NCERT Class 7 Science Tenth Chapter Respiration in Organisms Exercise Solutions
Respiration in Organisms
What is called cells?
Ans. Small microscopic units called cells.
Define cellular respiration.
Ans. The process of breakdown of food in the cell with the release of energy is called cellular respiration.
What is called aerobic respiration?
Ans. When breakdown of glucose occurs with the use of oxygen it is called aerobic respiration.
Define anaerobic respiration.
Ans. Food can also be broken down, without using oxygen. This is called anaerobic respiration.
Define anaerobes.
Ans. There are some organisms such as yeast that can survive in the absence of air. They are called anaerobes.
Why you get muscle cramps after heavy exercise?
Ans. The cramps occur when muscle cells respire anaerobically. The partial breakdown of glucose produces lactic acid. The accumulation of lactic acid causes muscle cramps.
What is called inhalation.
Ans. The taking in of air rich in oxygen into the body is called inhalation.
What is called exhalation.
Ans. Giving out of air rich in carbon dioxide is known as exhalation.
Define breathing rate.
Ans. The number of times a person breathes in a minute is termed as the breathing rate.
What is the average breathing rate of an adult human being at rest?
Ans.15–18 times.
What is called diaphragm?
Ans. Chest cavity is surrounded by ribs on the sides. A large, muscular sheet called diaphragm.
What is called spiracles?
Ans. A cockroach has small openings on the sides of its body. Other insects also have similar openings. These openings are called spiracles.
What is called tracheae?
Ans. Insects have a network of air tubes called tracheae.
What is called stomata?
Ans. In a plant the roots take in air present in the soil. Leaves have tiny pores called stomata.
Name one single celled organism.
Ans. Yeast.
When we sneeze, why we should cover our nose?
Ans. When we sneeze, we should cover our nose so that the foreign particles we expel are not inhaled by other persons.
Why Smoking is harmful to us?
Ans. Smoking damages lungs. Smoking is also linked to cancer. It must be avoided.
Exercise Questions with Answers:
(1) Why does an athlete breathe faster and deeper than usual after finishing the race?
Ans. During heavy exercise, fast running the demand for energy is high. But the supply of oxygen to produce the energy is limited. Then anaerobic respiration takes places in the muscle cells to fulfil the demand of energy. Thats why, an athlete breathe faster and deeper than usual after finishing the race.
(2) List the similarities and differences between aerobic and anaerobic respiration.
Ans. The Similarities between aerobic and anaerobic respiration are:
(I) In Both’s food is broken down to release energy.
(II) In both aerobic and anaerobic respiration, takes place in cells.
The difference between aerobic and anaerobic respiration are as follows:
Aerobic respiration | Anaerobic respiration |
When breakdown of glucose occurs with the use of oxygen it is called aerobic respiration.
Example: Human being. |
Food can also be broken down, without using oxygen. This is called anaerobic respiration.
Example: Yeast. |
(3) Why do we often sneeze when we inhale a lot of dust-laden air?
Ans. When we inhale, the particles get trapped in the hair present in our nasal cavity. However, sometimes these particles may get past the hair in the nasal cavity. This may irritate the lining of the cavity, as a result of which we sneeze.
(4) Take three test-tubes. Fill ¾th 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?
Ans. In test tube A, the concentration of CO2 will be highest since the snail will release carbon dioxide during its respiration.
In test tube B, the concentration of CO2 will be very less because the plant will utilise the carbon dioxide to prepare food by photosynthesis.
In test tube C, the concentration of CO2 will be less because the carbon dioxide released by the snail during respiration will be taken in by the plant.
(5) Tick the correct answer:
(a) In cockroaches, air enters the body through
(i) lungs
(ii) gills
(iii) spiracles
(iv) skin
Ans. (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
Ans. (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
Ans. (ii) 15–18
(d) During exhalation, the ribs
(i) move outwards
(ii) move downwards
(iii) move upwards
(iv) do not move at all
Ans. (ii) move downwards
(6) 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
Ans:
(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) 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. (T/F)
Ans. False.
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)
Ans. False.
(iii) Frogs breathe through their skins as well as their lungs. (T/F)
Ans. True.
(iv) The fishes have lungs for respiration. (T/F)
Ans. False.
(v) The size of the chest cavity increases during inhalation. (T/F)
Ans. True.
(8) 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.
(i) The air tubes of insects >>> Trachea
(ii) Skeletal structures surrounding chest cavity >>> Ribs
(iii) Muscular floor of chest cavity >>> Diaphragm
(iv) Tiny pores on the surface of leaf >>> Stomata
(v) Small openings on the sides of the body of an insect >>> Spiracles
(vi) The respiratory organs of human beings >>> Lungs
(vii) The openings through which we inhale >>> Nostrils
(viii) An anaerobic organism >>> Yeast
(ix) An organism with tracheal system >>> Ant
(9) 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.
Ans. (b) The amount of air available to a person is less than that available on the ground.