Long Notes on Photosynthesis
1. Introduction
Photosynthesis is the process by which green plants and some other organisms prepare their own food
using carbon dioxide, water, sunlight, and chlorophyll. The word photosynthesis comes from “photo”
meaning light and “synthesis” meaning putting together or making. Photosynthesis is one of the most
important biological processes on Earth because it provides food and oxygen and forms the foundation of
most food chains.
2. Definition
Photosynthesis is the process in which green plants use light energy to convert carbon dioxide and water
into glucose, releasing oxygen as a by-product.
Overall equation: Carbon dioxide + Water → Glucose + Oxygen
Chemical form: 6CO■ + 6H■O → C■H■■O■ + 6O■
3. Requirements for Photosynthesis
Sunlight: Provides the energy required to drive photosynthesis.
Chlorophyll: The green pigment found mainly in chloroplasts that absorbs light energy.
Carbon dioxide: Obtained from the atmosphere and entering leaves mainly through stomata.
Water: Absorbed from the soil by roots and transported to leaves through xylem.
4. Where Does Photosynthesis Occur?
Photosynthesis mainly occurs in leaves. Leaves are adapted for photosynthesis because they have a
large surface area, many chloroplasts, stomata for gas exchange, veins for transport, and a generally thin
structure.
5. Chloroplast
The chloroplast is the main organelle where photosynthesis occurs in plant cells.
Outer membrane: Forms the outer boundary.
Inner membrane: Helps control movement of substances.
Stroma: Fluid-filled region where the light-independent reactions occur.
Thylakoids: Flattened membrane-bound structures containing chlorophyll and other pigments.
Grana: Stacks of thylakoids.
Stroma lamellae: Connect different grana.
6. Role of Chlorophyll
Chlorophyll captures light energy. Chlorophyll a and chlorophyll b are important forms in plants.
Chlorophyll absorbs particular wavelengths of visible light, especially in the red and blue regions, while
more green light is reflected.
1. Introduction
Photosynthesis is the process by which green plants and some other organisms prepare their own food
using carbon dioxide, water, sunlight, and chlorophyll. The word photosynthesis comes from “photo”
meaning light and “synthesis” meaning putting together or making. Photosynthesis is one of the most
important biological processes on Earth because it provides food and oxygen and forms the foundation of
most food chains.
2. Definition
Photosynthesis is the process in which green plants use light energy to convert carbon dioxide and water
into glucose, releasing oxygen as a by-product.
Overall equation: Carbon dioxide + Water → Glucose + Oxygen
Chemical form: 6CO■ + 6H■O → C■H■■O■ + 6O■
3. Requirements for Photosynthesis
Sunlight: Provides the energy required to drive photosynthesis.
Chlorophyll: The green pigment found mainly in chloroplasts that absorbs light energy.
Carbon dioxide: Obtained from the atmosphere and entering leaves mainly through stomata.
Water: Absorbed from the soil by roots and transported to leaves through xylem.
4. Where Does Photosynthesis Occur?
Photosynthesis mainly occurs in leaves. Leaves are adapted for photosynthesis because they have a
large surface area, many chloroplasts, stomata for gas exchange, veins for transport, and a generally thin
structure.
5. Chloroplast
The chloroplast is the main organelle where photosynthesis occurs in plant cells.
Outer membrane: Forms the outer boundary.
Inner membrane: Helps control movement of substances.
Stroma: Fluid-filled region where the light-independent reactions occur.
Thylakoids: Flattened membrane-bound structures containing chlorophyll and other pigments.
Grana: Stacks of thylakoids.
Stroma lamellae: Connect different grana.
6. Role of Chlorophyll
Chlorophyll captures light energy. Chlorophyll a and chlorophyll b are important forms in plants.
Chlorophyll absorbs particular wavelengths of visible light, especially in the red and blue regions, while
more green light is reflected.
