Exercises

1. Match structures given in Column I with functions given in Column II.

Column I	Column II
(i) Stomata	(a) Absorption of water
(ii) Xylem	(b) Transpiration
(iii) Root hairs	(c) Transport of food
(iv) Phloem	(d) Transport of water
	(e) Synthesis of carbohydrates

Answer.

Column I	Column II
(i) Stomata	(b) Transpiration
(ii) Xylem	(d) Transport of water
(iii) Root hairs	(a) Absorption of water
(iv) Phloem	(c) Transport of food

2. Fill in the blanks.

(i) The blood from the heart is transported to all parts of the body by the __________.

(ii) Haemoglobin is present in __________ cells.
(iii) Arteries and veins are joined by a network of __________.
(iv) The rhythmic expansion and contraction of the heart is called __________.
(v) The main excretory product in human beings is __________.
(vi) Sweat contains water and __________.
(vii) Kidneys eliminate the waste materials in the liquid form called __________.
(viii) Water reaches great heights in the trees because of suction pull caused by __________.

Answer

(i) The blood from the heart is transported to all parts of the body by the arteries.

(ii) Haemoglobin is present in red blood cells.

(iii) Arteries and veins are joined by a network of capillaries.

(iv) The rhythmic expansion and contraction of the heart is called heart beat.

(v) The main excretory product in human beings is urea.

(vi) Sweat contains water and salts.

(vii) Kidneys eliminate the waste materials in the liquid form called urine.

(viii) Water reaches great heights in the trees because of suction pull caused by transpiration.

3. Choose the correct option:

(a) In plants, water is transported through
     (i) xylem            (ii) phloem           (iii) stomata                (iv) root hair
Answer. (i) xylem

(b) Water absorption through roots can be increased by keeping the plants
      (i) in the shade           (ii) in dim light              (iii) under the fan             (iv) covered with a polythene bag
Answer. (iii) under the fan

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

Answer.

(i) Transport of materials in a plant or in a animal is necessary for carrying out metabolic activities.
(ii) Transportation of materials help in the supply of nutrients and energy to each every parts of animals and plants need energy which they get from the transported materials.
(iii) Also, the waste materials produced during metabolic activities are toxic and hence need to be removed from the body by transportation.

5. What will happen if there are no platelets in the blood?

Answer. Platelets are responsible for clotting of blood. If there are no platelets, the blood would not clot in case of an injury. This will lead to excess blood loss and finally in death of the person.

6. What are stomata? Give two functions of stomata.

Answer. The tiny holes or openings present under the leaves of the plants is called stomata.
Two functions of stomata:
(i) It helps in breathing of the plants.
(ii) It helps in exchange of gases takes place inside the plants cells.

7. Does transpiration serve any useful function in the plants? Explain.

Answer. Transpiration serves very important function in plants. Transpiration creates the transpiration pull, which is responsible for the rise of water to great heights in tall plants and other trees.

8. What are the components of blood?

Answer. The main components of blood are:
(i) Plasma
(ii) Red blood cells (RBC)
(iii) White blood cells (WBC)
(iv) Platelets

9. Why is blood needed by all the parts of a body?

Answer. Blood transports substances like digested food from the small intestine to the other parts of the body. It carries oxygen from the lungs to the cells of the body. It also transports waste for removal from the body. So, it acts as a carrier of various substances. Every part of the body needs certain substances to perform its functions. Additionally, every part creates some waste products for removal. Blood is needed by all parts of the body so that various substances can be supplied to them and waste can be removed from them.

10. What makes the blood look red?

Answer. The presence of red pigment called haemoglobin in red blood cells (RBC) makes the blood look red.

11. Describe the function of the heart.

Answer. Functions of the heart:
(i) It helps in the circulation of oxygen rich blood throughout the body by the pumping.
(ii)It receives oxygenated blood from the lungs.
(iii) It also pumps back the blood carrying carbon dioxide to the lungs.
(iv) It shows rhythmic contraction and relaxation for movement of blood.

12. Why is it necessary to excrete waste products?

Answer. When our cells perform their functions, certain waste products are released. These are toxic for our body and hence need to be removed from the body.

13. Draw a diagram of the human excretory system and label the various parts.

Answer.