Transport of water, minerals and food in plants

1. Why do plant need water?

Ans.1. It transports substances in the solution form from one part to another.

2. It is used for making food by the process of the process of photosynthesis.

3. The excess water evaporates from the surface of leaves by the process of transpiration. It provides suction pull that causes ascent of sap. It also provides a cooling effect.

2.Why are minerals important for plants ?

Ans. Minerals ( nutrients ) are necessary for the growth and development of plants.

3. What are the features of root hair that help in the absorption of water?

Ans. Features of root hair that help in the absorption of water-

1. They have a large surface area that allows more absorption of water.

2. Numerous tiny pores are present all over the membranes of root hair. Water molecules enter through these pores.

3. The cell wall of root hair is freely permeable and the cell membrane is semi-permeable.

4. The cell sap of root cells is more concentrated (contains more solute) than the surrounding soil water.

 4. Define-

(a) Diffusion- It is the movement of molecule ( solid, liquid or gas ) from a region of higher  concentration to a region of lower concentration until a equilibrium is reached.

(b) Osmosis-  It is the movement of water molecules from the region of higher water concentration to the region of lower water concentration through a semi-permeable membrane.

(c) Active Transport- The movement of particle from a region of lower concentration to a region of higher concentration by utilizing energy is called active transport.

5. What is transpiration? How does the process of absorption of water by root hair depend upon transpiration?

Ans. The loss of excess water from plants mainly through leaves as water vapour is called transpiration.

                        Transpiration helps in ascent of sap. Due to transpiration, the concentration of water in the cells of leaves decreases thus, creating a suction force. As a result, water from the cells below that rises upwards. Water molecules are pulled up because of their tendency of cohesion, i.e., sticking with each other.

6. Write an experiment to show that plants lose water through their leaves?

Ans. Aim: To show that plants lose water through their leaves.

            Things needed: One small and well watered potted plant, two polythene bags and two threads.

Method:

1. Take a small and well-watered potted plant.

2. Cover one branch of the plant with a polythene bag.

3. Remove the leaves from another branch of the same plant and cover with another polythene bag.

4. Tie both the polythene bags tightly with thread.

5. Now, place the plant in sunlight for 5-6 hours.