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A student, Maria, has type O blood and her sister has type AB. What are the genotypes of their...

Question:

A student, Maria, has type O blood and her sister has type AB. What are the genotypes of their parents?

ABO blood type in humans

Humans have 3 possible alleles for blood type- A,B,O. A and B are co dominant- meaning that if both A and B are present then both alleles are expressed {blood type AB}. Allele O is the recessive allele. If either A or B is present with O, then the dominant A or B will be the resulting genotype. For example, AO would be blood type A and so would AA. Since O is recessive, only those individuals with the genotype OO would have the blood type "O".

Answer and Explanation: 1

For Maria to be OO- each of her parents had to give her an O. So we know that Mom is ?O and Dad is ?O. Then we look at her sister, AB. She had to have gotten A from one parent and B from the other. So we know that parent 1 was AO and parent 2 was BO. Since blood is not sex-linked, gender is not a concern.


Learn more about this topic:

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Blood Types: ABO System, Red Blood Cell Antigens & Blood Groups

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Chapter 13 / Lesson 5
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Blood types are determined by antigens found in red blood cells. Learn about the blood types, red blood cell antigens, agglutination, the ABO system, the blood groups, and the definitions of universal donor and universal recipient blood types.


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