Overview
This lecture covers the essential life processes in living organisms, including nutrition, respiration, transportation, and excretion, focusing on core definitions, key systems, and important diagrams and distinctions.
Life Processes: Overview
- Life processes are basic activities essential for sustaining and maintaining life in organisms.
- Four main life processes: Nutrition, Respiration, Transportation, and Excretion.
Nutrition
- Nutrition is obtaining and utilizing food for energy, growth, and development.
- Two main types: 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 plants/algae) and chemosynthesis (e.g., purple sulfur bacteria).
- Heterotrophic nutrition includes holozoic (eating solid food, e.g., humans), parasitic (living off another organism, e.g., leeches), and saprophytic (feeding on dead matter, e.g., mushroom).
- Photosynthesis: 6CO2 + 12H2O --(chlorophyll/sunlight)--> C6H12O6 + 6O2 + 6H2O; glucose stored as starch in plants, as glycogen in animals.
Human Digestive System
- Five steps: Ingestion (mouth), Digestion (enzymes break down food), Absorption (small intestine, villi), Assimilation (cells use nutrients), Egestion (removal of waste).
- Enzymes: Salivary amylase (mouth, starch to maltose), pepsin (stomach, protein digestion), bile (liver, fat emulsification), pancreatic enzymes (trypsin, lipase, amylase).
- Small intestine absorbs nutrients via finger-like villi; large intestine absorbs water.
Respiration
- Respiration is breaking down glucose in cells to produce energy (ATP).
- Two types: Aerobic (with oxygen, more energy, final products: CO2, H2O) and Anaerobic (without oxygen, less energy, products: ethanol/lactic acid).
- Human respiratory system: Air moves from nostrils ā pharynx ā larynx ā trachea (rings of cartilage) ā bronchi ā bronchioles ā alveoli (site of gas exchange).
- Alveoli are thin-walled, richly supplied with blood vessels; hemoglobin carries O2/CO2.
Transportation
- Transportation moves food, water, oxygen, and waste through the body.
- Blood (connective tissue) contains plasma, RBCs (carry oxygen via hemoglobin), WBCs (defense), platelets (clotting).
- Blood vessels: Arteries (away from heart, thick-walled), veins (to heart, valves prevent backflow), capillaries (connect arteries and veins).
- Heart: Four chambers (left/right atrium & ventricle), double circulation separates oxygenated/deoxygenated blood; pulmonary and systemic circuits ensure efficient distribution.
Excretion
- Excretion removes metabolic waste like urea, uric acid, excess water.
- Human excretory system: Kidneys (filtration via nephrons), ureters (carry urine), bladder (stores urine), urethra (expels urine).
- Nephron processes: Glomerular filtration (Bowman's capsule), selective reabsorption, tubular secretion.
Life Processes in Plants
- Plants transport water/minerals via xylem (root to leaf), food via phloem (bidirectional).
- Water moves up by root pressure and transpiration pull (loss of water as vapor from leaves).
- Excretion in plants: Oxygen/CO2 released via stomata, water via transpiration, storing waste as gum/resin, shedding leaves.
Key Terms & Definitions
- Autotrophic Nutrition ā organisms produce food from inorganic substances.
- Heterotrophic Nutrition ā organisms rely on other organisms for food.
- Photosynthesis ā process by which green plants make food using CO2, water, sunlight, and chlorophyll.
- Stomata ā small pores on leaf underside for gas exchange and transpiration.
- Villi ā finger-like projections in small intestine that absorb nutrients.
- Aerobic Respiration ā respiration with oxygen, producing more energy.
- Anaerobic Respiration ā respiration without oxygen, producing less energy.
- Alveoli ā air sacs in lungs where gas exchange occurs.
- Hemoglobin ā iron-containing pigment in RBCs that carries oxygen.
- Artery ā blood vessel carrying blood away from heart.
- Vein ā blood vessel carrying blood to heart.
- Nephron ā functional unit of kidney for filtration.
- Xylem ā plant tissue for water/mineral transport.
- Phloem ā plant tissue for food transport.
Action Items / Next Steps
- Complete the homework chart on gastric gland functions.
- Review and practice drawing and labeling diagrams (heart, nephron, digestive tract).
- Memorize key equations and definitions, especially for photosynthesis and types of respiration.
- Practice assertion-reasoning and MCQ questions from the lecture.