Grade 7 Ch 10 Life Processes in Plants



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 by product.

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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