Class 10 CBSE important notes for Life Processes Exam 2026

SK CLASSES

Premium Class 10 Science Study Notes

Chapter: Life Processes

Complete CBSE-ready biology notes for concept clarity, board exam preparation, quick revision and foundation-level understanding.

Class: 10 CBSE

Subject: Science

Difficulty: Board + Foundation Level

Institute: SK Classes

Chapter Focus: Nutrition, Respiration, Transportation, Excretion

Best For: School Exams, Boards, Quick Revision

1. Chapter Overview

Life processes are the basic functions performed by living organisms to maintain life. These include nutrition, respiration, transportation and excretion.

Why do organisms need life processes?

Living organisms are made of cells. Cells continuously need energy, raw materials, water, oxygen and removal of wastes. Even when an organism is sleeping or resting, internal maintenance activities continue.

Food intake

→

Digestion

→

Absorption

→

Energy release

→

Waste removal

Major life processes at a glance

Life Process	Main Function	Important Organs / Structures
Nutrition	Obtaining and using food	Mouth, stomach, small intestine, liver, pancreas, villi
Respiration	Breaking down food to release energy	Nose, trachea, lungs, diaphragm, mitochondria
Transportation	Movement of materials inside body	Heart, blood, arteries, veins, capillaries; xylem and phloem in plants
Excretion	Removal of metabolic wastes	Kidneys, ureters, urinary bladder, urethra; leaves and roots in plants

Real-life importance

• Digestion explains why food must be chewed properly.
• Respiration explains why athletes breathe faster during exercise.
• Transportation explains how oxygen reaches each body cell.
• Excretion explains why kidneys are essential for maintaining water and salt balance.

NutritionDigestionRespirationATP Blood circulationTranspirationExcretionNephron

2. Important Definitions

Term	Definition
Nutrition	The process by which organisms take in food and use it for energy, growth, repair and maintenance.
Autotrophic nutrition	Mode of nutrition in which organisms prepare their own food from simple inorganic substances. Example: green plants.
Heterotrophic nutrition	Mode of nutrition in which organisms depend on other organisms for food.
Holozoic nutrition	Nutrition in which complex food is ingested, digested, absorbed and assimilated. Example: humans, Amoeba.
Parasitic nutrition	Nutrition in which an organism obtains food from a living host. Example: Cuscuta, tapeworm.
Saprotrophic nutrition	Nutrition in which organisms obtain food from dead and decaying organic matter. Example: fungi.
Digestion	Breakdown of complex food into simpler, soluble and absorbable substances.
Respiration	Biochemical process in which food is broken down to release energy.
Aerobic respiration	Breakdown of glucose in the presence of oxygen to release energy, carbon dioxide and water.
Anaerobic respiration	Breakdown of glucose in the absence of oxygen to release energy.
Glycolysis	First step of respiration in which glucose is broken into pyruvate in the cytoplasm.
Transportation	Movement of substances such as food, gases, water, minerals and wastes inside an organism.
Translocation	Movement of prepared food from leaves to other parts of the plant through phloem.
Excretion	Removal of harmful metabolic wastes from the body.
Nephron	Structural and functional unit of the kidney.

Board Exam Tip: Definitions should include the key function and one correct example where required. Avoid vague answers such as “nutrition means eating food.”

3. Nutrition

3.1 Meaning of nutrition

Nutrition is the process by which living organisms obtain food and use it for energy, growth, repair and protection from diseases.

3.2 Types of nutrition

Type	Meaning	Examples
Autotrophic	Organism makes its own food using carbon dioxide, water and sunlight.	Green plants, algae
Heterotrophic	Organism depends on other organisms for food.	Humans, animals, fungi

3.3 Heterotrophic nutrition: main types

Mode	Explanation	Example
Holozoic	Food is taken inside the body and digested internally.	Human beings, Amoeba
Parasitic	Food is obtained from a living host, usually harming it.	Cuscuta, lice, tapeworm
Saprotrophic	Food is obtained from dead and decaying matter by external digestion.	Mushroom, bread mould

3.4 Nutrition in Amoeba

Amoeba shows holozoic nutrition. It captures food with the help of temporary finger-like projections called pseudopodia.

Ingestion

→

Food vacuole formation

→

Digestion

→

Absorption

→

Assimilation

→

Egestion

Diagram: Nutrition in Amoeba — labels to show Pseudopodia ↓ __________________ / \ / Food vacuole \ ← Food particle | Digestion | | Nucleus | \ / \__________________/ ↑ Cell membrane Exam labels: pseudopodia, food vacuole, nucleus, cell membrane, food particle.

Common Mistake: Students often write that Amoeba uses mouth for ingestion. Correction: Amoeba does not have a fixed mouth; it uses pseudopodia.

4. Human Digestive System

4.1 Alimentary canal

The alimentary canal is a long muscular tube from mouth to anus where food is ingested, digested, absorbed and egested.

Mouth

→

Oesophagus

→

Stomach

→

Small intestine

→

Large intestine

→

Rectum

→

Anus

Diagram: Human Alimentary Canal — labels to show Mouth ↓ Oesophagus ↓ Stomach ← Liver + Gall bladder release bile ↓ Pancreas releases pancreatic juice Small intestine ← Villi present for absorption ↓ Large intestine ↓ Rectum ↓ Anus Exam labels: mouth, oesophagus, stomach, liver, gall bladder, pancreas, small intestine, large intestine, rectum, anus.

4.2 Digestion in mouth

• Food is chewed by teeth, increasing surface area.
• Salivary glands secrete saliva.
• Saliva contains salivary amylase, which begins digestion of starch.

Reaction: Starch + Salivary amylase → Simple sugars

4.3 Digestion in stomach

Secretion	Source	Function
Hydrochloric acid	Gastric glands	Makes medium acidic and kills many germs.
Pepsin	Gastric glands	Begins digestion of proteins.
Mucus	Gastric glands	Protects stomach lining from acid.

4.4 Role of liver and pancreas

Organ	Secretion	Function
Liver	Bile	Emulsifies fats and makes the medium alkaline.
Gall bladder	Stores bile	Releases bile into small intestine when required.
Pancreas	Pancreatic juice	Contains enzymes for digestion of carbohydrates, proteins and fats.

4.5 Small intestine and villi

The small intestine is the main site of complete digestion and absorption. Its inner wall has numerous finger-like projections called villi.

Why are villi important? Villi increase the surface area for absorption and contain blood vessels that transport absorbed food to body cells.

Diagram: Villi in Small Intestine Small intestine wall | | | | | ← Villi V V V V V One villus: /\ / \ ← Thin wall /____\ |||| ← Blood capillaries |||| Function: increases surface area for absorption.

4.6 Large intestine

The large intestine absorbs water from undigested food. The remaining waste is stored in the rectum and removed through the anus.

5. Respiration

5.1 Meaning of respiration

Respiration is the process in which glucose is broken down inside cells to release energy. This energy is stored in the form of ATP and used for life activities.

Aerobic respiration: Glucose + Oxygen → Carbon dioxide + Water + Energy

5.2 Breathing vs Respiration

Breathing	Respiration
Physical process of taking in oxygen and giving out carbon dioxide.	Biochemical process of breaking down food to release energy.
Occurs in respiratory organs.	Occurs inside cells.
No energy is released directly.	Energy is released as ATP.

5.3 Steps of respiration

Glucose

→

Glycolysis in cytoplasm

→

Pyruvate

→

Aerobic / anaerobic breakdown

5.4 Glycolysis, Krebs cycle and fermentation

Process	Site	Explanation for Class 10
Glycolysis	Cytoplasm	Glucose is broken down into pyruvate. This is the first step of respiration.
Krebs cycle	Mitochondria	Part of aerobic respiration where pyruvate is further broken down completely to release more energy.
Fermentation	Yeast cells / cytoplasm	Anaerobic breakdown of glucose producing ethanol, carbon dioxide and energy.

Foundation Note: Krebs cycle is not required in deep biochemical detail at CBSE Class 10 level. Students should know that complete breakdown of pyruvate occurs in mitochondria in the presence of oxygen.

5.5 Aerobic vs Anaerobic Respiration

Feature	Aerobic Respiration	Anaerobic Respiration
Oxygen	Required	Not required
Breakdown of glucose	Complete	Incomplete
Products	Carbon dioxide, water, energy	Ethanol + carbon dioxide + energy in yeast; lactic acid + energy in muscles
Energy released	More	Less
Site	Cytoplasm and mitochondria	Mainly cytoplasm

In yeast

→

Glucose

→

Ethanol + CO₂ + Energy

In muscles

→

Glucose

→

Lactic acid + Energy

6. Human Respiratory System

6.1 Respiratory tract

Nostrils

→

Nasal cavity

→

Pharynx

→

Larynx

→

Trachea

→

Bronchi

→

Bronchioles

→

Alveoli

Diagram: Human Respiratory System — labels to show Nasal cavity ↓ Trachea ↓ Bronchi / \ Left Right lung lung \ / Bronchioles ↓ Alveoli Diaphragm below lungs Exam labels: nasal cavity, trachea, bronchi, lungs, alveoli, diaphragm.

6.2 Alveoli: site of gas exchange

• Alveoli are tiny balloon-like structures in lungs.
• They provide large surface area for exchange of gases.
• They have thin walls and are surrounded by blood capillaries.
• Oxygen diffuses from alveoli into blood; carbon dioxide diffuses from blood into alveoli.

6.3 Role of diaphragm

Inhalation	Exhalation
Diaphragm contracts and moves downward.	Diaphragm relaxes and moves upward.
Chest cavity volume increases.	Chest cavity volume decreases.
Air pressure inside lungs decreases.	Air pressure inside lungs increases.
Air enters the lungs.	Air moves out of lungs.

Important Exam Point: Rings of cartilage are present in the trachea to prevent it from collapsing when there is less air.

6.4 Respiration in plants

Plants also respire. Gaseous exchange occurs through stomata in leaves, lenticels in stems and root hairs in roots. Respiration occurs throughout the day and night, while photosynthesis occurs only in the presence of light.

7. Transportation in Human Beings

7.1 Need for transport system

Multicellular organisms have large bodies, so diffusion alone is not enough to supply oxygen, food and water to all cells. Therefore, humans need a circulatory system.

7.2 Components of blood

Component	Function
Plasma	Liquid part of blood; transports food, carbon dioxide, hormones and wastes.
Red blood cells	Contain haemoglobin; transport oxygen.
White blood cells	Fight infections and provide immunity.
Platelets	Help in blood clotting.

7.3 Blood vessels

Feature	Arteries	Veins	Capillaries
Direction	Carry blood away from heart	Carry blood towards heart	Connect arteries and veins
Wall	Thick and elastic	Thin	Very thin, one-cell thick
Valves	Absent	Present	Absent
Pressure	High	Low	Very low
Usually carry	Oxygenated blood, except pulmonary artery	Deoxygenated blood, except pulmonary vein	Exchange materials with tissues

7.4 Human heart

The human heart is a muscular pumping organ with four chambers: right atrium, right ventricle, left atrium and left ventricle.

Diagram: Human Heart — simplified flow Body → Vena cava → Right atrium → Right ventricle ↓ Lungs ↓ Pulmonary vein ← Left atrium ← Oxygenated blood ↓ Left ventricle → Aorta → Body Exam labels: right atrium, right ventricle, left atrium, left ventricle, vena cava, pulmonary artery, pulmonary vein, aorta.

7.5 Double circulation

In humans, blood passes through the heart twice during one complete cycle. This is called double circulation.

Type	Pathway	Function
Pulmonary circulation	Heart → Lungs → Heart	Oxygenation of blood
Systemic circulation	Heart → Body → Heart	Supply of oxygen and nutrients to body cells

7.6 Diastole and systole

Term	Meaning
Systole	Contraction of heart chambers to pump blood.
Diastole	Relaxation of heart chambers to receive blood.

Why is separation of oxygenated and deoxygenated blood important? It allows efficient supply of oxygen to body cells and supports high energy needs in warm-blooded animals.

8. Transportation in Plants: Xylem and Phloem

8.1 Xylem

Xylem transports water and minerals from roots to other parts of the plant. Movement is mostly upward.

8.2 How water moves in xylem

• Root hairs absorb water and minerals from soil.
• Water enters xylem vessels.
• Transpiration from leaves creates a suction pull.
• This pull helps draw water upward through xylem.

Soil water

→

Root hairs

→

Root xylem

→

Stem xylem

→

Leaves

8.3 Phloem

Phloem transports food prepared in leaves to growing and storage parts of the plant. This movement is called translocation.

8.4 Xylem vs Phloem

Feature	Xylem	Phloem
Material transported	Water and minerals	Food / sugars
Direction	Mainly upward	Both upward and downward
Energy requirement	Mostly passive due to transpiration pull	Requires energy in the form of ATP
Main cells	Vessels and tracheids	Sieve tubes and companion cells

Diagram: Transport in Plants Leaves ↑ Xylem: water + minerals upward ↓ Phloem: food transported to roots/stem/fruits Stem ↑ Root hairs absorb water and minerals from soil

Common Mistake: Students write that phloem transports water. Correction: phloem transports prepared food; xylem transports water and minerals.

9. Excretion in Human Beings

9.1 Meaning of excretion

Excretion is the process of removing metabolic wastes from the body. In humans, the main nitrogenous waste is urea.

9.2 Human excretory system

Kidneys

→

Ureters

→

Urinary bladder

→

Urethra

Diagram: Human Excretory System — labels to show Left kidney Right kidney | | Ureter Ureter \ / \ / Urinary bladder | Urethra Exam labels: kidney, ureter, urinary bladder, urethra, renal artery, renal vein.

9.3 Nephron: functional unit of kidney

Each kidney contains many nephrons. A nephron filters blood and forms urine.

Diagram: Nephron — important labels Afferent arteriole → Glomerulus ↓ Bowman's capsule ↓ Tubule system ↓ Collecting duct → Urine Exam labels: glomerulus, Bowman's capsule, tubule, collecting duct, capillaries.

9.4 Steps in urine formation

Step	What happens?
Filtration	Blood is filtered in glomerulus. Water, salts, urea and small molecules enter Bowman's capsule.
Selective reabsorption	Useful substances such as glucose, amino acids, salts and water are reabsorbed into blood.
Urine formation	Remaining waste forms urine and passes into collecting duct.

9.5 Dialysis

Dialysis is an artificial method of removing wastes from blood when kidneys are not functioning properly. It works as an artificial kidney.

9.6 Excretion in animals and plants

Organism / Group	Excretory waste / Method
Humans	Urea, excess salts and water removed mainly by kidneys.
Aquatic animals	Often excrete ammonia directly into water.
Birds and reptiles	Excrete uric acid to conserve water.
Plants	Remove waste through leaves, bark, resins, gums, root exudates and transpiration.

10. NCERT-Based Important Points

• Life processes are required for maintenance of living organisms.
• Diffusion alone is insufficient in large multicellular organisms.
• Amoeba takes food using pseudopodia.
• Salivary amylase digests starch in the mouth.
• Hydrochloric acid in stomach makes medium acidic and kills microbes.
• Bile does not contain digestive enzymes, but it helps in fat digestion by emulsification.
• Small intestine is the main site of digestion and absorption.
• Villi increase surface area for absorption.
• Glycolysis takes place in cytoplasm.
• Complete breakdown of pyruvate in presence of oxygen occurs in mitochondria.
• Alveoli provide large surface area for gaseous exchange.
• Cartilage rings prevent collapse of trachea.
• Arteries carry blood away from heart; veins carry blood towards heart.
• Human heart has four chambers and shows double circulation.
• Xylem transports water and minerals; phloem transports food.
• Nephron is the functional unit of kidney.

Common mistakes and correction tips

Mistake	Correct Understanding
Writing “respiration means breathing”.	Breathing is physical gas exchange; respiration is cellular energy release.
Writing “bile digests fat directly”.	Bile emulsifies fats and helps enzymes act efficiently.
Confusing pulmonary artery and vein.	Pulmonary artery carries deoxygenated blood to lungs; pulmonary vein carries oxygenated blood to heart.
Writing xylem and phloem both transport food.	Xylem transports water/minerals; phloem transports food.
Writing kidney stores urine.	Kidney forms urine; urinary bladder stores urine.

11. Exam-Oriented Questions

A. Very Short Answer Questions

1. Define life processes.
2. Name the enzyme present in saliva.
3. What is the function of bile?
4. Name the site of complete digestion in humans.
5. What are villi?
6. Where does glycolysis occur?
7. Name the functional unit of kidney.
8. Which blood cells help in clotting?
9. What is translocation?
10. What is systole?

B. Short Answer Questions

1. Why is diffusion insufficient in multicellular organisms?
2. Explain nutrition in Amoeba.
3. State the role of HCl, pepsin and mucus in stomach.
4. How are alveoli suited for gaseous exchange?
5. Differentiate between arteries and veins.
6. What is double circulation? Why is it important?
7. How does transpiration help in upward movement of water?
8. Explain selective reabsorption in nephron.

C. Long Answer Questions

1. Describe the human digestive system with functions of major organs and glands.
2. Explain aerobic and anaerobic respiration with examples.
3. Describe the structure and working of human heart. Add a labelled diagram.
4. Explain the human excretory system and urine formation in nephron.
5. Compare transportation in humans and plants.

D. Assertion-Reason Questions

1. Assertion: Villi are present in the small intestine.
Reason: Villi increase surface area for absorption of digested food.

2. Assertion: Trachea does not collapse even when there is less air.
Reason: It is supported by rings of cartilage.

3. Assertion: Human beings have double circulation.
Reason: Blood passes through the heart twice in one complete cycle.

4. Assertion: Phloem transport requires energy.
Reason: Movement of food in phloem is called translocation.

E. Diagram-Based Questions

1. Draw a labelled diagram of the human alimentary canal and label stomach, liver, pancreas and small intestine.
2. Draw the respiratory system and label trachea, lungs, alveoli and diaphragm.
3. Draw a labelled diagram of the human heart.
4. Draw a nephron and label Bowman's capsule, glomerulus, tubule and collecting duct.
5. Draw nutrition in Amoeba and label pseudopodia and food vacuole.

F. Numerical / Data-Based Questions

1. A person has a pulse rate of 72 beats per minute. How many times does the heart beat in 10 minutes?
2. If a student breathes 18 times per minute at rest, estimate the number of breaths taken in 30 minutes.
3. A person drinks 2.5 L water in a day and loses 1.5 L through urine. How much water is lost through sweat, breathing and other processes if total water loss is 2.5 L?

12. Case Study-Based Questions

Case Study 1: Digestion

Rohan ate a meal containing rice, dal and fried snacks. Digestion of starch began in his mouth. In the stomach, protein digestion started. Later, bile and pancreatic juice helped complete digestion in the small intestine.

1. Name the enzyme that begins starch digestion.
2. Which gland secretes bile?
3. What is the role of bile in fat digestion?
4. Why is small intestine called the main site of digestion?

Case Study 2: Respiration

During a race, a student started breathing rapidly. After running, he felt cramps in his leg muscles. The teacher explained that muscle cells sometimes respire anaerobically when oxygen supply is insufficient.

1. What is the product formed in muscles during anaerobic respiration?
2. Why does breathing rate increase during exercise?
3. Where does aerobic respiration mainly occur after glycolysis?
4. Differentiate between breathing and respiration.

Case Study 3: Transportation

Blood from the body enters the right side of the heart and is pumped to the lungs. After oxygenation, it returns to the left side of the heart and is pumped to the body.

1. What is this type of circulation called?
2. Which blood vessel carries blood from heart to lungs?
3. Which blood vessel carries oxygenated blood from lungs to heart?
4. Why is this system important in humans?

Case Study 4: Excretion

A patient with kidney failure was advised dialysis. The doctor explained that the kidneys normally filter blood and remove urea, excess salts and water.

1. What is dialysis?
2. Name the functional unit of kidney.
3. Which organ stores urine?
4. What is selective reabsorption?

13. Quick Revision Sheet

Major Processes

• Nutrition: food intake and use
• Respiration: energy release
• Transportation: movement of materials
• Excretion: removal of wastes

Important Reactions

• Aerobic respiration: Glucose + O₂ → CO₂ + H₂O + Energy
• Yeast fermentation: Glucose → Ethanol + CO₂ + Energy
• Muscle anaerobic respiration: Glucose → Lactic acid + Energy

Digestive Glands

• Salivary gland: saliva + amylase
• Gastric gland: HCl, pepsin, mucus
• Liver: bile
• Pancreas: pancreatic juice

Important Diagrams

• Human alimentary canal
• Nutrition in Amoeba
• Human respiratory system
• Human heart
• Human excretory system
• Nephron

Must-Remember Terms

• Pseudopodia
• Villi
• Alveoli
• Haemoglobin
• Double circulation
• Transpiration pull
• Translocation
• Nephron

One-Line Exam Facts

• Small intestine is the main site of digestion and absorption.
• Alveoli are thin-walled and richly supplied with capillaries.
• Left ventricle has thick muscular walls.
• Phloem transport requires ATP.
• Kidney forms urine; bladder stores urine.

Final Board Strategy: Learn diagrams with labels, practise differences in table form, and write answers using keywords such as “surface area”, “diffusion”, “oxygenated”, “deoxygenated”, “selective reabsorption”, “transpiration pull” and “ATP”.

14. Answer Key / Hints

Very Short Hints

1. Maintenance functions of living organisms.
2. Salivary amylase.
3. Emulsification of fats and making medium alkaline.
4. Small intestine.
5. Finger-like projections for absorption.
6. Cytoplasm.
7. Nephron.
8. Platelets.
9. Transport of food through phloem.
10. Contraction of heart chambers.

Assertion-Reason Answers

Question	Answer
1	Both assertion and reason are true, and reason correctly explains assertion.
2	Both assertion and reason are true, and reason correctly explains assertion.
3	Both assertion and reason are true, and reason correctly explains assertion.
4	Both assertion and reason are true, but reason does not fully explain why energy is required.

Numerical Answers

1. 72 × 10 = 720 heartbeats.
2. 18 × 30 = 540 breaths.
3. Other losses = 2.5 L − 1.5 L = 1.0 L.

Prepared by: SK Classes
Module Type: Premium CBSE Science Notes
Chapter: Life Processes

```