3.2 Natural Selection

Question 1

What is an ecological niche?

Answer 1

The role of an organism in its environment. How it feeds, its predators and how it interacts with the non-living environment around it

Question 2

What is adaptation?

Answer 2

The process by which an organism becomes fitted to its environment

Question 3

What are the different types of adaptation?

Answer 3

Anatomical
Phsiological
Behavioural

Question 4

What are physiological adaptations?

Answer 4

Changes to the metabolism of an organism

Question 5

What are anatomical adaptations?

Answer 5

Changes to the actual structure of an organism

Question 6

What are behavioural adaptations?

Answer 6

Changes in the behaviour of an organis

Question 7

Why does a population have natural genetic diversity?

Answer 7

Random mutations of genes

Genetic variation from meiosis

Question 8

What selection pressures can cause natural selection?

Answer 8

Predators
Availability of food
Diseases

Question 9

Explain the steps of natural selection

Answer 9

Genetic variation
Selection pressure
Allele gives advantage
Organisms survives
Reproduce
Over many generations
Allele frequency increases

Question 10

What is evolution?

Answer 10

The development of new types of living organisms from pre-existing types by the accumulation of genetic differences over a period of time

Question 11

What are pieces of evidence for evolution?

Answer 11

Fossils
DNA molecule is the same
DNA as a molecular clock
Proteonomic and genomics
Ribosomal RNA studies

Question 12

How can DNA be used as a molecular clock?

Answer 12

Mutations happen at a constant rate so you can estimate time of divergence into two species of a species

Question 13

What is a species?

Answer 13

A group of organisms which can interbreed to form fertile offspring

Question 14

What is the gene pool?

Answer 14

All the possible genes and alleles present in a population

Question 15

What is speciation?

Answer 15

The process by which a species is formed from another one

Question 16

Give the stages of speciation

Answer 16

Reproductive isolation
Separate gene pools
Different selection pressures on the gene pools
Natural selection occurs
Change in allele frequency
Different so cannot breed

Question 17

In what ways can reproductive isolation be brought about?

Answer 17

Allopatric speciation

Sympatric speciation

Question 18

What is allopatric speciation?

Answer 18

When two populations are physically separated from each other using a physical barrier so they cannot interbreed and gene pools cannot mix

Question 19

What is sympatric speciation?

Answer 19

When two populations can mix freely but they cannot interbreed

Question 20

Give examples of changes which can lead to sympatric speciation?

Answer 20

Mismatched genitalia
Behavioural changes
Formation of sterile offspring

Question 21

What is stabilising selection?

Answer 21

Environmental conditions are stable and favourable alleles are preserved. Gets rid of abnormalities

Question 22

What is directional selection?

Answer 22

Where conditions change so that it’s favourable to change in one direction

Question 23

What is disruptive selection?

Answer 23

Mean trait is eliminated

Extreme traits are favoured