Life Processes in Plants
1. Plant Growth
- Plants grow by developing new leaves, branches, increasing height, and thickening stems.
Essential Factors:
- Water: Absorbed by roots from soil, keeps plants hydrated.
- Sunlight: Provides energy for growth.
- Nutrients: Minerals from soil support growth.
2. Photosynthesis
- Definition: The process by which plants produce food (glucose) using sunlight.
Requirements:
- Sunlight: Provides energy to drive the process.
- Chlorophyll: Green pigment in leaves that captures sunlight.
- Carbon dioxide (CO₂): Taken from the air through stomata.
- Water: Absorbed by roots from soil.
Products:
- Glucose: Used for energy or stored as starch.
- Oxygen: Released into the air as a byproduct.
Word Equation:
Carbon dioxide + Water → (Sunlight + Chlorophyll) → Glucose + Oxygen
- Main Site: Leaves, known as “food factories,” but other green parts with chlorophyll (e.g., stems) can also perform photosynthesis.
- Importance: Produces food for plants and oxygen for the environment.
3. Role of Leaves in Food Production
- Leaves: Broad, flat structures designed to capture sunlight efficiently.
- Chlorophyll: Green pigment in leaves essential for photosynthesis.
- Starch Storage: Leaves store glucose as starch.
4. Gas Exchange
- Stomata: Tiny pores on the surface of leaves (mostly lower surface).
Function:
- Allow carbon dioxide to enter for photosynthesis.
- Release oxygen produced during photosynthesis.
- Also involved in respiration (exchange of CO₂ and O₂).
5. Transport in Plants
Xylem:
- Tube-like structures in stems, branches, and leaves.
- Transports water and minerals from roots to other parts.
Phloem:
- Tube-like structures that transport food (glucose/starch) from leaves to other parts (e.g., roots, seeds, fruits).
- Food can be stored in roots, seeds, or other parts.
Importance: Ensures all plant parts receive water, minerals, and food for growth and survival.
6. Respiration
- Definition: Process where plants break down glucose to release energy for growth and other functions.
Requirements:
- Glucose: Produced during photosynthesis.
- Oxygen: Taken from the air.
Products:
- Carbon dioxide: Released as a byproduct.
- Water: Released in small amounts.
- Energy: Used for plant growth and activities.
Word Equation:
Glucose + Oxygen → Carbon dioxide + Water + Energy
- Occurrence: Happens in all plant parts (green and non-green), day and night.
7. Importance of Plant Processes
- Photosynthesis: Produces food for plants and oxygen for all living beings, maintaining environmental balance.
- Respiration: Provides energy for plant growth and survival.
- Transport: Ensures water, minerals, and food reach all plant parts.
- Gas Exchange: Supports photosynthesis and respiration through stomata.
- Balance in Nature: Photosynthesis and respiration maintain CO₂ and O₂ levels in the atmosphere.
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