1. A pea plant with yellow seeds is crossed with a pea plant with green seeds. All of the offspring have yellow seeds. the allele for yellow seeds is...
A. Dominant because all the offspring have yellow seeds
B. recessive because all the offspring have yellow seeds.
C. dominant because all of the offspring inherited two alleles for yellow seeds.
D. recessive because all of the offspring inherited two alleles for yellow seeds ****
2. Two tall pea plants with yellow seeds and smooth pods are crossed. All of the offspring are crossed. All of the offspring are tall. Three offspring have smooth pods and one has wrinkled pods. allele for wrinkled pods
A, must be dominated because the traits does not appear in the parent plants.
B, must be recessive because the trait does not appear in the parent plants.****
C, must be dominant because the trait appears in the parent plants.
D, must be recessive because the trait appears in the parent plants.
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To determine the answers to these questions, we need to understand the concept of dominant and recessive alleles in genetics.
1. In question 1, a pea plant with yellow seeds is crossed with a pea plant with green seeds, and all of the offspring have yellow seeds. This tells us that the yellow seed trait is expressed in all the offspring. In genetics, a dominant allele is one that is always expressed when present, while a recessive allele is only expressed when there are no dominant alleles present. Since all the offspring have yellow seeds, which means the trait is expressed, we can conclude that the allele for yellow seeds is dominant. Therefore, option C. dominant because all of the offspring inherited two alleles for yellow seeds is the correct answer.
2. In question 2, two tall pea plants with yellow seeds and smooth pods are crossed, and all of the offspring are tall. However, only one of the offspring has wrinkled pods, while the others have smooth pods. This tells us that the wrinkled pod trait is not expressed in the parent plants, but it appears in one of the offspring. In genetics, if a trait does not appear in the parent plants but appears in the offspring, then it is likely a recessive trait. Recessive traits can be masked by dominant traits when present, but expressed when there are no dominant alleles present. Therefore, option B. must be recessive because the trait does not appear in the parent plants is the correct answer.
Remember, dominant and recessive alleles depend on their expression in offspring, and understanding the phenotypic traits observed can help determine the dominance or recessiveness of a specific allele.