Question

the f, cross when mendel examined the f, plants, he found that traits produced by the recessive alleles reappeared in this generation. about one fourth of the f, plants showed the trait controlled by the recessive allele. why did these traits appear to disappear in the f, generation and then reappear in the f, generation? explaining the f, cross mendel assumed that a dominant allele had masked the corresponding recessive allele in the f, generation. however, the recessive trait did appear in the f, generation. this indicates that at some point the allele for yellow pods had separated, or segregated, from the allele for green pods. mendel suggested that the segregation of the alleles for yellow and green pods occurred during the formation of the reproductive cells, or gametes (gam eetz). the formation of gametes all of the f, plants inherited an allele (g) for green pods from the green parent and an allele (g) for yellow pods from the yellow parent. (for each trait, we use a capital letter to represent the dominant allele, and the same letter in lowercase to represent the recessive allele). because the allele for green pods is dominant, all of the f, plants (gg) have green pods. during gamete formation, the alleles for each gene segregate from each other, so that each gamete carries only one allele for each gene. each f, plant produces two kinds of gametes, those with the green pod allele (g) and those with the yellow pod allele (g). when a gamete with the allele for yellow pods pairs with another gamete with the allele for yellow pods, the resulting f, plant (gg) has yellow pods. if one or both gametes that pair have the allele for green pods (gg or gg), an f, plant with green pods is produced. visual reading tool: segregation a cross between yellow-pod and green-pod pea plants results in only green-pod plants in the f, offspring. when the f, offspring are crossed with themselves, the yellow pods reappear in the f, generation. use the figure to answer the questions. 1. in the figure, label each individual in the f, generation with the alleles it inherited from the f, generation. 2. what color is a pod with the gg alleles? 3. what color is a pod with the gg or gg alleles? 4. describe in your own words how a plant with a yellow pod can have two green-pod parents.

Explanation:

1. The \(F_2\) generation is formed by the combination of gametes from \(F_1\) generation (\(Gg\times Gg\)). The possible combinations are \(GG\), \(Gg\), \(Gg\), \(gg\).
2. As per the text, the allele \(g\) is recessive for yellow pods. When an individual has \(gg\) alleles (homozygous recessive), the recessive trait (yellow color) is expressed.
3. The allele \(G\) is dominant for green pods. For \(GG\) (homozygous dominant) and \(Gg\) (heterozygous), the dominant allele \(G\) masks the recessive allele \(g\), so the pods are green.
4. Each parent (\(Gg\)) can produce two types of gametes (\(G\) and \(g\)). When two gametes with \(g\) allele (one from each parent) combine during fertilization, the resulting \(F_2\) plant has \(gg\) alleles, expressing the recessive yellow - pod trait.

Answer:

1. From left - to - right in the \(F_2\) generation: \(GG\), \(Gg\), \(Gg\), \(gg\).
2. Yellow.
3. Green.
4. Each green - pod parent (\(Gg\)) has one dominant (\(G\)) and one recessive (\(g\)) allele. During gamete formation, alleles segregate. If a gamete with \(g\) allele from one parent combines with a gamete with \(g\) allele from the other parent, the offspring has \(gg\) alleles, resulting in a yellow - pod plant.