📘Class 10 Science – Chapter: Life Processes Notes

💡 Introduction to Life Processes

  • Life processes are the basic activities performed by living organisms to maintain life.

  • These include nutrition, respiration, transportation, excretion, reproduction, growth, etc.

🌿 Nutrition

  • Nutrition is the process by which organisms take in food and utilize it for energy.

Heterotrophic Nutrition:

  • Seen in animals, fungi, and some bacteria.

  • Types:

    • Holozoic: e.g., humans

    • Saprophytic: e.g., fungi

    • Parasitic: e.g., leech

Autotrophic Nutrition:

  • Organisms make their own food.

  • Example: Green plants

Photosynthesis:

  • Process by which green plants make food using sunlight.

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

Mechanism of Photosynthesis:

  1. Light absorption: Chlorophyll absorbs sunlight in the chloroplasts.

  2. Water splitting (Photolysis): H2O splits into H+ and O2.

  3. Carbon fixation: CO2 is converted into glucose through Calvin cycle.

  4. Formation of glucose: Energy stored in glucose is used by plant.

Structure of Human Digestive System:

Organ Function
Mouth Chewing, saliva mixes with food
Stomach Protein digestion begins
Small Intestine Digestion completes, absorption occurs
Large Intestine Absorbs water

Mechanism of Human Digestion:

  1. Ingestion through mouth.

  2. Salivary amylase breaks starch into maltose.

  3. Gastric glands secrete HCl and pepsin in stomach for protein digestion.

  4. Pancreatic enzymes (trypsin, amylase, lipase) complete digestion in small intestine.

  5. Absorption through villi in small intestine into blood.

Example: The digestion of carbohydrates starts in the mouth with salivary amylase.

🌬️ Respiration

  • Breaking down of food (glucose) to release energy.

Types:

  • Aerobic Respiration:

    • Uses oxygen

    • Produces more energy

    • Equation: Glucose + O2 → CO2 + H2O + Energy

  • Anaerobic Respiration:

    • Without oxygen

    • Produces less energy

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

Mechanism of Respiration:

  1. Glycolysis (in cytoplasm): Glucose (6C) → 2 Pyruvate (3C)

  2. Krebs Cycle (in mitochondria): Pyruvate → CO2 + ATP + NADH

  3. Electron Transport Chain: NADH → ATP (energy stored as ATP)

Example: Our muscles perform anaerobic respiration during heavy exercise.

⛰ Transportation

  • Movement of substances like nutrients, gases, waste within the body.

In Human Beings:

  • Circulatory system (Heart, blood, blood vessels)

Component Function
Heart Pumps blood
Arteries Carry blood away from heart
Veins Bring blood to heart
Capillaries Exchange of materials

Double Circulation: Blood passes through the heart twice in one complete cycle.

Mechanism of Circulation:

  1. Right atrium receives deoxygenated blood from the body.

  2. Moves to right ventricle → pumped to lungs for oxygenation.

  3. Oxygenated blood returns to left atrium → left ventricle → body.

Example: Oxygenated blood goes from lungs to heart, then to the body.

In Plants:

  • Xylem: Transports water

  • Phloem: Transports food

Mechanism in Plants:

  • Xylem: Water moves via root pressure, capillarity, and transpiration pull.

  • Phloem: Food is transported via pressure flow from source to sink (active transport).

🚽 Excretion

  • Removal of metabolic waste products from the body.

In Humans:

  • Main organ: Kidneys

  • Others: Lungs (CO2), Skin (sweat)

Urine Formation Stages:

  1. Filtration: Blood filtered in Bowman’s capsule.

  2. Reabsorption: Glucose, water reabsorbed in tubules.

  3. Secretion: Excess salts and ions secreted into tubule.

Mechanism of Urine Formation:

  1. Blood enters nephron → glomerulus filters small molecules.

  2. Tubules reabsorb needed substances (water, glucose).

  3. Remaining waste forms urine → collected in bladder.

Equation: NH3 + CO2 → Urea (formed in liver)

In Plants:

  • Waste products like oxygen and water vapor excreted via stomata.

  • Other wastes stored in vacuoles or shed with leaves, bark, fruit.

Hand written Notes Of CELL: The Fundamental unit of Life