Life Processes in Plants
Class 07 Scienceplants require both sunlight and water for their growth.
Animals get their food from plants, either directly by eating plants or indirectly by eating animals that in turn eat plants for their nutrition and growth.
Photosynthesis
Plants store food in the form of starch, a type of carbohydrate. This starch is produced in the leaves of a plant which, by design, are generally broad and flat. These are mostly green because of the presence of a green pigment called chlorophyll, that helps in capturing sunlight efficiently.
The sunlight, water, chlorophyll and carbon dioxide are essential for the synthesis of food in plants. This process by which plants prepare food in the presence of sunlight and chlorophyll is called photosynthesis. A leaf is the primary site for photosynthesis.
During photosynthesis, food is actually produced in the form of glucose, a simple carbohydrate. This glucose not only serves as an instant source of energy but also later gets converted into starch for storage. The word equation of photosynthesis is:
$$ \text{Carbon dioxide} + \text{Water} \xrightarrow[\text{chlorophyll}]{\text{sunlight}} \text{Glucose} + \text{Oxygen} $$
How do leaves exchange gases during photosynthesis?
Photosynthesis requires carbon dioxide, and oxygen is released in the process. Stomata, present on the surface of leaves, help in the exchange of gases.
Transport in Plants
Transport of Water and Minerals
All living beings need water to grow. Plants use water in the process of photosynthesis. Water, along with minerals present in the soil, is taken up by the roots of a plant. Minerals are important nutrients for the growth of plants.
Water and minerals are transported to the leaves and other parts of plants through the xylem (thin tube-like structure). The water transported through the xylem is used to perform various functions.
Transport of Food
Leaves are the primary site for photosynthesis. The food prepared by plants in the leaves is transported to all parts of the plant. This food is transported through another set of thin tube-like structures called the phloem. The transported food may also be stored in some other parts of a plant, such as seeds and roots.
Respiration in Plants
During respiration, glucose is broken down in the presence of oxygen, releasing carbon dioxide, water, and energy. The word equation for the process of respiration is
Glucose + Oxygen → Carbon dioxide + Water + Energy
The energy produced during respiration is used by plants for their growth and development. All parts of a plant, green or non-green, carry out respiration.