Chapter 5 — Life Processes

Chapter 5 of the Class 10 Science NCERT textbook, "Life Processes", covers the essential maintenance functions — nutrition, respiration, transportation, and excretion — that all living organisms must carry out continuously to survive and repair their ordered internal structures.

• Nutrition: making and breaking down food — Autotrophic plants make their own food by photosynthesis using carbon dioxide, water, sunlight, and chlorophyll, while heterotrophs use enzymes to break down complex food. In humans this digestion runs along the alimentary canal from mouth to anus.
• Respiration and transport in the body — Respiration releases energy as ATP, aerobically or anaerobically, to power the cell. A four-chambered heart drives double circulation through blood vessels, keeping oxygenated and deoxygenated blood separate for efficient delivery.
• Removing waste in animals and plants — Animals excrete nitrogenous waste as kidneys filter blood through nephrons and reabsorb useful substances. Plants instead transport water via xylem and food via phloem, and shed waste through vacuoles, falling leaves, and resins.

1. 01Photosynthesis in autotrophs converts CO2 and water into carbohydrates using sunlight and chlorophyll; stomata regulate gas exchange and guard cells control stomatal opening.
2. 02In human digestion, salivary amylase acts on starch in the mouth, gastric glands secrete HCl and pepsin in the stomach, and the small intestine completes digestion with bile and pancreatic juice; villi absorb digested food.
3. 03Aerobic respiration (in mitochondria) releases far more energy than anaerobic respiration; glucose is first broken down to pyruvate in the cytoplasm, with ATP as the universal energy currency.
4. 04The human heart has four chambers enabling double circulation; oxygenated and deoxygenated blood are kept separate; haemoglobin in red blood corpuscles carries oxygen.
5. 05In plants, xylem transports water and minerals upward (driven by transpiration pull and root pressure); phloem translocates photosynthesis products using ATP-driven osmotic pressure.
6. 06Human excretion: kidneys filter blood via nephrons (Bowman's capsule + tubules), selectively reabsorb useful substances, and excrete urea in urine; plants excrete waste via vacuoles, falling leaves, resins, and gums.