UNIT 3 - Natural Selection, Adaption & Behaviour

Question 1

What is a mutation?

Answer 1

A random change to genetic material. Mutations are spontaneous and are the only sources of new alleles

Question 2

What can mutations be?

Answer 2

-Neutral,
-Advantageous,
-Disadvantageous,

Question 3

What are some of the factors which increase the rate of mutation?

Answer 3

-radiation (X-rays, UV)
-some chemicals (e.g. those found in cigarettes)

Question 4

What is an adaptation?

Answer 4

It is an inherited characteristic that makes an organism well suited to survive in its environment

Question 5

What does variation within a population make possible?

Answer 5

It makes it possible for a population to evolve over time in response to changing environmental conditions

Question 6

What is Natural Selection?

Answer 6

Natural selection is a process where organisms which are better adapted to their environment survive and reproduce, passing on their favourable alleles. Those organisms which are less well adapted die before they reproduce

Question 7

When does natural selection occur?

Answer 7

When there are selection presssures

Question 8

What are some examples of selection pressures?

Answer 8

-Temperature: some organisms may be better adapted to colder temperatures.
-Predators: some organisms might be better adapted to camouflage and avoid predators.

Question 9

Explain the process of natural selection:

Answer 9

1) Species produce more offspring than the environment can sustain.
2)Variation exists between members of a species.
3)The best adapted survive.
4)Those who survive reproduce, passing on their favourable alleles that give a selective advantage.
5)This happens over many generations and these alleles increase in frequency within the population.

Question 10

What is speciation?

Answer 10

Speciation is the evolution of new species from pre-existing ones.

Question 11

When can speciation occur?

Answer 11

When populations become isolated from each other by a barrier and interbreeding is prevented

Question 12

What are the different types of isolating barriers?

Answer 12

-Geographical
-Ecological
-Behavioural

Question 13

What do isolating barriers do?

Answer 13

Split the population into sub-populations

Question 14

What occurs in each sub-populations?

Answer 14

Mutations occur in each sub-population causing new variation within each sub-population

Question 15

Describe the process of the formation of a new species:

Answer 15

-Isolating barriers
-Mutations occurs in sub-populations
-Natural selection happens in each sub-population due to different selection pressures.
-Speciation