Chemistry Liquids MDCAT 2011
PMDC Verified Question 70 of 73
DNA molecule is double stranded, in which two chains of DNA are twisted around each other by:
A
Hydrogen bonds
B
Van der Waal's forces
C
Covalent bonds
D
Dative bonds
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Hydrogen bonds
Concept:

The double-helical structure of DNA is stabilized by secondary intermolecular forces between complementary nitrogenous bases.

Formula:

Not applicable.

Solution:

  • The two strands of DNA are held together by hydrogen bonds forming between specific base pairs.


  • Adenine (A) pairs with Thymine (T) via two hydrogen bonds, and Guanine (G) pairs with Cytosine (C) via three hydrogen bonds.


Why other options are incorrect:

Covalent bonds hold the sugar-phosphate backbone together, not the two opposing strands. Van der Waals forces assist in base-stacking stabilization but are not the primary connecting force between the strands. Dative bonds are not relevant here.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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