3.4.4 Genetic Diversity and Adaptation

Question 1

Define genetic diversity

Answer 1

the number of different alleles of genes in a population.

Question 2

Describe how a student made a 1 in 10 dilution
and then used this to make a 1 in 1000 dilution of
the original liquid culture of bacteria

Answer 2

1. 1 part bacterial culture to 9 parts water
2. Mix
3. Repeat using 9 parts fresh (sterile) liquid and 1 part of 10–1 and 10–2 dilutions to make 10–3 dilution

Question 3

Why would a 1 in 10 dilution not be appropriate
to use to determine cell numbers?

Answer 3

1. Count unlikely to be accurate / repeatable / reproducible / reliable
2. Because too many cells; Or cells will be overlapping

Question 4

Explain how the use of antibiotics has led to
antibiotic-resistant strains of bacteria.

Answer 4

1. Some bacteria have alleles for resistance
2. Exposure to antibiotics creates a selection pressure
3. Antibiotics kill bacteria that are not resistant
4. Resistance strains survive and reproduce

Question 5

Describe the aseptic techniques used to transfer
bacterial culture onto an agar plate.

Answer 5

1. Use sterile pipette/syringe
2. Flame top of the bottle
3. Lift lid of agar plate at an angle
4. Use sterile spreader
5. Place pipette/spreader onto disinfectant

Question 6

Describe the principles of natural selection in the
evolution of a population.

Answer 6

Random mutation can result in new alleles of a genes.
Many mutations are harmful but, in certain environments, the new allele of a gene might benefit its possessor,
leading to increased reproductive success.
The advantageous allele is inherited by members of the next generation.
over many generations, the new allele increases in frequency in the population.