Ans.2) (i) (b) (ii) (d) (iii) (a) (iv) (c)
2. Fill in the blanks.
(i) The blood from the heart is transported to all parts of the body by the---------------. (arteries)
(ii) Hemoglobin is present in ----------------- ce ll. (red blood)
(iii) Arteries and Veins are joined by a network o f ------------. (capilaries)
(iv) The rhythmic expansion and contraction of th e heart is called -------------. (heartbeat)
(v) The main excretory product in human beings is ----- -----------. (Urea)
(vi) Sweat contains water and ---------------.(salts)
(vii) Kidney eliminates 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 options:
(a) In plants, water is transported through
(i) Xylem
(ii) Phloem
(ii) Stomata
(iv) Root hair
Ans.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.
Ans.In dim light
4. Why is transport of materials necessary in a pla nt or in an animal? Explain.
Ans.Different parts of the body perform different wo rks. For example, in plants roots absorb water and leaves prepare food utilizing the water. The food is also required by root. So, there is no utility of water absorb by roots if it does not reach leaf or food prepared by leaf if it does not reach to root. So, transport system is necessary.
5. What will happen if there are not platelets in t he blood?
Ans.Blood cannot clot without the platelets. So, if there is any cut, blood continue to flow and ultimately the person dies.
6. What are stomata? Give two functions of stomata.
Ans.Small pores in leaves of plants are called stoma ta.
Functions of stomata-
(i) Exchange of carbon dioxide and oxygen.
(ii) Transpiration to remove excess of water.
7. Does transpiration serve any useful function in the plants? Explain.
Ans.(1) Ascent of sap:Transpiration developes tension in the water column which makes it possible for the water to rise from the xylem of the roots to the top of the plant.
(2) Removal of excess water : Plants absorb far more water than is actully required by the plants.Transpiration helps in removing this excess water.
(3) Absorption & distribution of salts: The rate of salt absorption increases with the rate of transpiration.
(4) Cooling effect:- Sunlight that falls on the leaf can raises the leaf temprature by 30-40 degree centigrade above the atmospheric temperature,and thus harm the leaf tissues.A major portion of this energy is dissipated by transpiration when the water evaporates leading to a cooling effect..
(5) Development of root system: Transpiration allows extensive development of the root system that supports the heavy aerial growth against storms & allows absorption of mineral salts & water.
8. What are the components of blood?
Ans.Red blood cells, white blood cells, platelets and plasma.
9. Why blood needed by all the parts of a body?
Ans.Blood carries digested food and oxygen to all pa rts of body. It also carries away the waste products.
10. What makes the blood look red?
Ans.Due to the presence of red pigment called Haemoglobin
11. Describe the functions of the heart.
Ans.Heart collects and distributes blood from and t o all parts of body. Rhythmic contraction and relaxation creates pressure to send blood to all parts of the body.
12. Why is it necessary to excrete waste products?
Ans.The waste products produced in various metaboli c process in our body are harmful for the body.
13. Draw a diagram of the human excretory system an d label the various parts.
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