LIFE PROCESSES (CBSE 10TH BIOLOGY)

 

What are Life Processes?

Life processes are the basic functions performed by living organisms to maintain life.
Examples: Nutrition, respiration, transportation, excretion.

1. Nutrition

Types of Nutrition:

• Autotrophic: Organisms make their own food (e.g., plants).
• Heterotrophic: Organisms depend on other organisms for food (e.g., animals).

➤ Photosynthesis (in plants):

Definition: Process by which green plants prepare food using sunlight, CO₂ and water.

Equation:

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

Steps:

• Absorption of light energy by chlorophyll.

• Conversion of light energy to chemical energy.

• Splitting of water molecules (Photolysis).

• Reduction of CO₂ to carbohydrates (glucose).

Nutrition in Humans (Holozoic):

• Ingestion → Digestion → Absorption → Assimilation → Egestion

• Important digestive enzymes:

  • Saliva: Amylase (breaks starch)

  • Stomach: Pepsin (proteins), HCl (acidic medium)

  • Small intestine: Lipase, Trypsin, Amylase (complete digestion)

• Villi in the small intestine absorb nutrients.

2. Respiration

Types:

• Aerobic Respiration (with oxygen):

  • Glucose → CO₂ + H₂O + Energy (38 ATP)

• Anaerobic Respiration (without oxygen):

  • Glucose → Alcohol + CO₂ + Energy (in yeast)

  • In muscles: Glucose → Lactic acid + Energy

➤ Site:

• Cytoplasm (glycolysis), Mitochondria (Kreb's cycle)

3. Transportation

 In Human Beings:

• Circulatory System: Heart, blood, and blood vessels.

• Heart: 4 chambers (Right atrium, Right ventricle, Left atrium, Left ventricle)

  • Double circulation: Pulmonary and systemic circulation

• Blood components:

  • RBCs (carry oxygen via hemoglobin)

  • WBCs (fight infection)

  • Platelets (blood clotting)

  • Plasma (transports nutrients, hormones)

➤ In Plants:

• Xylem: Transports water and minerals (root to leaves)

• Phloem: Transports food (leaves to other parts - translocation)

4. Excretion

➤ In Humans:

• Excretory organ: Kidneys

• Nephron: Functional unit of kidney

  • Filtration occurs in glomerulus

  • Reabsorption of useful substances

  • Urine formation and collection in bladder

• In Plants:

  • Remove waste through:

    • Stomata, lenticels

    • Storage in leaves and bark (which later shed)

    • Excretion of resins, latex, gums

• Key Terms to Remember:

• Autotrophs: Self-nourishing (e.g., green plants)

• Heterotrophs: Dependent on others for food

• Peristalsis: Wave-like muscular movement of food

• Transpiration: Loss of water vapor from plant leaves

• Ultrafiltration: Filtration in glomerulus of kidney

• Lymph: Fluid part of blood without RBCs