Chapter 6: Life Processes

Introduction

• The processes which maintain body functions and are necessary for survival are called life processes.
• Main life processes: Nutrition, Respiration, Transportation, Excretion.

Nutrition

• Definition: Process by which organisms obtain nutrients from food and utilize them for energy, building, and repairing tissues.
• Nutrients: Substances required for growth and maintenance (e.g., carbohydrates, proteins, vitamins, minerals).
• Types of Nutrition: Autotrophic and Heterotrophic.

Autotrophic Nutrition

• Organisms prepare their food from inorganic materials (water and CO2) in the presence of sunlight.
• Examples: Green plants using photosynthesis.
• Photosynthesis: Conversion of CO2 and water to glucose and oxygen in the presence of chlorophyll and sunlight.
  • Equation: 6 CO2 + 6 H2O → C6H12O6 + 6 O2
  • Events in Photosynthesis: Absorption of light by chlorophyll, conversion to chemical energy, splitting of water, reduction of CO2 to carbohydrates.

Heterotrophic Nutrition

• Organisms depend on others for food.
• Types: Saprophytic, Parasitic, and Holozoic Nutrition.

Saprophytic Nutrition

• Organisms obtain food from dead and decaying matter.
• Examples: Bacteria, fungi.

Parasitic Nutrition

• Organisms live on/in the host, deriving food without killing them.
• Examples: Mosquitoes, lice.

Holozoic Nutrition

• Involves ingestion, digestion, absorption, assimilation, and egestion of organic material.
• Examples: Humans, amoeba.

Nutrition in Plants

• Photosynthesis Process: Absorption of light, conversion to chemical energy, splitting of water, reduction of CO2.
• Chloroplast: Contains chlorophyll; site of photosynthesis.

Nutrition in Amoeba

• Amoeba engulfs food using pseudopodia, digests it in food vacuole, absorbs nutrients, and egests the waste.

Nutrition in Humans

• Processes: Ingestion, digestion, absorption, assimilation, excretion.
• Digestive System Components: Mouth, esophagus, stomach, small intestine, large intestine, rectum, anus.
• Digestive Enzymes: Amylase (starch), Pepsin (proteins), Lipase (fats).

Respiration

• Definition: Process of breaking down food to release energy in the presence of oxygen (breathing included).
• Stages: External respiration (breathing and gas exchange), Internal respiration (gas exchange between blood and cells).
• Types: Aerobic and Anaerobic Respiration.

Aerobic Respiration

• Complete breakdown of food in the presence of oxygen.
• Equation: Glucose → Pyruvate + Energy (Cytoplasm); Pyruvate + Oxygen → CO2 + H2O + 38 ATP (Mitochondria).
• ATP: Energy currency of the cell.

Anaerobic Respiration

• Incomplete breakdown of food without oxygen.
• Types: Alcoholic fermentation (e.g., yeast), Lactic acid fermentation (e.g., muscle cells during heavy exercise).
• Equation for Alcoholic Fermentation: Glucose → Pyruvate → Ethanol + CO2 + 2 ATP.
• Equation for Lactic Acid Fermentation: Glucose → Pyruvate → Lactic Acid + 2 ATP.

Respiration in Plants

• Gas exchange through stomata, lenticels, and root hairs.
• Energy release through breakdown of glucose.

Respiration in Humans

• Components: Nostrils, pharynx, larynx, trachea, bronchi, bronchioles, alveoli.
• Process: Inhalation, gas exchange in alveoli, transportation of gases by blood, exhalation.
• Double Circulation: Blood passes through the heart twice during each cycle.

Transportation

• Definition: Movement of substances within the organism.

Transportation in Humans

• Components: Blood, lymph.
• Blood Composition: Plasma, RBCs, WBCs, platelets.
• Heart: Muscular organ pumping blood through arteries and veins.
• Blood Vessels: Arteries (carry oxygenated blood), veins (carry deoxygenated blood) with exceptions.
• Lymph: Colorless fluid important for circulating fats from intestine and draining excess tissue fluid.

Transportation in Plants

• Tissues: Xylem (transports water and nutrients), Phloem (transports food).
• Processes: Transpiration (xylem), Translocation (phloem).

Excretion

• Definition: Removal of harmful nitrogenous metabolic waste from the body.
• Types of Waste: Digestive, respiratory, nitrogenous.

Excretion in Humans

• Organs: Kidneys, ureters, urinary bladder, urethra.
• Kidney Function: Filters blood, removes waste.
• Nephron: Functional unit filtering blood and forming urine.
• Process: Filtration by Bowman’s capsule, reabsorption in Henle’s loop, collection in ducts, excretion by urethra.

Excretion in Plants

• Types of Waste: Gaseous (O2, CO2), Liquid (water), Solid (old leaves, bark).
• Process: Removal through stomata, lenticels, detachment of old parts.

Summary

• Life processes essential for maintaining body functions and ensuring survival.
• Nutrition, respiration, transportation, and excretion are interconnected and necessary for the proper functioning of living organisms.