Overview
This lecture covers the major concepts of the "Life Processes" chapter in biology, explaining nutrition, respiration, transportation, and excretion in detail with definitions, processes, examples, and key physiology relevant for board exams.
Introduction to Life Processes
- Life processes are the essential functions performed by living organisms to maintain life.
- Main life processes include nutrition, respiration, transportation, and excretion.
Nutrition
- Nutrition is the process by which living organisms obtain and utilize food.
- Importance: provides energy, supports growth and development, and repairs damaged tissues.
- Types: Autotrophic nutrition (organisms make their own food, e.g., plants), Heterotrophic nutrition (organisms depend on others for food, e.g., animals).
- Autotrophic types: Photosynthetic (plants use sunlight, CO₂, water, chlorophyll) and Chemosynthetic (organisms use chemicals for food, e.g., sulfur bacteria).
- Photosynthesis equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
- Glucose stored as starch in plants and as glycogen in animals.
- Stomata control gas exchange and transpiration in plants.
Heterotrophic Nutrition
- Types: Holozoic (ingestion and internal digestion, e.g., humans), Saprotrophic (external digestion and absorption, e.g., fungi), Parasitic (depend on host for food, e.g., lice, Cuscuta).
- Human digestive system includes alimentary canal and associated organs; digestion is mechanical and enzymatic, absorption occurs in small intestine via villi.
Respiration
- Respiration is the process of obtaining energy (ATP) from food, with or without oxygen.
- Breathing is a physical process; respiration is a chemical process involving energy release.
- Types: Aerobic (with oxygen, produces CO₂, H₂O, ATP), Anaerobic (without oxygen, produces ethanol/lactic acid and less energy).
- In humans, gas exchange occurs in alveoli, where oxygen binds to hemoglobin in RBCs.
Transportation
- Transport system distributes substances throughout the organism.
- In humans, the circulatory system includes blood, blood vessels (arteries, veins, capillaries), and the heart.
- Blood contains plasma (liquid part), RBCs (carry oxygen), WBCs (immunity), and platelets (clotting).
- The heart pumps blood through double circulation: pulmonary (lungs) and systemic (body).
- Arteries carry blood away from the heart under high pressure; veins carry blood to the heart under low pressure; capillaries connect arteries and veins.
Lymphatic System
- Lymph is a colorless fluid, part of the lymphatic system, important for fluid balance, fat transport, and immunity.
Transportation in Plants
- Xylem transports water and minerals upward from roots to leaves (unidirectional).
- Phloem transports food in all directions (bidirectional).
- Translocation is the movement of food through phloem.
Excretion
- Excretion removes metabolic waste from the body.
- Human excretory system: Kidneys filter blood, remove urea, excess water; urine passes through ureter to bladder then expelled via urethra.
- Nephron is the functional unit of the kidney, involving filtration, selective reabsorption, tubular secretion.
- Dialysis artificially filters blood when kidneys fail.
Excretion in Plants
- Plants excrete excess water via transpiration and gases via stomata; waste may be stored in vacuoles or secreted as resins/gums.
Key Terms & Definitions
- Life Processes — Basic functions needed for survival (nutrition, respiration, transportation, excretion).
- Autotrophic Nutrition — Organisms making their own food (e.g., plants).
- Heterotrophic Nutrition — Organisms needing other sources for food (e.g., animals).
- Photosynthesis — Process where plants use sunlight to synthesize food.
- Stomata — Tiny pores on leaves for gas exchange.
- ATP (Adenosine Triphosphate) — Energy currency of the cell.
- Aerobic Respiration — Respiration using oxygen.
- Anaerobic Respiration — Respiration without oxygen.
- Alveoli — Tiny air sacs in lungs for gas exchange.
- Double Circulation — Blood passes twice through the heart during one complete cycle.
- Xylem — Plant tissue that transports water.
- Phloem — Plant tissue that transports food.
- Nephron — Functional unit of the kidney.
- Dialysis — Artificial filtration of blood.
Action Items / Next Steps
- Practice diagrams: digestive system, nephron, heart and circulation.
- Revise NCERT textbook line by line, focusing on definitions and key reactions.
- Solve practice/sample papers and past board questions.
- Review and memorize key processes: photosynthesis, respiration, nephron function.
- Prepare short notes or flashcards for key terms and definitions.