Best 100 MCQs on Respiration in Organisms

Best 100 MCQs on Respiration in Organisms. These 100 Multiple Choice Questions with Answer and Explanation will help you score full marks in your class 7 Science (Biology) exam.

Introduction MCQs on Respiration in Organisms (MCQs 1 to 25) – MCQs on Respiration in Organisms

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1. Why is respiration essential for all living organisms?

a) To produce food

b) To release energy from food

c) To create oxygen

d) To regulate body temperature

2. Respiration can be defined as the process of:

a) Taking in oxygen and releasing carbon dioxide

b) Converting sunlight into food

c) Releasing energy from food

d) Transporting nutrients throughout the body

3. Most organisms rely on which type of respiration?

a) Anaerobic respiration

b) Aerobic respiration

c) Photosynthesis

d) Chemosynthesis

4. Which gas is crucial for aerobic respiration?

a) Carbon dioxide

b) Nitrogen

c) Oxygen

d) Hydrogen

5. Some organisms can survive without oxygen through:

a) Anaerobic respiration

b) Aerobic respiration

c) Fermentation

d) Both a) and c)

6. The energy released during respiration is stored in the form of:

a) ATP (Adenosine Triphosphate)

b) Glucose

c) Carbon dioxide

d) Water

7. The process of breaking down glucose in the presence of oxygen is called:

a) Glycolysis

b) Krebs cycle

c) Electron transport chain

d) Cellular respiration

8. The first step in both aerobic and anaerobic respiration is:

a) Krebs cycle

b) Electron transport chain

c) Glycolysis

d) Fermentation

9. Where does the Krebs cycle take place in eukaryotic cells?

a) Cytoplasm

b) Mitochondria

c) Nucleus

d) Ribosomes

100 MCQs on Respiration in Organisms

10. The final stage of aerobic respiration, producing the most ATP, is:

a) Glycolysis

b) Krebs cycle

c) Electron transport chain

d) Fermentation

11. Which of the following is NOT a product of aerobic respiration?

a) Carbon dioxide

b) Water

c) ATP

d) Oxygen

12. Anaerobic respiration in humans leads to the production of:

a) Lactic acid

b) Ethanol

c) Carbon dioxide

d) Water

13. Yeast cells undergo fermentation to produce:

a) Lactic acid

b) Ethanol and carbon dioxide

c) Oxygen

d) ATP only

14. The energy yield from anaerobic respiration is __________ compared to aerobic respiration.

a) Much higher

b) Slightly higher

c) Much lower

d) The same

15. The breathing process in humans involves:

a) Inhalation and exhalation

b) Gas exchange in the lungs

c) Transport of gases in the blood

d) All of the above

16. The tiny air sacs in the lungs where gas exchange occurs are called:

a) Alveoli

b) Bronchi

c) Trachea

d) Diaphragm

17. Which respiratory organ is responsible for voice production in humans?

a) Larynx

b) Pharynx

c) Trachea

d) Lungs

18. The respiratory system in fish utilizes:

a) Lungs

b) Gills

c) Skin

d) Tracheae

19. Insects breathe through a network of tubes called:

a) Tracheae

b) Gills

c) Lungs

d) Skin

20. Plants exchange gases through tiny pores on their leaves called:

a) Stomata

b) Lenticels

c) Guard cells

d) Trichomes

100 MCQs on Respiration in Organisms

21. The process by which plants release water vapor into the atmosphere is called:

a) Respiration

b) Transpiration

c) Photosynthesis

d) Evaporation

22. Respiration in plants occurs:

a) Only during the day

b) Only during the night

c) Both day and night

d) Only in the presence of sunlight

23. The overall chemical equation for aerobic respiration is:

a) C6H12O6 + 6O2 → 6CO2 + 6H2O + energy

b) 6CO2 + 6H2O + energy → C6H12O6 + 6O2

c) C6H12O6 → 2C2H5OH + 2CO2 + energy

d) 2C2H5OH + 2CO2 + energy → C6H12O6

24. Which of the following is an adaptation for respiration in aquatic plants?

a) Large leaves

b) Air spaces in stems and roots

c) Thick cuticle

d) Deep roots

25. The rate of respiration is influenced by:

a) Temperature

b) Oxygen availability

c) Activity level

d) All of the above

MCQs on Types of Respiration (26-50) – MCQs on Respiration in Organisms

500 MCQ Class 10 History

26. Aerobic respiration is the process where:

a) Glucose is broken down in the absence of oxygen

b) Energy is released from food without the need for oxygen

c) Glucose is broken down in the presence of oxygen to release energy

d) Carbon dioxide is converted into glucose

27. The primary products of aerobic respiration are:

a) Oxygen, water, and energy

b) Carbon dioxide, water, and energy

c) Glucose, oxygen, and water

d) Lactic acid, carbon dioxide, and energy

28. Which of the following statements is true about aerobic respiration?

a) It is less efficient than anaerobic respiration

b) It produces a small amount of ATP

c) It occurs in the cytoplasm of the cell

d) It is the primary energy-producing pathway in most organisms

29. The cellular organelle responsible for aerobic respiration is the:

a) Nucleus

b) Ribosome

c) Mitochondrion

d) Chloroplast

30. The energy currency of cells, produced in large quantities during aerobic respiration, is:

a) Glucose

b) ATP

c) Carbon dioxide

d) Water

100 MCQs on Respiration in Organisms

31. Anaerobic respiration is a process where:

a) Glucose is broken down in the presence of oxygen

b) Energy is released from food without the need for oxygen

c) Carbon dioxide is converted into glucose

d) Oxygen is produced as a byproduct

32. Compared to aerobic respiration, anaerobic respiration:

a) Produces more ATP

b) Produces less ATP

c) Produces the same amount of ATP

d) Does not produce any ATP

33. Which of the following organisms can perform anaerobic respiration?

a) Bacteria

b) Yeast

c) Muscle cells during intense activity

d) All of the above

34. The byproducts of anaerobic respiration can include:

a) Lactic acid

b) Ethanol (alcohol)

c) Carbon dioxide

d) All of the above

35. In humans, anaerobic respiration in muscle cells leads to the production of:

a) Lactic acid

b) Ethanol

c) Carbon dioxide only

d) Water only

36. Yeast cells utilize anaerobic respiration (fermentation) to produce:

a) Lactic acid and carbon dioxide

b) Ethanol and carbon dioxide

c) Oxygen and water

d) ATP only

37. Which of the following is NOT an advantage of anaerobic respiration?

a) Allows survival in oxygen-depleted environments

b) Enables rapid energy production during intense activity

c) Produces a large amount of ATP

d) Can be utilized by a variety of organisms

38. The first step in both aerobic and anaerobic respiration is:

a) Krebs cycle

b) Electron transport chain

c) Glycolysis

d) Fermentation

39. The fate of pyruvate in aerobic respiration is to:

a) Be converted into lactic acid

b) Enter the Krebs cycle

c) Be converted into ethanol

d) Be excreted from the cell

40. In anaerobic respiration, pyruvate is converted into:

a) Lactic acid or ethanol, depending on the organism

b) Acetyl-CoA

c) Carbon dioxide and water

d) ATP directly

100 MCQs on Respiration in Organisms

41. The electron transport chain, a crucial part of aerobic respiration, occurs in the:

a) Cytoplasm

b) Inner mitochondrial membrane

c) Outer mitochondrial membrane

d) Nucleus

42. The final electron acceptor in the electron transport chain of aerobic respiration is:

a) Oxygen

b) Carbon dioxide

c) Water

d) NADH

43. Which stage of aerobic respiration produces the most ATP?

a) Glycolysis

b) Krebs cycle

c) Electron transport chain

d) Pyruvate oxidation

44. The net gain of ATP molecules from one glucose molecule in aerobic respiration is approximately:

a) 2 ATP

b) 32 ATP

c) 38 ATP

d) 100 ATP

45. In anaerobic respiration, the net gain of ATP molecules from one glucose molecule is:

a) 2 ATP

b) 32 ATP

c) 38 ATP

d) 100 ATP

46. Which of the following is an example of fermentation in food production?

a) Baking bread

b) Brewing beer

c) Making yogurt

d) All of the above

47. The buildup of lactic acid in muscles during intense exercise can cause:

a) Muscle cramps and fatigue

b) Increased energy levels

c) Improved muscle performance

d) Enhanced oxygen uptake

48. The process of converting lactic acid back into glucose in the liver is called:

a) Glycolysis

b) Cori cycle

c) Krebs cycle

d) Fermentation

49. Some bacteria can utilize inorganic compounds like sulfur or iron as energy sources in a process called:

a) Chemosynthesis

b) Photosynthesis

c) Anaerobic respiration

d) Fermentation

50. The diversity of respiratory pathways across different organisms reflects:

a) The adaptability of life to various environments

b) The evolutionary history of different groups

c) The importance of energy production for survival

d) All of the above

100 MCQs on Respiration in Organisms

MCQs on Respiration in Different Organisms (51-75) – MCQs on Respiration in Organisms

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Humans and Animals

51. The main organs of respiration in humans are the:

a) Heart and blood vessels

b) Lungs and diaphragm

c) Stomach and intestines

d) Kidneys and bladder

52. The tube that connects the mouth and nose to the lungs is called the:

a) Esophagus

b) Trachea

c) Bronchi

d) Alveoli

53. The trachea branches into two tubes called:

a) Bronchioles

b) Alveoli

c) Bronchi

d) Capillaries

54. The tiny air sacs in the lungs where gas exchange takes place are the:

a) Bronchioles

b) Alveoli

c) Bronchi

d) Capillaries

55. The process of taking air into the lungs is called:

a) Exhalation

b) Inhalation

c) Respiration

d) Ventilation

56. During exhalation, the diaphragm:

a) Contracts and moves upward

b) Relaxes and moves upward

c) Contracts and moves downward

d) Relaxes and moves downward

57. Gas exchange in the lungs occurs by:

a) Diffusion

b) Active transport

c) Osmosis

d) Filtration

58. The oxygen-carrying protein in red blood cells is:

a) Hemoglobin

b) Myoglobin

c) Albumin

d) Fibrinogen

59. Fish breathe through specialized organs called:

a) Lungs

b) Gills

c) Tracheae

d) Skin

60. Insects have a network of tubes called __________ for respiration.

a) Gills

b) Lungs

c) Tracheae

d) Alveoli

Plants

61. The process by which plants make their own food using sunlight is called:

a) Respiration

b) Photosynthesis

c) Transpiration

d) Fermentation

62. The green pigment essential for photosynthesis is:

a) Chlorophyll

b) Carotenoid

c) Anthocyanin

d) Xanthophyll

63. The reactants of photosynthesis are:

a) Carbon dioxide and water

b) Glucose and oxygen

c) Sunlight and chlorophyll

d) ATP and NADPH

64. The products of photosynthesis are:

a) Carbon dioxide and water

b) Glucose and oxygen

c) Sunlight and chlorophyll

d) ATP and NADPH

65. Photosynthesis occurs in the __________ of plant cells.

a) Mitochondria

b) Chloroplasts

c) Vacuoles

d) Nucleus

100 MCQs on Respiration in Organisms

66. Plants also respire to:

a) Release energy from stored food

b) Produce oxygen

c) Take in carbon dioxide

d) Make their own food

67. The tiny pores on leaves that facilitate gas exchange are called:

a) Stomata

b) Lenticels

c) Guard cells

d) Trichomes

68. Stomata are usually open during the:

a) Day

b) Night

c) Both day and night

d) Only when the plant is wilting

69. The cells that control the opening and closing of stomata are called:

a) Guard cells

b) Epidermal cells

c) Mesophyll cells

d) Palisade cells

70. Which of the following factors does NOT affect the opening and closing of stomata?

a) Light intensity

b) Carbon dioxide concentration

c) Water availability

d) Soil pH

71. The process of water loss from plants through stomata is called:

a) Respiration

b) Photosynthesis

c) Transpiration

d) Evaporation

72. Lenticels are small pores found on the:

a) Leaves

b) Stems and roots

c) Flowers

d) Seeds

73. Plants primarily exchange gases during:

a) Respiration only

b) Photosynthesis only

c) Both respiration and photosynthesis

d) Neither respiration nor photosynthesis

74. The balance between photosynthesis and respiration in plants is crucial for:

a) Maintaining atmospheric oxygen and carbon dioxide levels

b) Providing food for other organisms

c) Regulating the global climate

d) All of the above

75. The amazing diversity of respiratory adaptations in organisms showcases:

a) The power of evolution to solve challenges

b) The interconnectedness of life on Earth

c) The beauty and complexity of the natural world

d) All of the above

100 MCQs on Respiration in Organisms

MCQs on Factors Affecting Respiration (76-90) – MCQs on Respiration in Organisms

Temperature

76. How does an increase in temperature generally affect the rate of respiration?

a) It decreases the rate of respiration

b) It has no effect on the rate of respiration

c) It increases the rate of respiration

d) It initially increases, then decreases the rate of respiration

77. In ectothermic animals like reptiles, how does a decrease in environmental temperature affect their respiration rate?

a) It increases their respiration rate

b) It decreases their respiration rate

c) It has no effect on their respiration rate

d) It causes them to switch to anaerobic respiration

78. Why do warm-blooded animals like mammals maintain a relatively constant body temperature?

a) To conserve energy

b) To optimize enzyme activity and metabolic processes

c) To avoid overheating

d) To adapt to their environment

79. Which of the following situations would likely lead to an increased respiration rate in humans?

a) Sitting quietly and reading a book

b) Sleeping soundly at night

c) Running a marathon

d) Meditating in a calm environment

80. How does fever affect the respiration rate?

a) It decreases the respiration rate

b) It has no effect on the respiration rate

c) It increases the respiration rate

d) It causes irregular breathing patterns

Oxygen Availability – 100 MCQs on Respiration in Organisms

81. What happens to the rate of aerobic respiration when oxygen levels decrease?

a) It increases

b) It decreases

c) It remains the same

d) It becomes erratic

82. In conditions of low oxygen availability, some organisms can switch to:

a) Anaerobic respiration

b) Photosynthesis

c) Chemosynthesis

d) Hibernation

83. Which of the following environments would likely have organisms adapted to low oxygen conditions?

a) High mountain peaks

b) Deep ocean sediments

c) Waterlogged soils

d) All of the above

84. How do plants respond to flooding, which reduces oxygen availability in the soil?

a) They increase their rate of photosynthesis

b) They develop air spaces in their roots

c) They close their stomata to conserve water

d) They stop respiring altogether

85. In humans, how does high altitude affect respiration?

a) It increases the respiration rate

b) It decreases the respiration rate

c) It has no effect on the respiration rate

d) It causes the lungs to shrink

Activity Level – 100 MCQs on Respiration in Organisms

86. Why does physical activity lead to an increase in respiration rate?

a) To supply more oxygen to muscles

b) To remove excess carbon dioxide

c) To generate more ATP for energy

d) All of the above

87. During intense exercise, muscle cells may switch to anaerobic respiration, resulting in the production of:

a) Lactic acid

b) Ethanol

c) Carbon dioxide only

d) Water only

88. How does regular exercise benefit the respiratory system?

a) It strengthens the diaphragm and intercostal muscles

b) It increases lung capacity

c) It improves the efficiency of gas exchange

d) All of the above

89. Which of the following activities would likely have the highest respiration rate?

a) Sleeping

b) Walking

c) Sprinting

d) Watching TV

100 MCQs on Respiration in Organisms

90. Even at rest, the body requires a certain level of respiration to maintain basic functions. This is called the:

a) Basal metabolic rate

b) Resting heart rate

c) Anaerobic threshold

d) Respiratory quotient

Revision MCQs (91-100) – MCQs on Respiration in Organisms

91. Why is respiration absolutely crucial for the survival of all living organisms?

(a) It helps in maintaining body temperature.

(b) It aids in the transportation of nutrients.

(c) It is responsible for the breakdown of food to release energy.

(d) It helps in the excretion of waste products.

92. The incredible variety of respiratory processes seen across different organisms showcases:

(a) The adaptability of life to thrive in diverse environments.

(b) The limitations of evolution.

(c) The uniformity of life processes.

(d) The challenges faced by organisms in obtaining oxygen.

93. What term defines the process of breaking down glucose in the presence of oxygen to release energy?

(a) Anaerobic respiration

(b) Fermentation

(c) Aerobic respiration

(d) Photosynthesis

94. Which of the following processes involves the breakdown of glucose in the absence of oxygen?

(a) Aerobic respiration

(b) Anaerobic respiration

(c) Photosynthesis

(d) Transpiration

95. What are the tiny pores on the surface of leaves that facilitate gas exchange called?

(a) Lenticels

(b) Stomata

(c) Trichomes

(d) Cuticle

100 MCQs on Respiration in Organisms

96. The energy currency of cells, produced during respiration, is:

(a) Glucose

(b) ATP (Adenosine Triphosphate)

(c) Carbon dioxide

(d) Water

97. The process by which plants make their own food using sunlight is known as:

(a) Respiration

(b) Photosynthesis

(c) Transpiration

(d) Fertilization

98. The breathing mechanism in humans involves two main processes:

(a) Inhalation and exhalation

(b) Ingestion and digestion

(c) Circulation and excretion

(d) Photosynthesis and respiration

99. The microscopic air sacs in the lungs where the actual exchange of gases takes place are called:

(a) Bronchi

(b) Bronchioles

(c) Alveoli

(d) Trachea

100. The molecule that acts as the primary energy carrier in cells, generated during respiration, is known as:

(a) Glucose

(b) ATP (Adenosine Triphosphate)

(c) Carbon dioxide

(d) Water