NEET 2020 · Class 12

Molecular Basis of Inheritance

If the distance between two consecutive base pairs is 0.34 nm and the total number of base pairs of a DNA double helix in a typical mammalian cell is 6.6 × 10^9 bp, then the length of the DNA is approximately

  1. (A)2.5 meters
  2. (B)2.2 meters
  3. (C)2.7 meters
  4. (D)2.0 meters

The NCERT line that answers it

Verbatim line

Taking the distance between two consecutive base pairs as $0.34 \text{ nm}$ ( $0.34 \times 10^{-9} \text{ m}$ ), if the length of DNA double helix in a typical mammalian cell is calculated (simply by multiplying the total number of bp with distance between two consecutive bp, that is, $6.6 \times 10^9 \text{ bp} \times 0.34 \times 10^{-9} \text{ m/bp}$ ), it comes out to be approximately 2.2 metres.

Chapter
Molecular Basis of Inheritance
Section
5.1.2 Packaging of DNA Helix

The answer appears as a continuous sentence in NCERT. This is that sentence.

How this line gives the answer

0, emb=1.0, combined=1.0). Verified: high — The span explicitly states the calculation (6.6 × 10^9 bp × 0.34 × 10^{-9} m/bp) and the result (approximately 2.2 metres), which directly matches the question's parameters and correct answer.

We did this for 1,565 questions.

Every one traced to the exact sentence in NCERT that answers it, including 90% of the 2026 paper. Sit a mock on the real NEET 2027 computer interface and every mark you drop comes back with its line attached.

Take the free 5-minute checkMore from this chapter

Question text is reproduced from the published NEET 2020 paper for study and commentary. NCERT text is quoted, not redistributed; textbooks remain at ncert.nic.in. Our mapping method, including its measured error rates, is published at /methodology.