Match the genetic disorder (Column I) with its molecular basis (Column II)
Column I
P. Sickle-cell anemia
Q. Xeroderma pigmentosum
R. Tay-Sachs disease
S. Down Syndrome
Column II
1. Mutation in nucleotide excision repair
2. Trisomy of chromosome 21
3. Mutation in β-globin gene
4. Mutation in hexosaminidase A gene
P-1; Q-4; R-2; S-3
P-3; Q-4; R-1; S-2
P-3; Q-1; R-4; S-2
P-4; Q-2; R-3; S-1
ANSWER
P-3; Q-1; R-4; S-2 — option (C)
Official answer: CSource: Official answer key, GATE 2024 BT (IISc Bengaluru)
Sickle-cell anemia is caused by a point mutation (Glu6Val) in the β-globin (HBB) gene, producing abnormal hemoglobin HbS. So P matches 3.
Xeroderma pigmentosum results from defective nucleotide excision repair (NER), leaving cells unable to repair UV-induced pyrimidine dimers in DNA. So Q matches 1.
Tay-Sachs disease is a lysosomal storage disorder caused by deficiency of the enzyme hexosaminidase A (encoded by the HEXA gene), leading to accumulation of GM2 ganglioside in neurons. So R matches 4.
Down Syndrome arises from trisomy of chromosome 21 due to meiotic nondisjunction — a numerical chromosomal abnormality, not a single-gene mutation. So S matches 2.
Combining the pairs: P-3, Q-1, R-4, S-2, which corresponds exactly to option (C).
KEY IDEA
Each genetic disorder in Column I is matched to its correct molecular/genetic basis in Column II by recalling the specific gene or chromosomal defect underlying each disease.
WATCH OUT FOR
Confusing xeroderma pigmentosum (a DNA repair defect, NER) with a numerical chromosomal abnormality, or mixing up Tay-Sachs disease (an enzyme-deficiency lysosomal storage disorder) with Down Syndrome (a trisomy), since both involve well-known eponymous disease names that students sometimes swap.
From the GATE 2024 BT paper. Every question of this paper · Download the full paper · All 11 Population & evolution questions, with notes
