Question

In cucumber orange fruit colour R is dominant over cream fruit colour R. A cucumber plant homozygous for orange fruits is crossed with plant homozygous for cream fruits. The F1 are intercrossed to produce the F2. (May 2013, 7 marks) i. Give the genotypes and phenotypes of the parents, the F1 and the F2. ii. Give the genotypes and phenotypic ratio of the offsprings of a back cross between the F1 and the orange parent. iii. Give the genotype and phenotype of a back cross between the F1 and the cream parent.

Answer 1

Answer:

(i) Genotypes of F1 parents: Dominant

Genotypes of F2 parents: Recessive

Phenotypes of F1 parents: All orange

Phenotypes of F2 parents: Some are cream and may are orange

(ii) 3:1

(iii) The backcross results in genotypes Rr and rr in 1:1 ratio and phenotypes are orange and cream respectively.

Explanation:

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