Chapter 12 of NCERT Class 11 Biology, Respiration in Plants, explains how plants break down food to release energy. Unlike animals, plants don’t have specialised respiratory organs. They rely on every living cell for respiration. This chapter gives us a detailed understanding of cellular respiration, glycolysis, Krebs cycle, fermentation and how energy is stored in the form of ATP. The chapter also highlights the role of mitochondria and enzymes involved in the entire process.
I chose to write about this topic because plant respiration is often underestimated in school studies, even though it’s just as important as photosynthesis. Many students find it difficult because of the chemical equations and multiple steps involved. When I studied this chapter, I realised how essential it is to break it down into smaller concepts to really understand how plants stay alive and active, even though they don’t breathe like animals. Also, for NEET aspirants, this is a scoring chapter if your concepts are clear. So through this post, I wanted to share an easy breakdown of this chapter and also provide the NCERT PDF download link for your revision.
Understanding Respiration in Plants
Plants need energy for growth, repair, reproduction, and other cellular processes. This energy is released through respiration, where glucose is broken down, and ATP is produced.
Key Concepts from the Chapter
- What is Respiration?
- A process where food (mainly glucose) is broken down to release energy
- This energy is stored as ATP and used for cellular activities
- Types of Respiration
- Aerobic Respiration: Uses oxygen, releases more energy
- Anaerobic Respiration: Takes place without oxygen (e.g., fermentation)
- Anaerobic is common in microorganisms and some plant tissues during oxygen deficiency
- Stages of Respiration
- Glycolysis (in cytoplasm):
- First step
- Glucose is broken into pyruvic acid
- Net gain of 2 ATP and 2 NADH molecules
- Fermentation (if no oxygen):
- Pyruvate is converted to ethanol or lactic acid
- No ATP is generated
- Aerobic Pathway (if oxygen is present):
- Pyruvate enters mitochondria
- Undergoes Link Reaction → Krebs Cycle → Electron Transport Chain
- Produces 36 ATP from one molecule of glucose
- Glycolysis (in cytoplasm):
- Krebs Cycle
- Also called Citric Acid Cycle
- Happens in mitochondria
- Produces CO₂, ATP, NADH, FADH₂
- Key for energy production in plants
- Electron Transport System (ETS)
- Final step in mitochondria
- Electrons are transferred to oxygen
- Produces maximum ATP (around 34)
- Respiratory Quotient (RQ)
- RQ = CO₂ produced / O₂ consumed
- RQ depends on the type of substrate used (carbohydrates, fats, proteins)
- Difference Between Plant and Animal Respiration
- Plants don’t have special respiratory organs
- Gaseous exchange takes place through stomata and lenticels
- Respiration happens in every living cell of the plant
Download PDF
Click Here to Download NCERT Class 11 Biology Chapter 12: Respiration in Plants PDF
