Quiz on Respiration in Organisms

Respiration is the biological process through which living organisms release energy from the food they consume. This energy is essential for growth, repair, and carrying out all life activities. Respiration occurs in every cell and can be of two types — aerobic (in the presence of oxygen) and anaerobic (without oxygen). In aerobic respiration, glucose combines with oxygen to produce carbon dioxide, water, and energy. In anaerobic respiration, less energy is produced, and by-products like lactic acid or alcohol are formed. In humans, respiration involves breathing — inhaling oxygen and exhaling carbon dioxide — but it also includes cellular respiration that happens in mitochondria. Plants also respire, taking in oxygen and giving out carbon dioxide continuously, though photosynthesis occurs only in daylight.

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MCQ Questions on Quiz on Respiration in Organisms

Q. What is the main purpose of respiration?

A. To absorb oxygen

B. To release energy from food

C. To store carbon dioxide

D. To produce water

Correct: Option (B)

Explanation: Respiration releases energy stored in food molecules, which is used for various life processes.

Q. Which gas is essential for aerobic respiration?

A. Carbon dioxide

B. Nitrogen

C. Oxygen

D. Hydrogen

Correct: Option (C)

Explanation: Oxygen is necessary for aerobic respiration to release energy from glucose.

Q. Where does cellular respiration mainly occur in the cell?

A. Nucleus

B. Mitochondria

C. Ribosome

D. Golgi apparatus

Correct: Option (B)

Explanation: Mitochondria are known as the 'powerhouse of the cell' because they carry out cellular respiration.

Q. Which of the following is a by-product of aerobic respiration?

A. Oxygen

B. Carbon dioxide

C. Nitrogen

D. Alcohol

Correct: Option (B)

Explanation: During aerobic respiration, carbon dioxide and water are released as by-products.

Q. What type of respiration occurs in yeast during fermentation?

A. Aerobic respiration

B. Anaerobic respiration

C. External respiration

D. Photosynthesis

Correct: Option (B)

Explanation: Yeast respires anaerobically in the absence of oxygen, producing alcohol and carbon dioxide.

Q. Which of the following is an example of anaerobic respiration in humans?

A. Breathing normally

B. Muscle activity during heavy exercise

C. Sleeping

D. Digesting food

Correct: Option (B)

Explanation: During intense exercise, muscles may not get enough oxygen and produce energy anaerobically, forming lactic acid.

Q. What is produced at the end of aerobic respiration?

A. Energy, carbon dioxide, and water

B. Alcohol and oxygen

C. Lactic acid only

D. Glucose and nitrogen

Correct: Option (A)

Explanation: Aerobic respiration of glucose yields energy (ATP), carbon dioxide, and water.

Q. In which organ do humans exchange oxygen and carbon dioxide?

A. Heart

B. Lungs

C. Liver

D. Brain

Correct: Option (B)

Explanation: Gas exchange in humans takes place in the lungs through tiny air sacs called alveoli.

Q. What is the process of taking in oxygen and giving out carbon dioxide called?

A. Photosynthesis

B. Excretion

C. Breathing

D. Digestion

Correct: Option (C)

Explanation: Breathing is the physical process of inhaling oxygen and exhaling carbon dioxide.

Q. Which of the following statements is true about respiration in plants?

A. Plants respire only at night

B. Plants respire only during the day

C. Plants respire both day and night

D. Plants do not respire

Correct: Option (C)

Explanation: Plants respire continuously to release energy, though photosynthesis happens only in the presence of sunlight.

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