NEET Biology: Plant Water Relations questions with solutions

Q1. The spray of PMA causes

1. Decrease in transpiration
2. Increase in transpiration
3. Increase in absorption
4. Increase in guttation

Answer: Increase in transpiration

PMA spray promotes conditions that increase stomatal opening, so more water vapor escapes from the leaf surface. That means transpiration rises rather than falls.

Q2. When a cell is placed in pure water then?

1. Wall pressure is increased
2. Turgor pressure is increased
3. water potential of cell is increased
4. All the above

Answer: Turgor pressure is increased

Pure water has a higher water potential than the cell sap, so water moves into the cell by osmosis. This increases the pressure of the cell contents against the cell wall, i.e., turgor pressure.

Q3. Percentage of water left in the soil when a plant begins to wilt is known as

1. Wilting coefficient
2. pH value of soil
3. Field capacity
4. Water holding cpacity

Answer: Wilting coefficient

The percentage of water remaining in soil when a plant starts to wilt is called the wilting coefficient. It represents the minimum soil moisture level at which plants can no longer extract enough water to stay turgid.

Q4. Non-osmotic theory' for active absorption of water was proposed by

1. Thimann and Kramer
2. O. Hertig
3. Atkins and Priestly
4. J. C. Bose

Answer: Thimann and Kramer

Thimann and Kramer proposed the non-osmotic theory, which explains active water absorption as a process not driven solely by osmotic gradients. Their work is associated with the idea that living root tissues can actively participate in water uptake.