variation in phenotypes

Question 1

Describe variation due to genetic factors

Answer 1

Variation due to the different alleles in a population.

Usually controlled by a single gene, distinct categories with no intermediates (eg A,B,AB,O blood types), not influenced by environmental factors.

Genetic variation arises from mutations, meiosis, random fertilisation of games.

Question 2

Describe variation due to environmental influences

Answer 2

Environmental factors affect the way in which an organisms genes are expressed, the gene sets the limits but the environment determines where within this the organism lies.

Examples of environmental conditions: pH, climatic conditions, availability of food.

Environmental variation affects chacteristics controlled by polygenes (more than one gene)