GENETICS QUESTION!! 1. In corn, R is a gene for red kernel pigment; its recessiv
ID: 172728 • Letter: G
Question
GENETICS QUESTION!!
1. In corn, R is a gene for red kernel pigment; its recessive allele r determines yellow kernel pigment. A cross is made between a diploid r/r female and a trisomic R/r/r male. If pollen grains with extra chromosomes are inviable, the ratio of red to yellow kernels expected in the offspring would be:
1 red : 5 yellow
1 red : 2 yellow
1 red : 1 yellow
2 red : 1 yellow
5 red: 1 yellow
2. A pair of wild type fruit flies of unknown origin are mated and produce wild type F1 offspring. The F1s are allowed to interbreed and produce an all wild type F2. When the F2s are allowed to interbreed they produce an F3 that is 75% wild type and 25% mutant. If the mutant phenotype is due to a recessive mutation in an autosomal maternal effect gene, what are the genotype of the original parents?
A. male m/m
female m/m
B. male m/+
female m/+
C. male +/+
female m/m
D. male m/m
female +/+
E. male m/+
female m/m
A.1 red : 5 yellow
B.1 red : 2 yellow
C.1 red : 1 yellow
D.2 red : 1 yellow
E.5 red: 1 yellow
Explanation / Answer
In corn, R is a gene for red kernel pigment; its recessive allele r determines yellow kernel pigment. A cross is made between a diploid r/r female and a trisomic R/r/r male. If pollen grains with extra chromosomes are inviable, the ratio of red to yellow kernels expected in the offspring would be:
ANS....(B)
A pair of wild type fruit flies of unknown origin are mated and produce wild type F1 offspring. The F1s are allowed to interbreed and produce an all wild type F2. When the F2s are allowed to interbreed they produce an F3 that is 75% wild type and 25% mutant. If the mutant phenotype is due to a recessive mutation in an autosomal maternal effect gene, what are the genotype of the original parents?
ANS...(C)
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