UNIT 2 - KA2

Question 1

Evolution

Answer 1

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

Question 2

What two types of changes occur during evolution

Answer 2

• Non random
• Random

Question 3

How do changes in allele frequency occur during evolution

Answer 3

During evolution, changes in allele frequency occur through the non random processes of natural selection and sexual selection and the random process of genetic drift

Question 4

What does natural selection act on

Answer 4

Natural selection acts on genetic variation in populations

Question 5

What does variation in traits arise as a result of

Answer 5

Variation in traits arises as a result of mutation

Question 6

What is the original source of new sequences of DNA

Answer 6

Mutation is the original source of new sequences of DNA

Question 7

What can new DNA sequences be

Answer 7

These new sequences can be novel alleles

Question 8

What are most mutations.. can they be beneficial?

Answer 8

Most mutations are harmful or neutral but in rare cases they may be beneficial to the fitness of an individual

Question 9

How much offspring do populations produce

Answer 9

Populations produce more offspring than the environment can support

Question 10

What can individuals with variations that are better suited to the environment do

Answer 10

Individuals with variations that are better suited to their environment tend to survive longer and produce more offspring, breeding to pass on those alleles that conferred an advantage to the next generation.

Question 11

What does selection result in

Answer 11

Selection results in the non random increase in the frequency of advantageous alleles and the non- random decrease in the frequency of deleterious alleles

Question 12

Sexual selection

Answer 12

Sexual selection is the non - random process involving the selection of alleles that increases the individuals chances of mating and producing offspring

Question 13

What can sexual selection lead to

Answer 13

Sexual selection may lead to sexual dimorphism

Question 14

What can sexual selection be due to

Answer 14

Sexual selection can be due to male-male rivalry amd female choice

Question 15

Male-male rivalry

Answer 15

Large size or weaponry increases access to females through conflict

Question 16

Female choice

Answer 16

Female choice involves females assessing the fitness of males

Question 17

When does genetic drift occur

Answer 17

Genetic drift occurs when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next

Question 18

Why is genetic drift more important in small populations

Answer 18

Genetic drift is more important in small populations, as alleles are more likely to be lost from the gene pool

Question 19

When do population bottlenecks occur

Answer 19

Population bottlenecks occur when a population size is reduced for at least one generation

Question 20

When does founder effects occur

Answer 20

Founder effects occur through the isolation of a few members of a population from a larger population

Question 21

What is the effect of founder effects on gene pool

Answer 21

The gene pool of the new population is not representative of that in the original gene pool

Question 22

Why are gene pools altered by genetic drift

Answer 22

A gene pool is altered by genetic drift because certain alleles may be under represented or over represented and allele frequencies change

Question 23

What is the rate of evolution when selection pressures are strong

Answer 23

Where selection pressures are strong the rate of evolution can be rapid

Question 24

What are selection pressures

Answer 24

Selection pressures are the environmental factors that influence which individuals in a population pass on their alleles

Question 25

Biotic selection pressures

Answer 25

- competition - predation - disease - Parasitism

Question 26

Abiotic selection pressures

Answer 26

- changes in temperature - light - humidity - pH - salinity

Question 27

What is fitness an indication of

Answer 27

Fitness is an indication of an individuals ability to be successful at surviving and reproducing.

Question 28

What is fitness a measure of

Answer 28

Fitness is a measure of the tendency of some organisms to produce more surviving offspring than competing members of the same species

Question 29

What does fitness refer to in terms of gene pool

Answer 29

It refers to the contribution made to the gene pool of the next generation by individual genotypes

Question 30

How can fitness be defined

Answer 30

Fitness can be defined in absolute or relative terms

Question 31

What is absolute fitness

Answer 31

Absolute fitness is the ratio between the frequency of individuals of a particular genotype after selection to those before selection

Question 32

Formula for absolute fitness

Answer 32

Frequency of a particular genotype after selection / frequency of a particular genotype before selection

Question 33

What happens if the absolute fitness is 1

Answer 33

It the absolute fitness is 1, then the frequency of the genotype is stable

Question 34

What does a value greater than one convey

Answer 34

A value greater than 1 conveys an increase in the genotype

Question 35

What does a value less than 1 convey

Answer 35

A value less than 1 conveys a decrease in the genotype

Question 36

What is relative fitness

Answer 36

Relative fitness is the ratio of the number of surviving offspring per individual of a particular genotype to the number of surviving offspring per individual of the most successful genotype

Question 37

Formula for relative fitness

Answer 37

Number of surviving offspring per individual of a particular genotype / number of surviving offspring per individual of the most successful genotype

Question 38

Co evolution

Answer 38

Co evolution is the process by which two or more species evolve in response to selection pressures imposed by each other

Question 39

What is the effect of a change in the traits of one species to others

Answer 39

A Change in the traits of one species acts as a selection pressure on the other species

Question 40

Where is co evolution frequently seen

Answer 40

Co evolution is frequently seen in pairs of species that have symbiotic interactions

Question 41

Symbiosis

Answer 41

Co evolved intimate relationships between members of two different species

Question 42

What is the impact of co-evolved relationships

Answer 42

The impacts of these relationships can be positive (+) negative (-) or neutral (0) for the individuals involved

Question 43

Mutualism

Answer 43

Both organisms in the interaction are interdependent on eachother for resources or other services. As both organisms gain from the relationship the interaction is (+/+)

Question 44

Commensalism

Answer 44

Only one of the organisms benefits (+/0)

Question 45

Parasitism

Answer 45

The parasite benefits in terms of energy or nutrients and the host is harmed as the result of the loss of these resources (+/-)

Question 46

What are mutualism commensalism and parasitism

Answer 46

Types of symbiotic interactions

Question 47

What does the red queen hypothesis state

Answer 47

The red queen hypothesis states that in a co-evolutionary relationship change in the traits of one species can act as a selection pressure on the other species

Question 48

How must red queen hypothesis species adapt

Answer 48

This means that species in these relationships must adapt to avoid extinction