Variation In Phenotype

Question 1

What does genetic variation arises as a result of what?

Answer 1

Mutations (main source)- these sudden changes to genes and chromosomes may, or may not, be passed on to the next generation

Meiosis - special form of nuclear division produces new combinations of alleles before they are passed into gametes, all of which are therefore different

Random fertilisation of gametes - in sexual reproduction this produces new combinations of alleles and the offspring are therefore different form the parents. Which gamete fuses with which at fertilisation is a random process further adding to the variety of offspring two parents can produce

Question 2

How does environmental influences variation

Answer 2

They affect the way an organism genes are expressed. The genes set limits, but it is largely the environment that determines where, within those limits, an organism lies.

Question 3

What are some examples of environmental influences

Answer 3

Climatic conditions e.g. Temp, rainfall,

Soil conditions

pH

Food availability

Question 4

Why is it difficult to draw conclusions about the causes of variation in any particular case?

Answer 4

As it is very hard to distinguish between the effects of the many genetic and environmental influences that combine to produce differences between individuals

Question 5

Any conclusions drawn about variation should be treated how?

Answer 5

They are usually tentative and should be treated with caution