GENETICS QUESTION!!!! 1. One form of male sterility ( Ms ) in corn is maternally
ID: 221550 • Letter: G
Question
GENETICS QUESTION!!!!
1. One form of male sterility (Ms) in corn is maternally transmitted. Plants of a male sterile line crossed with normal pollen give male-sterile plants. In addition, some lines of corn are known to carry a dominant nuclear restorer allele (Rf-1) that restores pollen fertility in male sterile lines. Another dominant restorer (Rf-2) has been found on a different chromosome. Either or both of the restorer alleles will restore pollen fertility in male sterile lines.
If a male-sterile plant is crossed with pollen from a plant homozygous for Rf-1, what is the phenotype of the F1?
fertile females; sterile males
sterile females; fertile males
1/2 fertile females; 1/2 sterile females; 1/2 sterile males; 1/2 fertile males
fertile females; fertile males
sterile females; sterile males
2. One form of male sterility (Ms) in corn is maternally transmitted. Plants of a male sterile line crossed with normal pollen give male-sterile plants. In addition, some lines of corn are known to carry a dominant nuclear restorer allele (Rf-1) that restores pollen fertility in male sterile lines. Another dominant restorer (Rf-2) has been found on a different chromosome. Either or both of the restorer alleles will restore pollen fertility in male sterile lines.
A male-sterile plant is crossed with pollen from a plant homozygous for Rf-1. An F1 plant from this cross is used as the ovule donor, and crossed with pollen from a normal plant (rf-1/ rf-1). What phenotypes are produced by this cross?
fertile females; sterile males
sterile females; fertile males
fertile females; 1/2 fertile males; 1/2 sterile males
1/2 fertile females; 1/2 sterile females; 1/2 fertile males; 1/2 sterile males
fertile females; fertile males
A.fertile females; sterile males
B.sterile females; fertile males
C.1/2 fertile females; 1/2 sterile females; 1/2 sterile males; 1/2 fertile males
D.fertile females; fertile males
E.sterile females; sterile males
Explanation / Answer
1. MSt females x Rf/Rf males would generate all fertile Rf/+. Option d is the correct answer.
2. MSt females x +/+ males would generate 1/2 male sterile +/+ and 1/2 male fertile Rf/+. So the correct answer is option c.
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