B17 variation and selection

Question 1

describe what is meant by variation

Answer 1

• differences between individuals
• of the same species

Question 2

what does continuous variation result in

Answer 2

• range of phenotypes between 2 extremes
• eg body length

Question 3

what does discontinuous variation result in

Answer 3

• limited number of phenotypes with no intermediates
• eg ABO blood groups

Question 4

describe what is meant by mutation

Answer 4

• a genetic change
• the way in which new alleles are formed

Question 5

describe natural selection

Answer 5

• genetic variation within populations
• production of many offspring
• struggle for survival, including competition for resources
• individuals better adapted to environment more likely to reproduce
• pass alleles to next generation

Question 6

describe selective breeding

Answer 6

• selection by humans of individuals with desirable features
• cross them to produce next generation
• selection of offspring showing desirable features

Question 7

what is the development of strains of antibiotic-resistant bacteria an example of

Answer 7

natural selection

Question 8

how does selective breeding by artificial selection benefit us

Answer 8

• improve crop plants
• improve domesticated animals