Photosynthesis For Grade 7: Simplifying How Plants Prepare Their Food

Photosynthesis is something that happens around us every day, even though we often do not notice it. It is the natural process by which green plants make their own food using sunlight, water, and carbon dioxide from the air. 

In this article, we explain what photosynthesis is, how it works inside plants, and why it is so important for humans, animals, and the environment.

Table of Contents 

• What is Photosynthesis
• Conditions Essential for Photosynthesis

What is Photosynthesis?

The process by which autotrophs, such as green plants, make their food using carbon dioxide and water in the presence of sunlight and chlorophyll is called photosynthesis (photo means light and synthesis means to put together).

The term ‘photosynthesis’ was coined by the American botanist Charles Reid Barnes in 1893.

Plants are green due to the presence of a green pigment called chlorophyll that traps sunlight needed for photosynthesis.

During the process of photosynthesis, carbon dioxide and water combine to form glucose, and oxygen is released as a by-product. Glucose is formed during this process and is stored in the form of starch. It is transported in the form of sucrose.

During this process, solar energy is converted into chemical energy. The exchange of gases (carbon dioxide and oxygen) takes place through small pores called stomata (singular stoma)that are present on the leaves.

The water enters the plant from the roots. It is then transported to the leaves with the help of vascular tissue called xylem. The food prepared in the leaves is transported to various parts of plant via phloem (vascular tissue).

Conditions Essential for Photosynthesis

The following are the general conditions necessary for photosynthesis:

1. Presence of chlorophyll.
2. Presence of light.
3. Availability of carbon dioxide.
4. Availability of water.

Let's look into each in detail.

1. Presence of chlorophyll

The cells in green leaves and young stem contain tiny structures called chloroplasts. 

Chloroplasts are the cell organelles that contain green-coloured pigment called chlorophyll. Whereas, chlorophyll present in the grana (singular granum) absorbs solar energy

2. Presence of light

As the intensity of light increases, the rate of photosynthesis also increases. The chlorophyll present in the grana of the chloroplasts absorbs light and helps in the completion of photosynthesis.

3. Availability of carbon dioxide

Availability of carbon dioxide is crucial for photosynthesis. The rate of photosynthesis decreases if the level of carbon dioxide is less in the atmosphere.

Green plants obtain carbon dioxide from the atmosphere through stomata. Each stoma has the ability to open and close which is controlled by the guard cells surrounding it. When stoma opens, air enters the leaves.

4. Availability of water

The rate of photosynthesis decreases if less water is available. Water and minerals are absorbed by the roots and carried to all the parts of the plant with the help of thin tube-like structures called xylem.

Till now, we have learned that photosynthesis is the essential process by which green plants prepare their own food using sunlight, water, and carbon dioxide with the help of chlorophyll present in the chloroplasts. We also understood the conditions required for this process and how it supports plant growth and survival.