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Friday, May 1, 2020

Respiration in Organisms-Class 7th-Science-Chapter 10

Respiration in Organisms-Class 7th-Science-Chapter 10

Chapter 10 - Respiration in Organisms - Class 7th - Science


Q1: Define Cellular respiration.
Ans. Cellular Respiration is defined as the process of breakdown of food in the cell with the release of energy. It takes place in the cells of all organisms.
Q2: Why does an athlete breathe faster and deeper than usual after finishing the race?
Ans. An athlete needs to supply extra energy to his muscle cells which have worked hard during running. For this, he breathes faster and deeper so that more oxygen is supplied to the cells. This speeds up the breakdown of food and as a result, more energy is released.

Q3: List the similarities and differences between aerobic and anaerobic respiration.
Ans. The similarity between aerobic and anaerobic respiration:
In both aerobic and anaerobic respiration, the food is broken down to release energy.
Differences between aerobic and anaerobic respiration:
Aerobic respiration
Anaerobic respiration
It is the process of breakdown of food in the presence of oxygen.
It is the process of breakdown of food in the absence of oxygen.
Its end products are CO2 and H2O.
End products of anaerobic respiration can be lactic acid or CO2 and alcohol.
It takes a long time to release energy.
It is a fast process as compared to aerobic respiration.
It produces a large amount of energy.
It produces a small amount of energy as compared to aerobic respiration.
Examples: It occurs in most plants and animals.
Examples: Yeast, bacteria, human muscle cells, etc. respire anaerobically.

Q4. Why do we often sneeze when we inhale a lot of dust-laden air?
Ans. Sneezing expels the foreign particles from the inhaled air so that only clean air enters our body. It usually occurs because of the irritation in the upper breathing passage. This irritation happens when we inhale some unwanted particles and they get trapped in our nasal cavity. Smoke, dust, pollen, etc. are some of the unwanted particles that may cause sneezing.
Q5: 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?
Ans.
Concentration of CO2 Test-Science 7th

Test tube A will have the highest concentration of CO2. This is because test tube A contains snail. Snail is an organism that breathes in O2 and breathes out CO2. Hence, CO2 concentration increases in test tube A. Test tube B contains a water plant, which takes in CO2 for food synthesis and gives out O2. Hence, more O2 concentration is found in test tube B. Test tube C contains both a snail and a plant. The CO2 produced by the snail is utilized by the plant for its food synthesis and the O2 released by the plant is utilized by the snail for respiration. Therefore, test tube A has the highest concentration of CO2
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Q6: Tick the correct Ans.
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 √
ii. Alcohol
(iv) water
Ans. (ii) Lactic Acid
(c) The 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
Q7: Match the items in Column I with those in Column II:
Ans.
Column I
Column 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

Q8: Mark ‘T’ if the statement is true and ‘F’ if it is false:
Ans. (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)
Q9: 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.
Ans.
(i) Trachea
(ii) Ribs
(iii) Diaphragm
(iv) Stomata
(v) Spiracles
(vi) Lungs
(vii) Nostrils
(viii) Yeast
Q10: 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 the air is higher than that on the ground.
(d) The pressure of air is higher than that on the ground.

Ans. 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 the air is higher than that on the ground.
(d) The pressure of air is higher than that on the ground.
Q11: Give two examples of each of the following:
(1). Animals that breathe through gills
Ans. Fish, Tadpole
(2). Animals that breathe through spiracles
Ans. Cockroach, Butterfly
(3). Animals that breathe through skin
Ans. Earthworm, Frog


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