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Cfe Advanced Higher Biology - Unit 2 > 2.2 ORGANISMS > Flashcards

Flashcards in 2.2 ORGANISMS Deck (29)
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1
Q

What is evolution?

A

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

2
Q

Evolution occurs through which processes?

A

Random and non-random processes

3
Q

Give an example of a random evolutionary process.

A

Genetic drift

4
Q

What is genetic drift?

A

The random change in the frequency of a particular allele within a population

5
Q

In which type of population is genetic drift more important?

A

Small populations

6
Q

Why is genetic drift important to small populations?

A

Alleles are more likely to be lost from the gene pool

7
Q

Give two examples of a non-random evolutionary process.

A

Natural selection, sexual selection

8
Q

Why are natural and sexual selection described as non-random processes?

A

Certain alleles become more frequent in the population because they confer a selective advantage

9
Q

What is mutation?

A

The original source of new DNA sequences

10
Q

What is the result of mutation?

A

Variation in traits arises as novel alleles are formed

11
Q

Mutations can be?

A

Neutral, harmful or beneficial to the evolutionary fitness of an individual

12
Q

What are the two types of fitness?

A

Absolute fitness, relative fitness

13
Q

What is absolute fitness?

A

Ratio of frequencies of a particular genotype from one generation to the next

14
Q

What is relative fitness?

A

Ratio of surviving offspring of one genotype compared with other genotypes

15
Q

What happens when organisms produce more offspring than the environment can support?

A

Individuals with variations more suited to the environment are more likely to survive and breed

16
Q

What happens to selected alleles?

A

They become more frequent in subsequent generations through inheritance

17
Q

What is the result of high selection pressures?

A

Rate of evolution becomes rapid

18
Q

Name four ways to increase the rate of evolution.

A

High selection pressures, shorter generation times, warmer environments, sharing of beneficial DNA

19
Q

How is DNA shared?

A

Through sexual reproduction and horizontal gene transfer

20
Q

What is horizontal gene transfer?

A

Transfer of DNA sequences using plasmids

21
Q

What is co-evolution?

A

When a change in traits of one species acts as a natural selection pressure on the other species and vice versa

22
Q

When does co-evolution occur?

A

When pairs of species interact frequently or closely

23
Q

Give four examples of co-evolutionary relationships.

A

Herbivores and plants, pollinators and plants, predators and prey, parasites and hosts

24
Q

What is the term given to ongoing co-evolution?

A

Red Queen Hypothesis

25
Q

What does the Red Queen Hypothesis state?

A

Both organisms must “keep running in order to stay still”

26
Q

What does the Red Queen Hypothesis explain?

A

Sexual reproduction evolved as a way to produce variation more readily than relying on mutation alone

27
Q

Co-evolution can be described as?

A

An ‘arms race’

28
Q

How can parasites increase their fitness?

A

Better their ability to feed, reproduce and find new hosts

29
Q

How can hosts increase their fitness?

A

Better their ability to resist and tolerate parasitism