Question

Due to low atmospheric pressure, the rate of transpiration will

• A. increase
• B. decrease rapidly
• C. decrease slowly
• D. remain unaffected

Answer 1

The correct option is A

increase

Low humidity outside the leaf favours transpiration because, in such a situation, vapour pressure gradient between the internal leaf atmosphere and the external atmosphere is very sharp. The vapour pressure of the atmosphere decreases with altitude just like atmospheric pressure (it means the air is drier at high altitudes). Therefore, high altitude plants often show xeromorphic adaptations to reduce transpiration.