Question

Among pea plants, we see more peas with smooth pods than with constricted pods. if a plant with constricted pods is mated with a plant with smooth pods, the offspring have smooth pods. when the offspring mature, and two of them are mated, they have a 25 percent chance of producing offspring with constricted pods. identify the offspring with homozygous alleles for the smooth pod trait.

Answer 1

OK if we said the the allel for smooth is (S ) and it is dominant and the allel for constricted is (s) and it is recessive , so we started by mating two pure pea plant one smooth and one constricted the offspring would have a genotype of (Ss) and it'S phenotype is smooth, and if that offspring did self pollination it will produce 4 offsprings with genotype as follow: 1 (SS) : 2 (Ss ) : 1 (ss) so there would be 3 smooth and one constricted which will be the last one (ss )

Answer 2

There is only one offspring with homozygous alleles (SS) for the smooth pod trait out of the total four offspring. The frequency of this offspring with homozygous alleles (SS) for the smooth pod trait is

`(1)/(4) * 100\\25`%

Step-by-step explanation:

First Cross -

Let us assume that the genotype of parents in the first cross is

Smooth pod parent - SS

Constricted pod Parent - ss

Offspring produced after first cross are as shown in the punnet square below -

S S

s Ss Ss

s Ss Ss

All the offsprings are heterozygous (Ss) smooth

Second Cross -

The second cross is being carried between the two offsprings (Ss)

Offspring produced after second cross are as shown in the punnet square below -

S s

S SS Ss

s Ss ss

SS - homozygous smooth pod offsprings

Ss - heterozygous smooth pod offsprings

ss - homozygous constricted pod offsprings

There is only one offspring with homozygous alleles (SS) for the smooth pod trait out of the total four offspring. The frequency of this offspring with homozygous alleles (SS) for the smooth pod trait is

`(1)/(4) * 100\\25`%