4. Inheritance of the color of wheat kernels works in a similar way to human ski
ID: 207333 • Letter: 4
Question
4. Inheritance of the color of wheat kernels works in a similar way to human skin color but it is only controlled by two genes (A/a and B/b). You can think of it in this way, for every dominant allele (A or B) the wheat kernel will gain one "unit" of red color. No red color is gained for any recessive allele (a or b). If a wheat plant which is homozygous dominant for both genes is crossed with one which is heterozygous for both genes, what is the predicted ratio of phenotypes (dark red, red, light red) in the cross?Explanation / Answer
Ans- The ratio will be
1:2:1 for dark red:red:light red kernels
Because the no.of plants according to the punnet's square is 4 dark red: 8 red: 4 light red.
Now homozygous dominant wheat plant has genotype of AABB and heterozygous will have genotype AaBb, when these are crossed the resulting gametes and genotypes produced are shown in the table below:
Gametes
AB
AB
AB
AB
AB
AABB
dark red
AABB
dark red
AABB
dark red
AABB
dark red
Ab
AABb
red
AABb
red
AABb
red
AABb
red
aB
AaBB
red
AaBB
red
AaBB
red
AaBB
red
ab
AaBb
light red
AaBb
light red
AaBb
light red
AaBb
light red
Gametes
AB
AB
AB
AB
AB
AABB
dark red
AABB
dark red
AABB
dark red
AABB
dark red
Ab
AABb
red
AABb
red
AABb
red
AABb
red
aB
AaBB
red
AaBB
red
AaBB
red
AaBB
red
ab
AaBb
light red
AaBb
light red
AaBb
light red
AaBb
light red
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