Multiple choice

Assertion (A): DNA shows hypochromicity on heating. Reason (R): Heat denaturation of DNA causes the double helix structure to unwind to form single-stranded DNA.

Directions: In the following question there are two statements, Assertion (A) and Reason (R). Consider both the statements independently and mark your answers as under:

1. If A and R both are correct and R is the correct explanation of A.
2. If A and R both are correct and R is not the correct explanation of A.
3. If A is correct and R is incorrect.
4. If A is incorrect and R is correct.
5. If A and R both are incorrect.

  1. 1

  2. 2

  3. 3

  4. 4

  5. 5
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Correct answer. A is incorrect and R is correct. DNA shows hyperchromicity on heating. Heat denaturation of DNA causes the double helix structure to unwind to form single-stranded DNA. When DNA in solution is heated above its melting temperature, the double-stranded DNA unwinds to form single-stranded DNA. The bases become unstacked and can thus, absorb more light.

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