Question

(a) Why is transport of materials necessary in an organism (plant or animal)?
(b) What is the need of special tissues or organs for transport of substances in plants and animals?
(c) How are water and minerals transported in plants?
(d) How is food transported in plants?

Answer 1

(a) Transport of materials is necessary in plants and animals as every cell needs a regular supply of nutrients and oxygen to provide energy during respiration.

(b) Organisms like plants and animals need special tissues and organs for the transport of substances because tissues and organs can easily transport the essential substances like food, oxygen and water from one part of the body to another. For example, the xylem tissues of roots, stems and leaves are interconnected and form a continuous network of channels to transport water to all parts of the plant body.

(c) Water and minerals are absorbed by the cells of the root hair. The root hair is in direct contact with the water present between the soil particles. As the water is absorbed by the roots from the soil, it is transported to various parts of the plants through the xylem tubes. Water is mainly pulled from the leaves by transpiration. Transpiration creates a suction pressure, as a result of which water is forced into the xylem cells of the roots. Then, there is a steady movement of water from the root xylem to all the parts of the plant, through interconnected water conduction elements.

(d) The transport of food from the leaves to the other parts of the plant occurs through the vascular tissue called phloem. The food (sugar) made in leaves is loaded into the sieve tubes of phloem tissue by using the energy derived from ATP. As a result, the osmotic pressure in the tissue increases, causing the water to move into it. This high pressure produced in the phloem, moves the food to all the parts of the plant that have less pressure in their tissues. This process is helpful in moving the food materials according to the needs of the plant.