(a)(i) State Mendel’s laws of inheritance. (ii) State five applications of genetics in medicine. (iii) State three disadvantages of inbreeding. (b)(i) What ...

(a)(i) Mendel's laws of inheritance

• Law of Segregation (First Law): the two alleles (factors) controlling a character separate during the formation of gametes, so that each gamete carries only one allele of the pair.
• Law of Independent Assortment (Second Law): the alleles of different genes (characters) are distributed to the gametes independently of one another during gamete formation.

(a)(ii) Five applications of genetics in medicine

1. Genetic counselling of couples to predict the risk of hereditary diseases in their children.
2. Diagnosis of inherited disorders such as sickle-cell anaemia and haemophilia.
3. Blood group determination for safe blood transfusion.
4. Production of medicines such as insulin and vaccines by genetic engineering.
5. Determination of paternity and identification through DNA (fingerprinting).

(a)(iii) Three disadvantages of inbreeding

1. It brings together harmful recessive genes, so hereditary defects appear more often.
2. It reduces genetic variation (leads to loss of hybrid vigour).
3. It can reduce fertility, vigour and resistance to disease in the offspring.

(b)(i) What is evolution?

Evolution is the gradual change in the characteristics of living organisms over a long period of time, so that new species arise from pre-existing ancestral forms.

(b)(ii) Convergent versus divergent evolution