A tall pea plant results from a dominant tall allele. A short phenotype requires that an individual has two recessive alleles. A short pea plant (pp) is crossed with a tall pea plant (Pp).

Question

What is the frequency of short offspring (pp) from this crossing?
(1 point)
• 0.75
• 0.5
• 1.0
• 0.25

Answer 1

To determine the frequency of short offspring (pp) from the cross between a short pea plant (pp) and a tall pea plant (Pp), we can use a Punnett square.

1. The genotypes of the parent plants are:

   • Short plant: pp
   • Tall plant: Pp

2. The possible gametes from each parent are:

   • The short plant can only produce gametes with the recessive allele: p
   • The tall plant can produce two types of gametes: P (dominant) and p (recessive)

3. The Punnett square for this cross would look like this:

   | | P | p | |---|---|---| | p | Pp | pp | | p | Pp | pp |

4. From the Punnett square, the possible genotypes of the offspring are:

   • Pp (tall)
   • pp (short)

5. The genotypic ratio can be calculated:

   • 2 Pp (tall) : 2 pp (short) or simplified to 1 Pp : 1 pp

6. The frequency of short offspring (pp) is therefore 2 out of 4 total offspring, which simplifies to 0.5.

Thus, the frequency of short offspring (pp) from this cross is 0.5.