Photosynthesis vs Respiration Practice Questions
20 free Photosynthesis vs Respiration practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which of the following best distinguishes photosynthesis from respiration in plants?
- A Photosynthesis releases energy, respiration stores energy
- B Photosynthesis uses oxygen; respiration produces carbon dioxide
- C Photosynthesis is anabolic, respiration is catabolic
- D Photosynthesis occurs in mitochondria; respiration in chloroplasts
Correct answer: Photosynthesis is anabolic, respiration is catabolic
Photosynthesis is an anabolic process that synthesizes glucose using light energy. Respiration is a catabolic process that breaks down glucose to release energy.
Which gas is released during photosynthesis but consumed during respiration?
- A Carbon dioxide
- B Nitrogen
- C Oxygen (O₂)
- D Hydrogen
Correct answer: Oxygen (O₂)
Oxygen is released as a by-product of the light reactions of photosynthesis. It is consumed during aerobic respiration as the final electron acceptor.
Which cellular organelle is common to both photosynthesis and respiration?
- A Plastid
- B Mitochondrion
- C Cytoplasm
- D Lysosome
Correct answer: Cytoplasm
Both processes involve reactions in the cytoplasm, such as glycolysis in respiration. Photosynthesis and respiration also rely on cytoplasmic intermediates.
What is the primary energy currency generated in respiration but consumed indirectly in photosynthesis?
- A NADPH (electron carrier)
- B ATP (adenosine triphosphate)
- C FADH2 (electron carrier)
- D Glucose (primary fuel)
Correct answer: ATP (adenosine triphosphate)
ATP is generated during respiration and used by cells for metabolic activities. Photosynthesis consumes ATP during the Calvin cycle to synthesize carbohydrates.
Which process occurs only in the presence of light, unlike respiration?
- A Glycolysis
- B Electron transport
- C Light reactions
- D Krebs cycle
Correct answer: Light reactions
Light reactions of photosynthesis require light energy to proceed. Respiration does not require light and can occur both day and night.
Which statement correctly compares raw materials of photosynthesis and respiration?
- A Both require glucose and oxygen as raw materials
- B CO2 and H2O for photosynthesis; glucose and O2 for respiration
- C Both require carbon dioxide and oxygen to function
- D Respiration uses CO2 and H2O, photosynthesis uses glucose
Correct answer: CO2 and H2O for photosynthesis; glucose and O2 for respiration
Photosynthesis uses carbon dioxide and water to produce glucose. Respiration uses glucose and oxygen to release energy.
Which process results in a net gain of organic matter in plants?
- A Cellular respiration
- B Fermentation
- C Photosynthesis
- D Transpiration
Correct answer: Photosynthesis
Photosynthesis synthesizes organic compounds like glucose, leading to a net gain of biomass. Respiration breaks down these compounds.
In which form is energy stored after photosynthesis but released during respiration?
- A Heat energy
- B Chemical energy in glucose
- C Light energy
- D Mechanical and kinetic energy
Correct answer: Chemical energy in glucose
Photosynthesis stores energy in the chemical bonds of glucose. Respiration releases this stored chemical energy for cellular use.
Which process fixes atmospheric carbon into organic molecules?
- A Respiration
- B Photorespiration
- C Photosynthesis
- D Fermentation
Correct answer: Photosynthesis
Photosynthesis fixes atmospheric carbon dioxide into carbohydrates. Respiration releases carbon dioxide back into the atmosphere.
Which of the following occurs in respiration but not in photosynthesis?
- A Electron transport chain
- B Release of CO2
- C ATP synthesis
- D Redox reactions
Correct answer: Release of CO2
Carbon dioxide is released during respiration as a waste product. In photosynthesis, carbon dioxide is utilized rather than released.
Which pigment is essential for photosynthesis but has no direct role in respiration?
- A Cytochrome
- B Chlorophyll
- C Hemoglobin
- D Beta-carotene
Correct answer: Chlorophyll
Chlorophyll absorbs light energy required for photosynthesis. Respiration does not involve light absorption or chlorophyll.
Which process is directly responsible for maintaining atmospheric oxygen levels?
- A Aerobic respiration
- B Transpiration
- C Photosynthesis
- D Decomposition
Correct answer: Photosynthesis
Photosynthesis releases oxygen during the splitting of water molecules. Respiration consumes oxygen rather than producing it.
Which of the following best explains why respiration is considered the reverse of photosynthesis?
- A Both occur in the same cellular organelle
- B Reactants of one are products of the other
- C Both require light energy
- D Both occur only in daytime and require sunlight
Correct answer: Reactants of one are products of the other
The products of photosynthesis, glucose and oxygen, are used as reactants in respiration. Similarly, respiration releases CO2 and water used in photosynthesis.
Which metabolic pathway is common to both plant and animal respiration but absent in photosynthesis?
- A Calvin cycle
- B Light reaction
- C Glycolysis
- D Photolysis
Correct answer: Glycolysis
Glycolysis occurs in the cytoplasm of both plant and animal cells during respiration. It is not involved in photosynthesis.
Which statement about energy flow in photosynthesis and respiration is correct?
- A Both convert stored chemical energy into visible light energy
- B Photosynthesis converts light energy into chemical energy
- C Respiration converts light energy into ATP
- D Both store energy in oxygen molecules
Correct answer: Photosynthesis converts light energy into chemical energy
Photosynthesis converts light energy into chemical energy stored in glucose. Respiration converts this chemical energy into ATP.
Which of the following occurs in chloroplasts but not in mitochondria?
- A ATP synthesis
- B Electron transport
- C Carbon fixation
- D Oxidation-reduction reactions
Correct answer: Carbon fixation
Carbon fixation occurs during the Calvin cycle in chloroplasts. Mitochondria are involved in oxidation of glucose, not carbon fixation.
Why is respiration essential even in photosynthetic tissues?
- A To synthesize chlorophyll molecules properly
- B To release excess oxygen
- C To provide ATP for cellular activities
- D To absorb light energy
Correct answer: To provide ATP for cellular activities
Respiration provides ATP required for growth, repair, and maintenance of cells. Photosynthesis alone cannot meet immediate energy needs.
Which compound links photosynthesis and respiration most directly?
- A ATP
- B Chlorophyll
- C Glucose
- D Carbon dioxide
Correct answer: Glucose
Glucose is synthesized during photosynthesis and broken down during respiration. It serves as the main link between the two processes.
Which statement is correct regarding the timing of photosynthesis and respiration in plants?
- A Photosynthesis occurs only at night
- B Respiration occurs only during the day
- C Both occur simultaneously during the day
- D Respiration ceases as soon as light is available
Correct answer: Both occur simultaneously during the day
Respiration occurs continuously, both day and night. Photosynthesis occurs during the day, so both processes occur simultaneously during daylight.
Which process contributes directly to the buildup of dry weight in plants?
- A Cellular respiration
- B Photosynthesis
- C Fermentation
- D Transpiration
Correct answer: Photosynthesis
Photosynthesis produces carbohydrates that contribute to plant biomass and dry weight. Respiration reduces stored organic matter.