CBSE Class 10 Chapter 5 Life Processes Notes​

Life Processes Class 10 Notes: As the Class 10 Science board exam approaches, many students feel confused between topics like nutrition and respiration or struggle with labelled diagrams of the heart, nephron, and stomata. Since this chapter includes both plant and human systems, it often feels lengthy and difficult to revise.

Here, These notes clearly explain all four major life processes in a structured and exam-focused manner:

• Nutrition: Obtaining and utilising food

• Respiration: Releasing energy from food

• Transportation: Movement of substances within the body

• Excretion: Removal of metabolic wastes

Key differences, flowcharts, and important diagrams are explained in a clear way to reduce confusion and help students revise efficiently. Focused preparation at this stage will help in writing accurate, well-labelled, and stepwise answers in the Class 10 board exam.

What Are Life Processes?

Life processes are the basic activities that living organisms carry out to maintain and continue life.

These include taking in food, releasing energy, transporting substances within the body, and removing waste products. This section of CBSE Class 10 Science Notes Chapter 5 explains how these vital processes function in different organisms and ensure their survival.

Biology Notes Class 10 CBSE Life Processes

Life Processes Class 10 Notes provide a concise summary of essential biological functions like nutrition, respiration, transportation, and excretion. These notes help students understand how organisms maintain life and prepare effectively for exams.

1. Nutrition

Nutrition is the process by which an organism obtains food from its environment and utilizes it to generate energy, build and repair tissues, and maintain growth and overall body functions. It ensures that living organisms have the necessary nutrients and energy to carry out life processes such as movement, reproduction, and cellular activities.

Autotrophic Nutrition

• Organisms synthesize their own food from inorganic substances like CO₂ and water.

• Example: Green plants, autotrophic bacteria

• Process: Photosynthesis

• Occurs in chloroplasts

• Uses sunlight, carbon dioxide, water, and chlorophyll to produce glucose and oxygen

• Stomata regulate gas exchange and minimize water loss

Heterotrophic Nutrition

• Organisms cannot make their own food and depend on other organisms.

• Example: Humans, animals, fungi

• Types include Holozoic (internal digestion), Saprophytic (dead matter), and Parasitic (living host)

Respiration

Respiration is the biochemical process of breaking down food to release energy in the form of ATP.

Breathing vs Respiration

Aerobic and Anaerobic Respiration

Human Respiratory System

Air Pathway:
Air enters the body through the nostrils, passes through the nasal passage (filters, warms, and moistens air), moves into the pharynx, larynx, and then down the trachea (supported by cartilaginous rings to prevent collapse). From the trachea, air flows into the bronchi, then into smaller bronchioles, and finally reaches the alveoli.

Alveoli:

• Tiny balloon-like sacs at the end of bronchioles

• Provide a large surface area for efficient gas exchange

• Surrounded by a dense network of blood capillaries

• Oxygen diffuses into the blood, while carbon dioxide diffuses out

• Moist lining allows gases to dissolve for faster diffusion
  
  

Respiration in Plants

• Gas Exchange: Occurs through stomata (leaves), lenticels (stems), and root surfaces

• Oxygen and Carbon Dioxide:

• Daytime: Oxygen is released (photosynthesis) and carbon dioxide is absorbed

• Nighttime: Plants respire in the dark, consuming oxygen and releasing carbon dioxide

• Allows plants to maintain energy for growth and metabolism

Transportation in Humans

Transportation is the process of moving essential substances such as food, oxygen, hormones, and metabolic wastes to and from different parts of the body. It ensures that all cells receive nutrients, oxygen, and hormonal signals, while wastes are removed efficiently to maintain homeostasis.

Human Circulatory System

The human circulatory system is a closed transport system consisting of:

1. Heart – The muscular pump that circulates blood throughout the body

1. Blood – The circulating fluid that carries gases, nutrients, hormones, and wastes

2. Blood Vessels – Tubes that transport blood to and from all parts of the body

This system ensures efficient transport of materials, supports thermoregulation, and helps in defense against infections.

Components of Blood

4. Excretion

Excretion is the biological process by which organisms remove metabolic waste products from the body. This is essential to maintain internal balance (homeostasis) and prevent the accumulation of harmful substances that can disrupt normal body functions.

A. Human Excretory System

The human excretory system removes nitrogenous wastes, excess water, and salts from the blood. The main organs involved are:

1. Kidneys – Filter blood to remove urea, salts, and excess water.

2. Ureters – Tubes that transport urine from the kidneys to the urinary bladder.

3. Urinary Bladder – Stores urine temporarily before excretion.

4. Urethra – Tube through which urine is expelled from the body.

Kidneys

• Paired, bean-shaped organs located on either side of the vertebral column.

• Filter nitrogenous wastes like urea, uric acid, and other soluble toxins from the blood.

• Help regulate water balance, salt levels, and blood pressure.

Nephron

The nephron is the structural and functional unit of the kidney. Each kidney contains millions of nephrons, which carry out the filtration, reabsorption, and secretion processes necessary to form urine.

Key Structures of Nephron:

• Bowman’s capsule – Cup-shaped structure surrounding the glomerulus; site of initial filtration

• Glomerulus – A network of capillaries where blood is filtered under pressure

• Tubules – Proximal tubule, loop of Henle, distal tubule; responsible for reabsorption and secretion

• Collecting duct – Collects urine from multiple nephrons and sends it to the ureter

Steps of Urine Formation

1. Glomerular Filtration

• Blood enters the glomerulus under pressure.

• Water, salts, glucose, amino acids, and nitrogenous wastes are filtered into Bowman’s capsule, forming filtrate.

2. Selective Reabsorption

• Useful substances such as glucose, amino acids, and most water are reabsorbed into the blood through capillaries surrounding the tubules.

3. Tubular Secretion

• Additional wastes like urea, creatinine, and excess ions are secreted into the tubules.

• The final fluid, urine, contains wastes in water and is transported to the bladder via ureters.

Artificial Kidney (Hemodialysis)

• Used when kidneys fail to filter blood efficiently

• Blood is passed through a machine where it is filtered externally, removing waste products.

• Unlike natural kidney function, no selective reabsorption occurs, so careful monitoring of diet and fluid intake is required.

B. Excretion in Plants

Plants also produce metabolic wastes but lack a complex excretory system. Wastes are removed by:

1. Stomata – Tiny pores on leaves that release oxygen (by-product of photosynthesis) and CO₂.

2. Lenticels – Pores on stems that allow gas exchange.

3. Transpiration – Excess water and soluble salts are removed through evaporation from leaves.

4. Leaf Fall – Plants store some waste products (e.g., tannins, resins) in leaves, which are later shed.

Note: Unlike animals, plants do not have specialized organs for excretion; instead, they store or release wastes into the environment.

Importance of Excretion

• Maintains chemical balance and water balance in the body

• Removes toxic substances that can damage cells

• Regulates blood pressure and volume

• Ensures proper functioning of enzymes and metabolic pathways

Key Mechanisms of Life Processes

Photosynthesis Process

Plants convert carbon dioxide and water into glucose using sunlight. Oxygen is released as a by-product. This process supplies food to almost all living organisms directly or indirectly.

Human Digestion Flow

Food passes from mouth to stomach through the esophagus. Enzymes break down food in the stomach and small intestine. Nutrients are absorbed in the small intestine, and waste is eliminated through the large intestine.

Gas Exchange in Alveoli

Oxygen diffuses into blood from alveoli, while carbon dioxide diffuses out. This exchange is efficient due to thin walls and a large surface area.

Urine Formation

Urine formation occurs through filtration, reabsorption, and secretion in the nephron, ensuring removal of waste while conserving useful substances.

Tips to Score High Marks in Life Processes 

As the Class 10 board exam approaches, this chapter can become scoring if you focus on presentation and conceptual clarity. Based on exam trends and evaluation patterns, keep these points in mind:

• Prioritise Diagrams with Labelling: Practice neat, well-labelled diagrams of the human heart, nephron, alveolus, and stomata. Examiners award marks separately for correct labelling and structure.

• Write Stepwise Processes: For topics like urine formation, photosynthesis, and digestion, always present answers in sequential steps (filtration → reabsorption → secretion). Avoid paragraph-style explanations in 3–5 mark questions.

• Learn Differences in Tabular Form: Questions on Breathing vs Respiration and Aerobic vs Anaerobic Respiration are frequently asked. Present them in a clear comparison table to secure full marks.

• Memorise Balanced Equations: Practice writing the chemical equation of aerobic respiration and word equations for anaerobic respiration accurately, including correct symbols.

• Use Scientific Keywords: Terms like ATP, diffusion, hemoglobin, chloroplast, mitochondria, homeostasis should be used precisely. Avoid vague explanations.

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