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Q115
(IAS/1999)
Science & Technology › Basic Science (Physics, Chemistry, Biology) › Plant anatomy physiology
Answer Verified
For which one of the following is capillarity not the only reason ?
Result
Your answer:
—
·
Correct:
D
Explanation
Capillarity (capillary action) readily explains blotting of ink and the spread/wetting of water on porous textiles: porous blotting paper and cotton fibres draw liquid into narrow pores by adhesion and cohesion, causing absorption and upward/climbing wetting. Capillarity also causes limited upward movement of soil moisture (capillary rise) in porous media [1]. However, movement of water from roots to foliage is not due to capillarity alone: transpiration from leaves generates a suction (transpiration pull) which, together with cohesion of water molecules and root pressure, drives the continuous upward flow in xylem vessels; capillarity only assists over short distances and cannot account for whole-plant ascent by itself [1].
Sources
- [1] https://www.usgs.gov/water-science-school/science/capillary-action-and-water
- [2] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.8 > p. 95
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