X BIOLOGY-LIFE PROCESS- PLANTS [1]

1.            How is food transported in plants? ,Or  What is translocation?  Elaborate.

Transporation of soluble products of photosynthesis is called translocation and it occurs in the part of vascular tissue known as Phloem. Besides this phloem also transport amino acids and other substances. These substances are especially delivered to the storage organs of roots, fruits and seed and to growing organs. Phloem transports food materials from the leaves to different parts of the plant body. Unlike Xylem it transport material in both direction. The transportation of food in phloem is achieved by using energy from ATP. As a result, the osmotic pressure in the tissue increases causing water to move into it. This pressure moves the material in the phloem to the tissues which have less pressure. This is helpful in moving materials according to the needs of the plant. For example, the food material, such as sucrose, is transported into the phloem tissue using ATP energy. The translocation of food and other substances takes place in sieve tubes with the help of adjacent companion cells in both direction

2.            Write the methods used by the plants to get rid of excretory products.

Plants get rid of:

1. water by transpiration.

2. waste products may store in vacuoles or may be stored in leaves which fall off.

3.resine and gums are stored in xylem.

4.some waste substance may be excreted in the soil.

5. as by products move out of the plants by diffusion through stomata.

3.            How is lymph formed? Write its functions.

Through the pores present in the walls of capillaries, some amount of plasma, proteins and blood cells escape into intercellular spaces in the tissues to form the tissue fluid or lymph. From intercellular spaces, it enters into lymphatic capillaries, which join to form lymph vessels, which open into larger veins. Lymph carries digested and

4.            How do the alveoli of lungs in human body help in the exchange of gases?

Alveoli provides a surface for the exchange of gases.An extensive network of blood vessels is present in the wall of the alveoli. By lifting our ribs and flatten the diaphragm, the chest cavity becomes spacious. Air is sucked into the lungs and alveoli.The oxygen from the breath, diffuses into the blood and CO2 from the blood brought from the body, diffuses out into the air.