NCERT 7th Class (CBSE) Science: Transportation in Animals and Plants

Question: Why is transport of materials necessary in a plant or an animal? Explain.

Answer: Transport of materials is necessary for plants or animals because due to it the nutrients and oxygen are made available to all the parts of the body. If the transport of necessary nutrients and oxygen does not take place in the body, the body will not be able to survive.

Question: What will happen if there are no platelets in the blood?

Answer: The blood platelets are responsible for the clotting of the blood. When some injury occurs blood starts flowing. But it clots on its own. If there are no platelets, the blood will not be able to clot and keep on flowing. Huge loss of blood ultimately causes death.

Question: What are stomata? Give two junctions of stomata.

Answer: There are small openings on the lower surface of the leaves. These pores are called stomata. These openings are surrounded with guard cells.

Functions of stomata:

1. It helps in the transpiration of water, i.e., the loss of excess water from the plant.
2. Loss of water from the stomata creates an upward pull, i.e., suction pull which helps in absorption of water from the roots.
3. They help in exchange of gases.

Question: Does transpiration serve any useful function in plants? Explain.

Answer:

1. It helps to enhance the absorption of water and dissolved minerals by creation of a suction pull.
2. It helps in getting rid of the excess water.
3. It helps in transport of water and minerals to leaves and leaves use the water for photosynthesis.
4. It produces a cooling effect on the plant.

Question: What are the components of blood?

Answer: There are four components of blood:

1.  Plasma is a liquid part of blood which is yellowish in colour and contain 90% water. It contains food, enzymes, wastes and proteins etc.
2. Red blood cells are disc shaped cells containing red coloured pigment called haemoglobin in it. Haemoglobin helps in transportation of oxygen.
3. White blood cells are the fighting cells which protect us against bacteria and foreign materials causing infections.
4. Platelets help in clotting of the blood.