Diversity, Classification and Variation- Genetic Diversity and Natural Selection

Question 1

What are alleles?

Answer 1

Different versions of a single gene

Question 2

What is genetic diversity?

Answer 2

The number of different alleles of genes in a species or population

Question 3

How is genetic diversity within a population increased?

Answer 3

Mutations in the DNA as new alleles are formed and different alleles being introduced into a population when individuals from another population migrate into them and reproduce (known as gene flow)

Question 4

What allows natural selection to occur?

Answer 4

Genetic diversity

Question 5

What is a genetic bottleneck?

Answer 5

An event that causes a big reduction in a population

Question 6

What is the result of a genetic bottleneck?

Answer 6

Reduces the number of different alleles in the gene pool and so reduces genetic diversity

Question 7

What do the survivors of a genetic bottleneck do?

Answer 7

Reproduce and a larger population is created from a few individuals

Question 8

What is the founder effect?

Answer 8

It describes what happens when just a few organisms from a population start a new colony and there are only a small number of different alleles in the initial gene pool

Question 9

How can the founder effect occur?

Answer 9

As a result of migration leading to geographical separation or if a new colony is separated from the original population for another reason

Question 10

What can randomly-occurring mutations result in?

Answer 10

A new allele being formed which can be harmful so that mutated allele will usually quickly die out

Question 11

How can some mutations be beneficial?

Answer 11

Alleles that are beneficial to an organism help the organism to survive in certain environments

Question 12

What happens to the frequency of an allele that increases the chances of an organism surviving?

Answer 12

Its frequency within a population can increase

Question 13

What is the process of natural selection?

Answer 13

1. There’s a differential reproductive success in a population- individuals with an allele that increases their chance of survival are more likely to survive, reproduce and pass on their genes (including beneficial alleles) than the individuals with different alleles
2. A greater proportion of the next generation inherits the beneficial allele
3. So the frequency of the beneficial allele increases from generation to generation
4. Over generations this leads to evolution as the advantageous alleles become more common in the population

Question 14

What are behavioural adaptations?

Answer 14

Ways an organism acts that increases its chance of survival and reproduction

Question 15

What is a physiological adaptation?

Answer 15

Processes inside an organism’s body that increase its chance of survival

Question 16

What is an anatomical adaptation?

Answer 16

Structural features of an organism’s body that increase its chances of survival