10 BIOLOGY LIFE PROCESSES – NUTRITION REVISION NOTES

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 LIFE PROCESSES –NUTRITION REVISION NOTES

1. Difference Between Living and Non-Living

  • Living organisms show molecular movements.

  • Visible movement is not a compulsory sign of life.

  • Even when sleeping or resting, living beings perform life processes.

  • Viruses show no molecular movement outside host → controversy about being alive.

2. Why Are Molecular Movements Necessary?

  • Living organisms are highly organised structures.

  • Environmental effects cause continuous damage and breakdown.

  • To remain alive:

    • Repair

    • Maintenance

    • Replacement
      must occur continuously.

  • All these require movement of molecules.

3. What Are Life Processes?

  • Life processes are the maintenance activities of living organisms.

  • They occur:

    • During activity

    • During rest

    • During sleep

  • Energy is required for these processes.

4. Basic Life Processes

The four essential life processes are:

  1. Nutrition

  2. Respiration

  3. Transportation

  4. Excretion

5. Nutrition

Definition

  • Process of taking food from outside and using it for:

    • Energy

    • Growth

    • Repair

Types of Nutrition

A. Autotrophic Nutrition

  • Organisms prepare their own food.

  • Examples: green plants, some bacteria

  • Process: Photosynthesis

Photosynthesis Equation

6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O

Steps of Photosynthesis

  • Absorption of light energy by chlorophyll

  • Conversion of light energy to chemical energy

  • Reduction of CO₂ to carbohydrates

Raw Materials

  • CO₂ → air (through stomata)

  • Water → soil (through roots)

  • Sunlight → sun

  • Chlorophyll → chloroplast

B. Heterotrophic Nutrition

  • Organisms depend on others for food.

  • Examples: animals, fungi

Types

  • Holozoic – humans, animals

  • Saprophytic – fungi

  • Parasitic – cuscuta, leech

6. Nutrition in Amoeba

  • Uses pseudopodia to engulf food.

  • Food forms a food vacuole.

  • Digestion occurs inside vacuole.

  • Undigested food expelled outside.

7. Nutrition in Human Beings

Alimentary Canal

Mouth → Oesophagus → Stomach → Small intestine → Large intestine → Anus

Digestion Process

Mouth

  • Teeth crush food.

  • Saliva contains salivary amylase.

  • Starch → sugar.

Oesophagus

  • Food pushed by peristaltic movements.

Stomach

  • Gastric glands secrete:

    • HCl – acidic medium, kills germs

    • Pepsin – digests proteins

    • Mucus – protects stomach lining

Small Intestine

  • Longest part of alimentary canal.

  • Receives:

    • Bile – emulsifies fats, neutralises acid

    • Pancreatic juice – digests proteins, fats, starch

  • Complete digestion occurs here.

Villi

  • Finger-like projections

  • Increase surface area

  • Absorb digested food into blood

Large Intestine

  • Absorbs water

  • Forms faeces

  • Waste removed through anus

8. Dental Caries

  • Caused by bacteria acting on sugars.

  • Acid formation softens enamel.

  • Plaque prevents saliva action.

  • Prevented by brushing after meals.