PATHOLOGY MCQ
GENETICS AND DISEASE
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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GG
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Gg
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gg
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all of the choices result in yellow
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Detailed explanation-1: -G g, G g : g g, g g . The mode of inheritance shows that each of the two alleles is inherited independently from the other, with a 3:1 phenotypic ratio for each. The genotype for yellow offspring is identified as GG, Gg, andGg G G, G g, a n d G g (dominant traits).
Detailed explanation-2: -But we know that yellow pods are a recessive character, and that recessive characters are expressed only in a homozygous recessive individual. Thus the genotype of this plant must be gg. The cross, therefore, is Gg X gg.
Detailed explanation-3: -There are special names that are given to specific combinations of alleles in a genotype. A genotype that has two copies of the same allele, for example: GG or gg, is called homozygous. Alternatively, a genotype that has two different alleles, for example: Gg, is called heterozygous.
Detailed explanation-4: -Thus the green-pod parent (Gg) will produce two kinds of gametes-G and g. The yellow-pod parent (gg) will produce g gametes. As you can see, 1/2 of the offspring are genotype Gg and 1/2 are gg. Step 6 Determine the phenotypes of the offspring.