Life Processes Class 10 Notes Biology Science Chapter 6

What are Life Processes ?

  • Living beings are complex organisations of molecules which perform various life processes like growth, respiration, digestion, reproduction, excretion etc., which makes them different from non-living.
  • The basic processes or functions performed by living organisms to keep them alive are called life processes.

Nutrition is defined as the process of intake of nutrients and its utilisation by an organism in various biological activities.

  • In autotrophic mode of nutrition, organisms prepare their own food and they are called autotrophs. Organisms prepare food by the process of photosynthesis.
  • Photosynthesis is the process by which chlorophyll containing cells prepare glucose using carbon dioxide and water in presence of light energy and oxygen gas is released as a by product during this process.
  • 6CO2 + 12H2O Sunlight/Chlorophyll C6H12O6 + 6O2 + 6H2O [Equation for photosynthesis]

Steps of nutrition in human beings

Organs of the digestive system

Nutrition in amoeba


  • Respiration is a biological process by which glucose is oxidized to release energy in the form of ATP which is the energy currency of the cell.

$$\text{C}_6\text{H}_{12}\text{O}_6\space+\space6\text{O}_2 \xrightarrow{\text{Sunlight}}6\text{CO}_2\space+\space6\text{H}_2\text{O}\space+\space\text{Energy}\space [\text{Equation\space for\space respiration}]$$

  • During aerobic respiration, 38 molecules of ATP are released whereas during anaerobic respiration only 2 molecules of ATP are released.
  • Tobacco is a plant and its leaves are smoked, chewed, or sniffed for a variety of effects. Tobacco contains nicotine, an addictive substance. Smoked tobacco products include cigarettes, cigars, bidis, and kreteks.
  • Smoking can destroy the cilia or tiny hairs in the airway that keep dirt and mucus out of lungs.

Breathing process in human beings


  • The essential substances like food, water, oxygen etc., need to be carried from one part of the body to another which is done by transport system.
  • Arteries carry oxygenated blood except pulmonary artery.
  • Veins carry deoxygenated blood except pulmonary vein.
  • Capillaries are thin walled blood vessels where exchange of gases and materials like food occurs.
  • Valves allow the blood to flow in one direction i.e., they prevent back flow of the blood.
  • When blood flows from atria to ventricles atria contracts and ventricle relaxes, this is called ventricular diastole.
  • When blood flows from ventricles to blood vessels, ventricles contract and atrium relaxes, this is called ventricular diastole.
  • The force exerted by blood on the walls of blood vessels is called blood pressure.
  • The normal blood pressure of human beings is 120/80 mm of Hg.
  • As blood flows in our heart twice so circulation in human beings is called double circulation.

Double Circulation


  • The process of removal of mainly nitrogenous waste substances from our body is called excretion.
  • In case of kidney failure due to infections or injury or other factors artificial kidney is used.
  • Artificial kidney is a device that removes nitrogenous wastes from our body by dialysis.
  • Organ donation is the donation of biological tissue or an organ of the human body, from a living or dead person to a living recipient in need of a transplantation. Organ transplantation is the only option to save lives in patients affected by terminal organ failures and improve their quality of life.
1. Life Processes: The processes like nutrition, respiration, growth, excretion etc. which together keep the living organisms alive and perform the function of body maintenance are called life processes. 9. Holozoic nutrition: It is the mode of nutrition in which an organism feeds on solid food which is a complex organic matter by the process of ingestion, then the food is subsequently digested and absorbed and finally undigested residue is removed from the body.
2. Autotrophic nutrition: It is the mode of nutrition in which organisms prepare their own food by utilising the raw materials from the surroundings and thus, do not depend on others for their food. 10. Peristalsis: The contraction and expansion movement of muscular wall of oesophagus when food (bolus) passes from mouth to stomach.
3. Photosynthesis: It is a biological process in which organisms prepare their own food by using inorganic raw materials like water, carbon dioxide in presence of chlorophyll and sunlight or light energy and oxygen is evolved as a byproduct during this process. 11. Chyme: It is the semi solid paste formed by the churning of partially digested food from the stomach mixed with gastric juice secreted by the stomach.
4. Chlorophyll: It is a green pigment found within the chloroplasts of green plants and some algae which traps solar energy for the process of photosynthesis. 12. Respiration: It is a complex process which involves gaseous exchange i.e., oxygen is taken in and carbon dioxide is given out as well as oxidation of glucose in cells to release chemical energy in the form of ATP.
5. Light reaction: The series of reactions which occurs only in presence of light inside the granum of chloroplast where there is formation of oxygen molecule due to photolysis of water and production of assimilatory powers like NADPH and ATP 13. Transportation: It is a life process in which a substance synthesized or absorbed in one part of the organism is carried to the other parts of the body.
6. Dark reaction: The series of reactions in which carbon dioxide is converted to glucose in absence of light utilising the assimilatory powers like NADPH and ATP in stroma of chloroplast. 14. Excretion: It is a biological process where there is removal of nitrogenous wastes from our body produced due to metabolism.
7. Photolysis: The reaction in which water splits to produce hydrogen , protons, electrons and oxygen by using light energy trapped by chlorophyll. 15. Osmoregulation: The process of maintaining a constant osmotic condition in the body by regulating the water and solute concentration of body fluids.
8. Heterotrophic nutrition: It is the mode of nutrition in which the organisms depends upon other organisms for food i.e., they obtain their food from autotrophs. 16. Dialysis: It is an artificial process of removal of metabolic wastes and excess water from the body by using a machine in order to maintain the normal water and solute concentration in our body.