In tomatoes, the allele T for tall plant height is dominant to dwarf allele t, the P allele for smooth is dominant to the p allele for peach fuzz skin, and the allele R for round fruit dominant to the recessive r allele for oblong fruit. The genes controlling these traits are linked on chromosome 1 in the tomato genome, and the genes are arranged in the order and with the recombination frequencies shown:
Gene T P R
Recombination _____.02____.02__
Question1: A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?
A. The tall, peach fuzz, round plant will produce Tpr gametes. The pure-breeding dwarf, smooth, oblong plant will produce tPR gametes.
B.The tall, peach fuzz, round plant will produce TpR gametes. The pure-breeding dwarf, smooth, oblong plant will produce tPr gametes.
C.The tall, peach fuzz, round plant will produce tpR gametes. The pure-breeding dwarf, smooth, oblong plant will produce TPr gametes.
D.The tall, peach fuzz, round plant will produce TPR gametes. The pure-breeding dwarf, smooth, oblong plant will produce tpr gametes
Question2: A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?
A. The F1 are tall, peach fuzz, round and have the genotype TpR/tpr.
B.The F1 are dwarf, smooth, round and have the genotype tpR/tPr.
C.The F1 are tall, smooth, round and have the genotype TpR/tPr.
D. The F1 are tall, smooth, oblong and have the genotype TpR/tPr.
E.None of the above.
Question3: A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is a dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?
A. 39.2%tpR, 39.2%TPr, 0.8%tPr, 0.8%TpR, 9.8%Tpr, 9.8%tPR, 0.2%TPR, and 0.2%tpr.
B. 39.2%TpR, 39.2%tPr, 0.8%Tpr, 0.8%tPR, 9.8%TPr, 9.8%tpR, 0.2%TPR, and 0.2%tpr.
C. 39.2%TPR, 39.2%tpr, 0.8%tPr, 0.8%TpR, 9.8%Tpr, 9.8%tPR, 0.2%tpR, and 0.2%TPr.
D. 39.2%TpR, 39.2%tPr, 0.8%TPr, 0.8%tpR, 9.8%Tpr, 9.8%tPR, 0.2%TPR, and 0.2%tpr.
E. None of the above.
Question1: A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?
D. The tall, peach fuzz, round plant will produce TPR gametes. The pure-breeding dwarf, smooth, oblong plant will produce tpr gametes.
Question2: A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?
C.The F1 are tall, smooth, round and have the genotype TpR/tPr.
Question3: A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is a dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?
B. 39.2%TpR, 39.2%tPr, 0.8%Tpr, 0.8%tPR, 9.8%TPr, 9.8%tpR, 0.2%TPR, and 0.2%tpr.
Question 1: The correct answer is D. The tall, peach fuzz, round plant will produce TPR gametes. The pure-breeding dwarf, smooth, oblong plant will produce tpr gametes.
To answer these questions, we need to understand the concepts of dominance and recombination.
Dominance: In genetics, dominance refers to the relationship between alleles of a gene. If one allele is dominant over another, it means that its trait will be expressed in the individual, even if the other allele is present.
Recombination: Recombination is the process by which genetic material is exchanged between chromosomes during meiosis (the process of forming gametes). It can result in the shuffling of alleles and the creation of new combinations of traits.
Now let's go through each question:
Question 1: A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?
To determine the gamete genotypes, we need to consider the alleles for each trait and their dominance relationships. In this case, the tall allele (T) is dominant to the dwarf allele (t), the smooth allele (P) is dominant to the peach fuzz allele (p), and the round allele (R) is dominant to the oblong allele (r).
The pure-breeding tall, peach fuzz, round plant will be homozygous dominant for all three traits (TTPPRR). So, its gametes would carry one allele for each trait: T, P, and R. Therefore, the correct answer is A: The tall, peach fuzz, round plant will produce Tpr gametes.
The pure-breeding dwarf, smooth, oblong plant will be homozygous recessive for all three traits (ttpprr). So, its gametes would carry the recessive alleles: t, p, and r. Therefore, the correct answer is A: The pure-breeding dwarf, smooth, oblong plant will produce tPR gametes.
Question 2: A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?
When a pure-breeding tall, peach fuzz, round plant (gametes: Tpr) is crossed with a pure-breeding dwarf, smooth, oblong plant (gametes: tPR), we need to consider the recombination frequencies provided.
Since there is a recombination frequency of 0.02 between the T and P genes, and the P gene is in the middle between the T and R genes, it means that 0.02 of the offspring's gametes will have a recombination event between T and P. This will result in the gamete genotype tpR.
Therefore, the correct answer is B: The F1 are dwarf, smooth, round and have the genotype tpR/tPr.
Question 3: A pure-breeding tall, peach fuzz, round plant is crossed to a pure-breeding plant that is a dwarf, smooth, oblong. What are the gamete genotypes produced by each of these plants?
The recombination frequencies provided between the genes T and P (0.02) and P and R (0.02) indicate the likelihood of recombination during gamete formation.
To calculate the gamete genotypes produced, we multiply the recombination frequencies by 100 to get percentages.
For the tall, peach fuzz, round plant, the genotypes would be Tpr (39.2%), TPr (0.8%), tPr (9.8%), and tpR (0.2%).
For the dwarf, smooth, oblong plant, the genotypes would be tPR (9.8%), tPr (39.2%), Tpr (0.8%), and tpR (0.2%).
Therefore, the correct answer is D: 39.2% TpR, 39.2% tPr, 0.8% TPr, 0.8% tpR, 9.8% Tpr, 9.8% tPR, 0.2% TPR, and 0.2% tpr.
I hope this explanation helps clarify the process of determining gamete genotypes and understanding the concepts of dominance and recombination in genetics.