Topic 7A: Inheritance

Question 1

Describe and explain three ways in which a scientist would ensure he used aseptic techniques to move agar cubes onto a new agar plate. [3]

Answer 1

1. Wash hands to kill microbes;
2. Burning Bunsen close by to create upwards current of air;
3. Disinfect bench to kill microbes;
4. Flame equipment to kill microbes;
5. Lift lid slightly to prevent entry of microbes

Question 2

Give two differences between mitosis and meiosis. [2]

Answer 2

Mitosis given first:

1. One division, two divisions in meiosis;
2. (Daughter) cells genetically identical, daughter cells genetically different in meiosis;
3. Two cells produced, four cells produced in meiosis;
4. Diploid to diploid, diploid to haploid in meiosis;
5. Separation of homologous chromosomes only in meiosis;
6. Crossing over only in meiosis;
7. Independent segregation only in meiosis

Question 3

What might cause deviations between observed and expected values in genetics? [3]

Answer 3

1. Small sample size;
2. Random fertilisation of gametes;
3. (Unexpected) linked genes;
4. (Unexpected) epistasis;
5. (Unexpected) lethal genotypes