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Multiple Choice
In a monohybrid cross between two heterozygous individuals (Aa x Aa), what is the expected genotypic ratio of the offspring?
A
3 AA : 1 aa
B
2 AA : 2 Aa
C
1 Aa : 3 aa
D
1 AA : 2 Aa : 1 aa
Verified step by step guidance
1
Start by understanding that a monohybrid cross involves one gene with two alleles. In this case, the alleles are 'A' and 'a'. Each parent is heterozygous, meaning they have one dominant allele 'A' and one recessive allele 'a'.
Set up a Punnett square to visualize the possible combinations of alleles from each parent. Each parent can contribute either 'A' or 'a' to the offspring.
Label the top of the Punnett square with the alleles from one parent (A and a) and the side with the alleles from the other parent (A and a).
Fill in the Punnett square by combining the alleles from the top and side. This will give you four possible combinations: AA, Aa, Aa, and aa.
Count the occurrences of each genotype in the Punnett square. You should find one AA, two Aa, and one aa, leading to the genotypic ratio of 1 AA : 2 Aa : 1 aa.