CBSE Class 10 Science Life Processes Quick Revision for Board Exams
Life processes, including nutrition, respiration, transportation, and excretion, are essential for organism survival. Organisms obtain food via autotrophic or heterotrophic modes. Respiration breaks down glucose for energy. Transportation circulates substances through circulatory and vascular systems. Excretion removes metabolic waste to maintain bodily functions.
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The chapter Life Processes is one of the most important chapters in CBSE Class 10 Science. It carries good weightage in the board exam and includes many diagram-based and short-answer questions.
In this quick revision guide, we will revise all important topics of Life Processes Class 10 in an easy method so that you can prepare effectively for your board exams.
Life Processes
Life Processes are the basic and essential activities or processes that occur within every living organism to maintain life and enable survival. Without these processes, an organism cannot stay alive.
The four fundamental life processes discussed in this topics are:
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Nutrition
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Respiration
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Transportation
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Excretion
These processes are universal, though their mechanisms vary with organism complexity. For example, in single-celled organisms like Amoeba, all four processes occur within that single cell.
Topic 1: Nutrition
Nutrition is the process by which a living organism obtains and utilizes food.
|
Feature |
Nutrition |
Nutrients |
|---|---|---|
|
Definition |
The overall process of obtaining and using food for energy, growth, and repair. |
The chemical components of food that provide nourishment, such as carbohydrates, proteins, fats, vitamins, and minerals. |
Modes of Nutrition
Nutrition is broadly classified into two main types based on how organisms obtain their food.
1. Autotrophic Nutrition
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Organisms, known as autotrophs, produce their own food from simple inorganic substances available in the environment (e.g., COβ, water).
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Example: Plants.
2. Heterotrophic Nutrition
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Organisms, known as heterotrophs, cannot produce their own food and depend on other organisms for nourishment.
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Examples: Humans, animals, fungi.
Topic 2: Respiration
Breathing supplies the oxygen for cellular respiration and removes the carbon dioxide produced.
|
Feature |
Breathing |
Respiration |
|---|---|---|
|
Definition |
The physical process of inhaling and exhaling air (exchange of gases). |
The chemical process of breaking down food (glucose) in cells to release energy. |
|
Location |
Occurs in the lungs. |
Occurs inside the body's cells (cytoplasm and mitochondria). |
|
Nature |
A physical process (mechanical movement). |
A biochemical process (chemical reactions). |
|
Energy |
Does not produce energy. |
Produces energy in the form of ATP. |
The Human Respiratory System
The respiratory system moves air for gas exchange.
The Path of Air During Inhalation:
Nostrils β Nasal Passage β Nasal Cavity β Pharynx β Larynx β Trachea β Bronchi β Lungs β Bronchioles β Alveoli
Alveoli: Tiny, balloon-like air sacs at the end of bronchioles. They are thin-walled and surrounded by capillaries, making them the primary sites of gas exchange. Oxygen diffuses into blood, and carbon dioxide diffuses from blood into alveoli to be exhaled.
Topic 3: Transportation
Transportation is the life process that moves substances from one part of an organism to another, essential for processes like cellular respiration. It occurs in both animals and plants.
Transportation in Animals (Humans)
Human transportation involves two systems:
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Circulatory System
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Lymphatic System
The Circulatory System
The human circulatory system includes:
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Blood: Fluid medium.
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Blood Vessels: Network of tubes.
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Heart: Pumping organ.
Transportation in Plants
Plants have a Vascular System composed of Xylem and Phloem.
|
Feature |
Xylem |
Phloem |
|---|---|---|
|
Substance Transported |
Water and minerals |
Food (sugars from photosynthesis) |
|
Direction of Flow |
Unidirectional: Always upwards from roots. |
Bidirectional: Upwards and downwards, from leaves to wherever food is needed. |
|
Driving Mechanism |
Physical forces: Transpiration pull and Root Pressure. Does not require ATP. |
Chemical energy: Requires ATP. |
|
Process Name |
Ascent of Sap |
Translocation |
Topic 4: Excretion
It is crucial to differentiate between Egestion and Excretion.
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Egestion: Removal of undigested, unabsorbed food from the digestive tract.
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Excretion: Removal of metabolic waste (e.g., urea, COβ) from the body.
Complex organisms like humans have a specialized Excretory System.
The Human Excretory System
This system filters metabolic waste from blood and expels it as urine.
Key Organs and the Path of Urine:
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Kidneys: Filter blood to produce urine.
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Ureters: Carry urine from kidneys to bladder.
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Urinary Bladder: Stores urine temporarily.
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Urethra: Expels urine from the body.
Functions of the Kidneys:
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Remove nitrogenous wastes.
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Regulate body's water balance.
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Maintain blood's pH.
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Eliminate toxic substances.
The Nephron: The Functional Unit of the Kidney
Each kidney contains millions of nephrons, the structural and functional units for urine formation.
Basic Structure of a Nephron:
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Bowman's Capsule: Cup-shaped, encloses the glomerulus.
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Glomerulus: Dense bundle of blood capillaries.
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Tubule: Long, coiled tube.
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Collecting Duct: Collects urine from multiple nephrons.
The Process of Urine Formation in the Nephron:
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Glomerular Filtration: High pressure in the glomerulus forces water, salts, glucose, amino acids, and urea from blood into the Bowman's capsule, forming filtrate.
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Selective Reabsorption: Essential substances (most water, glucose, amino acids) are selectively reabsorbed back into the blood capillaries from the tubule.
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Tubular Secretion: Waste products remaining in blood are actively secreted from capillaries into the tubule.
The remaining fluid, now urine, flows into the collecting duct and then to the ureter.