Class 10th Science Chapter 5 – Life Processes | Respiration – Aerobic and Anaerobic Respiration

Life Processes – Respiration

Class 10 Science | Aerobic and Anaerobic Respiration | CBSE + Foundation + Competitive

Respiration – Aerobic and Anaerobic Respiration

1. Respiration क्या है? | What is Respiration?

English:
Respiration is the biochemical process by which food molecules such as glucose are broken down to release energy.

हिन्दी:
श्वसन (Respiration) वह जैव-रासायनिक प्रक्रिया है जिसमें ग्लूकोज जैसे भोजन के अणुओं का विघटन करके ऊर्जा मुक्त की जाती है।

यह ऊर्जा मुख्य रूप से ATP (Adenosine Triphosphate) के रूप में उपलब्ध होती है।

2. Respiration की आवश्यकता | Need of Respiration

जीवों को विभिन्न जीवन-क्रियाओं के लिए ऊर्जा की आवश्यकता होती है।

• Growth – वृद्धि
• Movement – गति
• Repair – कोशिकीय मरम्मत
• Active transport – सक्रिय परिवहन
• Cell division – कोशिका विभाजन
• Body temperature and other metabolic activities

मुख्य विचार:

Food + Oxygen → Energy + Carbon Dioxide + Water

यह समीकरण विशेष रूप से aerobic respiration को दर्शाता है।

3. Breathing और Respiration में अंतर

Breathing	Respiration
Breathing is the physical process of taking in oxygen and giving out carbon dioxide.	Respiration is a biochemical process that releases energy from food.
यह मुख्यतः गैसों का आदान-प्रदान है।	यह कोशिकाओं के अंदर होने वाली रासायनिक प्रक्रिया है।
Breathing occurs through respiratory organs.	Respiration occurs inside cells.
Breathing does not directly release usable cellular energy.	Respiration releases energy in usable form such as ATP.

4. Glucose का विघटन | Breakdown of Glucose

Respiration की शुरुआत कोशिका के cytoplasm में glucose के टूटने से होती है। Glucose का molecular formula:

C₆H₁₂O₆

Glucose सबसे पहले टूटकर Pyruvate बनाता है।

Glucose (C₆H₁₂O₆) → Pyruvate

यह प्रारम्भिक चरण glycolysis कहलाता है।

5. Glycolysis | ग्लाइकोलाइसिस

English:
Glycolysis is the first stage of glucose breakdown. It occurs in the cytoplasm of the cell.

हिन्दी:
ग्लाइकोलाइसिस ग्लूकोज के विघटन का पहला चरण है। यह कोशिका के cytoplasm में होता है।

इस प्रक्रिया में एक glucose molecule से दो pyruvate molecules बनते हैं।

C₆H₁₂O₆ → 2 Pyruvate

इसके बाद pyruvate की आगे की प्रक्रिया oxygen की उपलब्धता पर निर्भर करती है।

6. Pyruvate के तीन प्रमुख मार्ग

Condition	Pathway	Products
Presence of oxygen	Aerobic respiration	CO₂ + H₂O + large amount of energy
Absence of oxygen in yeast	Alcoholic fermentation	Ethanol + CO₂ + some energy
Insufficient oxygen in muscle cells	Lactic acid fermentation	Lactic acid + some energy

7. Aerobic Respiration | वायवीय श्वसन

Definition:
Aerobic respiration is the breakdown of glucose in the presence of oxygen to release energy.

हिन्दी:
वायवीय श्वसन वह प्रक्रिया है जिसमें oxygen की उपस्थिति में glucose का पूर्ण विघटन होता है और अधिक मात्रा में ऊर्जा मुक्त होती है।

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy

Aerobic respiration में glucose का लगभग पूर्ण oxidation होता है। इसके मुख्य products:

• Carbon dioxide – CO₂
• Water – H₂O
• Energy – ATP

यह प्रक्रिया मुख्य रूप से mitochondria में आगे जारी रहती है। इसलिए mitochondria को अक्सर: Powerhouse of the cell कहा जाता है।

8. Anaerobic Respiration | अवायवीय श्वसन

Definition:
Anaerobic respiration is the breakdown of glucose in the absence of oxygen.

हिन्दी:
अवायवीय श्वसन वह प्रक्रिया है जिसमें oxygen की अनुपस्थिति में glucose का अपूर्ण विघटन होता है।

Glucose → Ethanol + CO₂ + Energy

यह प्रक्रिया yeast में alcoholic fermentation के रूप में देखी जाती है।

9. Yeast में Anaerobic Respiration

Yeast एक unicellular microorganism है। Oxygen की कमी में yeast glucose को ethanol और carbon dioxide में बदलता है।

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + Energy

यह प्रक्रिया: Alcoholic fermentation कहलाती है।

Uses:

• Bread making
• Alcohol production
• Fermentation industries

Bread बनाने में CO₂ dough को फूलाने में सहायता करता है।

10. Muscle Cells में Anaerobic Respiration

जब हम बहुत तेज physical exercise करते हैं, तब muscles को oxygen की आवश्यकता तेजी से बढ़ जाती है। कभी-कभी oxygen की supply demand से कम पड़ जाती है। ऐसी स्थिति में muscle cells में pyruvate का परिवर्तन lactic acid में हो सकता है।

Glucose → Lactic Acid + Energy

या सरल रूप में:

Pyruvate → Lactic Acid + Energy

Important: Muscles में lactic acid का accumulation थकान और cramps से associated हो सकता है। Exercise के बाद oxygen supply सामान्य होने पर lactic acid आगे metabolise किया जा सकता है।

11. Mitochondria की भूमिका

Mitochondria कोशिका का प्रमुख energy-releasing organelle है। Aerobic respiration में glucose breakdown से प्राप्त pyruvate mitochondria में आगे process होता है। इस प्रक्रिया से अधिक मात्रा में ATP बनती है।

Mitochondria = Major site of aerobic energy release

12. ATP क्या है? | What is ATP?

ATP का पूरा नाम: Adenosine Triphosphate ATP को कोशिका की energy currency कहा जाता है। जब ATP टूटता है तो usable energy उपलब्ध होती है।

ATP → ADP + Pi + Energy

यह energy cellular activities में उपयोग की जाती है।

13. Aerobic और Anaerobic Respiration में अंतर

Basis	Aerobic Respiration	Anaerobic Respiration
Oxygen	Oxygen required	Oxygen not required
Glucose breakdown	More complete	Incomplete
Products	CO₂ + H₂O	Ethanol + CO₂ or Lactic acid
Energy	More energy	Less energy
Main site	Cytoplasm + mitochondria	Mainly cytoplasm
Examples	Most plants and animals under normal oxygen supply	Yeast and muscle cells under oxygen shortage

14. Energy Release की तुलना

Aerobic respiration में glucose का अधिक complete breakdown होने के कारण anaerobic respiration की तुलना में अधिक energy release होती है।

Aerobic Respiration → More Energy

Anaerobic Respiration → Less Energy

15. Plants में Respiration

Plants भी respiration करते हैं। Plants में respiration के लिए oxygen का उपयोग और carbon dioxide का release होता है। Plants में गैसों का exchange मुख्यतः:

• Stomata – leaves
• Lenticels – stems
• Root surface – roots

के माध्यम से होता है।

16. Photosynthesis और Respiration का संबंध

Photosynthesis	Respiration
Food is synthesised.	Food is broken down.
Usually requires light.	Occurs continuously in living cells.
CO₂ is used.	CO₂ is released in aerobic respiration.
O₂ is released.	O₂ is used in aerobic respiration.
Energy is stored in food.	Energy is released from food.

17. Respiration का महत्व

Respiration द्वारा प्राप्त energy का उपयोग:

1. Growth
2. Movement
3. Repair
4. Cell division
5. Active transport
6. Synthesis of cellular materials
7. Maintenance of life processes

18. Quick Concept Summary

Concept	Key Point
Respiration	Food breakdown to release energy.
Glycolysis	Glucose → 2 Pyruvate; occurs in cytoplasm.
Aerobic	Uses oxygen and releases more energy.
Anaerobic	Does not require oxygen and releases less energy.
Yeast	Produces ethanol + CO₂.
Muscles	Can produce lactic acid when oxygen is insufficient.
ATP	Usable energy currency of the cell.
Mitochondria	Main site of aerobic energy release.

19. MCQs – Multiple Choice Questions

Question 1. Respiration is mainly concerned with:

A) Release of energy from food

B) Formation of chlorophyll

C) Absorption of sunlight

D) Formation of soil

Answer: A

Question 2. Glycolysis occurs in:

A) Nucleus

B) Cytoplasm

C) Ribosome

D) Chloroplast

Answer: B

Question 3. The first major product of glucose breakdown is:

A) Ethanol

B) Lactic acid

C) Pyruvate

D) Oxygen

Answer: C

Question 4. Aerobic respiration requires:

A) Nitrogen

B) Carbon dioxide

C) Hydrogen

D) Oxygen

Answer: D

Question 5. The main products of aerobic respiration are:

A) Ethanol and CO₂

B) CO₂ and H₂O

C) Lactic acid and oxygen

D) Glucose and oxygen

Answer: B

Question 6. Anaerobic respiration in yeast produces:

A) Ethanol and CO₂

B) Water and oxygen

C) Glucose and oxygen

D) Only water

Answer: A

Question 7. During vigorous exercise, muscle cells may produce:

A) Ethanol

B) Methane

C) Lactic acid

D) Acetic acid

Answer: C

Question 8. ATP stands for:

A) Adenine Transfer Protein

B) Adenosine Triphosphate

C) Active Transport Protein

D) Adenosine Tetraphosphate

Answer: B

Question 9. Mitochondria are mainly associated with:

A) Aerobic respiration

B) Photosynthesis

C) Protein synthesis only

D) Digestion

Answer: A

Question 10. Anaerobic respiration releases:

A) More energy than aerobic respiration

B) Equal energy

C) Less energy

D) No energy

Answer: C

Question 11. Fermentation in yeast is associated with formation of:

A) Lactic acid

B) Ethanol

C) Oxygen

D) Glucose

Answer: B

Question 12. Carbon dioxide is released during:

A) Aerobic respiration

B) Photosynthesis only

C) Water absorption

D) Mineral uptake

Answer: A

Question 13. Which molecule is called the energy currency of the cell?

A) DNA

B) RNA

C) ATP

D) Glucose

Answer: C

Question 14. Complete aerobic respiration produces:

A) Ethanol

B) Lactic acid

C) Methane

D) Carbon dioxide and water

Answer: D

Question 15. Which organism commonly performs alcoholic fermentation?

A) Yeast

B) Human RBC

C) Earthworm

D) Fish

Answer: A

Question 16. Glucose contains:

A) 6 carbon atoms

B) 5 carbon atoms

C) 4 carbon atoms

D) 3 carbon atoms

Answer: A

Question 17. The formula of glucose is:

A) C₂H₅OH

B) CH₄

C) C₆H₁₂O₆

D) CO₂

Answer: C

Question 18. When oxygen is insufficient in muscles, pyruvate may form:

A) Ethanol

B) Lactic acid

C) Methanol

D) Glucose

Answer: B

Question 19. The physical process of taking oxygen into the body is:

A) Respiration

B) Digestion

C) Breathing

D) Excretion

Answer: C

Question 20. Which process releases more energy from one glucose molecule?

A) Aerobic respiration

B) Anaerobic respiration

C) Fermentation only

D) None

Answer: A

Question 21. During alcoholic fermentation, pyruvate is converted into:

A) Protein

B) Ethanol and CO₂

C) Oxygen

D) Water only

Answer: B

Question 22. Respiration is:

A) An energy-releasing process

B) A process of sunlight absorption

C) A process of water filtration

D) A process of DNA copying only

Answer: A

Question 23. The organelle known as the powerhouse of the cell is:

A) Nucleus

B) Golgi body

C) Mitochondria

D) Ribosome

Answer: C

Question 24. Which is NOT a product of aerobic respiration?

A) Carbon dioxide

B) Water

C) Energy

D) Ethanol

Answer: D

Question 25. Bread dough rises mainly due to:

A) Oxygen

B) Carbon dioxide

C) Nitrogen

D) Hydrogen

Answer: B

Question 26. Anaerobic respiration occurs:

A) Only in plants

B) Only in animals

C) In the absence of oxygen

D) Only in chloroplasts

Answer: C

Question 27. Which process is associated with lactic acid formation?

A) Photosynthesis

B) Anaerobic respiration in muscles

C) Digestion

D) Transpiration

Answer: B

Question 28. Which gas is generally consumed during aerobic respiration?

A) Oxygen

B) Carbon dioxide

C) Nitrogen

D) Hydrogen

Answer: A

Question 29. The first stage of glucose breakdown occurs in:

A) Nucleus

B) Cytoplasm

C) Vacuole

D) Cell wall

Answer: B

Question 30. Which statement is correct?

A) Anaerobic respiration always produces more energy.

B) Aerobic respiration does not use oxygen.

C) Yeast can perform alcoholic fermentation.

D) Respiration occurs only during daytime.

Answer: C

20. Subjective Questions – 1 to 6 Marks

1 Mark
Question 1. What is respiration?

Answer: Respiration is the process of breakdown of food to release energy.

1 Mark
Question 2. Where does glycolysis occur?

Answer: Glycolysis occurs in the cytoplasm.

1 Mark
Question 3. Name the energy currency of the cell.

Answer: ATP – Adenosine Triphosphate.

1 Mark
Question 4. Name the product formed during anaerobic respiration in yeast.

Answer: Ethanol and carbon dioxide are formed.

2 Marks
Question 5. Differentiate between breathing and respiration.

Answer: Breathing is the physical exchange of gases, whereas respiration is the biochemical breakdown of food to release energy.

2 Marks
Question 6. What is aerobic respiration?

Answer: Aerobic respiration is the breakdown of glucose in the presence of oxygen, producing carbon dioxide, water and energy.

2 Marks
Question 7. What is anaerobic respiration?

Answer: Anaerobic respiration is the breakdown of glucose without oxygen. It produces less energy and products such as ethanol and CO₂ in yeast or lactic acid in muscles.

2 Marks
Question 8. Why is ATP called the energy currency of the cell?

Answer: ATP stores usable chemical energy and releases it when required for cellular activities. Therefore, it is called the energy currency of the cell.

3 Marks
Question 9. Explain glycolysis.

Answer: Glycolysis is the first stage of glucose breakdown. It occurs in the cytoplasm. One glucose molecule is converted into two pyruvate molecules with release of some energy.

3 Marks
Question 10. Explain anaerobic respiration in yeast.

Answer: In the absence of oxygen, yeast breaks down glucose to form ethanol, carbon dioxide and a small amount of energy.

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + Energy

3 Marks
Question 11. Why do muscles develop cramps during vigorous exercise?

Answer: During vigorous exercise, oxygen supply may become insufficient for the increased energy demand. Muscle cells may then carry out anaerobic respiration, producing lactic acid. Accumulation of lactic acid is associated with muscle fatigue and cramps.

3 Marks
Question 12. Write the equation for aerobic respiration.

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy

4 Marks
Question 13. Differentiate between aerobic and anaerobic respiration.

Answer:

• Aerobic respiration requires oxygen; anaerobic respiration does not.
• Aerobic respiration involves more complete breakdown of glucose.
• Aerobic respiration releases more energy.
• Anaerobic respiration produces ethanol + CO₂ in yeast or lactic acid in muscles.

4 Marks
Question 14. Explain the fate of pyruvate under different conditions.

Answer:

• In the presence of oxygen → CO₂ + H₂O + more energy.
• In yeast without oxygen → ethanol + CO₂ + some energy.
• In muscle cells with insufficient oxygen → lactic acid + some energy.

4 Marks
Question 15. Explain the role of mitochondria in respiration.

Answer: Mitochondria are the major site of aerobic energy release. Pyruvate formed during glycolysis enters mitochondria and is further oxidised in the presence of oxygen. This results in the formation of CO₂, water and a large amount of usable energy.

4 Marks
Question 16. Explain why aerobic respiration releases more energy than anaerobic respiration.

Answer: In aerobic respiration glucose undergoes a more complete oxidation in the presence of oxygen. Therefore, more chemical energy stored in glucose becomes available as ATP. Anaerobic respiration involves incomplete breakdown, so less energy is released.

5 Marks
Question 17. Describe the complete process of glucose breakdown during respiration.

Answer:

• Glucose first undergoes glycolysis in the cytoplasm.
• One glucose molecule forms two pyruvate molecules.
• In the presence of oxygen, pyruvate is further oxidised in mitochondria.
• Carbon dioxide and water are formed.
• A large amount of energy is released and stored in ATP.

5 Marks
Question 18. Explain aerobic and anaerobic respiration with suitable equations.

Answer: Aerobic respiration occurs in the presence of oxygen:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy

Anaerobic respiration occurs without oxygen. In yeast:

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + Energy

In muscles under oxygen shortage:

Pyruvate → Lactic Acid + Energy

5 Marks
Question 19. Explain fermentation and mention its applications.

Answer: Fermentation is an anaerobic process in which microorganisms such as yeast convert sugars into products such as ethanol and carbon dioxide. Applications include:

• Alcohol production
• Bread making
• Food processing
• Industrial production of fermented products

6 Marks
Question 20. Explain respiration in detail and compare aerobic and anaerobic respiration.

Answer: Respiration is the biochemical breakdown of food to release energy. Glucose first undergoes glycolysis in the cytoplasm and forms pyruvate. Aerobic pathway:

Glucose + O₂ → CO₂ + H₂O + Large amount of Energy

Anaerobic pathway in yeast:

Glucose → Ethanol + CO₂ + Small amount of Energy

In muscle cells under oxygen shortage:

Pyruvate → Lactic Acid + Energy

Aerobic respiration produces more energy because glucose is more completely oxidised.

6 Marks
Question 21. Draw/describe the pathway of glucose breakdown.

Glucose
↓
Glycolysis
↓
2 Pyruvate

From pyruvate:

With Oxygen
↓
CO₂ + H₂O + More Energy

Without Oxygen – Yeast
↓
Ethanol + CO₂ + Less Energy

Insufficient Oxygen – Muscles
↓
Lactic Acid + Less Energy

6 Marks
Question 22. Why is respiration essential for survival?

Answer: Respiration provides energy required for all essential life processes. The released energy is used for growth, movement, repair, active transport, synthesis of biomolecules, cell division and maintenance of cellular functions. Without continuous energy supply, cells cannot perform their vital activities.

3 Marks
Question 23. Why does yeast produce alcohol in the absence of oxygen?

Answer: In the absence of oxygen, yeast cannot carry out aerobic respiration efficiently. It therefore obtains energy through anaerobic fermentation, during which glucose is converted into ethanol and carbon dioxide.

3 Marks
Question 24. Why is anaerobic respiration less efficient?

Answer: Anaerobic respiration involves incomplete breakdown of glucose. A significant amount of chemical energy remains in the products such as ethanol or lactic acid. Hence, less energy is released.

2 Marks
Question 25. Name the two types of respiration based on oxygen requirement.

Answer: 1. Aerobic respiration
2. Anaerobic respiration

2 Marks
Question 26. Name the two products of alcoholic fermentation.

Answer: Ethanol and carbon dioxide.

3 Marks
Question 27. What happens to pyruvate when oxygen is available?

Answer: When oxygen is available, pyruvate enters mitochondria and undergoes further oxidation, producing carbon dioxide, water and a large amount of energy.

4 Marks
Question 28. Why are mitochondria called the powerhouse of the cell?

Answer: Mitochondria are the major site of aerobic respiration and produce a large amount of ATP. Since ATP supplies usable energy for cellular activities, mitochondria are commonly called the powerhouse of the cell.

5 Marks
Question 29. Explain the importance of ATP in living organisms.

Answer: ATP stores chemical energy in a readily usable form. Energy released during respiration is captured in ATP. When the cell requires energy, ATP can be broken down to release it. This energy is used for movement, active transport, synthesis, growth, repair and other cellular activities.

6 Marks
Question 30. Explain the complete difference between aerobic and anaerobic respiration with examples and equations.

Feature	Aerobic	Anaerobic
Oxygen	Required	Not required
Breakdown	More complete	Incomplete
Energy	More	Less
Products	CO₂ + H₂O	Ethanol + CO₂ or lactic acid
Example	Normal cellular respiration	Yeast / oxygen-starved muscles

Aerobic equation:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy

Yeast anaerobic equation:

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + Energy

21. HOTS / Competency Based Questions

HOTS 1. A person runs very fast for a short period and experiences muscle fatigue. Why?

Answer: Vigorous exercise may temporarily reduce oxygen availability to muscles. Anaerobic respiration can then occur, producing lactic acid and contributing to muscle fatigue.

HOTS 2. Why does bread become soft and porous when yeast is added?

Answer: Yeast performs fermentation and releases CO₂. The gas gets trapped in the dough and causes it to expand, making bread porous.

HOTS 3. Why is aerobic respiration considered more efficient?

Answer: It involves more complete oxidation of glucose and therefore releases more usable energy.

HOTS 4. Why cannot cells depend only on anaerobic respiration for normal energy requirements?

Answer: Anaerobic respiration releases much less energy per glucose molecule and produces partially oxidised products.

22. CBSE Exam Golden Points

⭐ Remember:

• Respiration releases energy from food.
• Glycolysis occurs in cytoplasm.
• Glucose forms pyruvate during glycolysis.
• Aerobic respiration requires oxygen.
• Anaerobic respiration does not require oxygen.
• Aerobic respiration releases more energy.
• Yeast produces ethanol + CO₂ during fermentation.
• Muscle cells can produce lactic acid during oxygen shortage.
• Mitochondria are the major site of aerobic energy release.
• ATP is the energy currency of the cell.

23. One-Line Revision

Glucose → Glycolysis → Pyruvate → Different pathways depending on oxygen availability.

O₂ present: CO₂ + H₂O + More Energy
O₂ absent in yeast: Ethanol + CO₂ + Less Energy
O₂ insufficient in muscles: Lactic Acid + Less Energy