Life Processes Lecture Notes

Introduction

• All living organisms are made up of cells.
• Continuous movement of molecules into and out of cells is necessary for survival.
• Life processes are essential for maintaining and repairing bodies: Nutrition, Respiration, Transportation, Excretion.

Nutrition

• Definition: The process by which organisms obtain, digest, and absorb food.

Types of Nutrition

1. Autotrophic Nutrition

   • Green plants, algae, and some bacteria make food using inorganic substances (e.g., CO2, water) and sunlight.
   • Photosynthesis: Glucose is produced, releasing oxygen.
   • Chemical Equation: 6 CO2 + 12 H2O → C6H12O6 + 6 O2 + 6 H2O.
   • Raw materials: Carbon dioxide, water; Conditions: Sunlight and chlorophyll.
   • Experiments:
     • Variegated Leaf Experiment: Demonstrates chlorophyll's role in photosynthesis.
     • Potassium Hydroxide Experiment: Shows carbon dioxide's necessity.
   • Chloroplast Structure: Grana, thylakoids (chlorophyll), stroma.
   • Mechanism:
     1. Chlorophyll absorbs sunlight.
     2. Splits water molecules (photolysis).
     3. Hydrogen reacts with carbon dioxide to form glucose.
   • Nitrogen fixation by bacteria aids protein synthesis.

2. Heterotrophic Nutrition

   • Organisms obtain ready-made organic food.
   • Types:
     • Holozoic: Ingestion of solid organic material (e.g., humans, animals).
     • Saprophytic: Nutrients from dead matter (e.g., fungi, bacteria).
     • Parasitic: Nutrients from host organisms.
   • Example:
     • Amoeba: Uses pseudopodia to ingest food.
     • Paramecium: Uses cilia.

Human Digestive System

• Pathway: Mouth → Esophagus → Stomach → Small Intestine → Large Intestine → Anus.
• Digestive Juices: Salivary amylase, gastric juice (pepsin, HCl, mucus), pancreatic juice, bile.
• Nutrient Absorption: Small intestine's villi absorb nutrients into blood.

Respiration

• Definition: Chemical reaction in cells releasing energy from nutrients.

Types of Respiration

1. Aerobic Respiration

   • Requires oxygen; occurs in mitochondria.
   • Glucose → Pyruvic acid → Water + CO2; produces ATP.
   • ATP: Energy currency for cellular activities.

2. Anaerobic Respiration

   • No oxygen required; less ATP produced.
   • Examples: Bacteria, yeast, muscle cells during strenuous activity.
   • Alcoholic Fermentation: Pyruvic acid → Ethanol + CO2.

Breathing in Humans

• Respiratory System: Nostrils → Nasal cavity → Trachea → Bronchi → Bronchioles → Alveoli.
• Gas Exchange: Oxygen transported by hemoglobin; carbon dioxide in dissolved state.

Transportation

• Human Transport System: Blood (plasma, red/white cells), heart, blood vessels.
• Heart Function: Pumps oxygenated/deoxygenated blood.
  • Four chambers: Atria (receive blood), ventricles (pump blood).
  • Double Circulation: Blood flows through heart twice per cycle.

Blood Vessels

1. Arteries: Carry oxygenated blood; thick walls.
2. Veins: Carry deoxygenated blood; have valves.
3. Capillaries: Facilitate exchange of materials.

Blood Pressure

• Systolic/Diastolic measures; high BP can lead to complications.

Lymphatic System

• Function: Absorbs fats, collects extracellular fluid.

Transport in Plants

• Xylem: Water transport via roots; assisted by transpiration.
• Phloem: Translocation of food; requires energy from ATP.

Excretion

• Definition: Removal of nitrogenous wastes.

Human Excretory System

• Components: Kidneys, ureters, bladder, urethra.
• Nephrons: Filter blood, form urine.

Excretion in Plants

• Oxygen and excess water released through stomata.
• Gums and resins as waste products.

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