Life Processes — The 7 Life Processes (NCERT Class 10 Biology)

Life processes are the set of biological processes carried out by living organisms to stay alive and maintain their body functions. They are the characteristics that distinguish a living organism from a non-living thing.

Why are life processes important? • They maintain the structure and function of the body • They provide energy for all activities • They enable growth and repair • They allow reproduction to continue the species • They help organisms respond to changes in the environment

The 7 life processes (NCERT Class 10):

1. Nutrition
2. Respiration
3. Transportation
4. Excretion
5. Control and Coordination
6. Growth
7. Reproduction

Note: Some textbooks list 7 or 8 life processes. NCERT Class 10 Biology focuses on Nutrition, Respiration, Transportation, and Excretion in Chapter 6. Growth, Reproduction, and Control and Coordination are also covered in subsequent chapters.

1. Nutrition: Nutrition is the process by which organisms obtain and use food (nutrients) for energy, growth, and repair.

Types of nutrition: • Autotrophic nutrition: Organisms make their own food. Plants carry out photosynthesis — they use sunlight, CO₂, and water to produce glucose. 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂ • Heterotrophic nutrition: Organisms obtain food by eating other organisms. Includes: – Holozoic nutrition (animals — ingestion, digestion, absorption, assimilation, egestion) – Saprophytic nutrition (fungi, some bacteria — digest dead organic matter externally) – Parasitic nutrition (organisms live on a host and take nutrients from it)

2. Respiration: Respiration is the process by which organisms break down food (glucose) to release energy in the form of ATP.

Types of respiration: • Aerobic respiration (with oxygen): C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP (36–38 ATP molecules). More efficient. • Anaerobic respiration (without oxygen): – In yeast: C₆H₁₂O₆ → 2C₂H₅OH (ethanol) + 2CO₂ + 2 ATP (fermentation) – In muscles during intense exercise: C₆H₁₂O₆ → 2C₃H₆O₃ (lactic acid) + 2 ATP (causes muscle fatigue)

Respiration happens in every living cell. It is NOT the same as breathing — breathing is just gas exchange.

3. Transportation: Transportation is the process by which nutrients, gases, waste products, hormones, and other substances are moved around within the organism.

In humans (circulatory system): • Blood transports oxygen (via haemoglobin in RBCs), nutrients (glucose, amino acids), hormones, and waste (CO₂, urea) around the body • The heart pumps blood through arteries (away from heart), capillaries (exchange), and veins (back to heart) • Lymphatic system also plays a role in transporting fats and immune cells

In plants (vascular system): • Xylem: Transports water and dissolved minerals from roots to leaves (transpiration pull drives this) • Phloem: Transports food (glucose/sucrose) from leaves to all parts of the plant (translocation)

4. Excretion: Excretion is the process by which metabolic waste products are removed from the body.

In humans (excretory system): • Kidneys: Filter blood and produce urine (main excretory organ). Remove urea, excess salts, and water • Lungs: Excrete CO₂ and water vapour • Skin: Excretes some salts and urea through sweat • Liver: Converts ammonia (toxic) to urea (less toxic) — urea is then excreted by kidneys

In plants: • Plants excrete oxygen (during photosynthesis) and CO₂ (during respiration) through stomata • Some waste products are stored in leaves, bark, or as resins, gums, and latex • Excess water is removed by transpiration through stomata

5. Control and Coordination: This is the process by which organisms detect changes in their environment (stimuli) and respond to them in a coordinated way.

In humans: • Nervous system: Brain, spinal cord, and nerves detect stimuli and coordinate rapid responses (nerve impulses) • Endocrine system: Glands secrete hormones (chemical messengers) for slower, long-term control (growth, metabolism, reproduction) • Reflex actions are part of nervous coordination (fast, automatic responses)

In plants: • Plants respond to stimuli using plant hormones (phytohormones) • Auxins: Control cell elongation, phototropism (bending toward light) • Gibberellins: Control stem elongation and seed germination • Cytokinins: Promote cell division • Abscisic acid: Inhibits growth, causes stomata to close during water stress (drought) • Ethylene: Controls fruit ripening

6. Growth: Growth is the permanent increase in the size, mass, and complexity of an organism. It involves cell division (mitosis) and cell enlargement. • In animals: Growth occurs throughout the body, typically until adulthood • In plants: Growth occurs mainly at meristematic regions (shoot tip and root tip) throughout life • Growth requires nutrition and energy from respiration

7. Reproduction: Reproduction is the process by which organisms produce offspring of the same kind, ensuring continuation of the species. • Asexual reproduction: Offspring produced from one parent, genetically identical (clones). Examples: binary fission (bacteria), budding (Hydra, yeast), fragmentation (Planaria, Spirogyra), vegetative propagation (plants) • Sexual reproduction: Offspring produced from two parents; involves gametes (egg and sperm); genetic variation in offspring. Occurs in most animals and many plants.