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The symbols $I^A$, $I^B$, and $i$ represent blood types A, B, and O respectively, where $I$ stands for dominant and $i$ stands for recessive. Which Punnett square represents the cross between a woman with both A and B antigens and a man that has neither A nor B antigens?



I ${ }^{\text {A }}$$I ^{ B }$

i		$i _{ i }$$I ^8 i$

i		$I _{ i }$$I ^{ B _{ i }}$

$I ^{ A }$$I ^{ B }$

i		$i ^{ A } I$$I ^{ B _{ i }}$

1		$A _{ i }$$I ^{ B } j$

Verified Answer :

  • The woman's genotype is \(I^A I^B\) and the man's genotype is \(ii\).
  • To create the cross, set the woman's gametes (\(I^A, I^B\)) as columns and the man's gametes (\(i, i\)) as rows.
  • The resulting combinations in the Punnett square are \(I^A i\) and \(I^B i\) for every cell, indicating all offspring will have either Type A or Type B blood.
  • The provided table is correct as it matches the cross \(\boxed{@@TABLE_TOKEN_0@@}\)

Explanation

  1. Analyze the genotypes and identify the cross

The ABO blood group system is governed by three alleles: \(I^A\), \(I^B\), and \(i\). The woman is described as having both A and B antigens, which means she possesses both the \(I^A\) and \(I^B\) alleles. Therefore, her genotype is \(I^A I^B\). The man is described as having neither A nor B antigens, which corresponds to blood type O. In the ABO system, blood type O is recessive, and its genotype is \(ii\). We are asked to represent the cross between these two individuals, \(I^A I^B \times ii\), using a Punnett square.

  1. Determine gametes and setup the Punnett square structure

To create the Punnett square, we first identify the gametes that each parent can contribute.

  • The woman with genotype \(I^A I^B\) can produce gametes containing either the \(I^A\) allele or the \(I^B\) allele.
  • The man with genotype \(ii\) can only produce gametes containing the \(i\) allele.

We place the woman's alleles (\(I^A\) and \(I^B\)) as the column headers and the man's alleles (\(i\) and \(i\)) as the row headers.

  1. Fill the Punnett square and confirm accuracy

Now, we populate the cells of the Punnett square by crossing the alleles from the rows and columns:

  • Row 1, Column 1: \(i \times I^A = I^A i\)
  • Row 1, Column 2: \(i \times I^B = I^B i\)
  • Row 2, Column 1: \(i \times I^A = I^A i\)
  • Row 2, Column 2: \(i \times I^B = I^B i\)

This results in the following grid:

\(I^A\)\(I^B\) \) \(i\)\(I^A i\)\(I^B i\) \) \(i\)\(I^A i\)\(I^B i\) \)

This grid perfectly matches the structure provided in the problem, confirming it is the correct representation of the cross.

Examples

Punnett squares are widely used in genetics to predict the outcomes of crosses between parents with known genotypes. For instance, in clinical genetics, doctors use these tables to estimate the probability of offspring inheriting certain blood types or genetic traits, helping families understand the potential inheritance patterns for future children. By simply knowing the genotypes of parents, you can effectively map out all possible genetic combinations for their offspring.