1. Zebras naturally live in long grass and their stripes provide them with camouflage from predators. How would each of these theories explain the evolution of this animal?

a) Darwin’s theory

b) Lamarck’s theory

2. Darwin said that evolution came about due to natural selection.

a) Describe the idea of natural selection.

b) Give two reasons why Darwin’s theory wasn’t accepted in the 19^th century as it is today.

i. ______________________________________

ii. _____________________________________

3. Mutations are a form of rapid evolution

a) What is the answer to each of the following? Pick from the words below.

i. When a gene changes it is called a _______________

ii. A severe environmental disaster can lead to _______________

iii. The word to describe the differences shown by organisms of the same species is _______________

extinction / mutation / variation / allele

b) How do mutations back up Darwin’s theory of evolution?

ANSWERS

a) Individual organisms usually vary slightly to other members of the same species. A zebra with stronger stripes would have fit better into the long grassed environment and so would have been more likely to survive and breed. The genes of this zebra would then have been passed on. However, zebras with less prominent stripes would have less chance to survive and so their genes could not be passed on.

b) Lamarck believed that it was nature that changed living organisms. As a zebra having stripes was a useful feature this characteristic would have become stronger whereas not having big stripes would disappear. The big stripes would then be passed onto the next generation.

a) An individual organism usually varies a little to other members of the same species due to the fact that their genes are not identical. An organism who has characteristics that fit well in their environment is more likely to survive and therefore breed. Their genes, which include these advantageous features, are then passed onto their offspring thereby ensuring that this new generation is more likely to survive.

b)

i. Darwin lived in a Christian society in which everyone believed that God had made the world.

ii. There was not as much evidence as there is today.

a)

i. …mutation

ii. …extinction

iii. …variation

b) Because if there is a change in the environment, for example, a mutation gene can survive and change a species which is evidence of natural selection.