GENETICS QUESTION!! 1. One form of male sterility ( Ms ) in corn is maternally t
ID: 221551 • 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 heterozygous for Rf-1 and also for Rf-2, what is the phenotype of the F1?
fertile females; sterile males
fertile females; 3/4 fertile males; 1/4 sterile males
fertile females; 1/4 fertile males; 3/4 sterile males
fertile females; 1/2 fertile males; 1/2 sterile males
fertile females; fertile males
2. Which of the following scenarios is most likely to result in a hypomorphic mutation?
A. An alu element inserts into the exon of a ribosomal RNA gene
B. An Ac element that was inserted into the exon of a gene, tranposes via the cut and paste mechanism of transposition
C. A LINE element inserts into another LINE element in the human genome
D. An Ac element inserts into an intron
E. A transposable element contains a binding site for a transcriptional repressor and inserts adjacent to to a promotor
A.fertile females; sterile males
B.fertile females; 3/4 fertile males; 1/4 sterile males
C.fertile females; 1/4 fertile males; 3/4 sterile males
D.fertile females; 1/2 fertile males; 1/2 sterile males
E.fertile females; fertile males
Explanation / Answer
1. Fertile female and fertile male
The male sterile plant will donate 2 recessive allele (rf1, rf2) and the fertile pollen donate 2 dominant alleles (Rf1, Rf2). On crossing the F1 progeny will receive at least one dominant allele from the fertile plant which restores fertility. Hence it results in fertile plants.
2. Option E
The transposable element containing a bonding site of a professor will block the transcription initiation. Hence there might be a loss of function.
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