4.3.1 Classification and Evolution – Evidence for Natural Selection

Question 1

What does the term natural selection mean?

Answer 1

It is the term used to explain how features of the environment apply a selective force/pressure on the reproduction of individuals in a population affecting which alleles are being passed on.

Question 2

Where did Darwin predominantly develop his theories for natural selection?

Answer 2

The Galapagos Islands

Question 3

What did Darwin note about the variety of finch species on the islands?

Answer 3

They all originated from a single species of finch. They had a common ancestor.

Question 4

Who independently came to the same conclusions as Darwin?

Answer 4

Alfred Wallace

Question 5

What were Darwin’s four key observations?

Answer 5

1) Offspring generally appear similar to parents.
2) No two individuals are identical.
3) Organisms have the ability to produce large numbers of offspring.
4) Populations tend to remain fairly stable in size.

Question 6

From Darwin’s observations, what did he conclude?

Answer 6

• There is a struggle to survive.
• Better adapted individuals survive and pass on their characteristics.
• Over time, a number of changes may give rise to a new species.

Question 7

Herbert Spencer coined the term ‘survival of the fittest’. Explain how this relates to Darwin’s views.

Answer 7

Fittest means ‘best adapted to the environment’, and those which are best adapted survive to pass on their alleles.

Question 8

Why were fossils of interest to Darwin?

Answer 8

He saw similarities between past and present species and began to understand that fossil species gave rise to more modern species.

Question 9

How is it possible to date fossils?

Answer 9

Using carbon dating.

Question 10

Why is it difficult to fully rely on fossils for a record of past species?

Answer 10

Only a small number of organisms are ever fossilised, and fossil records are incomplete.

Question 10

Suggest why the fossil record of evolution is not complete.

Answer 10

Any of the following:
- Not all fossils have been found
- Fossils do not form easily – there may be no fossils of some/many organisms
- Erosion may have worn fossils away
- Movement of the ground caused by earthquakes may disrupt the record

Question 11

What type of molecule other than DNA is most suited to use as evidence for evolution by natural selection?

Answer 11

Proteins

Question 12

What can be extracted from ancient bones/fossils?

Answer 12

DNA