Why do we often sneeze when we inhale a lot of dust-laden air?

3

(a)

Take three test tubes. Fill 3/4th of each with water. Label them A, B and C. Keep a snail in test tube A, a water-plant in test tube B and in C, keep snail and plant both. Which test tube would have the highest concentration of CO₂?

3

(a)

Pick the odd one out from each of the groups given below on the basis of respiratory organs. Give reason for your answer.
(a) Cockroach, grasshopper, snail, ant
(b) Lizard, cow, earthworm, snake
(c) Crocodile, whale, dolphin, fish
(d) Snake, tadpole, crow, goat

3

(a)

After we work hard or perform physical activity, we feel hungry. Explain why

3

(a)

Observe the given figures carefully and answer the following questions.
(a) The amount of CO₂ be the highest in which jar. Why?
(b) The amount of CO₂ be the lowest in which one and why?

3

(a)

Observe the given diagram of human respiratory system. List the organs from (A) to (G).

3

(a)

Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction upwards, downwards or along the diagonal structures surrounding chest cavity
(iii) Muscular floor of chest cavity
(iv) Tiny pores on the surface of leaf
(v) Small openings on the sides of the body of an insect
(vi) The respiratory organs of human beings
(vii) The openings through which we inhale
(viii) An anaerobic organism
(ix) An organism with tracheal system

3

(a)

Explain an anaerobic respiration in yeast and in our muscles

3

(a)

Explain the respiratory system in humans.

3

(a)

After coming from football match Ravi had cramping in his leg muscles. His father Mr. Sharma who is a physical trainer in his school advised him to take hot water bath
On this situation answer the following questions:
(i) Why do we get muscle cramps after heavy exercise?
(ii) How far the advice given by Ravi's father is effective?
(iii) Which value is shown by Mr. Sharma?

3

(a)