Life on Earth - Evolution of Species T6

Question 1

Give two examples of isolation barriers and examples of each

Answer 1

Behavioural - Different Mating seasons

Geographical - River splitting population

Question 2

Biological definition of a species.

Answer 2

Organisms that can interbreed and produce fertile offspring

Question 3

Mutations can be classed as:

Answer 3

Disadvantages- majority
Neutral
Advantageous

Question 4

Mutation

Answer 4

Change in an organisms DNA

Question 5

Mutagenic agents

Answer 5

Chemicals that speed up the rate of mutations.
Dioxin (agent orange)
Depleted uranium

Question 6

Why is variation important to a species.

Answer 6

Genetic variation is an important force in evolution as it allows natural selection to increase or decrease frequency of alleles already in population. It is advantageous to a population as it enables some individuals to adapt to the environment while maintaining the survival of the population.

Question 7

Alleles

Answer 7

A variant form of a gene passed on from parent to infant

Question 8

Natural selection

Answer 8

Process through which population ma of living organisms adapt and change to suit their environment.

Question 9

Stages of natural selection

Answer 9

• Sexual reproduction produces many offspring.
• Inherited variation means that organisms are different from one another.
• Struggle for survival - competition for resources, deaths from predation, death from disease, unable do survive abiotic conditions.
• Survival of the fittest.
• Mating and offspring produced - favoured alleles are passed on.
• Process repeats with offspring.

Question 10

Stages of speciation.

Answer 10

• Species is together.
• Species is split by barrier i.e. mountain range.
• Mutations arise within each sub population -different environments favour different mutations.
• Whole population now has mutation.
• Even if barrier is removed each species is so different that can no longer interbreed and produce fertile offspring - thus new species are formed.

Question 11

Speciation.

Answer 11

The process by which a new species is formed due to the separation of a population.