Variation

Question 1

What is genetic variation?

Answer 1

• the variation in genotypes (i.e. the genes) between species or within a species

Question 2

What is phenotypic variation?

Answer 2

• Phenotypic variation - the variation in phenotypes between species or within a species e.g. variation in height, mass, shape, colour, blood type

Question 3

What is Interspecific variation?

Answer 3

• Interspecific variation is the variation between species

Question 4

What is Intraspecific variation?

Answer 4

• Intraspecific variation is the variation within species

Question 5

What is Continous Variation?

Answer 5

• No distinct groups, quantitative difference in phenotype e.g. mass, height

Question 6

What is discontinous Variation?

Answer 6

• distinct groups, qualitative differences in phenotypes e.g. blood, eye colour

Question 7

How does Environment cause variation?

Answer 7

• Length of sunlight hours (which may be seasonal)
• Supply of nutrients (food)
• Availability of water
• Temperature range
• Oxygen levels
• Changes in the factors above can affect how organisms grow and develop
• Variation in phenotype caused solely by environmental pressures or factors cannot be inherited by an organism’s offspring: Only alterations to the genetic component of gametes will ever be inherited

Question 8

How does genetics cause variation?

Answer 8

• Mutations: a random spotaneous change in the base sequence of DNA
• Meiosis:
• Independent assortment of homologous chromsomes
• crossing over that happens between the non-sister chromatids of homologous chromsomes
• random fertilsation of gametes - sperm and egg meet by chnace, contributing to novel combinations of alleles.

Question 9

What are the causes of discontinous variation?

Answer 9

• This type of variation occurs solely due to genetic factors
• The environment has no direct effect
• Phenotype = genotype

Question 10

What are the causes of continous variation?

Answer 10

• Continuous variation occurs when there are quantitative differences in the phenotypes of individuals within a population for particular characteristics
• Quantitative differences do not fall into discrete categories like in discontinuous variation
• Instead for these features, a range of values exist between two extremes within which the phenotype will fall