A summer squash plant that produces disc‑shaped fruit is crossed with a summer squash plant that produces long fruit. All of the F1 have disc‑shaped fruit. When the F1 are intercrossed, F2 progeny are produced in the ratio 9/16 disc‑shaped fruit, 6/16 spherical fruit, 1/16 long fruit. Give the genotypes of the F2 progeny.

Explanation:

In the given question,

suppose allele A and a determines the color of the fruit whereas allele B and b determines the shape of the fruit.

The genotype for white, disc shape fruits is- AABB

the genotype for yellow, long fruits is- aabb

F1 progeny will be- AABB x aabb

                                 AaBb

F2 cross-    AaBb    x    AaBb

                      AB          Ab          aB           ab

      AB        AABB       AABb    AaBB       AaBb

      Ab       AABb       AAbb     AaBb       Aabb

      aB        AaBB      AaBb      aaBB       aaBb

      ab        AaBb       Aabb      aaBb      aabb

          The genotype of F2 cross are-

1.  9/16 A- B- disc-shaped (like F1)

2. 3/16 A- bb spherical

3. 3/16 aa B- spherical

4. 1/16 aa bb long.

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