(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 ...
Question 1 Report
(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.
Answer Details
(a)
(i) Phenotype: the observable external appearance or characteristics of an organism, resulting from the interaction of its genotype and the environment.
(ii) Hybrid: an offspring produced by crossing two genetically different parents.
(iii) Dominant character: a trait that is expressed in an organism even when its contrasting allele is present.
(b) Key: Y = allele for yellow grains (dominant); y = allele for purple grains (recessive).
(c) Benefits of genetics in agriculture:
- It enables the selection and breeding of crop varieties and livestock with desirable qualities such as high yield, early maturity and resistance to diseases.
- It permits the production of hybrids with hybrid vigour, improved quality, drought tolerance or pest resistance.
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