Class 10 Science - Chapter 6: Life Processes

Introduction

• Life Processes maintain body functions and are necessary for survival.
• Main life processes: Nutrition, Respiration, Transportation, and Excretion.

Nutrition

Definition

• Process by which organisms obtain nutrients from food, utilize energy for daily activities, and build/repair tissues.

Nutrients

• Essential substances for growth and maintenance (e.g., carbohydrates, proteins, vitamins, minerals).

Types of Nutrition

• Autotropic Nutrition: Organisms make their own food from simple inorganic materials (e.g., plants through photosynthesis).
  • Photosynthesis: Converting CO2 and water to glucose and oxygen in presence of sunlight and chlorophyll.
  • Equation: 6 CO2 + 6 H2O -> C6H12O6 + 6 O2 (chlorophyll + sunlight)
  • Events in Photosynthesis: Absorption of light, conversion to chemical energy, splitting of water, reduction of CO2 to carbohydrates.
• Heterotropic Nutrition: Organisms depend on other organisms for food (e.g., humans, animals).
  • Types: Saprophytic (dead/decaying matter), Parasitic (living on/in host), Holozoic (ingestion/digestion).
• Examples: Nutrition in plants (photosynthesis), Nutrition in amoeba (engulfing food with pseudo-podia), Nutrition in humans (ingestion, digestion, absorption, assimilation, excretion).

Respiration

Definition

• Breakdown of food with oxygen to release energy; includes inhalation and exhalation.

Stages

1. External Respiration: Breathing (inhaling O2, exhaling CO2), Gases exchange (O2 to blood, CO2 from blood).
2. Internal Respiration: Exchange between blood and body cells.

Types of Respiration

• Aerobic: Complete breakdown in presence of oxygen, releases large energy (ATP).
  • Equation: glucose -> pyruvate + energy (cytoplasm) and pyruvate + O2 -> CO2 + H2O + 38 ATP (mitochondria).
• Anaerobic: Incomplete breakdown without oxygen, releases less energy.
  • Types: Alcoholic Fermentation (ethanol + CO2), Lactic Acid Fermentation (lactic acid)

Examples

• Plants: Photosynthesis and respiration through stomata, lenticels, root hairs.
• Humans: Complex process using respiratory system (lungs, bronchi, alveoli, etc.).

Transportation

Humans

• Blood System: Blood (plasma, RBC, WBC, platelets) transports substances.
• Heart: Pumps blood through arteries/veins (double circulation).
• Blood Vessels: Arteries carry oxygenated blood, veins carry deoxygenated blood.
• Lymph System: Lymph absorbs fats and excess tissue fluids.

Plants

• Xylem: Transports water/nutrients from roots upwards (transpiration).
• Phloem: Transports food from leaves to other parts (translocation).

Excretion

Definition

• Removal of harmful metabolic wastes from the body.

Types of Metabolic Wastes

• Digestive waste, respiratory waste (CO2), nitrogenous waste (urea, uric acid, water).

Humans

• Excretory System: Kidneys filter blood, remove waste as urine.
  • Components: Kidneys, ureters, urinary bladder, urethra.
  • Nephrons: Filtration units in kidneys (Bowman’s capsule, Henle’s loop).

Plants

• Types of Waste: Gaseous (O2, CO2), liquid (water), solid (old leaves, barks).
• Removal: Gases through stomata, water via transpiration, solid by shedding parts.

Conclusion

• Four main life processes: Nutrition, Respiration, Transportation, Excretion.
• Each process is vital for the maintenance and survival of living organisms.
• Understanding these processes helps us appreciate the complexity and functionality of living systems.