Energy required for the normal functioning of all life processes in plants depends on the food being produced. The process of food production by green plants in their leaves is called photosynthesis.
All living beings require energy to grow and live. This energy is received from the food that we eat. Animals depend on external food sources to meet the daily quota of energy. On the contrary, plants can prepare their own food, and are thus capable of producing their own energy. The process by which plants make their food is known as photosynthesis. The entire process of photosynthesis occurs inside the leaves, and hence leaves are called the powerhouse of plants.
The process by which green plants utilize solar energy to convert carbon dioxide absorbed from the atmosphere and water from the soil into glucose (plant food) in the presence of green-colored pigment (chlorophyll) is known as photosynthesis. Special structures present in the leaves help in the completion of this process. Leaves act as a photosynthetic unit. They are the most adapted and well-suited organs of the plants for photosynthesis because of the following reasons:
Highly specific functional structures that help in the process of photosynthesis are listed below:
Role of guard cells in opening and closing of stomata:
This repeated contraction and relaxation of guard cells is responsible for controlling the opening and closing of stomata. Thus, guard cells help monitor the amount of gaseous exchange occurring in the plant body.
Underlying the epidermis lies special tissues, called the mesophyll tissues. These tissues are usually of two types, palisade and spongy parenchyma. Chloroplasts are special cell organelles found in green plants, within these parenchymatous tissues. These chloroplasts are so named because they contain a special green-colored pigment called chlorophyll, an important pigment needed for photosynthesis.
Structure of chloroplast
This process takes place inside each thylakoid of the chloroplasts. As the name suggests, sunlight plays an important role during this phase. Thus it is sometimes referred to as the photochemical phase. The light-dependent phase takes place over two steps, which are as follows:
Step 1: Activation of chlorophyll The chlorophyll present inside thylakoids gets exposed to sunlight and gets activated.
Step 2: The splitting of water Activated chlorophyll leads to the breakdown of water molecules into its two components, hydrogen, and oxygen. This process of splitting water in the presence of energy is termed as photolysis (photo= light, lysis= breaking) of water. Photolysis of water takes place in the grana of a chloroplast.
Light independent phase or dark phase This reaction is independent of solar energy, occurs simultaneously with light-dependent reactions, and occurs in the stroma of the chloroplast. The main property of this phase is the conversion of produced glucose molecules to starch, which is stored in plant parts. Starch acts as an energy source during emergent conditions.
Importance of leaf
Several internal factors determine the rate of photosynthesis. These are as follows:
1. What is the role of leaves in photosynthesis?
The broad surface area of leaves allows for enhanced absorption of sunlight. Moreover, numerous pores, called stomata, allow easy gaseous exchange. Therefore, leaves act as the primary location for photosynthesis.
2. What are the 3 main functions of a leaf?
3. What is the role of leaf and chloroplast in photosynthesis?
Chloroplasts are special chlorophyll-containing cells present inside a leaf. Green colour pigment chlorophyll is very important for absorbing solar energy and, therefore, in photosynthesis processes.
4. Which part of a plant is primarily responsible for photosynthesis?
Photosynthesis primarily occurs inside a leaf of a plant.
5. Where does photosynthesis take place in a leaf?
Photosynthesis takes place inside the chloroplast of the leaf.
6. What do plants need for photosynthesis?
7. Why are plants green in color?
Green-colored pigment present inside the chloroplast of leaves is responsible for the green coloration of leaves.
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