q² = 1?

A

Frequency of recessive allele

AH Biology (51 decks)

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