Life Processes

INTRODUCTION:

Have you ever wondered why we feel hungry, why we breathe faster after running, why our heart beats non-stop, or why we need to urinate? All these are life processes—activities that keep us alive and distinguish living beings from non-living things. A stone doesn't need food or oxygen, but every living cell does. Understanding these four main processes (nutrition, respiration, transportation, excretion) makes it easy to score in Board 2026 because most questions are direct and diagram-based.

What are life processes?

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

Nutrition

Nutrition is the process of taking in food and converting it into energy and other vital nutrients required by the body.

Modes of nutrition

Mode	Meaning	Examples
Autotrophic	Organisms make their own food from simple inorganic substances (CO₂, H₂O)	Green plants, some bacteria
Heterotrophic	Organisms depend on other organisms for food	Animals, fungi, most bacteria

Autotrophs have chlorophyll to trap solar energy and produce food; heterotrophs cannot produce food and rely on consuming other organisms.

Photosynthesis (autotrophic nutrition in plants)

Green plants use sunlight, carbon dioxide from air, and water from soil to make glucose (food) and release oxygen.

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

Raw materials needed:

· Carbon dioxide (CO₂) from air through stomata

· Water (H₂O) from roots

· Sunlight (energy source)

· Chlorophyll (present in chloroplasts)

Significance of photosynthesis:

· Provides food for all living organisms

· Releases oxygen needed for respiration

· Source of fossil fuels (coal, petroleum)

Heterotrophic nutrition (types)


Type	How they get food	Examples
Holozoic	Ingestion of solid food	Humans, animals, Amoeba
Saprophytic	Feed on dead/decaying matter	Fungi, mushrooms
Parasitic	Feed on living host	Cuscuta (plant), tapeworm

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Nutrition in Amoeba (simple organism)

Amoeba uses finger-like projections called pseudopodia to engulf food particles. Food is trapped in a food vacuole where digestive enzymes break it down. Digested food is absorbed into cytoplasm; undigested waste is expelled by rupturing the cell membrane. This process is called phagocytosis.

Nutrition in human beings (complex organism)

The human digestive system includes: mouth, oesophagus (food pipe), stomach, small intestine, large intestine. Digestive glands include salivary glands, liver, pancreas, gastric glands, intestinal glands.

Table: Digestion step-by-step

Part	What happens	Enzymes/secretions
Mouth	Physical breakdown (chewing); starch → sugars	Salivary amylase
Stomach	Protein digestion begins; acidic medium	HCl, pepsin, rennin, mucus
Small intestine	Complete digestion; absorption of nutrients	Trypsin, lipase, bile
Large intestine	Water absorption; undigested food stored	None (bacteria help)

Role of HCl in stomach:

· Makes medium acidic for pepsin enzyme

· Kills bacteria in food

Role of bile (from liver):

· Makes medium alkaline for pancreatic enzymes

· Emulsifies fats (breaks large fat globules into smaller droplets)

Why is small intestine longer in herbivores than carnivores?
Herbivores eat grass/plants rich in cellulose, which takes longer to digest; carnivores eat flesh, which digests faster.

Villi in small intestine:
Finger-like projections that increase surface area for rapid absorption of digested food.

Class 10 Science Notes (Board Exam 2026)! Chapter 4 Carbon and its Compounds.

Respiration

Respiration is the process of breakdown of glucose (food) to release energy in cells.

General equation (in words): Glucose is broken down with or without oxygen to release energy, carbon dioxide, and water.

Types of respiration

Type	Oxygen needed?	Products	Where it occurs	Energy released
Aerobic	Yes	CO₂ + H₂O + Energy	Mitochondria	High (38 ATP)
Anaerobic	No	Lactic acid (animals) or Ethanol + CO₂ (yeast) + Energy	Cytoplasm	Low (2 ATP)

Equations:

Aerobic respiration:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP)

Anaerobic respiration (in muscles during exercise):
C₆H₁₂O₆ → Lactic acid + Energy (causes cramps)

Anaerobic respiration (in yeast - fermentation):
C₆H₁₂O₆ → Ethanol + CO₂ + Energy

Difference between breathing and respiration

Breathing	Respiration
Physical process (inhalation + exhalation)	Biochemical process (energy release)
Extracellular	Intracellular
Does not release energy	Releases energy
Involves lungs, diaphragm, rib muscles	Occurs in all body cells

Human respiratory system

Pathway of air:
Nostrils → Pharynx → Trachea (windpipe) → Bronchi → Bronchioles → Alveoli (air sacs in lungs)

Function of alveoli:

· Increase surface area for gas exchange

· Thin walls allow rapid exchange of O₂ and CO₂ between blood and air

Why do aquatic organisms breathe faster?
Water has less dissolved oxygen (~1%) compared to air (~21%), so aquatic animals must breathe faster to get enough oxygen.

Class 10 Science Chapter 3 Notes: Metals and Non-metals.

Transportation

Transportation is the process of moving nutrients, oxygen, water, hormones, and waste products to/from different parts of the body.

Transportation in human beings

Human circulatory system includes: heart, blood vessels (arteries, veins, capillaries), and blood.

Table: Blood vessels

Vessel	Function	Structure
Arteries	Carry oxygenated blood from heart to body	Thick, elastic walls; no valves
Veins	Bring deoxygenated blood from body to heart	Thin walls; have valves to prevent backflow
Capillaries	Exchange materials between blood and tissues	Very thin, one-cell thick walls

Exception: Pulmonary artery carries deoxygenated blood (heart → lungs); pulmonary vein carries oxygenated blood (lungs → heart).

Human heart structure

The heart has four chambers: two upper atria and two lower ventricles.

Why do ventricles have thicker walls than atria?
Ventricles pump blood to distant organs with high pressure; atria only receive blood.

Function of valves: Prevent backflow of blood between chambers.

Double circulation

Blood passes through the heart twice in one complete cycle: once from heart to lungs (pulmonary circulation) and once from heart to body (systemic circulation).

Pathway:
Body → Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lungs → Pulmonary vein → Left atrium → Left ventricle → Aorta → Body

Why is double circulation important?
It maintains separation of oxygenated and deoxygenated blood, ensuring efficient oxygen supply.

Blood in fishes (single circulation): Blood goes through heart only once per cycle; they have only two chambers.

Transportation in plants

Plants have two separate transport systems: xylem (water + minerals) and phloem (food).

Tissue	Transports	Direction	How
Xylem	Water + minerals	Roots → leaves (upward)	Transpiration pull, root pressure
Phloem	Food (glucose)	Leaves → all parts (up/down)	Translocation using energy (ATP)

Transpiration: Loss of water vapour from stomata in leaves; creates suction pull that helps water move upward.

Significance of transpiration:

· Helps in upward movement of water

· Distributes minerals throughout plant

· Provides cooling effect to leaves

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Excretion

Excretion is the removal of harmful metabolic waste products from the body.

Excretory system in humans

Main organs: Kidneys (pair), ureters (pair), urinary bladder, urethra.

Functional unit of kidney: Nephron (each kidney has ~1 million nephrons).

Structure of nephron

Parts: Bowman's capsule, glomerulus (blood capillaries), renal tubule, collecting duct.

Urine formation (3 steps)

Step	What happens	Where
1. Ultrafiltration	Blood filtered; water, urea, glucose, salts pass into Bowman's capsule	Glomerulus
2. Selective reabsorption	Useful substances (glucose, water, salts) reabsorbed into blood	Renal tubule
3. Tubular secretion	Additional wastes (K⁺, H⁺, drugs) secreted into filtrate	Renal tubule

Final urine contains: Water, urea, uric acid, salts.

What would happen if mucus is not secreted in stomach?
HCl would corrode the stomach lining, causing acidity and ulcers.

Excretion in plants

Plants excrete waste in different ways:

· Oxygen (from photosynthesis) released through stomata

· Excess water removed by transpiration

· Some waste stored in leaves that later fall off

· Resins, gums stored in old xylem

Class 10 Science Chapter 2 Notes: Acids, Bases & Salts.

MCQs PYQ

Q1. Most digestion and absorption occurs in:
(a) Small intestine
(b) Liver
(c) Stomach
(d) Large intestine
Answer: (a)
(CBSE 2020)

Q2. Anaerobic process:
(a) Takes place in yeast during fermentation
(b) Takes place in presence of oxygen
(c) Produces only energy in muscles
(d) Produces ethanol, oxygen and energy
Answer: (a)
(CBSE 2020)

Q3. Which one is correct about human circulatory system?
(a) Blood transports only oxygen
(b) Human heart has 5 chambers
(c) Valves ensure blood doesn't flow backwards
(d) Oxygenated and deoxygenated blood mix
Answer: (c)
(CBSE 2020)

Q4. Vein that brings blood to left atrium from lungs:
(a) Pulmonary artery
(b) Pulmonary vein
(c) Vena cava
(d) Aorta
Answer: (b)
(Board Term I, 2017)

Q5. Why doesn't grass-eating animal have small intestine as long as carnivore?
(a) True - herbivores have longer intestine
(b) False - both equal
(c) Carnivores need longer
(d) None
Answer: (a) Herbivores have longer intestine due to cellulose digestion.
(CBSE 2020)

Q6. Raw materials for photosynthesis are:
(a) CO₂, H₂O, sunlight, chlorophyll
(b) Only CO₂
(c) Only water
(d) Glucose
Answer: (a)
(Board Term I, 2016)

Q7. Function of alveoli:
(a) Filter blood
(b) Increase surface area for gas exchange
(c) Produce mucus
(d) Store air
Answer: (b)
(CBSE 2020)

Q8. What is translocation in plants?
(a) Loss of water
(b) Transport of food from leaves to other parts
(c) Absorption of water
(d) Photosynthesis
Answer: (b)
(Board Term I, 2016)

Q9. Basic filtration unit of kidney:
(a) Neuron
(b) Nephron
(c) Alveoli
(d) Villi
Answer: (b)
(CBSE 2018)

Q10. Why is breathing rate faster in aquatic organisms?
(a) Water has more oxygen
(b) Water has less dissolved oxygen (~1%) than air (~21%)
(c) They don't need oxygen
(d) They have small lungs
Answer: (b)
(CBSE 2020)

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Short Answer Questions (PYQ)

Q1. State the location and function of gastric glands.

Answer: Gastric glands are in the stomach wall; they secrete gastric juice containing HCl, pepsin, rennin, and mucus for digestion.
(Board Term I, 2014)

Q2. Differentiate between autotrophs and heterotrophs (any two points).

Answer:

Autotrophs make their own food from CO₂ and H₂O; heterotrophs depend on other organisms.
Autotrophs have chlorophyll; heterotrophs don't. (Board Term I, 2017)

Q3. Write three types of blood vessels and one feature each.

Answer:
(i) Arteries: carry blood from heart; thick elastic walls.
(ii) Veins: bring blood to heart; have valves, thin walls.
(iii) Capillaries: exchange materials; extremely thin walls. (Delhi 2019)

Q4. Write three differences between breathing and respiration.

Answer:

Breathing is physical; respiration is biochemical.
Breathing is extracellular; respiration is intracellular.
Breathing doesn't release energy; respiration releases energy. (Board Term I, 2016)

Q5. Define excretion. Name the basic filtration unit of kidney.

Answer: Excretion is removal of metabolic wastes from the body. Basic filtration unit is nephron. (CBSE 2018)

Class 10 Science Chapter-1: Chemical Reactions and Equations.

Long Answer Questions (PYQ)

Q1. (a) Why is nutrition necessary? (b) What causes movement of food in alimentary canal? (c) Why is small intestine longer in herbivores? (d) What if mucus is not secreted?

Answer:
(a) Energy for life activities, growth, and repair.
(b) Peristaltic movement (rhythmic contraction of muscles).
(c) Cellulose in plants takes longer to digest.
(d) HCl would damage stomach lining causing ulcers. (CBSE 2020)

Q2. (a) Function of alveoli. (b) Why is breathing faster in aquatic organisms? (c) Complete glucose breakdown pathway.

Answer:
(a) Increase surface area for gas exchange; thin walls allow rapid O₂/CO₂ exchange.
(b) Water has <1% dissolved O₂ vs 21% in air, so they breathe faster.
(c) Glucose → (with O₂) → CO₂ + H₂O + Energy (aerobic); (without O₂) → Lactic acid/Ethanol + Energy (anaerobic). (CBSE 2020)

Q3. Give reasons: (a) Ventricles have thicker walls than atria. (b) Transport in plants is slow. (c) Veins have valves, arteries don't.

Answer:
(a) Ventricles pump blood to distant organs with high pressure.
(b) Plants are less active; cells don't need materials quickly.
(c) Veins have low-pressure blood; valves prevent backflow. (CBSE 2020)

Q4. Describe structure and function of nephron with diagram.

Answer: Nephron has Bowman's capsule, glomerulus, renal tubule, collecting duct. Function: filtration of blood (ultrafiltration), reabsorption of useful substances, secretion of wastes, forming urine. (Board Term I, 2014)

Q5. Explain blood circulation in human beings (double circulation).

Answer: Deoxygenated blood from body → right atrium → right ventricle → lungs (via pulmonary artery) → oxygenated blood → left atrium → left ventricle → body (via aorta). Blood passes through heart twice per cycle. (CBSE 2020)

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Conclusion

Life Processes is scoring when you connect four main ideas: (1) how organisms get and use food (nutrition + digestion), (2) how they get energy from food (respiration), (3) how materials move inside the body (transportation via blood/xylem/phloem), and (4) how waste is removed (excretion via kidney/nephron). NCERT emphasizes diagrams (human digestive system, respiratory system, heart, nephron) and comparison tables—so practice drawing labeled diagrams and learn "why" questions like "Why is small intestine longer in herbivores?" or "Why do aquatic animals breathe faster?" Understanding these makes this chapter easy for Board Exam 2026.

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Download Class 10 Science Notes PDF

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Wednesday, January 21, 2026

NCERT Class 10 Science Ch 6 - Life Processes :Notes, PYQs for Board Exam.