Take three test-tubes. Fill æth of | Class 7 Science Chapter Respiration in Organisms, Respiration in Organisms NCERT Solutions

Why does an athlete breathe faster and deeper than usual after finishing the race?

The mountaineers carry oxygen with them because:

(a) At an altitude of more than 5 km there is no air.
(b) The amount of air available to a person is less than that available on the ground.
(c) The temperature of air is higher than that on the ground.
(d) The pressure of air is higher than that on the ground.

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

Match the items in Column I with those in Column II:
Column I                             Column II
(a) Yeast                             (i) Earthworm
(b) Diaphragm                    (ii) Gills
(c) Skin                               (iii) Alcohol
(d) Leaves                          (iv) Chest cavity
(e) Fish                               (v) Stomata
(f) Frog                               (vi) Lungs and skin
                                           (vii) Tracheae

List the similarities and differences between aerobic and anaerobic respiration.

Tick the correct answer:
(a) In cockroaches, air enters the body through
(i) lungs               (ii) gills
(iii) spiracles        (iv) skin

(b) During heavy exercise, we get cramps in the legs due to the accumulation of
(i) carbon dioxide       (ii) lactic acid
(iii) alcohol                 (iv) water

(c) Normal range of breathing rate per minute in an average adult person at rest is:
(i) 9ñ12                 (ii) 15ñ18
(iii) 21ñ24              (iv) 30ñ33

(d) During exhalation, the ribs
(i) move outwards         (ii) move downwards
(iii) move upwards        (iv) do not move at all

Mark ëTí if the statement is true and ëFí if it is false:

(i) During heavy exercise the breathing rate of a person slows down. (T/F)
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)
(iii) Frogs breathe through their skins as well as their lungs. (T/F)
(iv) The fishes have lungs for respiration. (T/F)
(v) The size of the chest cavity increases during inhalation. (T/F)

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 ó upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square.

(i) The air tubes of insects
(ii) Skeletal 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

Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food

Here is a crossword puzzle: Good luck!

Across
3. Liquid waste products
4. Solid waste extracted in sewage treatment
6. A word related to hygiene
8. Waste matter discharged from human body

Down
1. Used water
2. A pipe carrying sewage
5. Micro-organisms which causes cholera
7. A chemical to disinfect water

Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down                                               Across
(D) 1 : Thorough washing           (A) 1 : Keeps warm
      2 : Animal fibre                            2 : Its leaves are eaten by silkworms
      3 : Long thread like structure      3 : Hatches from egg of moth

Sketch the cross section of soil and label the various layers.

Solve the following crossword puzzle with the clues given:

Across
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.

Down
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.

Sketch the reproductive parts of a flower.

Describe how crystals of copper sulphate are prepared.

Write one similarity and one difference between the nutrition in amoeba and human beings.

Match the following :
(i) Land breeze blows during                                  (a) summer
(ii) Sea breeze blows during                                   (b) winter
(iii) Dark coloured clothes are preferred during      (c) day
(iv) Light coloured clothes are preferred during      (d) night

When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.

What are the components of blood?

Name the source from which litmus solution is obtained. What is the use of this solution?

Classify the following as motion along a straight line, circular or oscillatory motion:

(i) Motion of your hands while running.
(ii) Motion of a horse pulling a cart on a straight road.
(iii) Motion of a child in a merry-go-round.
(iv) Motion of a child on a see-saw.
(v) Motion of the hammer of an electric bell.
(vi) Motion of a train on a straight bridge.

Match the items given in Column I with those in Column II:
Column I                          Column II
Chlorophyll                       Bacteria
Nitrogen                            Heterotrophs
Amarbel                            Pitcher plant
Animals                             Leaf
Insects                              Parasite

How do elephant living in the tropical rainforest adapt itself?

Out of the following, which are the two terms related to silk production? Sericulture, floriculture, moriculture, apiculture and silviculture.

Hints:
(i) Silk production involves cultivation of mulberry leaves and rearing silkworms.
(ii) Scientific name of mulberry is Morus alba.

A simple pendulum takes 32 s to complete 20 oscillations. What is the time period of the pendulum?

Describe how crystals of copper sulphate are prepared.

The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder it exist as a liquid. When it comes out from the cylinder it
becomes a gas (Change – A) then it burns (Change – B). The following statements pertain to these changes. Choose the correct one.

(i) Process – A is a chemical change.
(ii) Process – B is a chemical change.
(iii) Both processes A and B are chemical changes.
(iv) None of these processes is a chemical change.

Can we survive only on raw, leafy vegetables/grass? Discuss.