A variety of squash may be long, round, or oval in shape. The color may be yellow, green, or white. A long, white variety crossed with a round, green one (both true-breeding) produces only oval, yellow F1’s.

The F2 progeny segregated into nine phenotypic classes in the following numbers:

long, green 9 long, white 7
long, yellow 15 round, yellow 16
oval, green 16 round, white 7
oval, yellow 32 oval, white 16
round, green 9

Question A. How many allele pairs are involved?
Question B. Construct an appropriate genetic map.
Question C. How many true-breeding varieties of squash could be established?