Q32 / 160 · AP EAMCET 2023 (15 May Shift 1) · Chemistry

Given below are two statements Assertion (A): Hydrolysis of DNA does not form equal number of $A$ and $T ; G$ and $C$ Reason (R): In DNA adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine The correct answer is

  • A
    Both $\mathrm{A}$ and $\mathrm{R}$ are correct and $\mathrm{R}$ is the correct explanation of $\mathrm{A}$
  • B
    Both $\mathrm{A}$ and $\mathrm{R}$ are correct but $\mathrm{R}$ is not the correct explanation of $\dot{A}$
  • C
    $\mathrm{A}$ is correct but $\mathrm{R}$ is incorrect
  • Correct answer
    D
    $\mathrm{A}$ is incorrect but $\mathrm{R}$ is correct

Solution

The pairing of the two helices of DNA is such that $A$ pairs with $T$ and $G$ pairs with $C$, through hydrogen bonding. Thus, number of $\mathrm{A}=$ number of $\mathrm{T}$ number of $\mathrm{G}=$ number of $\mathrm{C}$ Therefore, statement in Assertion (A) is wrong and Reason (R) is correct.

Hence, the correct answer is option: 'D'.

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