- Match the structures to its respective functions:
|Column I||Column II|
(3) Root hairs
(i) Absorption of water
(iii) Transport of food
(iv) Transport of water
(v) Synthesis of carbohydrates
|Column I||Column II|
(3) Root hairs
(ii) Transport of water
(iii) Absorption of water
(iv) Transport of food
- Fill the Blanks:
(i) The blood pumped by the heart is transported to all parts of the body by the _______.
(ii) Hemoglobin is present in _______ cells.
(iii) Vein and Arteries are joined by a network of _______.
(iv) The rhythmic expansion and contraction of heart is called _______.
(v) The main excretory product of human beings is _______.
(vi) Sweat constitutes of _______ and salt.
(vii) Kidneys eliminate the waste materials in the liquid form called _______.
(viii) Water is able to reach the top of the trees because of the suction pull caused by _______.
Ans. (i) arteries (ii) red blood cells (iii) capillaries (iv) heart beat (v) urea (vi) salts (vii) urine (viii) transpiration.
- Multiple choice questions:
(i) Water is transported in plants through
(a)Xylem (b) Phloem (c) Stomata (d) Root hair
Ans: (a) Xylem
(ii)Water absorption through roots will increase by keeping the plants
(a) In the shade (b) in dim light (c) under the fan (d) covered with a polythene bag
Ans: (c) Under the fan
- Why is the transport of materials necessary in a plant or an animal? Explain.
Ans. Transport of materials is essential for both plants and animals because it is the only way through which nutrients and oxygen are made available to all parts of the body. If in any case, the transport of the necessary nutrients and oxygen does not reach all parts of the body, then the body will not be able to survive.
- What would happen if there are no platelets in the blood?
Ans. The blood platelets are responsible for clotting of blood in case of an injury or a scratch. As we know, when an injury, occurs the blood starts flowing for a while and then it clots on its own. If in any case there are no platelets, the blood will not be able to clot and keeps on flowing. Huge loss of blood will ultimately lead to death.
- What are stomata? Give two functions of stomata.
Ans. The lower surfaces of the leaves have small openings. These openings or pores are called stomata. These pores are surrounded by guard cells.
Functions of stomata:
(i) It helps to eliminate excess water from the plant i.e, Transpiration
(ii) The process of loss of water from stomata will cause an upward pull, i.e. suction pull which in turn helps in absorption of water from roots.
(iii) They are responsible for the exchange of gases.
- What are the useful functions of transpiration in plants?
Ans. (i) By creating a suction pull, it enhances the absorption of dissolved minerals and water in the plants.
(ii) It gets rid of the excess water in plants.
(iii) It transports of minerals and water to leaves. Ye leaves use the water to carry out photosynthesis.
(iv) It creates a cooling effect in plants.
- What are the constituents of blood?
Ans. Blood constitutes of four main components:
(i) Plasma: It is the liquid part of the blood which is in yellowish color and contains 90% water. It also contains enzymes, food, proteins and other wastes.
(ii) Red Blood Cells: They are disc-shaped cells containing a red colored pigment called hemoglobin in it. Hemoglobin helps in transportation of oxygen.
(iii) White Blood Cells: These are the fighting cells and are also called as warrior cells which protect us from infections caused by bacteria and foreign materials.
(iv) Platelets: The platelets help in clotting of the blood.
- Why is blood very essential for proper functioning of all parts of the body?
Ans. Blood is essential for the functioning of all parts of the body as it contains digested food and oxygen in it. The main function of the blood is to supply the digested food and oxygen to various parts of the body to provide essential energy to them which helps the body to perform various functions.
- Why is blood red in color?
Ans. Hemoglobin present in blood is a red pigment. This pigment is responsible for the carrying oxygen to various parts of the body through blood.
- Explain the functions of the heart.
Ans. The blood with carbon dioxide from all parts of the body is received by the right auricle and ventricle. The impure blood which is collected, is pumped to the lungs for the purification. In lungs, the purification process takes place by exchanging the gases and the purified blood is sent back to the left auricle. Then it pumps the blood to the left ventricle, which finally pumps the purified blood to all parts of the body through arteries.
- Why is excretion of waste products necessary?
Ans. During the functioning of the body certain waste and toxic products are formed. For example urea etc.are toxic. When these toxic materials are not removed from the body, they get mixed with blood and can damage the cells present in the body. So, It is essential to remove such poisonous waste materials from our body.
- Sketch the human excretory system and label various parts.
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To score good marks in the examination students should also practice class 7 previous year science question papers and sample papers. Solving previous year questions papers and sample papers will help the students to know about the types of questions asked in the examination and the marking scheme.
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