Questions are taken verbatim from the NCERT textbook; answers were grounded against the chapter's content during generation. Items needing review are marked.
Your Progress - Chapter 60% complete
1Exercises8 questions
Q.1Why does an athlete breathe faster and deeper than usual after finishing the race?v
Answer:During a race, the athlete's muscles need much more energy, so the body needs more oxygen to break down food and release energy. Faster and deeper breathing supplies extra oxygen and removes extra carbon dioxide. It also helps oxidise lactic acid formed in muscles during heavy exercise.
Q.2List the similarities and differences between aerobic and anaerobic respiration.v
Answer:Similarity: both aerobic and anaerobic respiration break down food inside cells to release energy. Differences: aerobic respiration occurs in the presence of oxygen and produces carbon dioxide, water and a large amount of energy. Anaerobic respiration occurs without oxygen and produces less energy; in yeast it forms alcohol and carbon dioxide, while in muscles it can form lactic acid.
Q.3Why do we often sneeze when we inhale a lot of dust-laden air?v
Answer:Dust particles irritate the lining of the nasal cavity. Sneezing is a reflex action that forcefully expels air and helps remove these unwanted particles from the nose.
Q.4Take 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?v
Answer:Test-tube A would have the highest concentration of carbon dioxide. The snail respires and releases carbon dioxide. In test-tube B, the plant uses carbon dioxide during photosynthesis. In test-tube C, the plant uses some of the carbon dioxide released by the snail.
Q.5Tick 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) 9-12 (ii) 15-18 (iii) 21-24 (iv) 30-33
(d) During exhalation, the ribs
(i) move outwards (ii) move downwards (iii) move upwards (iv) do not move at allv
- a. lungs / gills / spiracles / skin
- b. CO2 / lactic acid / alcohol / water
- c. 9-12 / 15-18 / 21-24 / 30-33
- d. outwards / downwards / upwards / no movement
Answer:(a) (iii) spiracles
(b) (ii) lactic acid
(c) (ii) 15-18
(d) (ii) move downwards
Q.6Match the items in Column I with those in Column II:
Column I: Yeast, Diaphragm, Skin, Leaves, Fish, Frog. Column II: Earthworm, Gills, Alcohol, Chest cavity, Stomata, Lungs and skin.v
Answer:Yeast - Alcohol; Diaphragm - Chest cavity; Skin - Earthworm; Leaves - Stomata; Fish - Gills; Frog - Lungs and skin.
Q.7Mark 'T' if the statement is true and 'F' if it is false:
(a) During heavy exercise the breathing rate of a person slows down. (T/F)
(b) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)
(c) Frogs breathe through their skins as well as their lungs. (T/F)
(d) The fishes have lungs for respiration. (T/F)
(e) The size of the chest cavity increases during inhalation. (T/F)v
SolutionBreathing rate increases during exercise. Plants respire throughout day and night, though photosynthesis occurs in light. Frogs use both skin and lungs. Fish breathe through gills. During inhalation, the chest cavity expands.
Answer:(a) F
(b) F
(c) T
(d) F
(e) T
Q.9The mountaineers carry oxygen with them because:v
Answer:At high altitudes, the air is thinner and contains less available oxygen. Mountaineers carry oxygen cylinders so that their bodies can get enough oxygen for respiration.