Question

when two true breeding pea plants that show contrasting traits are crossed 1) mention the pod shape in F1 generation 2)work out the cross upto F2 generation 3) compute the relative fraction of various genotypes in the F2 generation

Answer 1

1.) Inflated pod shapes (Cc) in the F1 generation

2) See attached image for the work out of the cross from P generation to F2 generation.

3). CC- 1/4, Cc- 1/2, cc- 1/4

Step-by-step explanation:

This question is related to the pod shape trait encoded by a single gene in pea plants. The alleles for inflated pod shape (C) is dominant over the allele for constricted pod shape (c). This means that allele "C" will be expressed over allele "c" in a heterozygous state.

The two truebreeding parent plants will have genotypes: CC (inflated pod shape) and cc (constricted pod shape). When these two plants are crossed, an all heterozygous plant with genotype: Cc will be formed in the F1 generation. Since, C is dominant over c, the F1 Cc plants will have an inflated pod shape phenotype.

The F1 Cc plants are self-crossed to produce the F2 generation offsprings i.e. Cc × Cc. The gametes C and c will be produced by each F1 parent, which will be used to draw a punnet square (see attached image). From the cross, offsprings with genotypes: CC, Cc and cc are produced in the F2 generation.

CC (phenotypically inflated pod shape)- 1/4

Cc (phenotypically inflated pod shape)- 1/2 or 2/4

cc (phenotypically constricted pod shape)- 1/4