Question

A column of water within xylem vessels of tall trees does not break under its weight because of?

• A. Dissolved sugar in the water
• B. Lignification of xylem vessels
• C. Tensile strength of water
• D. Positive root pressure

Answer 1

The correct option is C

Tensile strength of water

The correct option is C.

Explanation of correct option:

1. Xylem is a vascular tissue that transports water and minerals from roots to the shoots.
2. It also provides mechanical strength to the plant.
3. A water column within xylem vessels of tall trees does not break under its weight due to the tensile strength of water.
4. This strength helps in resisting pulling force.
5. Tensile strength depends on water properties such as cohesion, adhesion, and surface tension.
6. These properties play an important role in the ‘ascent of sap.’

Explanation of incorrect option:

Option A:

1. Dissolved sugar in water decreases water potential.
2. As a result, water moves from the adjacent xylem into the phloem by osmosis.

Option B:

Lignin is water-resistant and provides mechanical strength to xylem vessels.

Option D:

1. Positive root pressure develops in the roots due to the active absorption of nutrients.
2. This pressure helps to push water upwards to a certain extent.

Final answer: A column of water within xylem vessels of tall trees does not break under its weight because of the tensile strength of water.