Year 12s: what will be the first way you research your future options? >>

GCSE Biology - Natural Selection help

Could you help me with these 2 questions:
1. All of the plants produced asexually were grown in exactly the same conditions. One of them produced orange fruits instead of red ones. What caused this to happen? (1 mark)

2. The following information is about rabbits in Australia:
* There were no rabbits in Australia until people introduced them
* The rabbit population increased quickly. They became a serious pest of crops and grassland
* Myxomatosis is a disease caused by a virus. It was introduced to control th numbers of rabbits. The disease spread quickly and soon reduced the rabbit population

After 5 years, most of the rabbits were resistant to the disease and so the population increased again.

Use the idea of natural selection to explain how the changes in the rabbit population occurred (4 marks)

Thankyou!

Reply 1

dinesh

It acted as a selection pressure, only those fit survived.
It decreased after the susecptible ones died, but then it had alot of resources etc for the resistant ones to thrive, hence increased growth.
Population size and envirnomental factors are the selection pressure. But when the environment can support a very large population, andno resource becomes limiting at the time, increase increaseincrease!.

Reply 2

NickiM

Thanks, so basicaly, survival of the fittest, the ones who had the least chance perished first, however, there were some rabbits who were resistant to the virus and these bred, carrying their resistance against the disease through the generations.

Reply 3

dinesh

yup
increased fequency of allele as a result, and now as they don't have non resistant ones eating up their food(this is in laymans terms) they get more, reproduce more resistant ones :smile:

Reply 4

No Future

1. Mutation
2. The rabbits who survived the disease were left to multiply and the rabbits thereafter were resistant to it ---> inc pop. Natural selection, yadda yadda.