in pea plants, the peas can be either rough or smooth, and either soft or hard.
ID: 61571 • Letter: I
Question
in pea plants, the peas can be either rough or smooth, and either soft or hard. You do some crosses and obtain the following results. Cross 1: purebred rough, soft pea * purebred smooth, hard pea gives F1: all rough, hard. Cross 2: rough, hard F1 * smooth, soft (note: test cross not self cross) gives F2: 115 rough soft, 110 smooth hard, 8 rough hard and 12 smooth soft. a) using letter of your own choosing, state the genotype of the parents, the F1, and each phenotypic class in the F2. B) which F2 progeny inherited parental type gamete from the F1 parent, and which inherited nonparental type? C)Are the genes for roughness and softeness linked? if so, wht is the recombinant frequency between the genes? in pea plants, the peas can be either rough or smooth, and either soft or hard. You do some crosses and obtain the following results. Cross 1: purebred rough, soft pea * purebred smooth, hard pea gives F1: all rough, hard. Cross 2: rough, hard F1 * smooth, soft (note: test cross not self cross) gives F2: 115 rough soft, 110 smooth hard, 8 rough hard and 12 smooth soft. a) using letter of your own choosing, state the genotype of the parents, the F1, and each phenotypic class in the F2. B) which F2 progeny inherited parental type gamete from the F1 parent, and which inherited nonparental type? C)Are the genes for roughness and softeness linked? if so, wht is the recombinant frequency between the genes? in pea plants, the peas can be either rough or smooth, and either soft or hard. You do some crosses and obtain the following results. Cross 1: purebred rough, soft pea * purebred smooth, hard pea gives F1: all rough, hard. Cross 2: rough, hard F1 * smooth, soft (note: test cross not self cross) gives F2: 115 rough soft, 110 smooth hard, 8 rough hard and 12 smooth soft. a) using letter of your own choosing, state the genotype of the parents, the F1, and each phenotypic class in the F2. B) which F2 progeny inherited parental type gamete from the F1 parent, and which inherited nonparental type? C)Are the genes for roughness and softeness linked? if so, wht is the recombinant frequency between the genes?Explanation / Answer
Since the entire F1 generation is rough hard, means rough and hard genes are dominant.
Let symbol for Rough be R, smooth be r; Let symbol for hard be H and soft be h.
Genotype of parents are RRHH and rrhh respectively.
Result of Cross 1 is F1:- will be RrHh.
Cross 2 is rough hard (RrHh) crossed with smooth soft (rrhh)
Ratio should have been 1:1:1:1 but it has changed. 8 rough hard and 12 smooth soft F2 progeny has inherited the parental type.
115 rough soft and 110 smooth hard F2 progeny has inherited non-parental type.
c) no, these genes are not linked. Because the ratio of recombinants is greater than the ratio of parental types.
percent recombination = 110+115/110+115+8+12
= 225/ 245*100 = 91.8% recombination.
The two genes are ~92 map units apart. If two genes are greater than 50 map units apart , they are unlinked.
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