Speciation

Question 1

Evidence for the early forms of life comes from…

Answer 1

…fossils.

Question 2

Fossils are what?

Answer 2

The remains of organisms from many years ago, which are found in rocks.

Question 3

Fossils can be formed:

Answer 3

From the hard parts of animals that do not decay so easily.
From parts of organisms that have not decayed due to one or more of the conditions for decay not being present.
When parts of organisms are replaced by other materials as they decay.
As preserved traces of organisms, eg: footprints, burrows and root traces.

Question 4

Many early forms of life were soft bodied which means what for the traces they left behind?

Answer 4

There are very few traces.

Question 5

What has geological activity meant for the traces of the early organisms?

Answer 5

It has destroyed most of them.

Question 6

What can we learn from fossils?

Answer 6

How much or how little different organisms have changed as life has developed on earth.

Question 7

Extinction may be caused by:

Answer 7

Changes to environment over geological time.
New predators.
New diseases.
New, more successful, competitors.
A single catastrophic event, eg: massive volcanic eruptions or collision with an asteroid.
Through the cyclical nature of speciation.

Question 8

New species arise as a result of:

Answer 8

Isolation (two populations becoming separated, eg: geographically).
Genetic variation (each population has a wide range of alleles that control their characteristics).
Natural selection (in each population the alleles that control the characteristics that the organism needs to survive are selected).
Speciation (the populations become so different that interbreeding is no longer possible).