Question

Which of the following inheritance is controlled by multiple alleles?
A)Colour blindness
B)Sickle cell anemia
C)Blood groups
D)Phenylketonuria

Answer 1

Hint: It is a classification of blood that is obtained by the presence or absence of antibodies in the red blood cells and also by inherited antigenic substances present on the surface of red blood cells. So, these are the chemical systems on the surface of blood cells.

Complete answer:
alleles are an alternative form of a gene and they are responsible for the difference in phenotyping expression of a given trait (for example brown eyes vs green eyes). A gene for which at least two alleles adjust is said to be polymorphic. The main particular gene adjusts in three or four allele forms known as multiple alleles.
-Example of multiple genes is the genes of ABO blood group system.
-The ABO system in humans is controlled by three alleles usually referred to as ${ I }^{ a }$, ${ I }^{ b }$ and ${ I }^{ c }$. I stand for hemagglutinin. ${ I }^{ a }$ and ${ I }^{ b }$ are codominant and thus produce a and b type of antigen, respectively which migrate to the surface of red blood cells. While ${ I }^{ o }$ is a recessive allele and produces no antigen.
-The different types of blood groups emerges from the different possible genotypes are-

Alleles	Blood group
${ I }^{ A }{ I }^{ A }$	A
${ I }^{ A }{ I }^{ O }$	A
${ I }^{ B }{ I }^{ B }$	B
${ I }^{ B }{ I }^{ O }$	B
${ I }^{ A }{ I }^{ B }$	AB
${ I }^{ O }{ I }^{ O }$	O

Additional Information: Colour blindness- color blindness is caused by an x-linked recessive allele. The recessive chromosome is represented as ${ X }^{ r }$ since males have only one X chromosome. If this chromosome has the red-green colorblind allele. The males will have a color perception defect.
Sickle cell anemia- it is a genetic condition having a pattern of autosomal recessive inheritance. This means that the condition is not linked to the sex chromosomes.
Phenylketonuria- it is an autosomal recessive disorder caused by a mutation in both alleles of the gene for phenylalanine hydroxylase found on chromosome 12 in the body. The enzyme Phenylalanine hydroxylase is an enzyme that changes the amino acid phenylalanine to tyrosine.

So, the correct answer is, "blood groups".

Note: Mainly four types of blood groups are defined by the ABO system-
blood group A- They have A-antigens on the red blood cells(RBC) present with the anti B antibodies in the plasma.
Blood group B- They have B-antigens on the RBC with anti A antibodies in the plasma.
Blood group O- They have no antigens but anti-A and anti-B antibodies both found in the plasma.
Blood group AB- Have both A and B antigens but there are no antibodies.