Question 60:
Match List I with List II:
| List I: Ion Channel Defects | List II: Disease |
|---|---|
| A. Na+ | (iii) Cystic fibrosis |
| B. Ca2+ | (iv) Dominant deafness |
| C. K+ | (i) Polycystic kidney disease |
| D. Cl | (ii) Generalized epilepsy |
Choose the correct answer from the options given below:
Cystic fibrosis involves a Cl⁻ channel defect (CFTR), while other matches link Na⁺ to epilepsy, Ca²⁺ to deafness, and K⁺ to polycystic kidney disease; option (D) correctly pairs them.
Correct Matching
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A. Na⁺ → (ii) Generalized epilepsy: Na⁺ channel mutations (e.g., SCN1A) cause hyperexcitability leading to seizures in generalized epilepsy.
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B. Ca²⁺ → (iv) Dominant deafness: Ca²⁺ channel defects (e.g., CACNA1D) disrupt hair cell function, causing autosomal dominant nonsyndromic deafness.
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C. K⁺ → (i) Polycystic kidney disease: While primarily PKD1/2 genes, some cases link to K⁺ channel dysfunction in polycystin regulation affecting renal cysts.
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D. Cl⁻ → (iii) Cystic fibrosis: CFTR Cl⁻ channel mutation (ΔF508 common) blocks anion transport, causing thick mucus and organ damage.
Option Analysis
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(A): Wrong; mismatches Na⁺-epilepsy, Ca²⁺-epilepsy swap, etc.
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(B): Wrong; Na⁺-cystic fibrosis incorrect (that’s Cl⁻).
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(C): Wrong; Na⁺-epilepsy swap, Cl⁻-kidney mismatch.
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(D): Correct; all pairs align with ion channel defects in listed diseases.
Ion channel defects matching List I ions to List II diseases is key for genetics and biochemistry in GATE Life Sciences, with Cl⁻ linked to cystic fibrosis via CFTR failure.
Ion Channel Basics in Disease
Ion channels control membrane potential; defects cause channelopathies—Na⁺ gain-of-function sparks epilepsy seizures, Ca²⁺ issues impair auditory transduction. K⁺ dysregulation promotes cyst growth in polycystic kidney disease; Cl⁻ block dehydrates mucus in cystic fibrosis.
Correct Matches Explained
CFTR (Cl⁻) mutation defines cystic fibrosis, affecting lungs/pancreas; Na⁺ channels (SCN genes) underlie epilepsy; Ca²⁺ channels cause deafness via cochlear dysfunction; K⁺ links to PKD cystogenesis.
Why Option (D)?
Standard exam logic: Cystic fibrosis = Cl⁻ hallmark; epilepsy = Na⁺ hyperexcitability; deafness often Ca²⁺; PKD K⁺-polycystin interplay.
GATE Prep Table
| Ion (List I) | Disease (List II) | Key Defect |
|---|---|---|
| Na⁺ | (ii) Generalized epilepsy | Gain-of-function seizures |
| Ca²⁺ | (iv) Dominant deafness | Hair cell failure |
| K⁺ | (i) Polycystic kidney disease | Cyst regulation loss |
| Cl⁻ | (iii) Cystic fibrosis | Mucus dehydration |
