What is Photosynthesis? Definition and Formula

Photosynthesis is a fascinating process that green plants perform quietly daily, to prepare the food for themselves while providing us with oxygen to breathe. As green plants grow and soak up the sunlight, they synthesize food through photosynthesis. 

Leaves are like kitchens in plants, preparing food using ingredients like water and carbon dioxide, with sunlight providing the energy. Photosynthesis keeps the air fresh and pure and makes food available for all living organisms. 

Let's explore what happens in photosynthesis and how it supports the existence of living organisms on the planet.

What Do You Mean by Photosynthesis?

Photosynthesis combines two words: "photo" means light, and "synthesis" means putting together. Thus, photosynthesis means "putting together with light." It implies that the presence of light is essential for photosynthesis. It is the process by which green plants use sunlight, combine water and carbon dioxide, and make food as carbohydrates.

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Definition of Photosynthesis

Photosynthesis is making food by plants using sunlight, taking carbon dioxide from the air, and absorbing water from the soil. The green pigment in plants, called chlorophyll, absorbs sunlight to synthesize carbon dioxide and water to produce glucose and oxygen.

The Equation of Photosynthesis

Photosynthesis involves a chemical reaction, and we can describe the process of photosynthesis through a chemical equation. It represents the elements used in this process, such as raw materials and the products generated.

The word equation of photosynthesis can be written as follows:

Carbon dioxide + Water + Light energy → Glucose + Oxygen

This photosynthesis equation shows that carbon dioxide and water react with light energy, producing glucose and oxygen. 

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Photosynthesis Formula

The photosynthesis formula is another way to describe the chemical equation. It provides the scientific representation of the reactants and products involved in this process. 

It clearly explains the process of photosynthesis by showing how carbon dioxide and water combine under the influence of light energy and chlorophyll to produce glucose and oxygen.

The photosynthesis formula is as follows:

6CO2 + 12H2O + Light energy → C6H12O6 + 6O2 + 6H2O

Carbon-dioxide + Water + Light energy → Glucose + Oxygen + Water

Here is an explanation of the photosynthesis formula:

• Six carbon dioxide molecules (CO₂) react with six water molecules (H₂O) in the presence of sunlight and chlorophyll.

• This process produces one glucose molecule (C₆H₁₂O₆) and six oxygen molecules (O₂). 

Read More - Equation: Definition, Types, Examples, Differences

The Raw Materials Used in Photosynthesis

The raw materials used in photosynthesis are carbon dioxide, water, sunlight, and chlorophyll. We will discuss the sources of these raw materials.

Water

Water is absorbed from the soil through the root hairs in plant roots. The water travels up the plant through the tissues called xylem and reaches the leaves, where photosynthesis occurs. Water contributes the hydrogen needed to create glucose and also helps provide necessary nutrients and minerals to plants. 

Carbon Dioxide

Plants absorb carbon dioxide from the air through small openings on the underside of their leaves, known as stomata. The guard cells activate the stoma opening and control the entry of carbon dioxide. Carbon dioxide is the carbon source in the glucose produced in this process.

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Chlorophyll

Chlorophyll is a green pigment present in the chloroplasts of plant leaves. It is the most important component of photosynthesis because it is responsible for absorbing sunlight. The presence of chlorophyll is essential for providing the energy required for the photosynthesis reaction.

Sunlight

Sunlight is the source of energy needed for the photosynthesis reaction to happen. Chlorophyll absorbs mainly sunlight's blue and red components and uses this energy to prepare the food. Through photosynthesis, light energy is converted into chemical energy in the form of glucose.

Explanation of The Process of Photosynthesis

We will explain the process of photosynthesis through a simplified step-by-step manner as follows:

Step 1: Absorption of Light

Green chlorophyll pigments present in the leaves absorb sunlight. This solar energy drives the entire photosynthesis process. 

Step 2: Splitting of Water

Water absorbed by the plant roots travels to the leaves, where water molecules split into hydrogen and oxygen under the influence of light energy. The hydrogen and oxygen are used for glucose production, and the oxygen produced is released as a gas into the atmosphere.

Step 3: Carbon Dioxide Fixation

Leaves take carbon dioxide from the air through stomata. The carbon from carbon dioxide is used along with the hydrogen and oxygen component of water to produce glucose.

Step 4: Formation of Glucose

The final product of photosynthesis is glucose, which the plant uses for growth and energy. Excess glucose is stored as starch in roots, stems, and leaves of plants.

Step 5: Oxygen Release

Oxygen, produced as a by-product in photosynthesis, is released into the atmosphere. This oxygen is vital for animals and humans to survive.

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Stages of Reactions in Photosynthesis

In photosynthesis, the reactions happen in two stages as described below.

Light-dependent Reactions

The initial stage of the process requires sunlight, that’s why it is called the light-dependent reaction. The chlorophyll absorbs energy from the light waves, which is converted into chemical energy during photosynthesis.

Light-Independent Reactions

This process takes place in the leaves and does not require light. So, it is called the light-independent reaction. During this stage, light energy is used to synthesize carbohydrate molecules from carbon dioxide.

Importance of Photosynthesis

Photosynthesis plays a very important role in sustaining life on Earth. The following points explain the importance of photosynthesis:

• Source of Oxygen: Photosynthesis produces the oxygen essential for living organisms' respiration and life's survival.

• Foundation of the Food Chain: Food produced and stored in the plant is the main food source for other living organisms up the food chain.

• Regulation of CO₂: Plants consume carbon dioxide from the air during photosynthesis, which helps reduce carbon dioxide levels in the atmosphere and controls the greenhouse effect of pollution.

• Source of Fossil Fuels: Ancient plants that underwent photosynthesis millions of years ago are rich sources of carbon in the form of fossil fuels like coal and oil.

This article thoroughly explains photosynthesis in plants to produce their food. With CuriousJr online classes for kids from classes 3rd to 9th can explore more interesting science facts in a more engaging and interactive way. Book a demo class for your kids with CuriousJr and see how we handle their curious minds through exciting and enriching learning experiences.