Photosynthesis is the process by which green plants, algae, and some bacteria prepare their own food using sunlight, carbon dioxide, and water. This process takes place mainly in the leaves, inside specialized cell structures called chloroplasts that contain the green pigment chlorophyll.
Photosynthesis is one of the most important biological processes on Earth because it produces food for plants and releases oxygen into the atmosphere.
What is the Equation of Photosynthesis?
The chemical equation of photosynthesis represents how plants convert carbon dioxide and water into glucose and oxygen in the presence of sunlight and chlorophyll.
Balanced Chemical Equation
Word Equation
Carbon Dioxide + Water → Glucose + Oxygen (in the presence of sunlight and chlorophyll)
Understanding Each Component of the Equation
Component
Formula
Role in Photosynthesis
Carbon Dioxide
CO₂
Taken from air through stomata
Water
H₂O
Absorbed by roots from soil
Sunlight
—
Provides energy for the process
Chlorophyll
—
Green pigment that traps sunlight
Glucose
C₆H₁₂O₆
Food produced by plants
Oxygen
O₂
Released into the atmosphere
How Does Photosynthesis Occur?
Photosynthesis occurs in the following steps:
Step 1: Absorption of Sunlight
Chlorophyll present in leaves absorbs solar energy.
This energy is required to drive the photosynthesis process.
Step 2: Absorption of Water
Roots absorb water from the soil.
Water is transported to leaves through xylem vessels.
Step 3: Intake of Carbon Dioxide
Carbon dioxide enters leaves through tiny pores called stomata.
Step 4: Formation of Glucose
Using solar energy, plants convert carbon dioxide and water into glucose.
Step 5: Release of Oxygen
Oxygen is produced as a by-product.
It is released into the atmosphere through stomata.
Why is the Equation Balanced?
The equation is balanced because the number of atoms of each element is equal on both sides.
Atom Count
Element
Reactants Side
Products Side
Carbon (C)
6
6
Hydrogen (H)
12
12
Oxygen (O)
18
18
Thus, the equation follows the law of conservation of mass.
Importance of Photosynthesis
1. Produces Food
Plants make glucose, which serves as their food.
2. Releases Oxygen
Photosynthesis supplies oxygen needed by living organisms.
3. Maintains Atmospheric Balance
It helps maintain the balance between oxygen and carbon dioxide.
4. Supports Food Chains
Plants are producers and form the base of most food chains.
5. Stores Solar Energy
Sunlight energy is stored as chemical energy in glucose.
Role of Chlorophyll in Photosynthesis
Chlorophyll is a green pigment found in chloroplasts.
Functions of Chlorophyll
Absorbs sunlight.
Converts light energy into chemical energy.
Enables food synthesis in plants.
Gives green color to leaves.
Without chlorophyll, photosynthesis cannot occur efficiently.
Conditions Necessary for Photosynthesis
Requirement
Importance
Sunlight
Source of energy
Chlorophyll
Traps solar energy
Water
Raw material
Carbon Dioxide
Raw material
Healthy Leaf Cells
Site of photosynthesis
NCERT-Based Key Points
Photosynthesis is the process of food preparation in green plants.
Chlorophyll is essential for capturing sunlight.
Carbon dioxide enters through stomata.
Water is absorbed by roots.
Glucose is the main food produced.
Oxygen is released as a by-product.
Photosynthesis occurs mainly in leaves.
Chloroplasts are the sites of photosynthesis.
Photosynthesis helps maintain atmospheric oxygen.
Flow of Photosynthesis
Sunlight
↓
Chlorophyll absorbs light
↓
Water + Carbon Dioxide
↓
Chemical Reactions
↓
Glucose Formation
↓
Oxygen Release
Real-Life Importance of Photosynthesis
Area
Contribution
Human Life
Provides oxygen
Agriculture
Increases crop production
Environment
Reduces atmospheric CO₂
Ecosystem
Supports food webs
Energy Cycle
Stores solar energy in plants
Summary
Photosynthesis is the process by which green plants prepare food using carbon dioxide and water in the presence of sunlight and chlorophyll. The process produces glucose as food and releases oxygen into the atmosphere. The balanced equation of photosynthesis is:
6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2
This process is essential for life because it provides food, oxygen, and energy for almost all living organisms.
Practice Questions
Very Short Answer Questions
1. What is photosynthesis?
Answer: Photosynthesis is the process by which green plants make food using sunlight, carbon dioxide, and water.
2. Which pigment absorbs sunlight?
Answer: Chlorophyll.
3. What gas is released during photosynthesis?
Answer: Oxygen.
4. What is the food produced during photosynthesis?
Answer: Glucose.
5. Through which pores does carbon dioxide enter leaves?
Answer: Stomata.
Short Answer Questions
1. Write the word equation of photosynthesis.
Answer: Carbon Dioxide + Water → Glucose + Oxygen (in the presence of sunlight and chlorophyll)
2. Why is photosynthesis important?
Answer: Photosynthesis provides food, releases oxygen, and maintains the balance of gases in the atmosphere.
3. What are the raw materials for photosynthesis?
Answer: Carbon dioxide and water.
4. What is the role of chlorophyll?
Answer: Chlorophyll absorbs sunlight and helps convert light energy into chemical energy.
5. Where does photosynthesis occur?
Answer: Photosynthesis occurs in the chloroplasts of green plant cells, mainly in leaves.
Fill in the Blanks
Photosynthesis takes place mainly in the __________. Answer: leaves
The green pigment in plants is called __________. Answer: chlorophyll
Plants absorb __________ from the soil. Answer: water
Carbon dioxide enters leaves through __________. Answer: stomata
__________ is released during photosynthesis. Answer: Oxygen
Glucose is the __________ prepared by plants. Answer: food
