Overview
This lecture covers the major life processes in living organisms: nutrition, respiration, transportation, and excretion, explaining key mechanisms in plants, animals, and humans.
Life Processes: Introduction
- Life processes are essential functions that sustain and maintain life in organisms.
- The four main life processes: Nutrition, Respiration, Transportation, and Excretion.
Nutrition
- Nutrition is the process by which organisms obtain and utilize food for energy, growth, and development.
- Types of nutrition: Autotrophic (organisms make their own food, e.g., plants) and Heterotrophic (organisms depend on others for food, e.g., animals).
- Autotrophic nutrition includes photosynthesis (in green plants/algae) and chemosynthesis (in some bacteria).
- Heterotrophic nutrition types: Holozoic (intake of solid food), Saprophytic (feed on dead matter), Parasitic (derive food from host without killing).
- Photosynthesis equation: 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O (in presence of sunlight and chlorophyll).
- Plants store glucose as starch, animals store it as glycogen.
Human Digestive System
- Digestion involves five steps: ingestion, digestion, absorption, assimilation, egestion.
- Mouth: mechanical breakdown, saliva with amylase digests starch.
- Esophagus: peristaltic movement moves food.
- Stomach: gastric juice (HCl for acidity, pepsin for protein digestion, mucus for protection).
- Small intestine: receives bile (breaks fat, neutralizes acid), pancreas secretes enzymes (trypsin, amylase, lipase).
- Absorption occurs in villi of the small intestine; large intestine reabsorbs water, anus removes waste.
Respiration
- Respiration is breaking down glucose in cells to release energy (ATP).
- Types: Aerobic (with oxygen, more energy, complete glucose breakdown) and Anaerobic (without/low oxygen, less energy, partial breakdown).
- Aerobic: glucose → pyruvate → CO₂ + H₂O + energy, occurs in mitochondria.
- Anaerobic: in yeast (alcohol + CO₂ + energy), in muscles (lactic acid + energy).
- Human respiratory system: air enters through nostrils → pharynx → larynx → trachea → bronchi → bronchioles → alveoli (site of gas exchange).
- Hemoglobin in blood binds oxygen and helps transport it; alveoli facilitate gas exchange.
Transportation
- Blood (connective tissue) transports oxygen, nutrients, waste.
- Blood components: plasma, RBCs (carry oxygen via hemoglobin), WBCs (immunity), platelets (clotting).
- Blood vessels: arteries (away from heart, mostly oxygenated), veins (to heart, mostly deoxygenated), capillaries (exchange).
- Human heart has four chambers (left/right atria and ventricles) to separate oxygenated and deoxygenated blood (double circulation).
- Double circulation: pulmonary (heart-lungs-heart) and systemic (heart-body-heart).
- Lymphatic system returns leaked tissue fluid to blood, aids fat transport, and provides immune defense.
Transportation in Plants
- Xylem transports water/minerals from roots to leaves via root pressure and transpiration pull.
- Phloem transports food from leaves to other plant parts (translocation).
- Xylem is mostly dead cells, unidirectional; phloem is mostly living, bidirectional.
Excretion
- Excretion removes metabolic waste (e.g., urea) from the body.
- Human excretory system: Kidneys (filter blood), ureters (carry urine), urinary bladder (store), urethra (expel).
- Nephron (kidney unit): filtration (glomerulus/Bowman's capsule), selective reabsorption, tubular secretion.
- Hemodialysis is artificial blood filtration for kidney failure.
- Plant excretion: gases via stomata, excess water via transpiration, waste stored in leaves/bark/gum.
Key Terms & Definitions
- Photosynthesis — process by which plants use sunlight to make food from CO₂ and H₂O.
- Aerobic respiration — energy production using oxygen, yielding more energy.
- Anaerobic respiration — energy production without oxygen, less efficient.
- Peristalsis — rhythmic contraction of esophagus muscles moving food.
- Villi — finger-like projections in small intestine for absorption.
- Hemoglobin — respiratory pigment in RBCs carrying oxygen.
- Double circulation — separation of oxygenated/deoxygenated blood in heart.
- Nephron — functional unit of kidney for filtration.
Action Items / Next Steps
- Complete the given homework: fill in the gastric gland chart.
- Review diagrams: heart, nephron, digestive system.
- Practice assertion-reasoning and MCQs for all life processes.
- Read relevant NCERT textbook sections for each subtopic.