6.2.2 Variation: Phenotype

Question 1

What is phenotypic variation

Answer 1

Variation in the phenotypes of organisms that are of the same species

Question 2

Species Def

Answer 2

• Group of organisms with the same genes
• Same common ancestry
• Can reproduce to produce fertile offspring

Question 3

What can cause phenotypic variation?

Answer 3

• Genetic factors (eg. Blood groups)
• Environmental factors (eg. Clones of plants will grow to different heights under different environmental conditions)
• Combination of genetics and environment (Recessive allele causing sickle cell anaemia has a high frequency in populations where malaria is present. Due to heterozygous individuals being resistant to malaria)
• Phenotype = Genotype + Environment

Question 4

What determines phenotype?

Answer 4

• Different alleles at gene loci
• Just 1 or more genes can change the phenotype of an organism

Question 5

Examples of environmental factors affecting phenotype

Answer 5

• Length of sunlight hours
• Food availability
• Water availability
• Temp range
• O2 levels

All influence growth and development.

Plants with tall genotype will not be able to grow in an environment with depleted minerals, sunlight and water

Variation in phenotype caused by environmental factors CANNOT be inherited genetically in the organism’s offspring

Question 6

Examples of how environment affects phenotypic variation

Answer 6

• Diet in animals
• Growing conditions in plants (plants grown in the dark, or plants that do not have access to enough Mg, turn yellow (chlorosis). Plants may develop long stems with small, curled leaves if grown in the dark, called etiolation)