Unit 2.2 - Evolution

Question 1

Define Evolution

Answer 1

Change that happens over generations in the proportion of individuals in a population which differ in one or more inherited traits `

Question 2

What are the three type of mutations?

Answer 2

Neutral
Positive
Negative

Question 3

What type of mutations increase the individual’s fitness?

Answer 3

Positive

Question 4

What are the three causes of evolution?

Answer 4

Genetic Drift, Natural Selection, Sexual Selection

Question 5

Is Genetic Drift random or non random?

Answer 5

Random

Question 6

Define Genetic Drift

Answer 6

Random increase/decrease in the frequency of inherited traits over a number of generations

Question 7

What type of populations does genetic drift have the biggest effect?

Answer 7

Small populations

Question 8

What is Natural Selection?

Answer 8

Non random process which affects the allele frequency in the population over generations

Question 9

What is Sexual Selection?

Answer 9

Non random increase in the frequency of alleles that increase reproductive chances

Question 10

Define Absolute Fitness

Answer 10

Ratio of frequencies of a particular genotype in one generation compared to the previous generation

Question 11

Define Relative Fitness

Answer 11

Compares the absolute fitness of one genotype with the absolute fitness of the most successful genotype

Question 12

What five factors influence the rate of evolution?

Answer 12

Selection Pressures
Generation Times
Environment Temperature
Sexual Reproduction
Horizontal Gene Transfer

Question 13

How do selection pressures influence rate of evolution?

Answer 13

Selection increases the heritability of beneficial traits. When there are higher selection pressures, the traits are being more favoured and so the rate of evolution will be more rapid

Question 14

How does shorter generation times increase rate of evolution?

Answer 14

More generations in a set period of time

More opportunities for selection pressures to operate and change frequency of traits in populations

Question 15

If it was a warmer environment would the rate of evolution be increased or decreased?

Answer 15

Increased

Question 16

Why would a warmer environment increase the rate of evolution?

Answer 16

When the environment gets warmer, all the enzymes in an organism work faster. The germ cells which produce gametes by meiosis divide more frequently and so there is more DNA replication meaning a greater chance of mutation

Question 17

What does Horizontal Gene transfer allow?

Answer 17

Sharing of beneficial DNA sequences between different lineages of bacteria

Question 18

What is co-evolution?

Answer 18

When a change in the trait of one species acts as a selection pressure on the other species

Question 19

What is the Red Queen Hypothesis?

Answer 19

States both species must keep ‘running to stay still’ and must keep evolving to keep up with the changes in the other species

Question 20

Give examples of co-evolution`

Answer 20

Plants and their Pollinators

• Angiosperms have evolved features to transfer the pollen more effectively to the animal and vice versa
• Animal species evolves features to get nectar more effectively

Parasites and their hosts

• Parasites are specific to their host species
• Hosts are better able to resist and tolerate parasitism are favoured
• Parasites are selected to be better able to feed, reproduce and transmit

Question 21

What is a selection pressure?

Answer 21

An external factor that affects the heritability of traits.

Question 22

What are the three types of horizontal gene transfer?

Answer 22

Conjunction, transformation, transduction