Question

Find the incorrect statement among the following: n(A) In sex-linked recessive traits, the gene is transmitted from an unaffected carrier female to some of the male progeny. n(B) Accumulation of phenylpyruvic acid in the brain results in mental retardation. n(C) Individuals affected by Down’s Syndrome will have congenital heart defects and are more intelligent. n(D) Turner’s Syndrome is caused due to the absence of one X chromosome.

• A. In sex-linked recessive traits, the gene is transmitted from an unaffected carrier female to some of the male progeny.
• B. Accumulation of phenylpyruvic acid in the brain results in mental retardation.
• C. Individuals affected by Down’s Syndrome will have congenital heart defects and are more intelligent.
• D. Turner’s Syndrome is caused due to the absence of one X chromosome.

Hint:

Accurate knowledge of genetic disorders aids in diagnosis and management.

Answer 1

The Correct Option is C

The incorrect statement is: Individuals affected by Down's Syndrome will have congenital heart defect and are more intelligent.

(A) Sex-linked inheritance - Correct: Carrier females (X^HX^h) can transmit recessive traits (e.g., hemophilia) to male offspring (X^hY).

(B) Phenylpyruvic acid accumulation - Correct: This is characteristic of phenylketonuria (PKU), causing intellectual disability if untreated.

(C) Down's Syndrome description - Incorrect: While congenital heart defects occur in ~50% cases, individuals typically have mild to moderate intellectual disability (not increased intelligence).

(D) Turner's Syndrome - Correct: 45,X karyotype (missing one X chromosome) causes this condition.

The incorrect statement is (C), as it contains a factual error regarding cognitive abilities in Down's Syndrome (Trisomy 21).