Overview
This lecture covers the essential life processes in living organisms, focusing on nutrition, respiration, transportation, and excretion in plants and animals, especially humans.
Life Processes Overview
- Life processes are activities that maintain homeostasis and proper functioning in all living organisms.
- Main life processes include nutrition, respiration, transportation, metabolism, reproduction, and excretion.
- Unicellular organisms handle these processes in one cell; multicellular organisms have specialized systems.
Nutrition
- Nutrition is how organisms acquire food for nourishment.
- Autotrophic nutrition: organisms (e.g., plants) make their own food via photosynthesis or chemosynthesis.
- Heterotrophic nutrition: organisms (e.g., animals, fungi) obtain energy from organic compounds; includes holozoic, saprophytic, and parasitic types.
- Humans have a complex digestive system with stages: ingestion, digestion, absorption, assimilation, and egestion.
- Main organs: mouth, oesophagus, stomach, small and large intestine.
- Digestive glands (salivary, liver, pancreas) secrete enzymes for food breakdown.
Respiration
- Respiration is the exchange of gases and energy production at the cellular level.
- Humans have a specialized respiratory system: nose to lungs, where gas exchange occurs in alveoli.
- Inhalation brings in oxygen; exhalation removes carbon dioxide.
- Respiration can be aerobic (with oxygen) or anaerobic (without oxygen).
- In plants, gas exchange occurs via stomata and lenticels.
Transportation
- Internal transport is vital for distributing essential substances throughout organisms.
- Human transportation is managed by the circulatory system: heart, blood, blood vessels.
- Heart pumps blood through arteries, veins, and capillaries in double circulation.
- In plants, xylem transports water; phloem transports food (translocation).
- Water movement in plants is aided by root pressure, osmosis, and transpiration.
Excretion
- Excretion removes metabolic wastes from the body.
- Human excretory system: kidneys (contain nephrons), ureters, bladder, urethra; forms urine.
- Nephron filters blood, reabsorbs useful substances, and excretes waste.
- Dialysis is used when kidneys fail.
- Plants expel gaseous wastes via stomata and store organic wastes in tissues or shed them.
Key Terms & Definitions
- Life Process — activities necessary for survival and maintenance in organisms.
- Autotrophic Nutrition — making own food using light or chemicals.
- Heterotrophic Nutrition — obtaining food from other organisms.
- Photosynthesis — process by which green plants make food using sunlight.
- Respiration — process for energy production and gas exchange.
- Peristalsis — wave-like muscular movement moving food through digestive tract.
- Villi — finger-like intestinal projections aiding absorption.
- Phloem/Xylem — tissues for food and water transport in plants.
- Nephron — kidney’s functional filtration unit.
Action Items / Next Steps
- Review short notes and MCQs for quick revision.
- Study diagrams of digestive, respiratory, circulatory, and excretory systems.
- Practice writing the overall equations for photosynthesis and aerobic respiration.