In pea plants, round is dominant over wrinkled. A homozygous round seed−producing plant is crossed with a homozygous wrinkled seed−producing plant.
What percent of the offspring would be expected to have round seeds?
Answer options with 5 options
A.
none
B.
25%
C.
50%
D.
75%
E.
100%
The cross between a homozygous round seed-producing plant and a homozygous wrinkled seed-producing plant is a cross between RR and rr. According to the given information, round (R) is dominant over wrinkled (r).
When two parents with different genotypes are crossed, the Punnett square can be used to determine the possible genotypes and phenotypes of the offspring.
The Punnett square for this cross would look like:
R R
---------------
r | Rr | Rr |
---------------
r | Rr | Rr |
---------------
From the Punnett square, we can see that all of the offspring will have the genotype Rr, which corresponds to round seeds. Therefore, the percent of the offspring expected to have round seeds is 100%.
Answer: E. 100%
To determine the percent of offspring expected to have round seeds, we need to consider the genotype of the parent plants and the nature of the genetic trait.
In this case, round is dominant over wrinkled. The homozygous round seed-producing plant would have the genotype RR, while the homozygous wrinkled seed-producing plant would have the genotype rr.
When these two plants are crossed, all of the offspring will receive one allele from each parent. Therefore, the possible genotypes of the offspring would be Rr (round) or rr (wrinkled).
Since round is dominant, any offspring with the genotype Rr will exhibit the round seed trait. So, to find the percent of offspring that are expected to have round seeds, we need to determine the percentage of offspring with the Rr genotype.
When two homozygous parents are crossed, all of the offspring will have the genotype Rr. Therefore, the answer is:
D. 75%
To determine the percent of the offspring that would be expected to have round seeds, we need to consider the principles of Mendelian genetics.
In this case, we are crossing a homozygous round-seed producing plant (RR) with a homozygous wrinkled-seed producing plant (rr). Since round is dominant over wrinkled, the genotype of the round-seed producing plant is RR, and the genotype of the wrinkled-seed producing plant is rr.
When we cross these two plants, we can create four possible combinations of alleles in the offspring: Rr, Rr, rr, and rr.
In this case, all the offspring will inherit an allele for round seeds from the homozygous round-seed parent (RR). Therefore, 100% of the offspring will have at least one allele for round seeds, meaning the answer is (E) 100%.
This is because the allele for round seeds is dominant, so even if the offspring inherits one allele for round seeds and one allele for wrinkled seeds (Rr), the round phenotype will be expressed.
Please note that this explanation assumes that there are no complications such as genetic modifiers or the possibility of mutations.