3.6 Evolution of species

Question 1

What is the definition of mutation?

Answer 1

A mutation is a random change in the structure of genetic material

Question 2

How can mutations be increased?

Answer 2

Can be increased by mutagenic agents such as :
Radiation e.g x-rays, uv light
Chemicals e.g nicotine, colchicine

Question 3

Name the 3 results of mutation

Answer 3

Harmful - genes that will decrease population
Beneficial - genes that may improve population
Neutral - no advantage or disadvantage

Question 4

Describe variation

Answer 4

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

Question 5

Describe natural selection/ survival of the fittest

Answer 5

The best adapted organisms within a population, with characteristics best suited to the environment survive, reproduce and pass on genes to offspring.

Question 6

What is speciatiation ?

Answer 6

The formation of new species after part of the population becomes isolated by an isolation barrier

Question 7

What are the 3 types of isolation barrier?

Answer 7

Geographical - rivers and mountains
Ecological - different habitats, soil pH
Behavioural - differences in courtship behaviour, physical differences.

Question 8

Speciation summary

Answer 8

I Must Not Smoke

I solation barrier
M utations
N atural selection
S peciation

Question 9

Stage 1 of speciation

Answer 9

a large inter-breeding population with a common gene pod

Question 10

Stage 2 of speciation

Answer 10

An isolation barrier appears preventing the flow of genes

Question 11

Stage 3 of speciation

Answer 11

Different mutations appear in each subpopulation

Question 12

stage 4 of speciation

Answer 12

Different selective pressures favour some mutations which become more common in the sub population

Question 13

Stage 5 of speciation

Answer 13

Over many generations barrier is removed, left with two different species who can no longer inter-breed