CLASS 10 SCIENCE
LIFE PROCESSES
Complete Chapter Explanation • VVI Questions • Easy Revision Tricks
Chapter Life Processes
Covers Nutrition • Respiration • Transportation • Excretion
Style Simple language + exam-ready answers + revision tricks
How to use these notes: First understand the explanation, then learn the VVI questions, and finally revise the chapter
with the memory tricks at the end.
1. LIFE PROCESSES — THE BASIC IDEA
A living organism has to continuously perform certain activities to remain alive. These activities are called life
processes. The main life processes in this chapter are nutrition, respiration, transportation and excretion.
Easy idea: A body needs food → releases energy from food → moves materials around the body → removes waste.
This is the basic story of the chapter.
2. NUTRITION
Nutrition is the process of taking food and using it for energy, growth, repair and maintenance.
Two main modes of nutrition:
• Autotrophic: Organisms make their own food. Green plants are autotrophs.
• Heterotrophic: Organisms obtain food from other organisms.
3. PHOTOSYNTHESIS
Green plants prepare food by photosynthesis. They use carbon dioxide from air and water from the soil. Light energy is
captured by chlorophyll.
Word equation: Carbon dioxide + Water → Glucose + Oxygen (in the presence of sunlight and chlorophyll).
What is needed? Sunlight, chlorophyll, carbon dioxide and water.
Where does it mainly happen? In green leaves, inside chloroplasts containing chlorophyll.
Stomata: Small pores on leaves that help in exchange of gases. They also play an important role in transpiration.
Memory trick: Photosynthesis = Sun + CO■ + Water → Food + O■.
4. HUMAN NUTRITION — DIGESTION
Humans show heterotrophic nutrition. Food must be broken down into simpler substances so that the body can absorb
and use it. The journey of food is:
Mouth → Oesophagus → Stomach → Small intestine → Large intestine → Rectum/Anus
• Mouth: Teeth chew food. Saliva mixes with food and salivary amylase starts starch digestion.
• Oesophagus: Peristalsis pushes food towards the stomach.
• Stomach: Gastric juice contains hydrochloric acid, pepsin and mucus. Protein digestion begins here.
• Small intestine: Bile, pancreatic juice and intestinal enzymes complete digestion. Villi absorb nutrients.
• Large intestine: Absorbs water and helps form faeces.
• Rectum and anus: Store and remove undigested waste.
Class 10 Science • Life Processes • Complete Notes • Page 1
, 5. RESPIRATION — HOW CELLS GET ENERGY
Respiration is the process in which food molecules are broken down to release usable energy. The energy is captured
mainly in the form of ATP.
Glucose → Pyruvate: The first breakdown of glucose occurs in the cytoplasm.
Aerobic respiration: In the presence of oxygen, further breakdown occurs and produces carbon dioxide, water and a
larger amount of energy.
Anaerobic respiration: Occurs without oxygen. In yeast, ethanol and carbon dioxide are produced. In muscles during
oxygen shortage, lactic acid may accumulate.
Easy trick: AERO = Air/Oxygen; ANAERO = No oxygen.
6. HUMAN RESPIRATORY SYSTEM
• Nasal passage: Filters, warms and moistens incoming air.
• Trachea: Carries air towards the lungs.
• Bronchi → Bronchioles: Branching air passages inside the lungs.
• Alveoli: Tiny air sacs with a large surface area and rich blood supply; gas exchange occurs here.
• Diaphragm: Muscular sheet that helps change the volume of the chest during breathing.
Inhalation: Diaphragm contracts and moves downward; chest volume increases and air enters. Exhalation: Diaphragm
relaxes; chest volume decreases and air moves out.
Class 10 Science • Life Processes • Complete Notes • Page 2
LIFE PROCESSES
Complete Chapter Explanation • VVI Questions • Easy Revision Tricks
Chapter Life Processes
Covers Nutrition • Respiration • Transportation • Excretion
Style Simple language + exam-ready answers + revision tricks
How to use these notes: First understand the explanation, then learn the VVI questions, and finally revise the chapter
with the memory tricks at the end.
1. LIFE PROCESSES — THE BASIC IDEA
A living organism has to continuously perform certain activities to remain alive. These activities are called life
processes. The main life processes in this chapter are nutrition, respiration, transportation and excretion.
Easy idea: A body needs food → releases energy from food → moves materials around the body → removes waste.
This is the basic story of the chapter.
2. NUTRITION
Nutrition is the process of taking food and using it for energy, growth, repair and maintenance.
Two main modes of nutrition:
• Autotrophic: Organisms make their own food. Green plants are autotrophs.
• Heterotrophic: Organisms obtain food from other organisms.
3. PHOTOSYNTHESIS
Green plants prepare food by photosynthesis. They use carbon dioxide from air and water from the soil. Light energy is
captured by chlorophyll.
Word equation: Carbon dioxide + Water → Glucose + Oxygen (in the presence of sunlight and chlorophyll).
What is needed? Sunlight, chlorophyll, carbon dioxide and water.
Where does it mainly happen? In green leaves, inside chloroplasts containing chlorophyll.
Stomata: Small pores on leaves that help in exchange of gases. They also play an important role in transpiration.
Memory trick: Photosynthesis = Sun + CO■ + Water → Food + O■.
4. HUMAN NUTRITION — DIGESTION
Humans show heterotrophic nutrition. Food must be broken down into simpler substances so that the body can absorb
and use it. The journey of food is:
Mouth → Oesophagus → Stomach → Small intestine → Large intestine → Rectum/Anus
• Mouth: Teeth chew food. Saliva mixes with food and salivary amylase starts starch digestion.
• Oesophagus: Peristalsis pushes food towards the stomach.
• Stomach: Gastric juice contains hydrochloric acid, pepsin and mucus. Protein digestion begins here.
• Small intestine: Bile, pancreatic juice and intestinal enzymes complete digestion. Villi absorb nutrients.
• Large intestine: Absorbs water and helps form faeces.
• Rectum and anus: Store and remove undigested waste.
Class 10 Science • Life Processes • Complete Notes • Page 1
, 5. RESPIRATION — HOW CELLS GET ENERGY
Respiration is the process in which food molecules are broken down to release usable energy. The energy is captured
mainly in the form of ATP.
Glucose → Pyruvate: The first breakdown of glucose occurs in the cytoplasm.
Aerobic respiration: In the presence of oxygen, further breakdown occurs and produces carbon dioxide, water and a
larger amount of energy.
Anaerobic respiration: Occurs without oxygen. In yeast, ethanol and carbon dioxide are produced. In muscles during
oxygen shortage, lactic acid may accumulate.
Easy trick: AERO = Air/Oxygen; ANAERO = No oxygen.
6. HUMAN RESPIRATORY SYSTEM
• Nasal passage: Filters, warms and moistens incoming air.
• Trachea: Carries air towards the lungs.
• Bronchi → Bronchioles: Branching air passages inside the lungs.
• Alveoli: Tiny air sacs with a large surface area and rich blood supply; gas exchange occurs here.
• Diaphragm: Muscular sheet that helps change the volume of the chest during breathing.
Inhalation: Diaphragm contracts and moves downward; chest volume increases and air enters. Exhalation: Diaphragm
relaxes; chest volume decreases and air moves out.
Class 10 Science • Life Processes • Complete Notes • Page 2
