Plant Nutrition

6.1 Photosynthesis

• Equation:
  • Word: $\text{Carbon dioxide + Water}\to \text{Glucose + Oxygen}$
  • Chemical: $6{\text{CO}}_2+6{\text{H}}_2\text{O}\to {\text{C}}_6{\text{H}}_{12}{\text{O}}_6+6{\text{O}}_2$
• Definition: Photosynthesis is the process by which plants convert light energy into chemical energy in the form of glucose.
• Occurs in: Chloroplasts (containing chlorophyll).
• Required: Light, water, carbon dioxide.

6.2 Adaptations of Leaves for Photosynthesis

Adaptation	Function
Large surface area	Absorbs more light.
Thin	Short diffusion distance for gases.
Chloroplasts	Contain chlorophyll for light absorption.
Stomata	Gas exchange (CO₂ in, O₂ out).

6.3 Factors Affecting Photosynthesis

• Light Intensity: More light increases photosynthesis up to a point.
• Carbon Dioxide: More CO₂ increases photosynthesis.
• Temperature: Optimum temperature around 25–35°C.
• Water: Required for photosynthesis and transport of nutrients.

6.4 Testing for Photosynthesis

• Test for Starch: Iodine solution → Blue-black color.
• Control Experiment: No light → No starch produced.
• Importance of CO₂: Remove CO₂ → No starch produced.