NEET 1998 · Class 11

Breathing and Exchange of Gases

The exchange of gases in the alveoli of the lungs takes place by

  1. (A)passive transport
  2. (B)active transport
  3. (C)osmosis
  4. (D)simple diffusion

The NCERT line that answers it

Verbatim line

O<sub>2</sub> and CO<sub>2</sub> are exchanged in these sites by simple diffusion mainly based on pressure/concentration gradient.

Chapter
Breathing and Exchange of Gases
Section
14.3 EXCHANGE OF GASES
Page
6
Words matched
13 of 16

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 'O₂ and CO₂ are exchanged in these sites by simple diffusion', which directly and conclusively identifies the specific mechanism of gas exchange in alveoli, distinguishing it from passive transport, active transport, and osmosis.

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 1998 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.