HEREDITY
MONOHYBRID CROSS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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3:1
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1:2:1
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1:1
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4:0
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Detailed explanation-1: -In the monohybrid cross, a testcross of a heterozygous individual resulted in a 1:1 ratio.
Detailed explanation-2: -If the alleles were incompletely dominant, the heterozygotes would have an intermediate phenotype different from both the homozygous dominant (SS) and the homozygous recessive (ss). There would be three different phenotypes among the offspring, and the ratio would be 1 (SS) : 2 (Ss) : 1 (ss).
Detailed explanation-3: -This 9:3:3:1 phenotypic ratio is the classic Mendelian ratio for a dihybrid cross in which the alleles of two different genes assort independently into gametes. Figure 1: A classic Mendelian example of independent assortment: the 9:3:3:1 phenotypic ratio associated with a dihybrid cross (BbEe × BbEe).
Detailed explanation-4: -In the given case, the crossing of RrYy (dihybrid) with rryy (homozygous recessive parent) gives 1:1:1:1 phenotypic ratio and 1:1:1:1 genotypic ratio.