3.6 Evolution

Question 1

Genetic variation

Answer 1

Members of the same species can be varied because if slightly different versions of the same gene

Question 2

Allele

Answer 2

An allele is a version of a gene

Question 3

Mutation

Answer 3

They are spontaneous, random changes to the genetic material of an organism. Mutations are the only way that the new alleles are added into a population.

Question 4

What is an advantageous mutation

Answer 4

A mutation that improves the survival of an organism

Question 5

What is a disadvantageous mutation

Answer 5

Mutations that are harmful to the survival of an organism

Question 6

Neutral mutation.

Answer 6

Mutations that are neither beneficial or harmful to an organism

Question 7

What is a mutagenic agent

Answer 7

Environmental factors that increase mutation rates

Question 8

Two mutagenic agents

Answer 8

1) UV radiation
2) Mustard gas

Question 9

Why is variation important

Answer 9

Variation within a population makes it possible for a population to evolve over time, in response to changing environmental factors

Question 10

Adaptation

Answer 10

Is an inherited characteristic that makes an organism well suited to survival in its environment / niche
New alleles produced by mutation can results in plants and animals becoming better adapted to their environment

Question 11

Natural selection

Answer 11

Species produce more offspring that the environment can sustain
It occurs when there are selection pressure
The best adapted individuals in a population survive to reproduce passing on the favourable alleles that confer the selection advantage. These alleles increase in frequency within the population

Question 12

Speciation

Answer 12

Is where two or more species are formed from one original species
It occurs after part of a population becomes isolated by an isolation barrier which can be geographical, ecological or behavioural

Question 13

I Am A New Species

Answer 13

I = Isolation
A = A mutation
N = Natural selection
S = Speciation

Question 14

Stages of speciation

Answer 14

1) Population of same species
2) Population is separated by an isolation barrier
3) Different mutations appear in both sides of the barrier due to selection barrier
4) Natural selection means those with favourable alleles survive

Question 15

Examples of isolation barriers

Answer 15

Geographical - Mountain ranges, rivers
Ecological - pH, climate
Behavioural- Mating, Food availability

Question 16

How can you tell the two population formed after specification are separate species ?

Answer 16

They will not be able to reproduce to produce fertile offspring