Bioenergetics introduces how living organisms obtain and use energy. This post includes Class 9 Biology Chapter 7 MCQs to help students test their understanding of cellular respiration, photosynthesis, ATP, and related biological processes.
1. What is the primary source of energy for living organisms?
- A. Proteins
- B. Sunlight ✅
- C. Minerals
- D. Vitamins
Explanation: Sunlight is the main energy source, especially for autotrophs that perform photosynthesis.
2. Which process converts light energy into chemical energy?
- A. Respiration
- B. Photosynthesis ✅
- C. Fermentation
- D. Digestion
Explanation: Photosynthesis uses sunlight to produce glucose, a chemical form of energy.
3. What is the chemical formula for glucose?
- A. C6H12O5
- B. C6H12O6 ✅
- C. CH4
- D. CO2
Explanation: Glucose has the molecular formula C6H12O6, essential for cellular respiration.
4. What is the main product of respiration used by cells for energy?
- A. CO2
- B. ATP ✅
- C. Oxygen
- D. Sugar
Explanation: ATP (adenosine triphosphate) stores and supplies energy for cellular functions.
5. What is released during aerobic respiration?
- A. Carbon dioxide and water ✅
- B. Oxygen and glucose
- C. Nitrogen and fats
- D. Proteins and energy
Explanation: Aerobic respiration breaks glucose with oxygen, producing CO₂, water, and ATP.
6. Which organelle is known as the powerhouse of the cell?
- A. Ribosome
- B. Mitochondria ✅
- C. Chloroplast
- D. Nucleus
Explanation: Mitochondria generate ATP through cellular respiration.
7. Which pigment is essential for photosynthesis?
- A. Hemoglobin
- B. Carotene
- C. Chlorophyll ✅
- D. Melanin
Explanation: Chlorophyll absorbs light energy, enabling plants to convert it into chemical energy.
8. In which part of the plant does photosynthesis mostly occur?
- A. Stem
- B. Root
- C. Leaves ✅
- D. Flowers
Explanation: Leaves contain chloroplasts where photosynthesis primarily takes place.
9. What is the role of stomata in photosynthesis?
- A. Absorb sunlight
- B. Allow gas exchange ✅
- C. Transport food
- D. Store water
Explanation: Stomata are pores that allow carbon dioxide to enter and oxygen to exit the leaf.
10. Which gas is used in cellular respiration?
- A. Nitrogen
- B. Carbon dioxide
- C. Oxygen ✅
- D. Hydrogen
Explanation: Oxygen is required in aerobic respiration to release energy from glucose.
11. What happens during anaerobic respiration?
- A. Oxygen is used
- B. Energy is produced without oxygen ✅
- C. ATP is not produced
- D. Glucose is not used
Explanation: Anaerobic respiration occurs without oxygen, producing less ATP than aerobic respiration.
12. In plants, which process stores energy in glucose?
- A. Photosynthesis ✅
- B. Respiration
- C. Transpiration
- D. Fermentation
Explanation: Photosynthesis converts light energy into chemical energy stored in glucose.
13. Which molecule is the universal energy currency of the cell?
- A. DNA
- B. ATP ✅
- C. Protein
- D. Starch
Explanation: ATP provides immediate energy for all cellular activities.
14. What is the role of water in photosynthesis?
- A. Absorbs sunlight
- B. Provides electrons and protons ✅
- C. Stores glucose
- D. Releases carbon dioxide
Explanation: Water is split during photosynthesis, releasing oxygen and supplying electrons and protons.
15. Which gas is released as a byproduct during photosynthesis?
- A. Carbon dioxide
- B. Nitrogen
- C. Oxygen ✅
- D. Hydrogen
Explanation: Oxygen is released as a byproduct when water molecules are split in photosynthesis.