Respiration in Plants – NEET 2025 Complete Notes (With Diagrams & PYQs)

respiration in plants neet notes, glycolysis neet, krebs cycle neet, electron transport chain neet, aerobic and anaerobic respiration

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🌱 Introduction – Let’s Breathe in Energy!

Hello NEET aspirants 👋

Aaj hum start kar rahe hain ek aur high-weightage chapter – Respiration in Plants.

Jaise photosynthesis me energy store hoti hai, waise respiration me energy release hoti hai!

💡 Simple definition:

> “Respiration is the process of oxidation of organic compounds (mainly glucose) to release energy (ATP).”

Matlab plant food banata bhi hai aur use tod kar energy bhi leta hai — smart multitasking organism hai na? 🌿😄

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⚡ 1. What Is Cellular Respiration?

Definition (NCERT-based):

> “Cellular respiration is a catabolic process in which organic compounds are broken down to release energy for cellular activities.”

Types:

1. Aerobic respiration – in presence of oxygen

2. Anaerobic respiration – in absence of oxygen

Overall equation:

C_6H_{12}O_6 + 6O_2 → 6CO_2 + 6H_2O + 686 kcal (energy)

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🌾 2. Phases of Respiration

Respiration occurs in 3 major stages 👇

Stage Site Key Process End Product

Glycolysis Cytoplasm Glucose → Pyruvate 2 ATP, 2 NADH

Krebs Cycle (TCA) Mitochondrial Matrix Acetyl CoA oxidation 2 ATP, CO₂, NADH, FADH₂

Electron Transport Chain (ETC) Inner Mitochondrial Membrane NADH oxidation 34 ATP, H₂O

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🧩 3. Glycolysis – The First Step of Respiration

Discovered by: Embden, Meyerhof & Parnas (EMP Pathway)

Site: Cytoplasm

Substrate: Glucose

End Product: 2 Pyruvate

Phases of Glycolysis:

1. Energy investment phase: 2 ATP used

2. Energy generation phase: 4 ATP produced

Net Gain:

ATP = 4 - 2 = 2, \quad NADH = 2

💡 Trick: “2-in, 4-out = Net 2 ATP profit!”

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🔥 4. Fate of Pyruvic Acid

Condition Process End Products Example

Aerobic Krebs cycle CO₂ + H₂O + Energy Plants, animals

Anaerobic Alcoholic fermentation Ethanol + CO₂ Yeast

Lactic acid fermentation Lactic acid Muscles, bacteria 

💡 Remember:

Aerobic = More ATP, Anaerobic = Less ATP

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🌀 5. Krebs Cycle (Citric Acid Cycle / TCA Cycle)

Discovered by: Sir Hans Krebs

Site: Mitochondrial matrix

Starting molecule: Acetyl CoA

End products (per glucose):

2 ATP

6 NADH

2 FADH₂

4 CO₂

💡 Mnemonic:

Citrate – Isocitrate – α-Ketoglutarate – Succinyl CoA – Succinate – Fumarate – Malate – Oxaloacetate

👉 Trick to remember: “Can I Keep Selling Sex For Money, Officer?” 😄

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⚡ 6. Electron Transport Chain (ETC)

Site: Inner mitochondrial membrane

Main steps:

NADH & FADH₂ donate electrons

Electrons move through complex I–IV

ATP formed by ATP synthase

Final electron acceptor = Oxygen (forms H₂O)

ATP yield: ~34 ATP

💡 Overall total:

1 Glucose → 38 ATP (36 net)

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🌿 7. Anaerobic Respiration

Occurs in absence of oxygen (in yeast or muscles).

Equation (in Yeast):

C_6H_{12}O_6 → 2C_2H_5OH + 2CO_2 + 2ATP

Equation (in Muscles):

C_6H_{12}O_6 → 2C_3H_6O_3 + 2ATP

💡 Key difference:

Ethanol & CO₂ → Yeast

Lactic Acid → Muscles

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🌾 8. Respiratory Quotient (RQ)

RQ = \frac{CO_2 \text{ evolved}}{O_2 \text{ consumed}}

Substrate RQ Value Example

Carbohydrates 1 Glucose

Fats < 1 Fatty acids

Proteins > 1 Organic acids

💡 Trick: “Fat burns slow → RQ low”

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🌱 9. Energy Yield Summary

Process ATP Produced

Glycolysis 2

Krebs Cycle 2

ETC 34

Total 38 ATP (36 Net)

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🌬️ 10. Amphibolic Pathway

Respiration sirf energy release nahi karta, balki intermediate compounds biosynthesis me bhi use hote hain.

Example:

Acetyl CoA → Fatty acids

α-Ketoglutarate → Amino acids

💡 Meaning: Amphibolic = Catabolic + Anabolic

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🧠 11. NEET PYQs (2018–2024)

Year Question Answer

2020 EMP pathway occurs in? Cytoplasm

2021 Number of ATP from 1 glucose? 36

2022 Final acceptor in ETC? Oxygen

2023 Where does Krebs cycle occur? Mitochondrial matrix

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📚 12. Quick Revision Table

Step Site ATP Gain Main Product

Glycolysis Cytoplasm 2 Pyruvate

TCA Cycle Mitochondria 2 CO₂, NADH

ETC Inner membrane 34 ATP, H₂O

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🎯 13. NEET Strategy

1. Revise all enzymes + locations + ATP yield.

2. Learn mnemonics for Krebs Cycle & ETC.

3. Practice PYQs (2016–2024).

4. Draw Glycolysis & TCA diagrams daily.

5. Understand difference between aerobic vs anaerobic clearly.

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🔗 Related Blogs

☀️ Photosynthesis in Higher Plants – Day 50

🌿 Plant Growth and Development – Day 52

🌸 Anatomy of Flowering Plants – Day 49

🌱 Transport in Plants – Day 20

🍃 Mineral Nutrition – Day 21

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🏁 Conclusion

Respiration in Plants ek conceptual + numerical chapter hai jahan se NEET me 2–3 questions regularly aate hain.

Bas yaad rakho bhai —