Bioenergetics is the study of how living organisms produce, store, and use energy for their life processes. Energy is essential for growth, movement, repair, and reproduction.
In this chapter, students will learn about ATP (the cell’s energy currency), Photosynthesis, and Cellular Respiration. These notes are designed to be easy to understand, follow the 2026 Punjab Board syllabus, and are perfect for exam preparation and quick revision.
Class 9 Biology Chapter 8 MCQs – Bioenergetics
1. Which type of chlorophyll is most common in plants?
(a) Chlorophyll a
(b) Chlorophyll b
(c) Chlorophyll c
(d) Chlorophyll d
Correct Answer:
✅ (a) Chlorophyll a
2. Which molecule donates electrons in the light-dependent reactions of photosynthesis?
(a) NADPH
(b) Water
(c) Oxygen
(d) Carbon dioxide
✅ Correct Answer: (b) Water
3. Which bond in ATP is considered a high-energy bond?
(a) Adenine–ribose bond
(b) First phosphate bond
(c) Outer phosphate bond
(d) Hydrogen bond
✅ Correct Answer: (c) Outer phosphate bond
4. Dark reactions of photosynthesis occur in:
(a) Thylakoid
(b) Stroma
(c) Cytoplasm
(d) Mitochondria
✅ Correct Answer: (b) Stroma
5. Which scientist discovered the details of dark reactions?
(a) Watson
(b) Darwin
(c) Melvin Calvin
(d) Mendel
✅ Correct Answer: (c) Melvin Calvin
6. Which colors of light are most effective for photosynthesis?
(a) Green and yellow
(b) Blue and red
(c) Violet and orange
(d) White and green
✅ Correct Answer: (b) Blue and red
Class 9 Biology Chapter 8 – Short Questions
1. Write the importance of oxidation–reduction reactions.
Answer:
Oxidation–reduction (redox) reactions are important because they help release energy from food molecules. During cellular respiration, glucose is oxidized and energy is released. This energy is then stored in the form of ATP, which cells use for different life processes. Redox reactions therefore play a key role in energy production and metabolism in living organisms.
2. What do ATP and ADP mean? What are the roles of these molecules in cellular metabolism?
Answer:
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ATP stands for Adenosine Triphosphate, and ADP stands for Adenosine Diphosphate.
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ATP is known as the main energy currency of the cell because it stores and provides energy for cellular activities.
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When ATP loses one phosphate group, it is converted into ADP, and energy is released.
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This released energy is used for important cellular processes such as muscle contraction, active transport, and synthesis of biomolecules.
Thus, ATP and ADP play a key role in cellular metabolism by storing and transferring energy within the cell.
3. List ways in which respiratory energy is used in the body.
Answer:
Respiratory energy in the form of ATP is used in the body for many important activities, such as:
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Muscle contraction and movement
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Active transport of substances across cell membranes
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Synthesis of proteins and other biomolecules
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Cell division and DNA replication
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Transmission of nerve impulses
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Maintaining body temperature
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Detoxification and removal of wastes
These processes require energy, which is supplied by ATP produced during cellular respiration.
📥 Download Chapter 8 Bioenergetics Notes PDF
Skip to PDF contentGet Class 9 Biology Chapter 8 – Bioenergetics complete notes including:
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ATP: The Cell’s Energy Currency
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Photosynthesis (Light & Dark Reactions)
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Cellular Respiration (Aerobic & Anaerobic)
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Important MCQs, Short Questions & Long Questions
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Why These Notes Are Helpful
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Simple and clear explanations for easy understanding
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Covers all key points of Chapter 8 as per Punjab Board syllabus
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Important questions included for exams
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Quick revision tips and bullet points for last-minute study