(a) Explain briefly the following terms:
(i) phenotype
(ii) hybrid
(iii) dominant character.
(b) Two varieties of maize, one with yellow (Y) grains and the other with purple (y) grains were crossed and all their offspring had yellow grains. When the offspring were crossed with the parent variety with purple grains, half of the resulting offspring had yellow grains, while the other half had purple grains. Using labelled diagrams only;
(i) deduce the genotype of the grains of the first filial generation,
(ii) show the results of the cross between the first filial generation and the parent purple variety.
(c) Mention two ways in which the application of genetics is beneficial to agriculture.
Explanation
(a)(i) Phenotype is the external appearance of an organism resulting from the interaction between the genotype and the environment
(ii) A hybrid is the offspring/progeny from a cross between two organisms/parents, which are genotypically different/having unlike traits/character
(iii) Dominant character is the feature/trait expressed by the hybrid/offspring/progeny, in the presence of its alternative form.
(c) Benefits of genetics in agriculture.
(i) It promotes cross breeding to produce offsprings of superior characters/hybrid vigour
(ii) It enhances animal/crop selection to obtain varieties of animals/crops with qualities such as early maturity higher yield, resistance to diseases
(iii) It leads to the development of genetic engineering which introduce genes of desired trait/character into an organism
(iv) In-breeding of desirable strains to obtain pure breed.