B17 - Variation And Selection

Question 1

Describe variation

Answer 1

Differences between individuals of the same species

Question 2

Continuous variation

Answer 2

A range of phenotypes between two extremes

Question 3

Discontinuous variation

Answer 3

A limited number of phenotypes with no intermediates

Question 4

Mutation

Answer 4

Genetic change. Mutation is the way new alleles are formed

Question 5

What causes variation

Answer 5

Environment and genes

Question 6

Phenotype

Answer 6

The observable characteristics of an organism

Question 7

Artificial selection

Answer 7

Humans choosing particular organisms with desireable characteristics to breed together and continuing this over many generations

Question 8

Genotype

Answer 8

The full set of genes it possesses in letter/symbol form , eg Bb

Question 9

Four steps of artificial selection

Answer 9

1. Choose individuals with desirable characteristics
2. Breed together
3. Select offspring with desirable characteristics
   Repeat step 1-3 over many generations

Question 10

Natural selection

Answer 10

A process in which individuals with advantageous features are more likely to survive, reproduce and pass on their alleles to the next generation

Question 11

Five steps of natural selection (VOSSA)

Answer 11

1. Genetic variation
2. Over production (too many offspring for environment to handle)
3. Struggle for existence (compete for resources)
4. Survival of the Fittest (best adapted survive & reproduce)
5. Advantages alleles are passed on (more favourable alleles in the environment)

Question 12

How does the population of antibiotic resistant bacteria increase

Answer 12

1. A mutation occurs in a bacterium that makes it resistant to antibiotics
2. Antibiotic are taken and all the other bacteria are killed by antibiotics
3. The resistant bacteria survives & reproduces
4. The advantageous allele is passed on to the offspring