Plant Growth and Photosynthesis

Photosynthesis Overview

• Location: Occurs in the leaves, specifically in chloroplasts.
• Pigment: Chlorophyll absorbs light energy (packets of energy).
• Process: Converts carbon dioxide (CO2) and water (H2O) into glucose (C6H12O6) and oxygen (O2).
• Chemical Equation:
  • 6CO2 + 6H2O + light energy → C6H12O6 + 6O2
  • The process requires light (endothermic reaction).

Energy Transfer

• Endothermic Reaction: Energy is transferred from the environment to chloroplasts by light.
• Sources of Reactants:
  • Carbon Dioxide: Diffuses into leaves through stomata.
  • Water: Taken up from soil by roots, transported via xylem.

Importance of Glucose

• Primary Product: Plants primarily require glucose.
• Oxygen: Generally abundant in the air, less critical for plants.

Uses of Glucose

1. Cellular Respiration:
   • Breaks glucose to release energy, similar to a battery.
   • Photosynthesis stores light energy in glucose; respiration releases it.
2. Making Cellulose:
   • Glucose forms cellulose, a complex carbohydrate for cell wall strength.
3. Making Starch:
   • Glucose forms starch for long-term energy storage.
   • Characteristics:
     • Compact, fits more in cells.
     • Insoluble, prevents osmotic water uptake.
4. Making Amino Acids:
   • Combines glucose with nitrate ions from soil.
   • Forms proteins from amino acids.
5. Making Oils and Fats:
   • Stored for future energy use, especially in seeds.

Factors Affecting Photosynthesis Rate

• Key Factors:
  • Light intensity
  • Temperature
  • Carbon dioxide concentration
  • Chlorophyll amount

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