Speciation

Question 0

How do fossils form? (3 marks)

Answer 0

Gradual replacement of hard parts by minerals
From casts or impressions of hard parts
From preservation where no decay happens ie amber or bog man.

Question 1

What is a fossil?

Answer 1

The remains of organisms from many years ago found in rocks

Question 2

What is extinction?

Answer 2

When a species doesn’t exist any more

Question 3

Why do species become extinct? (6 marks)

Answer 3

Destruction of habitat
New predator
New disease
New competitor which wins the competition!
A catastrophic event
Speciation

Question 4

What is a species?

Answer 4

A group of similar organisms who can reproduce to make fertile offspring

Question 5

What is isolation?

Answer 5

When populations of a species are separated by a barrier. This can be caused for example by a flood or an earthquake.

Question 6

How does speciation occur by natural selection? (6 marks)

Answer 6

When 2 populations become isolated by a physical barrier
The organisms will find themselves in potentially different conditions
The natural variety in alleles
Means that some characteristics will make them better adapted to the environment than others. These individuals will reproduce and pass on their alleles to the new generation
If individuals change enough to suit their new surroundings so that they could no longer mate and produce fertile offspring, then speciation is said to have occurred.