Key Area 2-Organisms

Question 1

What is evolution?

Answer 1

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

Question 2

What they’re processes lead to evolution?

Answer 2

• genetic drift
• natural selection
• sexual selection

Question 3

What is genetic drift?

Answer 3

A random process where a change in the frequency of particular alleles in a population occurs

Question 4

How does genetic drift occur?

Answer 4

Usually in small populations, influenced by the founder effect

Question 5

What is sexual selection?

Answer 5

The non-random proves of selection for traits that increase reproductive success in a species

Question 6

What is natural selection?

Answer 6

The non-random process as those offspring better adapted due to advantageous genes surviving, and as a result these advantageous genes increase in frequency among the population

Question 7

What process gives rise to new sequences of DNA and results in variation in traits?

Answer 7

Mutations

Question 8

What are three possible outcomes of mutations?

Answer 8

Harmful, neutral or beneficial

Question 9

What is absolute fitness?

Answer 9

The ratio of frequencies of a particular genotype from one generation to the next

Question 10

What is the stable value for absolute fitness?

Answer 10

1

Question 11

What is relative fitness?

Answer 11

The ratio of surviving offspring of one genotype compared with other genotypes

Question 12

How are relative values given?

Answer 12

Most successful is given restive value of one then less successful represented as a proportion of the most successful

Question 13

What is gene frequency?

Answer 13

The best suits individuals survive and pass on genes therefore through inheritance the favourable traits are more frequency in subsequent generations

Question 14

How does selection pressure affect evolution?

Answer 14

When selection pressure is high the rate of evolution is high

Question 15

What factors affect the rate of evolution?

Answer 15

• generation times are short
• environments are warmer
• sharing beneficial DNA sequences through horizontal transfer and sexual reproduction

Question 16

What is co-evolution?

Answer 16

When the evolution of one species affects the evolution of another closely associated species

Question 17

What circumstances give rise to co-evolution?

Answer 17

It’s usually seen in pairs of species that interact frequently or closely and a change in the traits of one species acts as a selection pressure on the other

Question 18

What are four examples of co-evolution?

Answer 18

• herbivores and plants
• pollinators and plants
• predators and prey
• parasites and hosts

Question 19

What is the role of selection pressure in evolution?

Answer 19

Selection pressure increases the rate of of co-evolution when one species changes traits and the other follows due to selection pressure

Question 20

What is the red queen hypothesis?

Answer 20

Both organisms must keep running in order to stay still

Question 21

What organisms are involved in the red queen hypothesis?

Answer 21

Parastites and hosts

Question 22

How do parasites and hosts represent the red queen hypothesis?

Answer 22

Hosts better able to resist and tolerate parasitism have greater fitness and parasites better able to feed, reproduce and find new hosts have greater fitness