Question

Imagine that you are performing a cross involving seed texture in garden pea plants. You cross true-bleeding round and wrinkled parents to obtain F1 offspring. Which of the following experimental results in terms of numbers of plants are closest to what you expect in the F2 progeny?6:10:190 round seeds:wrinkled seeds 810 round seeds:wrinkled seeds 810 wrinkled seeds 405.335 round seeds:wrinkled seeds

Answer 1

Answer:

610:190 round seeds: wrinkled seeds

Explanation:

A cross between two true breeds, involves crossing two parents that are each homozygous for the traits they carry.

A cross between a true breeding round parent (RR) and a true breeding wrinkled plant (rr), will produce all heterozygous offspring:

Rr : 100% in the F1 generation.

When these heterozygous offspring are crossed, Rr x Rr, the proportion obtained genotypically in the second filial generation is:

• 25% homozygous round (RR)

• 50% heterozygous (Rr)

• 25% homozygous wrinkled (rr)

Considering the importance of dominance in phenotypic expression, round seeds being dominant over wrinkled seeds, indicates that about 75% of the offspring are expected to appear round and 25% expected to appear wrinkled. Putting this phenotypic proportion into perspective,

610:190 round seeds:wrinkled seeds, is the ratio in line with the proportion expected to see in the F2 generation.