In pea plants, wrinkled seeds (W) is the dominant trait, while smooth seeds (w) is the recessive trait. Consider the cross Ww X WW.

Question

What will be the ratio of wrinkled to smooth seeds?
Responses
A 0:4 wrinkled:smooth0:4 wrinkled:smooth
B 2:2 wrinkled:smooth2:2 wrinkled:smooth
C 3:1 wrinkled:smooth3:1 wrinkled:smooth
D 4:0 wrinkled:smooth

Answer 1

To determine the ratio of wrinkled to smooth seeds in the cross Ww (heterozygous) and WW (homozygous dominant), we can set up a Punnett square.

Let's denote:

• W = wrinkled seeds (dominant)
• w = smooth seeds (recessive)

The parent genotypes:

• One parent (Ww) can contribute either W or w.
• The other parent (WW) can only contribute W.

The possible combinations from this cross would be:

• From Ww and WW, the offspring can be:
  • WW (from W and W)
  • WW (from W and W)
  • Ww (from W and w)
  • Ww (from W and w)

So the possible genotypes of the offspring are:

• 2 WW (wrinkled)
• 2 Ww (wrinkled)

Since both WW and Ww contribute to the dominant (wrinkled) phenotype, there are no smooth seeds (ww).

Thus, the ratio of wrinkled to smooth seeds is:

• 4 wrinkled : 0 smooth, which corresponds to option D.

The answer is D: 4:0 wrinkled:smooth.