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7th Grade > Biology

RESPIRATION IN ORGANISMS MCQs

Total Questions : 96 | Page 1 of 10 pages
Question 1. Smoking mainly damages which of the following organs?
  1.    Kidney
  2.    Brain
  3.    Lungs  
  4.    Liver 
 Discuss Question
Answer: Option C. -> Lungs  
:
C
Lungs get seriously damaged by smoking. Cigarette smoke contains chemicals such as tar and nicotine which heavily damage the alveoli. Long term smoking also increases the riskof cardiovascular diseases.
Question 2. What is the percentage of oxygen in inhaled and exhaled air? [2 MARKS]
 Discuss Question

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Percentage of oxygen: 1 Mark each
Percentage of oxygen in inhaled air is 21.
Percentage of oxygen in exhaled air is 16.4.
Question 3. Take three test tubes and label them as A, B and C. Fill 34th of each with water. Keep a snail in test tube A, a water plant in test tube B and in C, keep both snail and plant. In which of these test tubes CO2 (carbon dioxide) level will be higher? What does this experiment show? Explain what happens in each test tube separately. [5 MARKS]
 
 Discuss Question

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Observations: 1 Mark each
1. Test tube A will have the highest concentration of CO2.
2. The experiment shows respiration inanimals and plants.
3. Test tube A: During breathing, thesnail inhales dissolved oxygen from water and releasesCO2.
4. Test tube B: The water plants along with respiration performs photosynthesis (food preparation); therefore it absorbs CO2 and releases O2.
5. Test tube C: The CO2 released by the snail will be usedby the plantfor photosynthesis, thus there will be a balance of gases.
Question 4. The product of anaerobic respiration in muscles is:
  1.    Alcohol   
  2.    Lactic acid 
  3.    Water         
  4.    Carbon dioxide    
 Discuss Question
Answer: Option B. -> Lactic acid 
:
B
Our muscles generally respire aerobically. During heavy exercises, the demand for energy in these cells arehigh butthe supply of oxygen to produce energy is limited. In such situations, the muscle cells turn toanaerobic respirationto fulfil the energy demands. The anaerobic breakdown of glucose produces lactic acid in muscles.
Question 5. Which gas is used during the process of aerobic cellular respiration?
  1.    Oxygen
  2.    Carbon dioxide
  3.    Nitrogen
  4.    Carbon monoxide
 Discuss Question
Answer: Option A. -> Oxygen
:
A
Oxygen is required during the process of aerobic cellular respiration in the cell. Aerobic respiration is a process which utilises oxygen to breakdown glucose into carbon dioxide and water and release energy in the form of ATP.
It can be summarised as:
C6H12O6+6O26CO2+6H2O+38ATP
Question 6. What are the two steps of breathing? [2 MARKS]
 Discuss Question

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Steps: 1 Mark each
The two steps of breathing are - inhalation and exhalation.
Inhalationis the action of intake of air into the lungs from the atmosphere.
Exhalationis the action of moving air from the lungs into the atmosphere.
Question 7. What is cellular respiration? What are 2 types of cellular respiration?[3 MARKS]
 Discuss Question

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Types: 1 Mark each
Cellsneed a source ofenergy.Theygetthisenergyby breaking down glucose obtained from the food. This process is called 'cellular respiration'.
There are 2 types of cellular respiration -
During aerobic respiration, glucose is broken downinto carbon dioxide and water in the presence of oxygen to release energy.
Duringanaerobic respiration,glucose is broken downinto alcohol andcarbon dioxidein the absence of oxygen to release a little bit of energy.
Question 8. Name the chemical used to test the presence of CO2 in exhaled air. [1 MARK]
 
 Discuss Question

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Calcium hydroxide (chemical name forlimewater) reacts withcarbon dioxide in the exhaled air to form calcium carbonate which is insoluble in water and thus forms a milky white precipitate.
Question 9. State whether the following statements are true or false. Justify your statement.  [5 MARKS]
(1) During heavy exercise, the breathing rate of a person slows down.
(2) Plants carry out photosynthesis only during the day and respiration only at night.
(3) Frogs breathe through their skin as well as their lungs.
(4) At high altitudes, the lower air pressure makes it more difficult for oxygen to enter our respiratory systems.
(5) Glucose breaks down into lactic acid in the absence of oxygen.
 Discuss Question

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Statement and justification: 1 Mark each
(1)False. During heavy exercise, more oxygen is required to meet extra demand of energy. Therefore breathing rate increases.
(2)False. Photosynthesis occurs in the presence of sunlight. Respiration is a continuous process and occurs all the time (day and night).
(3)True. Frogs breathe through skin as well as through lungs. Thus they have moist-slippery skin and lungs to help them breathe on both land and water.
(4) True.Athigh altitudes, thelower air pressuremakes it more difficult foroxygento enter our respiratorysystems. That is why mountaineers carry oxygen with them.
(5)True. Muscle cells break down glucose into lactic acidwith the release of energy in the absence oxygen during heavy activities. This process is called anaerobic respiration.
Question 10. Our body needs food to produce ______.
  1.    carbon dioxde
  2.    water   
  3.    energy
  4.    oxygen 
 Discuss Question
Answer: Option C. -> energy
:
C
The food we eat is digested into smaller particles. The nutrients like carbohydrates, proteins, fats, vitamins and minerals are absorbed into the blood which transports it to all parts of the body. Of these nutrients,glucose is taken up by cells and broken down to produce carbon dioxide and water with the release of energy. This energy is used to carry out all life processes. Carbon dioxide that is produced during this process is expelled out of the body during exhalation.

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