Question

what is sickle cell trait?
○ having abnormally shaped red blood cells in the absence of sickle cell disease
○ having sickle cell disease due to environmental rather than genetic traits
○ a mild form of sickle cell disease
○ having a single copy of the mutated beta-globin gene

Explanation:

Sickle cell trait occurs when a person has one normal beta - globin gene and one mutated (sickle) beta - globin gene. People with sickle cell trait usually do not have symptoms of sickle cell disease. Option A is incorrect as having abnormally shaped red blood cells in the absence of sickle cell disease is not the definition of sickle cell trait. Option B is wrong because sickle cell disease is genetic. Option C is incorrect as sickle cell trait is not a form of sickle cell disease.

Answer:

D. having a single copy of the mutated beta - globin gene