Question

Sickle cell anemia is an example of
A. Epistasis
B. Codominance
C. Pleiotropy
D. Incomplete dominance

Answer 1

Hint: The gene mutation can cause various disorders. The sickle cell anemia is the disorder caused due to mutation in the gene. The single gene can show various expressions. The sickle cell red blood cell occurs due to change in genes. The dominant gene expresses itself and suppresses the recessive gene.

Complete answer:
Sickle cell anemia is the disorder in the red blood cells. It is an inherited disorder. It is the sex linked disease. The shape of red blood cells becomes sickle or crescent moon. It occurs by gene mutation. The codons change from GAG to GTG. The GTG codes as GUG which codes for valine.
Epistasis- A gene suppress the action of another gene is termed as epistasis. Skin colour of mice is the example of epistasis.
Codominance refers to the expression of phenotypes of both parents in the progeny. The ABO blood group type shows codominance.
Pleiotropy is the ability of a gene to show the multiple phenotypic effects. This phenomenon is called pleiotropy and the gene is called Pleiotropic gene. Sickle cell anaemia is the example of pleiotropy.
Incomplete dominance is the phenomenon in which appearance of new phenotypes in the progeny other than parental phenotypes occur. The characters of both the parents expressed incompletely and form the intermediate. The flower colour of Snapdragon shows this phenomenon.
The sickle cell anemia shows the pleiotropy phenomenon.

Hence, the correct answer is option (C).

Note: The phenylketonuria is caused due to deficiency of phenylalanine hydroxylase. It can occur due to pleiotropy in humans. The expression of a single mutated HBB gene produces numerous consequences throughout the body that’s why the sickle cell anemia is the pleiotropic disease. The mutated haemoglobin forms polymers and clumps together due to which red blood cells become disfigured sickle shape.