Chapter 10. Respiration in Organisms : Science CBSE NCERT Class VII ( 7th) Exercises Solution

Chapter 10. Respiration in Organisms : Science CBSE NCERT Class VII ( 7th) Exercises Solution


1. Question : Why does an athlete breathe faster and deeper than usual after finishing the race?
Answer : The food has stored energy, which is released during respiration. Therefore, all living organisms respire to get energy from food by breathing the air.  During heavy exercise, fast running , cycling, walking for many hours or heavy weight lifting, the demand for energy is high. Therefor,  to meet the extra demand of energy, an athlete breathes faster and deeper than usual after finishing the race .



2.Question :  List the similarities and differences between aerobic and anaerobic respiration.
Answer:  
Aerobic and Anaerobic Respiration
SimilaritiesDifferences
  1. Both are necessary for  the survival of living organism.
  2. In both type of respiration, the food is broken and   energy is released for the functioning of an organism.
  3. In both type of respiration, Carbon Dioxide, Water and Energy is produced finally
  1. An aerobic respiration takes place using oxygen, inhaled in breathing, where as an anaerobic respiration requires no oxygen.
  2. In aerobic respiration , breakdown of glucose results in production of Carbon Dioxide, Water and Energy where as in anaerobic respiration, the break down of glucose first  results in Lactic Acid and energy then lactic acid break down into carbon dioxide and water.
  3. An aerobic respiration uses respiratory organs such as lungs or gills where as anaerobic respiration take place at cellular or muscular level

3. Question : Why do we often sneeze when we inhale a lot of dust-laden air?
Answer : When we inhale a lot of dust-laden air, the dust particles get trapped in the hair present in our
nasal cavity. However, sometimes these particles may get past the hair in the nasal cavity. Then they irritate the lining of the cavity, as a result of which we sneeze. Sneezing expels these foreign particles from the inhaled air and a dust free, clean air enters our body.
4.Question :  Take three test-tubes. Fill the 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?
Answer : Test tube C will have the highest concentration of CO2, as it contains both snail and plant and together they will produce greater amount of CO2 from respiration.
5. Question : Tick the correct answer:
(a) In cockroaches, air enters the body through
(i) lungs
(ii) gills
(iii) spiracles
(iv) skin
Answer :  (iii) spiracles

(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
Answer :  (ii) lactic acid

(c) Normal range of breathing rate per minute in an average adult person at rest is:
(i) 9–12
(ii) 15–18
(iii) 21–24
(iv) 30–33
Answer :  (ii) 15–18

(d) During exhalation, the ribs
(i) move outwards
(ii) move downwards
(iii) move upwards
(iv) do not move at all
Answer:(ii) move downwards
6.Question :  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
Answer : 
Column IColumn II
(a) Yeast(iii) Alcohol
(b) Diaphragm(iv) Chest cavity
(c) Skin(i) Earthworm
(d) Leaves(v) Stomata
(e) Fish(ii) Gills
(f) Frog(vi) Lungs and skin

7.Question :  Mark ‘T’ if the statement is true and ‘F’ if it is false:
(i) During heavy exercise the breathing rate of a person slows down. (F)
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (F)
(iii) Frogs breathe through their skins as well as their lungs. (T)
(iv) The fishes have lungs for respiration. (F)
(v) The size of the chest cavity increases during inhalation. (T)
9.Question :  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 diagonals. Find the words for your respiratory system. Clues about those words are given below the square.

SVMPLUNGS
CZ
G		QWXNTL
RMATIDOTC
IYRXYMSRA
BRHIANTAY
STPTBZRCE
MIAMTSIHA
SPIRACLES
NEDKJNSAT

(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

Solution : 
SVMPLUNGS
CZ
G		QWXNTL
RMATIDOTC
IYRXYMSRA
BRHIANTAY
STPTBZRCE
MIAMTSIHA
SPIRACLES
NEDKJNSAT
  Downwards :
  RIBS, NOSTRIL, YEAST

  Upwards :
   DIAPHRAGM

   Across :
   LUNGS, ANT

   Diagonally :
   STOMATA









10.Question :  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.
Answer :  (b) The amount of air available to a person is less than that available on the ground.

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Extended Learning — Activities and Projects
1. Observe fish in an aquarium. You will find flap like structures on both
sides of their heads. These are flaps which cover the gills. These flaps
open and close alternately. On the basis of these observations, explain
the process of respiration in the fish.
2. Visit a local doctor. Learn about the harmful effects of smoking. You can
also collect material on this topic from other sources. You can seek help
of your teacher or parents. Find out the percentage of people of your
area who smoke. If you have a smoker in your family, confront him with
the material that you have collected.
3. Visit a doctor. Find out about artificial respiration. Ask the doctor:
(a) When does a person need artificial respiration?
(b) Does the person need to be kept on artificial respiration temporarily or permanently?
(c) From where can the person get supply of oxygen for artificial respiration?
4. Measure the breathing rate of the members of your family and some of your friends. Investigate:
(c) If the breathing rate of children is different from that of adults.
(d) If the breathing rate of males is different from that of females.
If there is a difference in any of these cases, try to find the reason.
You can read more on the following website:
www.health.howstuffworks.com/adam-200142.htm
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Did you know?
For us oxygen is essential, but for those organisms which do not use it, oxygen is toxic. In fact, our white blood cells use oxygen to kill invading bacteria. Even for humans, it may be dangerous to breathe pure oxygen
for long.
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