CBSE Class 10 Science Chapter 5 PDF Notes – Life Processes 2026-27

These Class 10 Science Chapter 5 PDF Notes explain Life Processes clearly: nutrition in plants and humans, respiration, transportation in humans and plants, and excretion, including the structure and working of the nephron.

Life Processes is the highest-weightage biology chapter. Labelled diagrams of the human digestive system, heart, alveoli, stomata and nephron are asked often, along with comparisons such as aerobic versus anaerobic respiration.

Use the table of contents below to jump to the part you need, or read top to bottom for a complete revision of the chapter.

Table of Contents

• Chapter Overview
• Important Topics and Concepts
• Aerobic vs Anaerobic Respiration
• Important Definitions and Terms
• Short Answer Questions
• Long Answer Questions
• MCQs with Answers
• Quick Revision Points
• Chapter Summary
• Exam Tips and PYQ Pattern
• Frequently Asked Questions
• Conclusion

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Chapter Overview

Life processes are the basic functions that keep living organisms alive and maintain their bodies: nutrition, respiration, transportation and excretion. Even when we sleep, these processes continue.

The chapter compares how plants and animals carry out each process. Plants make their own food by photosynthesis and transport water and food through xylem and phloem, while humans digest food, breathe through lungs, pump blood with a four-chambered heart and filter waste in the kidneys.

Important Topics and Concepts

Autotrophic nutrition and photosynthesis

Green plants make food from carbon dioxide and water using sunlight and chlorophyll: 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O (in the presence of sunlight and chlorophyll). Events: absorption of light by chlorophyll; splitting of water into hydrogen and oxygen; reduction of CO₂ to carbohydrates. Extra glucose is stored as starch. Gas exchange happens through stomata, which open and close with the help of guard cells. Desert plants take in CO₂ at night.

Heterotrophic nutrition

Organisms depend on others for food. Saprotrophs (fungi) break down food outside the body; parasites (cuscuta, ticks, lice, tapeworms) feed on living hosts; holozoic organisms take in whole food and digest it inside. Amoeba takes in food using pseudopodia, forming a food vacuole where it is digested.

Human digestive system

• Mouth: teeth chew food; salivary amylase converts starch into sugar.
• Oesophagus: food moves by rhythmic contraction of muscles (peristalsis).
• Stomach: gastric glands release HCl (acidic medium, kills germs), pepsin (digests proteins) and mucus (protects the stomach lining).
• Small intestine: longest part. Liver secretes bile, which makes the medium alkaline and emulsifies fats. Pancreatic juice has trypsin (proteins) and lipase (fats). Intestinal juice completes digestion into glucose, amino acids, fatty acids and glycerol.
• Villi in the small intestine increase surface area for absorption; they are rich in blood vessels.
• Large intestine absorbs excess water; the rest is removed through the anus, controlled by the anal sphincter.

Respiration

Glucose is first broken into pyruvate (3-carbon) in the cytoplasm. Then: (a) aerobic respiration in mitochondria gives CO₂ + water + a lot of energy; (b) anaerobic respiration in yeast gives ethanol + CO₂ + energy; (c) lack of oxygen in muscle cells gives lactic acid + energy, causing cramps. Energy is stored as ATP, the energy currency of the cell.

Human respiratory system

Air enters through nostrils (fine hairs and mucus filter it), passes the pharynx, larynx and trachea (with rings of cartilage that prevent collapse), then bronchi and bronchioles, and ends in balloon-like alveoli. Alveoli provide a huge surface for gas exchange with blood capillaries. Haemoglobin in red blood cells carries oxygen; CO₂ is mostly carried dissolved in blood. Plants exchange gases through stomata and lenticels.

Blood and the heart

• Blood has plasma (carries food, CO₂, nitrogenous waste), RBCs (oxygen), WBCs and platelets (clotting).
• The human heart has four chambers: two atria and two ventricles. The right side receives deoxygenated blood and sends it to the lungs; the left side receives oxygenated blood from the lungs and pumps it to the body.
• Ventricles have thicker walls because they pump blood to other organs. Valves prevent backflow.
• Double circulation: blood passes through the heart twice in one cycle, keeping oxygenated and deoxygenated blood separate. This is needed in birds and mammals, which need a lot of energy to maintain body temperature.
• Arteries carry blood away from the heart (thick, elastic walls); veins carry it back (valves); capillaries exchange materials with cells.
• Lymph (tissue fluid) carries digested fat and drains excess fluid back into the blood.
• Blood pressure: normal is about 120/80 mm Hg, measured by a sphygmomanometer.

Transportation in plants

Xylem carries water and minerals from roots to leaves. Root cells take in ions, creating a difference in concentration that draws water in; transpiration (loss of water vapour from leaves) creates a suction pull that moves water up, especially during the day. Phloem carries food (sucrose) from leaves to other parts; this is translocation, which uses energy from ATP.

Excretion in humans

The kidneys filter blood to remove nitrogenous wastes such as urea. Each kidney has many nephrons. Blood enters the glomerulus, and filtrate collects in Bowman’s capsule. As it passes along the tubule, useful substances like glucose, amino acids, salts and most water are reabsorbed. The urine then flows through the ureters to the urinary bladder and out via the urethra. If kidneys fail, an artificial kidney (haemodialysis) removes wastes.

Excretion in plants

Plants get rid of excess oxygen and water through stomata and transpiration. Other wastes are stored in vacuoles, in leaves that fall off, or as gums and resins in old xylem; some are excreted into the soil.

Aerobic vs Anaerobic Respiration

Important Definitions and Terms

Short Answer Questions

Q1. Why is diffusion insufficient to meet the oxygen needs of multicellular organisms like humans?

In large multicellular organisms, most cells are far from the surface. Diffusion is too slow to supply oxygen to all of them, so a respiratory system and blood transport are needed.

Q2. What are the functions of HCl, pepsin and mucus in the stomach?

HCl creates an acidic medium for pepsin and kills germs. Pepsin digests proteins. Mucus protects the stomach lining from the acid.

Q3. Why do ventricles have thicker muscular walls than atria?

Ventricles pump blood to the lungs and to all parts of the body under high pressure, so they need thick muscular walls. Atria only push blood into the ventricles.

Q4. What is the role of the guard cells?

Guard cells control the opening and closing of stomata. When they swell with water, the pore opens; when they lose water, it closes.

Q5. Why is the rate of breathing faster in aquatic organisms than in terrestrial ones?

Dissolved oxygen in water is much less than oxygen in air, so aquatic organisms must breathe faster to get enough oxygen.

Q6. Why do muscles get cramps after heavy exercise?

When oxygen is short, muscle cells break pyruvate into lactic acid by anaerobic respiration. Lactic acid build-up causes cramps.

Q7. What is the function of the villi?

Villi greatly increase the surface area of the small intestine for absorbing digested food. They have a rich blood supply that carries the absorbed food to all body cells.

Q8. How is the amount of urine produced regulated?

It depends on how much excess water and dissolved waste the body has. The kidney reabsorbs more water when the body needs it and less when there is excess, so urine volume changes.

Long Answer Questions

Q1. Describe the structure and functioning of a nephron.

The nephron is the basic filtration unit of the kidney. It has a cup-shaped Bowman’s capsule containing a cluster of capillaries called the glomerulus, followed by a long tubule that ends in a collecting duct.

1. Filtration: blood enters the glomerulus at high pressure, and water, glucose, salts, amino acids and urea pass into Bowman’s capsule.

2. Reabsorption: as the filtrate moves through the tubule, useful substances such as glucose, amino acids, salts and much of the water are reabsorbed into the surrounding capillaries.

3. The remaining fluid is urine, which passes into the collecting duct, then the ureter, and is stored in the urinary bladder before leaving through the urethra.

Tip: Draw and label the nephron: glomerulus, Bowman’s capsule, tubule, collecting duct, renal artery and vein branches.

Q2. Explain the double circulation of blood in humans.

Blood passes through the heart twice in one complete circuit of the body.

Pulmonary circulation: deoxygenated blood from the body enters the right atrium, goes to the right ventricle and is pumped to the lungs through the pulmonary artery. It returns oxygenated through the pulmonary veins to the left atrium.

Systemic circulation: oxygenated blood moves to the left ventricle and is pumped through the aorta to all body parts. Deoxygenated blood returns through the vena cava to the right atrium.

Importance: oxygenated and deoxygenated blood never mix, giving the body an efficient oxygen supply. This is vital for mammals and birds, which need high energy to keep a constant body temperature.

Q3. Describe the process of digestion of food in humans.

Mouth: food is chewed and mixed with saliva; salivary amylase turns starch into sugar.

Stomach: HCl, pepsin and mucus act; proteins start breaking down.

Small intestine: bile from the liver emulsifies fats and makes the medium alkaline; pancreatic juice provides trypsin for proteins and lipase for fats; intestinal juice finishes digestion into glucose, amino acids, fatty acids and glycerol.

Absorption: villi absorb digested food into the blood.

Large intestine: absorbs water; the waste is removed through the anus.

MCQs with Answers

1. The energy currency of the cell is
(a) Glucose (b) ATP (c) Pyruvate (d) Starch
Answer: (b) ATP

2. Which enzyme digests proteins in the stomach?
(a) Amylase (b) Lipase (c) Pepsin (d) Trypsin
Answer: (c) Pepsin

3. Bile is secreted by the
(a) Pancreas (b) Stomach (c) Liver (d) Gall bladder
Answer: (c) Liver – It is stored in the gall bladder.

4. Anaerobic respiration in yeast produces
(a) Lactic acid (b) Ethanol and CO₂ (c) Water and CO₂ (d) Pyruvate only
Answer: (b) Ethanol and CO₂

5. Exchange of gases in the lungs takes place in the
(a) Trachea (b) Bronchi (c) Alveoli (d) Diaphragm
Answer: (c) Alveoli

6. Which chamber of the heart pumps oxygenated blood to the body?
(a) Right atrium (b) Right ventricle (c) Left atrium (d) Left ventricle
Answer: (d) Left ventricle

7. Water moves up in plants mainly through
(a) Phloem (b) Xylem (c) Stomata (d) Cortex
Answer: (b) Xylem

8. The basic filtration unit of the kidney is the
(a) Neuron (b) Nephron (c) Alveolus (d) Villus
Answer: (b) Nephron

9. Normal blood pressure in humans is about
(a) 80/120 mm Hg (b) 120/80 mm Hg (c) 140/100 mm Hg (d) 100/60 mm Hg
Answer: (b) 120/80 mm Hg

10. Translocation of food in plants occurs through
(a) Xylem (b) Phloem (c) Root hairs (d) Guard cells
Answer: (b) Phloem

Quick Revision Points

• Life processes: nutrition, respiration, transportation, excretion.
• Photosynthesis needs CO₂, water, sunlight and chlorophyll; makes glucose and O₂.
• Stomach: HCl + pepsin + mucus; small intestine: bile, trypsin, lipase; villi absorb.
• Glucose → pyruvate in cytoplasm; aerobic completion in mitochondria.
• Four-chambered heart and double circulation keep blood separated.
• Xylem = water up (transpiration pull); phloem = food anywhere (translocation).
• Nephron: filtration in glomerulus, reabsorption in tubule.

Chapter Summary

Plants make food by photosynthesis, while animals obtain it from others and digest it through a long alimentary canal with enzymes and villi. Respiration releases energy from food, aerobically in mitochondria or anaerobically to form ethanol or lactic acid, and stores it as ATP.

Humans breathe through lungs with alveoli, and a four-chambered heart drives double circulation of blood through arteries, veins and capillaries. Plants move water up through xylem and food through phloem. Kidneys filter blood in nephrons to form urine, while plants remove wastes through stomata, leaves and resins.

Exam Tips and PYQ Pattern

• Labelled diagrams (digestive system, heart, nephron, alveoli, stomata) are asked almost every year.
• Comparison questions: aerobic vs anaerobic, xylem vs phloem, arteries vs veins.
• Expect case-based questions on digestion enzymes or on kidney failure and dialysis.
• Write the photosynthesis equation correctly with conditions above the arrow.

Frequently Asked Questions

Why is Life Processes important for boards?

It is the biggest biology chapter and carries high marks, with diagram-based and long answer questions.

Which side of the heart has oxygenated blood?

The left side (left atrium and left ventricle) carries oxygenated blood.

What is the difference between transpiration and translocation?

Transpiration is loss of water vapour from leaves; translocation is movement of food through phloem.

Conclusion

Life Processes explains how every living body keeps running. Learn each system with its diagram, focus on enzymes and the nephron, and practise comparison tables. Regular diagram practice alone can secure several marks in this chapter.

More Notes: Class 10 Science Chapter 4: Carbon and its Compounds notes | Class 10 Science Chapter 6: Control and Coordination notes | All Class 10 Science notes

Author Bio: Written and reviewed by the Nextoper Editorial Team, a group of CBSE science educators who build chapter notes directly from the NCERT textbook and past board paper patterns.

Freshness Note: These notes follow the NCERT Class 10 Science textbook (Reprint 2026-27) and the CBSE syllabus for the 2026-27 session. Last checked on 7 November 2026.