Class 10 Science • Complete Chapter Notes
Living organisms need energy and materials to maintain their bodies, grow and carry out essential activities. The basic maintenance activities performed by living organisms are called life processes.
The major life processes studied in this chapter are nutrition, respiration, transportation and excretion. These processes work together to maintain the functioning of an organism.
Nutrition is the process by which organisms obtain food and use it for energy, growth, repair and maintenance.
Organisms obtain food mainly through autotrophic or heterotrophic modes of nutrition.
Green plants prepare food by photosynthesis. Chlorophyll absorbs light energy, which is used to convert carbon dioxide and water into carbohydrates.
Stomata are small pores mainly present on the surfaces of leaves. They allow exchange of gases and also play an important role in transpiration.
Humans have a complex digestive system in which food passes through specialised organs where it is digested, absorbed and finally the undigested material is eliminated.
Digestion begins in the mouth. Food is mechanically broken down by chewing and mixed with saliva.
Salivary amylase begins the digestion of starch into simpler carbohydrates.
The stomach churns food and mixes it with gastric juice. Hydrochloric acid provides an acidic medium, while digestive enzymes help in digestion, especially of proteins.
The small intestine is the major site of completion of digestion and absorption of digested food.
Bile is produced by the liver and helps in the digestion of fats by making the medium alkaline and breaking large fat globules into smaller droplets.
Pancreatic juice contains enzymes that help digest carbohydrates, proteins and fats.
The inner lining of the small intestine contains numerous finger-like projections called villi. They increase the surface area available for absorption.
The large intestine absorbs water and some salts from the remaining undigested material. The remaining waste is then stored and eliminated from the body.
Respiration is the process by which food molecules are broken down to release usable energy for cellular activities.
Aerobic respiration takes place in the presence of oxygen and generally releases more energy.
Anaerobic respiration or fermentation can occur in the absence of oxygen. In yeast, glucose is converted into ethanol, carbon dioxide and energy.
Glucose is first broken down in the cytoplasm to form pyruvate. The further fate of pyruvate depends on the availability of oxygen and the organism or cell type.
| Condition | Main Product |
|---|---|
| Presence of oxygen | Carbon dioxide + water + more energy |
| Lack of oxygen in yeast | Ethanol + carbon dioxide + energy |
| Lack of oxygen in muscles | Lactic acid + energy |
The human respiratory system brings oxygen into the body and removes carbon dioxide.
Alveoli are tiny air sacs in the lungs where exchange of gases takes place between the air and the blood.
During inhalation, the diaphragm contracts and moves downward while the volume of the thoracic cavity increases. Air is drawn into the lungs.
During normal exhalation, the diaphragm relaxes and moves upward. The thoracic cavity volume decreases and air is pushed out of the lungs.
Multicellular organisms need specialised systems to transport food, oxygen, water and other substances to different parts of the body and to carry wastes away.
Blood is a connective tissue consisting of plasma, red blood cells, white blood cells and platelets.
| Component | Main Function |
|---|---|
| Plasma | Transport medium for dissolved substances. |
| Red Blood Cells | Transport oxygen using haemoglobin. |
| White Blood Cells | Help protect the body against infection. |
| Platelets | Help in blood clotting. |
The human heart is a muscular organ that pumps blood throughout the body.
The right side mainly handles deoxygenated blood from the body, while the left side mainly pumps oxygenated blood received from the lungs to the body.
| Vessel | Main Role |
|---|---|
| Arteries | Carry blood away from the heart. |
| Veins | Carry blood towards the heart. |
| Capillaries | Allow exchange of materials with tissues. |
Lymph is a fluid connective tissue involved in transport of materials and in maintaining fluid balance. It also plays a role in the body's defence.
Lymphatic vessels return excess tissue fluid to the bloodstream and help transport absorbed fats from the intestine.
Plants need to transport water, minerals and food between different parts.
Xylem transports water and dissolved minerals mainly from roots towards the aerial parts of the plant.
Phloem transports food, mainly sugars, from source regions to regions where it is needed or stored.
Water is absorbed from the soil by roots and is transported through xylem tissue.
Transpiration is the loss of water in the form of water vapour from the aerial parts of plants, mainly through stomata.
Loss of water by transpiration helps generate a pull that contributes to the upward movement of water through xylem.
The transport of food or organic solutes through phloem is called translocation.
Unlike the mainly upward transport of water through xylem, phloem transport can occur in different directions depending on where food is produced and where it is required or stored.
Excretion is the process by which metabolic waste products are removed from the body.
Kidneys filter the blood and help remove nitrogenous wastes while maintaining appropriate water and salt balance.
The nephron is the structural and functional unit of the kidney. Each kidney contains a very large number of nephrons.
When kidneys cannot adequately perform their filtering function, dialysis may be used to remove certain wastes and excess substances from the blood.
In haemodialysis, blood is passed through a special dialyser containing a selectively permeable membrane and then returned to the body.
Plants do not have specialised excretory organs like animal kidneys. They eliminate or store waste materials through several mechanisms.
| Life Process | Main Purpose |
|---|---|
| Nutrition | Obtaining and utilising food and nutrients. |
| Respiration | Releasing usable energy from food molecules. |
| Transportation | Moving materials between different parts of the body. |
| Excretion | Removing metabolic waste products. |
These notes are aligned with the NCERT Class 10 Science chapter on Life Processes. Use the official textbook and current CBSE resources for complete curriculum-aligned study.
NCERT – Life Processes Official PDF → NCERT Official Textbooks → CBSE Academic Curriculum 2026-27 →