Life Processes in Plants

Key Concepts

How Do Plants Grow?

Plants require several essential factors for their growth and development:

• Water: Absorbed from the soil by roots.
• Sunlight: Captured by the leaves.
• Air (Carbon Dioxide): Taken from the atmosphere.
• Minerals: Important nutrients present in the soil.

Photosynthesis: Preparing Food

Unlike animals, plants do not eat food; they produce it.

• Chlorophyll: A green pigment in leaves that captures solar energy.
• Stomata: Tiny pores on the lower surface of leaves that help in the exchange of gases (CO2 in, O2 out).
• The Process: Plants use water and carbon dioxide in the presence of sunlight and chlorophyll to produce glucose (a simple carbohydrate) and oxygen.
• Equation: Carbon dioxide + Water --(Sunlight/Chlorophyll)→ Glucose + Oxygen.
• Starch: The produced glucose is converted into starch for storage in different parts of the plant (roots, stems, fruits).
• Leaves as 'Food Factories': Because most food preparation happens in leaves, they are known as the food factories of the plant.

Transport in Plants

Plants have a specialized transport system (vascular tissue) to move substances:

1. Xylem: A tube-like structure that transports water and minerals from the roots to the leaves and other parts.
2. Phloem: Transports the prepared food from the leaves to all parts of the plant for usage and storage.

Respiration in Plants

Like all living beings, plants also respire to release energy from the food they produce.

• The Process: Glucose is broken down in the presence of oxygen to release energy, carbon dioxide, and water.
• Equation: Glucose + Oxygen → Carbon dioxide + Water + Energy.
• Occurrence: Respiration occurs in all parts of the plant (green and non-green) and continues both day and night.
• Balance: During the day, the CO2 produced in respiration is utilized in photosynthesis, and O2 produced in photosynthesis is used for respiration.

Ancient and Modern Knowledge

• Vrikshayurveda: An ancient Indian text that records observations about plant health, soil, and organic manures.
• Kamala Sohonie: A pioneering Indian scientist known for her work on plant respiration and nutritive values of foods.