Which genetic or chromosomal abnormality below is correctly matched with its description?
A)In phenylketonuria the child is unable to produce a critical enzyme,which results in an accumulation of poisons,and in turn causes mental retardation.
B)In Tay-Sachs disease,the body starts producing abnormally shaped red blood cells.
C)In Down syndrome,the brain tissues of the cortex degenerate,resulting in the death of the child.
D)In sickle-cell anemia,the child receives an extra chromosome resulting in mental retardation.

Question

Quizplus · Accepted Answer

Phenylketonuria is caused by a genetic deficiency in an enzyme that breaks down phenylalanine, leading to a buildup of toxic substances in the brain and causing mental retardation.

Answer: B
 Tay-Sachs disease is caused by a genetic deficiency in an enzyme that breaks down a fatty substance called GM2 ganglioside, leading to the accumulation of this substance in the brain and resulting in the destruction of nerve cells.

Answer: C
 Down syndrome is caused by an extra copy of chromosome 21 and can lead to intellectual disability, characteristic physical features, and an increased risk for certain health problems, but does not involve degeneration of brain tissue.

Answer: D
 Sickle-cell anemia is caused by a genetic mutation that results in abnormal hemoglobin molecules, causing red blood cells to become misshapen and leading to a range of health problems, but does not involve an extra chromosome or mental retardation.

Which Genetic or Chromosomal Abnormality Below Is Correctly Matched with Its