CBSE Class 10 - Life Processes Notes & MCQ

January 05, 2026

Life Processes

Life Processes

1. What are Life Processes?

Life processes are the maintenance functions that keep living organisms alive even when not growing or moving visibly.

  • Main life processes: Nutrition, Respiration, Transportation, Excretion
  • Energy is continuously required → obtained from outside (food).

2. Nutrition

Definition: Process of taking in food & using it for growth, repair & energy.

Types of Nutrition

  • Autotrophic: Organisms make their own food (e.g., green plants → photosynthesis)
  • Heterotrophic: Depend on others (e.g., animals, fungi, most bacteria)

2.1 Photosynthesis (Autotrophic Nutrition in Plants)

Equation:

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

Essential requirements:

  • Chlorophyll (in chloroplasts)
  • Sunlight
  • CO₂ (enters through stomata)
  • Water & minerals (from soil)

Here is a labelled cross-section of a leaf showing stomata, guard cells & chloroplasts (key sites for photosynthesis):

Stomata open/close by guard cells → controls gas exchange & water loss.

2.2 Heterotrophic Nutrition

    • Amoeba: Holozoic (engulfs food using pseudopodia → food vacuole → digestion)

Nutrition in Amoeba (step-by-step diagram):

    • Humans: Holozoic nutrition (complex digestive system)

Human Digestive System (labelled diagram) – very important for exams:

Image of the Labelled human digestive system class 10th

Key enzymes & their actions:

Organ/Part Enzyme Acts on Product
Mouth Salivary amylase Starch Maltose
Stomach Pepsin Proteins Peptones
Pancreas Trypsin, Amylase, Lipase Proteins, Starch, Fats Amino acids, Maltose, Fatty acids + Glycerol
Small Intestine Intestinal juice enzymes All above Glucose, Amino acids, etc.

Absorption: Mainly in small intestine (villi & microvilli increase surface area)

3. Respiration

Definition: Breakdown of food (glucose) to release energy (ATP).

Types:

  • Aerobic respiration: With oxygen (complete breakdown)
    C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (38 ATP)
  • Anaerobic respiration: Without oxygen
    • In muscles → Lactic acid + Energy (2 ATP) → causes cramps
    • In yeast → Ethanol + CO₂ + Energy (fermentation)

Human Respiratory System (labelled diagram showing lungs & alveoli):

Image of the human respiratory system showing lungs and alveoli

Gas exchange:

  • Alveoli → large surface area, thin walls
  • Haemoglobin in RBCs carries O₂
  • CO₂ mostly dissolved in blood plasma
  • Breathing mechanism → Diaphragm + ribs

4. Transportation

4.1 Transportation in Humans (Circulatory System)

Double circulation (very important concept):

  • Pulmonary circulation (heart → lungs → heart)
  • Systemic circulation (heart → body → heart)

Human Heart (sectional view with double circulation labelling):

Blood vessels:

  • Arteries: Thick, elastic, carry oxygenated blood (except pulmonary artery)
  • Veins: Thin, have valves, carry deoxygenated blood (except pulmonary vein)
  • Capillaries: Exchange site

Blood components: Plasma, RBCs (haemoglobin), WBCs, Platelets

4.2 Transportation in Plants

  • Xylem: Transports water & minerals upward (transpiration pull)
  • Phloem: Transports food (sucrose) in both directions (translocation – uses energy)

Xylem & Phloem in plant stem (diagram):

Image of xylem and phloem in a plant stem

5. Excretion

Definition: Removal of metabolic wastes (CO₂, urea, excess water, salts)

5.1 Human Excretory System

  • Main organs → Pair of kidneys, ureters, urinary bladder, urethra
  • Nephron: (functional unit – filtration, reabsorption, secretion)

Labelled diagram of Human Excretory System & Nephron:

Image of the human excretory system and nephron

Process in nephron:

  1. Glomerular filtration: Blood filtered in Bowman’s capsule
  2. Selective reabsorption: Glucose, amino acids, water, salts
  3. Tubular secretion: Extra wastes added

→ Urine formed (urea + uric acid + water + salts)

5.2 Excretion in Plants

No specific system → Wastes stored in: Vacuoles, Dead cells (bark), Fallen leaves, Gums/resins

Quick Revision Table – Life Processes at a Glance

Process Plants Animals/Humans Key Structure/Feature
Nutrition Photosynthesis Digestion in alimentary canal Chloroplast / Villi
Respiration Stomata + diffusion Lungs + alveoli Mitochondria (energy)
Transportation Xylem & Phloem Heart, blood vessels, blood Double circulation / Transpiration
Excretion Vacuoles, dead tissues Kidneys → nephrons Nephron (filtration unit)

MCQs: Life Processes

  1. Which of the following is NOT a life process?
    1. Nutrition
    2. Respiration
    3. Reproduction
    4. Excretion
    Answer: C) Reproduction
  2. The process by which green plants prepare their own food is called:
    1. Respiration
    2. Photosynthesis
    3. Transpiration
    4. Digestion
    Answer: B) Photosynthesis
  3. The raw materials required for photosynthesis are:
    1. Glucose and oxygen
    2. Carbon dioxide and water
    3. Nitrogen and hydrogen
    4. Starch and chlorophyll
    Answer: B) Carbon dioxide and water
  4. Which gas is released during photosynthesis?
    1. Carbon dioxide
    2. Nitrogen
    3. Oxygen
    4. Hydrogen
    Answer: C) Oxygen
  5. In which part of the plant cell does photosynthesis mainly occur?
    1. Nucleus
    2. Mitochondria
    3. Chloroplast
    4. Vacuole
    Answer: C) Chloroplast
  6. The opening and closing of stomata is controlled by:
    1. Epidermal cells
    2. Guard cells
    3. Subsidiary cells
    4. Mesophyll cells
    Answer: B) Guard cells
  7. Which enzyme present in saliva converts starch into maltose?
    1. Pepsin
    2. Trypsin
    3. Salivary amylase
    4. Lipase
    Answer: C) Salivary amylase
  8. The acidic medium in the stomach is created by:
    1. HCl
    2. NaOH
    3. Bile juice
    4. Pancreatic juice
    Answer: A) HCl
  9. The process of breaking down glucose to release energy in the absence of oxygen is called:
    1. Aerobic respiration
    2. Anaerobic respiration
    3. Photosynthesis
    4. Transpiration
    Answer: B) Anaerobic respiration
  10. In which organ of the human body does maximum absorption of digested food take place?
    1. Stomach
    2. Large intestine
    3. Small intestine
    4. Oesophagus
    Answer: C) Small intestine
  11. The functional unit of the human kidney is:
    1. Neuron
    2. Alveolus
    3. Nephron
    4. Villus
    Answer: C) Nephron
  12. Which blood vessel carries oxygenated blood from lungs to heart?
    1. Pulmonary artery
    2. Pulmonary vein
    3. Aorta
    4. Vena cava
    Answer: B) Pulmonary vein
  13. The mode of nutrition in Amoeba is:
    1. Autotrophic
    2. Saprotrophic
    3. Parasitic
    4. Holozoic
    Answer: D) Holozoic
  14. Transpiration pull helps in the upward movement of water in plants through:
    1. Phloem
    2. Xylem
    3. Stomata
    4. Root hair
    Answer: B) Xylem
  15. The energy currency of the cell is:
    1. Glucose
    2. ATP
    3. NADH
    4. Oxygen
    Answer: B) ATP
  16. Which of the following is a parasitic plant?
    1. Cuscuta
    2. Rhizobium
    3. Pitcher plant
    4. Mushroom
    Answer: A) Cuscuta
  17. In which part of the nephron does selective reabsorption of useful substances mainly occur?
    1. Glomerulus
    2. Bowman’s capsule
    3. Proximal convoluted tubule
    4. Collecting duct
    Answer: C) Proximal convoluted tubule
  18. The enzyme that breaks down proteins into amino acids in the small intestine is:
    1. Amylase
    2. Lipase
    3. Trypsin
    4. Pepsin
    Answer: C) Trypsin
  19. Double circulation of blood is found in:
    1. Fish
    2. Amphibians
    3. Reptiles
    4. Mammals
    Answer: D) Mammals
  20. Excess water and wastes in plants are mainly removed through:
    1. Transpiration
    2. Guttation
    3. Both A and B
    4. Respiration only
    Answer: C) Both A and B

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