CBSE Class 10 Science Notes – Life Processes (Chapter 5) PDF + Important Questions 2026

CBSE Class 10 Science Notes – Life Processes

Class 10 Biology | NCERT Chapter 5 | Board Exam Weightage: 8-10 Marks

CBSE Class 10 Notes for Chapter 5 provide complete coverage of the NCERT syllabus with exam-focused explanations. These CBSE Class 10 Science Notes include nutrition, respiration, transportation, and excretion with diagrams of human heart, nephron, and digestive system.

1. Introduction

Life processes are the basic functions performed by living organisms to maintain life. These include nutrition, respiration, transportation, and excretion. All living organisms need energy to perform various life activities, and this energy comes from food through the process of nutrition.

Why Living Organisms Need Life Processes:

• To obtain and utilize energy for metabolic activities
• To maintain body organization and repair damaged tissues
• To remove waste products from the body
• To maintain homeostasis (stable internal environment)
• To support growth and reproduction

Why This Chapter Matters:

• Board Exam Weightage: 8-10 marks (Theory + Practical)
• Highest weightage among Biology chapters
• High-scoring: Diagrams (heart, nephron, digestive system), processes, equations
• NCERT Chapter 5: Life Processes (2024-25 Edition)

2. Chapter Overview

CBSE Class 10 Science Notes for this chapter cover four main life processes:

• Nutrition: Autotrophic and heterotrophic nutrition, photosynthesis, human digestive system
• Respiration: Aerobic and anaerobic respiration, breathing vs respiration, ATP formation
• Transportation: In humans (heart, blood, blood vessels, double circulation) and plants (xylem, phloem, transpiration)
• Excretion: Human excretory system, nephron structure and function, urine formation, excretion in plants

3. CBSE Class 10 Science Notes – Nutrition

Autotrophic Nutrition (Photosynthesis)

Autotrophic nutrition is the mode of nutrition in which organisms synthesize their own food from simple inorganic substances like CO₂ and H₂O using sunlight energy. This process is called photosynthesis and occurs in green plants, algae, and some bacteria.

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in presence of sunlight and chlorophyll)

Carbon dioxide + Water → Glucose + Oxygen

Raw Materials for Photosynthesis:

• Carbon dioxide: Enters through stomata in leaves
• Water: Absorbed by roots from soil, transported through xylem
• Sunlight: Captured by chlorophyll in chloroplasts
• Chlorophyll: Green pigment present in chloroplasts

Events During Photosynthesis:

1. Absorption of light energy by chlorophyll
2. Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen
3. Reduction of carbon dioxide to carbohydrates (glucose) using hydrogen

Stomata and Guard Cells:

• Stomata are tiny pores on leaf surface for gaseous exchange
• Guard cells control opening and closing of stomata
• When water flows into guard cells → they swell → stomata open
• When water flows out → they shrink → stomata close
• Stomata close at night to prevent water loss

Heterotrophic Nutrition

Organisms that cannot synthesize their own food and depend on other organisms for nutrition.

Types of Heterotrophic Nutrition:

Type	Description	Examples
Holozoic	Ingestion of complex food, internal digestion	Humans, amoeba, cow
Saprophytic	Feeding on dead and decaying organic matter	Fungi (mushroom), bacteria
Parasitic	Obtaining nutrition from living host	Cuscuta (plant), tapeworm, lice

Nutrition in Amoeba (Holozoic Nutrition):

1. Ingestion: Food engulfed by pseudopodia forming food vacuole
2. Digestion: Food broken down by enzymes in food vacuole
3. Absorption: Digested food absorbed into cytoplasm
4. Assimilation: Food used for energy, growth, and repair
5. Egestion: Undigested food expelled out

Human Digestive System

The digestive system consists of the alimentary canal and associated glands.

Parts of the Alimentary Canal:

• Mouth: Food ingestion, mechanical digestion by teeth, chemical digestion by saliva (salivary amylase converts starch to maltose)
• Oesophagus: Transports food to stomach by peristalsis
• Stomach: Gastric glands secrete gastric juice (HCl, pepsin, mucus). HCl kills bacteria and provides acidic pH. Pepsin digests proteins.
• Small intestine: Longest part (about 6 meters). Receives bile from liver and pancreatic juice from pancreas. Complete digestion and absorption occur here.
• Large intestine: Absorbs water and minerals. Forms and stores faeces.
• Anus: Egestion of undigested waste

Associated Glands:

• Salivary glands: Secrete saliva containing amylase
• Liver: Produces bile (stored in gall bladder) which emulsifies fats
• Pancreas: Secretes pancreatic juice with enzymes (trypsin, lipase, amylase)

Emulsification: Bile salts break large fat globules into smaller droplets, increasing surface area for enzyme action. This is called emulsification.

4. CBSE Class 10 Science Notes – Respiration

What is Respiration?

Respiration is the process of breakdown of glucose (food) to release energy in the form of ATP. This energy is used for various life activities.

Steps of Respiration:

1. Glycolysis: Glucose (6C) → Pyruvate (3C) in cytoplasm
2. Breakdown of pyruvate: In presence or absence of oxygen

Aerobic Respiration

Takes place in the presence of oxygen in mitochondria. Complete breakdown of glucose occurs.

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (38 ATP)

Glucose + Oxygen → Carbon dioxide + Water + Energy

Anaerobic Respiration

Takes place in the absence of oxygen in cytoplasm. Incomplete breakdown of glucose occurs.

In Yeast (Fermentation):

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + Energy (2 ATP)

Glucose → Ethanol + Carbon dioxide + Energy

In Human Muscles (During vigorous exercise):

C₆H₁₂O₆ → 2C₃H₆O₃ + Energy (2 ATP)

Glucose → Lactic acid + Energy

Result: Accumulation of lactic acid causes muscle cramps

Difference Between Breathing and Respiration

Breathing	Respiration
Physical process	Chemical process
Involves inhalation and exhalation of air	Involves breakdown of glucose to release energy
No energy released	Energy released in form of ATP
Occurs in respiratory organs	Occurs in all living cells

Human Respiratory System

• Nasal passage: Filters, warms, and moistens air
• Trachea (Windpipe): Supported by C-shaped cartilage rings
• Bronchi: Two branches of trachea entering lungs
• Bronchioles: Smaller branches of bronchi
• Alveoli: Air sacs where gaseous exchange occurs

Features of Alveoli for Efficient Gas Exchange:

• Thin, moist walls (one cell thick)
• Large surface area (about 80 m² in humans)
• Rich blood supply
• Close proximity to capillaries

5. CBSE Class 10 Science Notes – Transportation

Transportation in Humans

The circulatory system consists of heart, blood, and blood vessels.

Human Heart

• Muscular organ about the size of a fist
• Located in the chest cavity, slightly tilted to the left
• Has four chambers: two upper atria and two lower ventricles
• Right side carries deoxygenated blood, left side carries oxygenated blood
• Septum separates right and left sides preventing mixing of blood

Double Circulation

Blood passes through the heart twice in one complete cycle:

1. Pulmonary Circulation (Heart → Lungs → Heart):

• Right ventricle pumps deoxygenated blood to lungs through pulmonary artery
• In lungs, CO₂ is released and O₂ is absorbed
• Oxygenated blood returns to left atrium through pulmonary veins

2. Systemic Circulation (Heart → Body → Heart):

• Left ventricle pumps oxygenated blood to all body parts through aorta
• O₂ is delivered and CO₂ is collected from tissues
• Deoxygenated blood returns to right atrium through vena cava

Advantages of Double Circulation:

• Keeps oxygenated and deoxygenated blood completely separate
• Ensures efficient oxygen supply to body tissues
• Maintains higher blood pressure for faster blood flow
• Supports high metabolic rate required by warm-blooded animals

Blood Components

Component	Function
Plasma (55%)	Transports nutrients, hormones, waste; maintains osmotic pressure
RBC (Erythrocytes)	Contains haemoglobin; transports oxygen
WBC (Leucocytes)	Fight infections; immunity
Platelets (Thrombocytes)	Blood clotting

Transportation in Plants

Xylem

• Transports water and minerals from roots to aerial parts
• Made of tracheids and vessels (dead cells)
• Transport is unidirectional (upward only)
• Mainly driven by transpiration pull

Phloem

• Transports food (sucrose, amino acids) from leaves to other parts
• Made of sieve tubes and companion cells (living cells)
• Transport is bidirectional (upward and downward)
• Requires energy (ATP) - called translocation

Transpiration

Loss of water vapor from aerial parts of plant, mainly through stomata.

Significance:

• Creates transpiration pull for upward movement of water
• Cools the plant
• Helps in absorption and distribution of minerals
• Maintains cell turgidity

6. CBSE Class 10 Science Notes – Excretion

Human Excretory System

Organs involved: Pair of kidneys, pair of ureters, urinary bladder, urethra.

Kidneys

• Bean-shaped organs located at the back of abdomen
• Basic filtration unit is nephron
• Each kidney contains about 1 million nephrons

Nephron Structure and Function

Nephron is the structural and functional unit of kidney.

Parts of Nephron:

1. Bowman's Capsule: Cup-shaped structure enclosing glomerulus
2. Glomerulus: Network of capillaries for blood filtration
3. Proximal Convoluted Tubule (PCT): Reabsorption of glucose, amino acids, water
4. Loop of Henle: Concentration of urine
5. Distal Convoluted Tubule (DCT): Selective reabsorption and secretion
6. Collecting Duct: Collects urine from nephrons

Urine Formation Steps

1. Filtration: Blood is filtered in glomerulus; filtrate contains water, glucose, salts, urea
2. Reabsorption: Useful substances (glucose, amino acids, most water) reabsorbed into blood
3. Secretion: Some waste substances secreted from blood into tubule
4. Concentration: Water reabsorbed according to body's need; concentrated urine formed

Composition of Urine: 95% water, 2.5% urea, 2.5% salts, uric acid, creatinine, and other waste products.

Excretion in Plants

Plants use different strategies for excretion:

• Oxygen: Released during photosynthesis (waste product of photosynthesis)
• CO₂: Released during respiration
• Water: Lost through transpiration and guttation
• Other wastes: Stored in vacuoles, bark, or leaves that fall off
• Resins and gums: Stored in old xylem

7. Important Points (Quick Revision)

• Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (sunlight, chlorophyll)
• Aerobic Respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 38 ATP
• Anaerobic Respiration in Yeast: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + 2 ATP
• Double Circulation: Pulmonary (heart-lungs-heart) + Systemic (heart-body-heart)
• Xylem: Water and minerals, unidirectional, dead cells
• Phloem: Food transport, bidirectional, living cells
• Nephron: Filtration → Reabsorption → Secretion → Concentration
• Haemoglobin deficiency: Causes anaemia, reduced oxygen carrying capacity

8. Solved Examples (CBSE Pattern)

Example 1: Photosynthesis Explanation (3 Marks)

Question: Write the equation for photosynthesis. Name the raw materials required and products formed.

Equation:

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in presence of sunlight and chlorophyll)

Raw Materials: Carbon dioxide (from air through stomata), Water (from soil through roots)

Products: Glucose (food), Oxygen (released into air)

Example 2: Difference Between Aerobic and Anaerobic Respiration (3 Marks)

Question: Differentiate between aerobic and anaerobic respiration. Name two organisms that undergo anaerobic respiration.

Aerobic Respiration	Anaerobic Respiration
Occurs in presence of oxygen	Occurs in absence of oxygen
Complete breakdown of glucose	Incomplete breakdown of glucose
More energy (38 ATP)	Less energy (2 ATP)
Products: CO₂ + H₂O	Products: Ethanol + CO₂ or Lactic acid

Organisms: Yeast, some bacteria, human muscle cells (during vigorous exercise)

Example 3: Diagram-Based Question (3 Marks)

Question: Draw a labelled diagram of the human heart and explain double circulation.

Double Circulation Explanation:

1. Pulmonary Circulation: Right ventricle → Pulmonary artery → Lungs → Pulmonary vein → Left atrium
2. Systemic Circulation: Left ventricle → Aorta → Body parts → Vena cava → Right atrium

Significance: Keeps oxygenated and deoxygenated blood separate; ensures efficient oxygen supply.

Example 4: 5-Mark Conceptual Question

Question: a) Describe the structure and functioning of nephrons.

b) What are the methods used by plants to get rid of excretory products?

a) Nephron Structure and Function:

Structure: Nephron consists of Bowman's capsule (encloses glomerulus), proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.

Function:

• Filtration: Blood filtered in glomerulus; filtrate enters Bowman's capsule
• Reabsorption: Useful substances (glucose, amino acids, water) reabsorbed in PCT and DCT
• Secretion: Waste substances secreted from blood into tubule
• Urine formation: Concentrated urine collected in collecting duct

b) Excretion in Plants:

• Oxygen released during photosynthesis
• CO₂ released during respiration
• Water lost through transpiration
• Wastes stored in vacuoles or old xylem (resins, gums)
• Wastes stored in leaves that fall off

Example 5: Case-Study Based Question

Passage: A person was diagnosed with kidney failure. The doctor suggested dialysis or kidney transplant. The patient's blood report showed high urea levels.

Questions: a) Why does kidney failure lead to high urea levels? b) What is the principle of dialysis? c) Why is kidney transplant better than lifelong dialysis?

a) Kidneys filter urea from blood. When kidneys fail, urea is not removed and accumulates in blood.

b) Dialysis works on the principle of diffusion across a semi-permeable membrane. Blood flows on one side, dialysing fluid on other side. Waste products diffuse from blood to fluid.

c) Kidney transplant is better because: patient can lead normal life, no need for regular dialysis sessions, better quality of life, more cost-effective in long run.

9. Smart Tricks & Memory Aids

N-R-T-E Memory Trick for Life Processes:

Nutrition → Respiration → Transportation → Excretion

Remember: "Nurse Ritu Treats Everyone"

Photosynthesis Equation Shortcut:

6-6-6-6 Rule: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Or: "6 Carbons, 6 Waters, 6 Oxygens out"

Blood Flow Direction Trick:

Right side of heart = Deoxygenated blood (both start with consonant)

Left side of heart = Oxygenated blood (both start with vowel)

Or: "Right De, Left O"

Nephron Filtration Shortcut:

Filtration → Reabsorption → Secretion → Concentration

Remember: "FRSC" or "Famous Rivers Sing Classics"

Board Answer-Writing Strategy:

1. Always draw diagrams where asked (carry 30-40% marks)
2. For processes: Write in points, not paragraphs
3. Include chemical equations for photosynthesis and respiration
4. Label diagrams clearly with proper spellings
5. For comparison questions: Use tables
6. Remember key terms: ATP, nephron, double circulation, transpiration

10. Visual Learning – Diagrams

Figure 1: Human Digestive System showing Mouth, Oesophagus, Stomach, Small Intestine, Large Intestine, and Associated Glands

ALT: CBSE Class 10 Science Notes Life Processes - Human Digestive System Diagram

Figure 2: Double Circulation in Humans - Pulmonary Circuit (Blue) and Systemic Circuit (Red)

ALT: CBSE Class 10 Science Notes Life Processes - Human Heart Double Circulation Diagram

Figure 3: Structure of Nephron showing Bowman's Capsule, Glomerulus, PCT, Loop of Henle, DCT, and Collecting Duct

ALT: CBSE Class 10 Science Notes Life Processes - Nephron Diagram

Figure 4: Photosynthesis Process in Chloroplast - Light Reactions and Calvin Cycle

ALT: CBSE Class 10 Science Notes Life Processes - Photosynthesis Diagram

Figure 5: Detailed Double Circulation showing Pulmonary and Systemic Circulation with Heart Chambers

ALT: CBSE Class 10 Science Notes Life Processes - Double Circulation Flow Diagram

11. Most Important Board Questions

1 Mark Questions ★

What is the basic filtration unit of the kidney?

Nephron

Name the pigment that carries oxygen in blood.

Haemoglobin

What is the process of loss of water from plant leaves called?

Transpiration

Which vessel carries blood from heart to lungs?

Pulmonary artery

2-3 Mark Questions ★★

Why is diffusion insufficient to meet oxygen requirements of multicellular organisms?

Multicellular organisms have large body size and complex structure. Diffusion is slow and cannot reach all cells efficiently. They need specialized respiratory and circulatory systems.

What would be the consequences of deficiency of haemoglobin?

Causes anaemia. Reduced oxygen carrying capacity leads to fatigue, weakness, shortness of breath, and pale skin.

Differentiate between xylem and phloem.

Xylem transports water and minerals, unidirectional, dead cells. Phloem transports food, bidirectional, living cells.

4-5 Mark Questions ★★★

Describe double circulation. Why is it necessary?

Double circulation involves pulmonary and systemic circulation. Necessary to keep oxygenated and deoxygenated blood separate, ensure efficient oxygen supply, maintain high metabolic rate.

Explain the process of nutrition in Amoeba with diagram.

Amoeba shows holozoic nutrition: ingestion by pseudopodia forming food vacuole, digestion by enzymes, absorption into cytoplasm, assimilation for energy, egestion of undigested food.

12. Common Mistakes to Avoid

Mistake	Correction
Confusing breathing and respiration	Breathing is physical (inhalation/exhalation); Respiration is chemical (breakdown of glucose)
Incorrect photosynthesis equation	6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (not 12H₂O in products)
Incomplete heart diagram	Label all 4 chambers, major blood vessels, and septum
Mixing xylem and phloem	Xylem = water, unidirectional; Phloem = food, bidirectional
Wrong blood vessels	Pulmonary artery carries deoxygenated blood (exception); Pulmonary vein carries oxygenated blood (exception)

13. Practice Section

Multiple Choice Questions (MCQs)

Q1. The process of photosynthesis occurs in which organelle?

1. Mitochondria
2. Chloroplast
3. Ribosome
4. Nucleus

Q2. Which of the following is the correct path of urine formation?

1. Filtration → Secretion → Reabsorption
2. Filtration → Reabsorption → Secretion
3. Reabsorption → Filtration → Secretion
4. Secretion → Filtration → Reabsorption

Q3. The breakdown of pyruvate in presence of oxygen takes place in:

1. Cytoplasm
2. Mitochondria
3. Nucleus
4. Chloroplast

Assertion-Reason Question

Assertion (A): The walls of alveoli are one cell thick.

Reason (R): Thin walls facilitate efficient exchange of gases.

Answer: Both A and R are true and R is the correct explanation of A.

Explanation: Thin walls (one cell thick) and rich blood supply in alveoli allow rapid diffusion of gases.

14. Frequently Asked Questions (FAQ)

What are life processes?

Life processes are the basic functions performed by living organisms to maintain life. These include nutrition (obtaining food), respiration (energy release), transportation (material movement), and excretion (waste removal). These processes are essential for survival, growth, and reproduction.

What is double circulation?

Double circulation is the process where blood passes through the heart twice in one complete cycle. It consists of pulmonary circulation (heart to lungs and back) and systemic circulation (heart to body and back). This ensures complete separation of oxygenated and deoxygenated blood for efficient oxygen supply.

What is nephron?

Nephron is the structural and functional unit of the kidney. It consists of Bowman's capsule, glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. Each kidney contains about 1 million nephrons that filter blood and form urine.

Are these CBSE Class 10 Science Notes based on NCERT?

Yes, these CBSE Class 10 Science Notes are 100% aligned with the latest NCERT textbook (2024-25 edition) for Chapter 5 "Life Processes" and follow the current CBSE syllabus and examination pattern.

Why is haemoglobin deficiency dangerous?

Haemoglobin deficiency causes anaemia. Since haemoglobin carries oxygen from lungs to body tissues, its deficiency reduces oxygen supply to cells. This leads to fatigue, weakness, shortness of breath, and reduced physical and mental performance. Severe deficiency can be life-threatening.

15. Conclusion

Master Life Processes for Board Success!

These comprehensive CBSE Class 10 Notes for "Life Processes" cover all essential concepts, diagrams, and solved examples to help you excel in your board examinations.

Key Takeaways:

• Master photosynthesis and respiration equations
• Practice drawing heart and nephron diagrams
• Understand double circulation thoroughly
• Remember differences between xylem and phloem
• Know the steps of urine formation

Next Chapter: Control and Coordination – CBSE Class 10 Notes

Best of luck for your CBSE Class 10 Board Examinations!

These CBSE Class 10 Science Notes are prepared by experienced Biology faculty following the latest NCERT curriculum.