Photosynthesis in Plants

Photosynthesis in Plants for Class 4 Science

Through this concept, the students will learn about photosynthesis in plants. The parts of a leaf diagram are provided in the concept.

After reading the concept, students will be able to:

Get an idea about the parts of a leaf for kids.
Know what is leaf blade.
Understand what is leaf margin.
Identify the leaf apex in various types of leaves.
Know that leaves are the main site of photosynthesis.
Explain the process of photosynthesis.
Understand the mechanism of photosynthesis and the products of photosynthesis.
Get an idea about the chemical reaction of photosynthesis.

Each concept is explained to class 4 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.

Download the worksheets and check your answers with the worksheet solutions for the concept of Photosynthesis in Plants provided in PDF format.

What is Photosynthesis?

Photosynthesis is the process by which green plants produce food inside their body. The process requires sunlight, water, carbon dioxide and chlorophyll. Photosynthesis is essential because without it there will be no existence of green plants, and hence, herbivorous animals too will be deprived of their food.

Site of photosynthesis:

The main site of photosynthesis is the green leaves.
The leaves have a green pigment called chlorophyll that helps in photosynthesis.

Parts of a Leaf:

Before learning about photosynthesis, let us know about the parts of a leaf as it is the place where photosynthesis occurs.

Petiole:
- The petiole is the stalk of the leaf.
- Petioles help in the firm attachment of the leaves to the plant body.
Midrib/Midvein:
- It is the central vein that runs along the middle of a leaf.
- It is involved in the transportation of water and nutrients.
- It also helps the leaf to remain in an upright position.
Leaf Blade:
- Leaf-blade is also called the lamina.
- It is the green, expanded and flattened part of the leaf.
- It is the photosynthetic part of a leaf.
Secondary/Lateral Veins:
- Secondary veins arise from the midrib or midvein and run laterally through the lamina.
- These also help in the transportation of water and nutrients.
Leaf Margin:
- It is the boundary area following the edge of the leaf.
- The leaf margin could be serrated or smooth.
Leaf Apex:
- The pointed tip of the leaf is called the leaf apex.

Process of Photosynthesis:

It is the process by which green plants transform environmental carbon dioxide and water into glucose and oxygen in the presence of sunlight.
The leaf blades are arranged so that they can absorb sufficient sunlight throughout the day.

Steps Involved in Photosynthesis:

Water is absorbed by the roots. It passes through the stem and finally reaches the leaves.

Carbon dioxide from the air passes through small pores in the leaves called stomata.

Chlorophyll, a green pigment in the leaves, absorbs the sun’s energy.

This energy then splits water into hydrogen and oxygen, and this process is called the photolysis of water.

Oxygen formed is released into the surrounding. Hydrogen combines with carbon dioxide to form glucose, which is the chief food of plants.

New Words

Serrated: Having a jagged and rough edge. The image shows a serrated leaf margin.

Glucose: It is a special type of substance made of carbon, hydrogen and oxygen. Green plants synthesize glucose as it is the primary source of energy in them. Plants do not utilize all the glucose they make; rather, they store some of it for future use. All living beings require glucose. So, animals meet their glucose need by eating plants or other foods containing glucose.

Stomata: These are tiny pores or holes present on the lamina of a leaf and help exchange gases and water with the surroundings.

Did You Know?

During the daytime, in the presence of sunlight, plants take in carbon dioxide gas and release oxygen gas as the end product of photosynthesis. However, at night, the opposite happens. Plants take in oxygen gas and give out carbon dioxide gas in the environment by the process of respiration.

Respiration is the reverse process of photosynthesis.
Not only plants but certain bacteria and algae too can produce their food as they contain chlorophyll.