Key area 6- Evolution of species

Question 1

What is a mutation?

Answer 1

A random change to genetic material

Question 2

What are alleles?

Answer 2

Different versions of the same gene (e.g. blue eyes and brown eyes)

Question 3

What does variation mean?

Answer 3

The difference within a population

Question 4

What does natural selection mean?

Answer 4

The process in which evolution occurs

Question 5

What does speciation mean?

Answer 5

The process that results in a species

Question 6

What is an isolation barrier?

Answer 6

A geographical, ecological or behavioural means that separates two species

Question 7

What is selection pressure?

Answer 7

A change in the environment for a living thing (e.g. a new predator appears in an ecosystem)

Question 8

What does adaption mean?

Answer 8

An inherited characteristic that makes an organism well suited to survival in it’s environment/niche

Question 9

What does evolution mean?

Answer 9

Evolution is the gradual change in organism over a very long period of time

Question 10

What are the three possible outcomes for how an organism is effected by a change to it’s DNA?

Answer 10

Neutral- mutation has no effect on organism, Positive- Mutation causes organism to gain a survival advantage, Negative- Mutation causes organism to be at a disadvantage,

Question 11

What 2 factors that effect rate of mutation?

Answer 11

1. Radiation 2. Chemicals

Question 12

Describe what happens during a mutation

Answer 12

A new source of alleles form a gene

Question 13

Why do mutations happen?

Answer 13

Mutations are spontaneous

Question 14

Where does variation come from?

Answer 14

Random and spontaneous mutations lead to different versions of genes.

Question 15

Why is variation important?

Answer 15

It allows a population to evolve over time in response to to environmental condition changes

Question 16

What does new alleles produced by a mutation result in?

Answer 16

It can result in plants and animals becoming better suited to their environment

Question 17

What is the name of the scientific theory that explains how evolution happens?

Answer 17

Natural selection

Question 18

When does natural selection occur?

Answer 18

When there are selection pressures on organisms- this could be a change in the environment, availability of food, new predators, disease temperature or light intensity

Question 19

What are the 4 steps of natural selection?

Answer 19

(1) Species produce more fertile offspring than the environment can sustain. (2) The best adapted individuals in a population survive. (3) Survivors reproduce and pass on favourable genes with the selective advantage. (4) The favourable alleles increase in frequency within the population

Question 20

What is the first stage of natural selection?

Answer 20

Species produce more fertile offspring than the environment can sustain

Question 21

What is the second stage of natural selection?

Answer 21

The best adapted individuals in a population survive

Question 22

What is the third stage of natural selection?

Answer 22

Survivors reproduce and pass on favourable genes with selective advantage

Question 23

What is the last stage of natural selection?

Answer 23

The favourable alleles increase in frequency within the population

Question 24

What are the 3 stages of speciation?

Answer 24

1. Isolation 2. Mutation 3. Natural selection

Question 25

What is isolation?

Answer 25

Part of the population becomes isolated by an isolation barrier- can be geographical, ecological or behavioural

Question 26

Give 3 examples of geographical isolation barriers

Answer 26

Rivers, oceans, mountains

Question 27

Give 2 examples of ecological isolation barriers

Answer 27

pH, different habitats

Question 28

Give an example of a behavioural isolation barrier

Answer 28

Differences in mating behaviour

Question 29

What occurs in the mutation stage of speciation?

Answer 29

Over a long period of time different mutations will occur in each sub population

Question 30

What occurs in the natural selection stage of speciation?

Answer 30

There will be different selection pressures acting in the two groups. Each sub-population evolves until they become so genetically different that they are two different species.