Biology Chapter 5: Life Processes

Introduction

• Life Processes: Essential functions performed by living organisms for survival and maintenance.
• Key Processes: Digestion, respiration, circulation, excretion, and growth.

Characteristics of Living Organisms

• Growth: Increase in size and mass over time.
• Respiration: Exchange of gases (O₂ in, CO₂ out).
• Excretion: Removal of metabolic wastes.
• Circulation: Transport of nutrients and waste products.

Nutrition

Definition

• Nutrition: Intake and utilization of food by an organism for growth, maintenance, and survival.

Types of Nutrition

1. Autotrophic

   • Definition: Organisms make their own food from inorganic substances (CO₂, water).
   • Example: Green plants (photosynthesis).
   • Process: Involves chlorophyll and sunlight.

2. Heterotrophic

   • Definition: Organisms obtain food from other organisms.
   • Examples: Animals, fungi, some bacteria.
   • Subtypes:
     • Saprophytic: Feed on dead organic matter (e.g., fungi, certain bacteria).
     • Parasitic: Feed on living hosts without killing them (e.g., lice, tapeworms).
     • Holozoic: Intake of solid food, digestion, absorption (e.g., humans, animals).

Nutrition in Humans

• Ingestion: Intake of food.
• Digestion: Breakdown of complex food into simpler substances.
• Absorption: Movement of digested food into the bloodstream.
• Assimilation: Utilization of absorbed food for energy, growth, and repair.
• Egestion: Removal of undigested food.

Digestive System

• Main Organs: Mouth, esophagus, stomach, small intestine, large intestine, anus.
• Salivary Glands: Produce saliva containing enzymes like salivary amylase.
• Gastric Glands: Secrete gastric juice (pepsin, HCl, mucus).
• Liver: Produces bile for fat digestion.
• Pancreas: Produces pancreatic juices containing enzymes.
• Small Intestine: Site of complete digestion and absorption.
• Large Intestine: Absorbs water, forms feces.

Respiration

Definition

• Respiration: Cellular process of breaking down food to release energy.

Types of Respiration

1. Aerobic

   • Definition: Occurs in the presence of oxygen.
   • Process: Glucose + O₂ -> CO₂ + H₂O + Energy (ATP)

2. Anaerobic

   • Definition: Occurs in the absence of oxygen.
   • Products: Ethanol, CO₂, and energy or lactic acid and energy.
   • Examples: Yeast (ethanol), muscle cells (lactic acid).

Human Respiratory System

• Main Organs: Nose, nasal cavity, pharynx, larynx, trachea, bronchi, lungs, alveoli.
• Processes: Inhalation and exhalation, gas exchange in alveoli.
• Diaphragm: Muscle aiding in breathing.
• Mechanism: Involves diaphragm and intercostal muscles.

Transportation

Circulatory System

• Components: Heart, blood, blood vessels.
• Heart: Muscular organ, pumps blood throughout the body.
• Blood Vessels: Arteries (carry oxygenated blood), veins (carry deoxygenated blood), capillaries (exchange between blood and tissues).
• Blood Components:
  • Plasma: Transports nutrients, waste products, gases.
  • Red Blood Cells: Carry oxygen.
  • White Blood Cells: Immune response, fighting infections.
  • Platelets: Blood clotting.
• Lymph: Colorless fluid, part of the immune system, returns interstitial fluid to the bloodstream.

Double Circulation in Humans

• Blood passes through the heart twice in one complete cycle (heart -> lungs -> heart -> body).

Transportation in Plants

• Xylem: Transports water and minerals from roots to various parts.
• Phloem: Transports food from leaves to other parts.
• Transpiration: Loss of water vapor from aerial parts; helps in upward movement of water.
• Root Pressure: Helps in upward movement of water, especially at night.

Excretion

Definition

• Excretion: Removal of metabolic wastes from the body.

Human Excretory System

• Main Organs: Kidneys, ureters, urinary bladder, urethra.
• Kidneys: Filter blood, produce urine.
• Nephrons: Functional units of kidneys that filter blood.
• Ureters: Transport urine from kidneys to bladder.
• Urinary Bladder: Stores urine until excretion.
• Urethra: Passage for urine to leave the body.

Excretion in Plants

• Methods:
  • Stomata: Removes gaseous wastes.
  • Transpiration: Removes excess water.
  • Leaf Fall: Discards wastes stored in leaves.
  • Gums and Resins: Stored in old xylem cells, serves as waste storage.
  • Roots: Discharge some wastes into the soil.