Class 10 Science Notes on Chapter 5 ‘Life Processes’: Complete Study Guide

Class 10 Science Notes on Chapter 5 ‘Life Processes’ explains the essential activities that living organisms perform to maintain life. From obtaining nutrition and releasing energy to transporting materials and removing waste, these processes help organisms survive and function properly.

These Class 10 Science Notes on ‘Life Processes’ cover all important concepts in a simple and easy-to-understand manner. You’ll learn about nutrition, respiration, transportation in humans and plants, excretion, the human digestive system, circulatory system, respiratory system, and excretory system. A clear understanding of these topics helps strengthen biology concepts and supports effective board exam preparation.

Topics Covered in Class 10 Science Notes on Chapter 5 ‘Life Processes’

Life Processes and Their Importance	Respiration and Types of Respiration
Nutrition in Living Organisms	Transportation in Human Beings
Autotrophic and Heterotrophic Nutrition	Transportation in Plants
Nutrition in Human Beings	Excretion in Human Beings and Plants

Class 10 Science Notes on Chapter 5 Life Processes: Important Topics at a Glance

How do living organisms obtain energy, transport materials, and remove waste from their bodies? Class 10 Science Notes on Chapter 5 ‘Life Processes’ explains the vital processes that keep organisms alive and help them maintain their internal balance. Understanding these processes provides a strong foundation for learning how different body systems work together.

What are Life Processes

Life processes are the basic functions performed by living organisms to maintain life. These activities continue throughout an organism's lifetime, even when it is resting or sleeping.

The four major life processes are:

• Nutrition
• Respiration
• Transportation
• Excretion

These processes supply energy, transport materials, remove wastes, and help organisms grow and survive.

Characteristics of Living Organisms

What makes an organism different from non-living things? Living organisms perform certain life processes that help them survive, grow, and maintain their bodies. These characteristics include:

• Nutrition: Living organisms need food to obtain energy and essential nutrients.
• Growth and Development: They increase in size and undergo changes throughout their life.
• Respiration: They release energy from food to carry out various activities.
• Excretion: They remove harmful waste products from their bodies.
• Response to Stimuli: They sense and react to changes in their surroundings.
• Reproduction: They produce new individuals to continue their species.
• Internal Molecular Movements: Molecules constantly move inside cells, helping in repair, maintenance, and proper functioning of the body.

Nutrition

Nutrition is the process by which organisms obtain food and use it to produce energy, grow, repair tissues, and carry out life processes.

Based on how organisms obtain food, nutrition is classified into two types:

• Autotrophic nutrition
• Heterotrophic nutrition

a. Autotrophic Nutrition and Photosynthesis

Autotrophs prepare their food using sunlight, carbon dioxide, and water through photosynthesis. This process occurs in green plants, algae, and some bacteria.

Concept	Details
Photosynthesis	Process by which green plants prepare glucose using sunlight and chlorophyll.
Word Equation	Carbon dioxide + Water → Glucose + Oxygen
Requirements	Sunlight, chlorophyll, carbon dioxide, and water
Steps	Chlorophyll absorbs sunlight, water breaks down, carbon dioxide combines with hydrogen to form glucose, and oxygen is released.
Importance	Produces food, releases oxygen, maintains gas balance, and supports food chains.
Stomata	Tiny pores on leaves that help in gas exchange and transpiration. Their opening and closing are controlled by guard cells.

b. Heterotrophic Nutrition

All organisms require food to obtain energy and perform essential life processes. Autotrophs, which prepare their own food through photosynthesis, differ from heterotrophs, which cannot make their own food. They depend directly or indirectly on other organisms for their nutritional needs.

The process of obtaining food from other organisms is called heterotrophic nutrition.

Examples of heterotrophs include:

• Humans
• Animals
• Fungi
• Most bacteria

Based on the method of obtaining food, heterotrophic nutrition is classified into three main types:

Type of Heterotrophic Nutrition	Description	Examples
Holozoic Nutrition	Organisms take in solid food and digest it internally. The digested nutrients are absorbed and used for energy, growth and repair.	Humans, amoeba, animals
Saprophytic Nutrition	Organisms obtain nutrients from dead and decaying organic matter. They release digestive enzymes to break down food and absorb the nutrients.	Fungi, and some bacteria
Parasitic Nutrition	Organisms obtain food from a living host and may harm it. They depend on the host for nutrients and survival.	Tapeworm, Cuscuta (dodder plant)

Thus, heterotrophic organisms rely on other sources of food to obtain energy and carry out their life processes. 

c. Nutrition in Amoeba

Amoeba follows a holozoic mode of nutrition and obtains food through a process called phagocytosis. 

During this process, Amoeba extends temporary projections called pseudopodia that surround and engulf the food particle, forming a food vacuole. 

Digestive enzymes present inside the food vacuole break down the food into simpler substances. The digested nutrients are then absorbed and used by the cell for energy and growth. Finally, the undigested food material is expelled from the body.

d. Nutrition in Human Beings

Human beings obtain nutrition through the holozoic mode of nutrition, where food is ingested, digested, absorbed and used by the body. 

The human digestive system breaks down complex food into simpler substances that can be absorbed and utilised for energy, growth and repair.

Part/Process	Description and Function
Mouth	Food is chewed into smaller pieces by teeth. Saliva containing salivary amylase begins the digestion of starch into simple sugars. It also moistens food and makes swallowing easier.
Oesophagus	Transports food from the mouth to the stomach.
Stomach	Mixes food with gastric juice containing hydrochloric acid (HCl), pepsin and mucus. HCl provides an acidic medium, pepsin digests proteins and mucus protects the stomach lining.
Small Intestine	The main site for digestion and absorption. Bile from the liver neutralises acidic food and emulsifies fats. Pancreatic enzymes like trypsin, lipase and amylase digest proteins, fats and carbohydrates. Intestinal juice completes digestion.
Large Intestine	Absorbs water from undigested food and helps form faeces.
Rectum	Stores faeces before they are removed from the body.
Anus	Helps in the removal of undigested waste materials.
Salivary Glands	Produce saliva containing salivary amylase to begin starch digestion.
Liver	Produces bile juice, which neutralises acidic food and breaks large fat droplets into smaller ones through emulsification.
Pancreas	Secretes digestive enzymes such as trypsin, lipase and amylase for digestion of proteins, fats and carbohydrates.
Absorption of Food	Digested nutrients are absorbed in the small intestine through finger-like projections called villi. Villi increase surface area, absorb nutrients and transfer them into the blood.

This coordinated process allows the body to obtain essential nutrients from food and use them for various life processes.

Respiration

All living organisms require energy to carry out essential life processes such as growth, movement and repair. This energy is obtained by breaking down food inside cells. The process of releasing energy from food is called respiration.

During respiration, energy is released and stored as ATP (Adenosine Triphosphate). ATP is known as the 'energy currency' of the cell, as it supplies energy for cellular activities.

Types of Respiration

Respiration occurs in two ways depending on the availability of oxygen. When oxygen is present, cells release energy through aerobic respiration. When oxygen is unavailable, they perform anaerobic respiration.

a. Aerobic Respiration

Aerobic respiration occurs in the presence of oxygen. It takes place mainly in the mitochondria and releases a large amount of energy.

Products formed:

• Carbon dioxide
• Water
• Large amount of ATP

b. Anaerobic Respiration

Anaerobic respiration occurs in the absence of oxygen. It occurs in organisms such as yeast and some bacteria. It also occurs in human muscle cells during strenuous exercise when the oxygen supply is insufficient.

Products formed:

In yeast:

• Alcohol
• Carbon dioxide
• Small amount of energy

In muscles:

• Lactic acid
• Small amount of energy

The buildup of lactic acid in muscles during strenuous activity causes muscle cramps.

Transportation

Every living organism needs essential substances like food, water, oxygen and minerals to carry out life processes. These materials must be transported to different parts of the body where they are required. Similarly, waste materials produced during metabolic activities need to be removed.

The process of moving essential substances and waste materials within an organism is called transportation. In humans, transportation is carried out by the circulatory system, while plants use specialised vascular tissues to transport water, minerals and food.

a. Transportation in Human Beings

The human body has a specialised transport system that supplies oxygen and nutrients to cells and removes waste products. This system is known as the circulatory system.

The circulatory system consists of:

• Heart
• Blood
• Blood vessels

i). Heart

The heart is a muscular organ that pumps blood throughout the body. It has four chambers that help maintain the proper flow of oxygenated and deoxygenated blood.

The four chambers are:

• Right atrium
• Right ventricle
• Left atrium
• Left ventricle

Function	Description
Pumping blood	Sends oxygenated blood to all body parts
Blood purification	Sends deoxygenated blood to the lungs for oxygenation

ii). Double Circulation

In humans, blood passes through the heart twice during one complete cycle of circulation. This is called double circulation.

Type of Circulation	Function
Pulmonary circulation	Transports deoxygenated blood from the heart to the lungs and returns oxygenated blood to the heart
Systemic circulation	Carries oxygenated blood from the heart to the body and returns deoxygenated blood

Importance of double circulation:

• Prevents mixing of oxygenated and deoxygenated blood
• Ensures efficient oxygen supply
• Supports high energy requirements of the body

iii. Blood

Blood is a fluid connective tissue that transports oxygen, nutrients, hormones and waste materials throughout the body.

Component of Blood	Function
Plasma	Transports food, hormones, carbon dioxide and waste materials
Red Blood Cells (RBCs)	Contain haemoglobin and carry oxygen
White Blood Cells (WBCs)	Fight infections and provide immunity
Platelets	Help in blood clotting and prevent excessive blood loss

iv). Blood Vessels

Blood flows through a network of blood vessels that transport it to different parts of the body.

Blood Vessel	Function and Features
Arteries	Carry blood away from the heart, have thick elastic walls and usually carry oxygenated blood
Veins	Carry blood towards the heart, have thin walls and contain valves
Capillaries	Smallest blood vessels with one-cell thick walls that allow exchange of materials between blood and tissues

v). Lymph

Lymph is a colourless tissue fluid that supports transportation and immunity in the body.

Functions of Lymph

• Returns excess fluid to the blood
• Transports absorbed fats
• Supports immunity

b. Transportation in Plants

Plants also require a transport system to move water, minerals and food between different parts. Since plants do not have a circulatory system, they use specialised vascular tissues called xylem and phloem.

Vascular Tissue	Function
Xylem	Transports water and minerals from roots to leaves
Phloem	Transports food prepared in leaves to other parts of the plant

1. Xylem

Xylem carries water and minerals absorbed by roots to different parts of the plant, especially the leaves.

Water movement occurs through:

• Root pressure
• Transpiration pull

2. Transpiration

Plants lose excess water as water vapour through stomata. This process is called transpiration.

Importance of Transpiration

• Creates transpiration pull
• Helps in the upward movement of water
• Regulates plant temperature

iii. Phloem

Phloem transports food prepared by leaves to other parts of the plant. This movement is called translocation.

It carries:

• Sugars
• Amino acids

Unlike xylem, phloem transport requires energy in the form of ATP

Excretion

All living organisms perform various life processes to survive. During these activities, harmful waste substances are produced inside the body. The process of removing these unwanted metabolic wastes is known as excretion.

Excretion helps maintain the internal balance of the body by preventing the accumulation of toxic substances and ensuring that organs function properly.

a. Excretion in Human Beings

In human beings, excretion is carried out by a specialised excretory system. This system filters waste materials from the blood and removes them from the body in the form of urine.

The human excretory system consists of:

• Kidneys
• Ureters
• Urinary bladder
• Urethra

1. Kidneys

The kidneys are the main organs of the excretory system. They filter the blood and remove harmful wastes such as urea, excess water and salts from the body.

The major functions of kidneys include:

• Filtering blood to remove waste products
• Removing urea from the body
• Regulating water balance
• Maintaining salt concentration in the body

2. Nephron

The kidneys contain millions of tiny structures called nephrons. A nephron is the structural and functional unit of the kidney because it performs the important functions involved in urine formation.

Each nephron helps remove waste materials from the blood and maintains the balance of water and salts required by the body.

Functions of Nephron

The main functions of a nephron include:

• Ultrafiltration: Filtering waste materials and excess substances from the blood
• Selective reabsorption: Absorbing useful substances such as water, glucose and salts back into the blood
• Tubular secretion: Removing additional waste substances from the blood into the urine
• Urine formation: Producing urine containing metabolic wastes

Urine Formation

Urine formation takes place in the nephrons through three main stages:

1. Filtration: Blood is filtered in the kidneys to remove waste substances.

2. Selective reabsorption: Useful substances are reabsorbed back into the blood.

3. Tubular secretion: Additional waste materials are added to the urine for removal.

After formation, urine follows this pathway:

Kidneys → Ureters → Urinary bladder → Urethra → Outside the body

Artificial Kidney (Dialysis)

When kidneys fail to function properly, an artificial kidney or dialysis machine is used to filter the blood.

Dialysis helps by:

• Removing nitrogenous wastes from the blood
• Filtering harmful substances
• Maintaining the balance of water and salts in the body

b. Excretion in Plants

Plants do not have a specialised excretory system like animals. Instead, they remove waste products through different methods.

Plants remove wastes by:

• Storing wastes in leaves, bark and fruits
• Storing waste substances such as gums and resins
• Releasing gases through stomata
• Removing certain substances into the surrounding soil
• Shedding old leaves and bark

Thus, both plants and animals have different mechanisms to remove waste materials and maintain a healthy internal balance.