Question

Assertion [A] : Bulk flow can be achieved either positive hydrostatic pressure gradient or a negative hydrostatic pressure gradient.
Reason [R] : Movement in the xylem is always bidirectional.

• A. A and R are correct. R is the correct explanation of A
• B. A and R are correct. R is not the correct explanation of A
• C. A is correct but R is incorrect
• D. A is incorrect but R is correct

Hint:

Remember, in xylem, water movement is unidirectional from roots to leaves, not bidirectional.

Answer 1

The Correct Option is C

Step 1: Understanding the assertion (A)
Bulk flow can occur when there is either a positive or negative hydrostatic pressure gradient. Positive pressure leads to the movement of water from high pressure to low pressure, while negative pressure also enables the flow, such as in the case of transpiration pull in plants.
Step 2: Understanding the reason (R)
Movement in the xylem is not always bidirectional. Xylem primarily moves water unidirectionally, from the roots to the leaves, driven by transpiration. Therefore, the statement in reason (R) is incorrect.
Final Answer: \[ A - \text{Correct}, \quad R - \text{Incorrect} \]