Question

Ascent of sap means
A. Upward movement of water and minerals in plants
B. Downward movement of organic nutrients
C. Movement of contents in a vacuole
D. Upward and downward movement of food materials

Answer 1

Sap is the fluid that circulates the vascular system of a plant. Xylem tissue is responsible for the ascent of sap in the plants. The transpiration pull, cohesion property of water and adhesion of cell walls are responsible for the ascent of sap.

Step by step answer: Option A) Upward movement of water and minerals in plants is called ascent of sap meaning, the ascending or upward pull of liquid surrounding the vascular system of the plant. The ascent of sap occurs in xylem tissue and is the upward movement of water and minerals from the root to the crown.
Option B) Downward movement of organic nutrients such as sugar (sucrose) occurs in phloem from the leaves to the roots of the plant. It can be bidirectional. It occurs due to the osmotic gradient formed in the leaves which allows water from the xylem into the cells and it makes it difficult for the sap to diffuse through the sieve tubes in phloem due to the turgor pressure created by the bulk flow of organic nutrients from leaves to roots.
Option C) Movement of contents in a vacuole is transported through several transporters present on the tonoplasts which either create gradients for the transport or form fusion of membrane vesicles. Vacuole stores waste substances and also certain flavonoids, tannins, carbohydrates, and certain proteins that form the energy source and helps maintain the turgor pressure.
Option D) Upward and downward movement of food materials is called translocation which occurs mainly through the phloem sieve tubes from the sucrose source to sink and is bidirectional. It is an ATP-driven process.
Hence, the correct answer is (A).

Note: Transpiration creates a transpiration pull and then due to osmosis, water is diffused from root hairs. The capillary action allows the upward movement of water from the root to the stem. And due to adhesion and cohesion between water molecules and cells, there is an upward force that drives water movement.