Photosynthesis Lecture Notes

Overview

• Photosynthesis is a critical process for life on Earth, providing food and energy.
• It's more complicated than the basic explanation here; advanced studies like botany cover this in more depth.
• Photosynthesis converts carbon dioxide and water into glucose and oxygen using sunlight.

Definition & Chemical Equation

• Photosynthesis produces carbohydrates (glucose) and releases oxygen as a by-product.
• Chemical Equation:
  • Reactants: Carbon dioxide (CO2) + Water (H2O) + Sunlight
  • Products: Glucose (C6H12O6) + Oxygen (O2)

Components Involved

• Chlorophyll: Pigment in green plants essential for photosynthesis.
• Chloroplast: Organelle where photosynthesis takes place.
  • Structure includes double membrane, stroma, and thylakoids (grana).
  • Contains ribosomes, mitochondria, and starch granules.

Phases of Photosynthesis

1. Light Phase (Light-dependent):

   • Occurs in the grana of chloroplasts.
   • Chlorophyll absorbs sunlight, converting it into chemical energy.
   • Photolysis: Splits water into hydrogen and oxygen.
   • Formation of ATP (Adenosine Triphosphate), an energy carrier.

2. Dark Phase (Light-independent/Calvin Cycle):

   • Occurs in the stroma of chloroplasts.
   • Uses ATP and NADPH from light phase to convert CO2 and hydrogen into glucose.
   • Glucose stored as starch, ADP and NADP return to light phase for reuse.

Importance of Photosynthesis

• Maintains oxygen and carbon dioxide levels in the atmosphere.
• Provides food for heterotrophic organisms.
• Enables energy transfer for cellular functions.

Factors Influencing Photosynthesis

1. Light Intensity:

   • Increased light increases photosynthesis to an optimal point.
   • Too much light causes stomata to close, limiting CO2 intake.

2. Temperature:

   • Optimal temperature for photosynthesis is 25°C.
   • Too high/low temperatures can denature enzymes or make them inactive.

3. Carbon Dioxide Concentration:

   • Increased CO2 increases the rate of photosynthesis.
   • Excess leads to a plateau in photosynthesis efficiency.

Greenhouses & Photosynthesis

• Greenhouses regulate light, temperature, and CO2 for optimal plant growth.
• Transparent to allow maximum light.
• Temperature controlled through ventilation and sometimes heating/cooling systems.
• CO2 regulated via tanks or organic decomposition.

Conclusion

• Photosynthesis is a complex but essential process for the sustenance of life.
• Understanding the basic structure and phases helps in grasping its importance.

Note: Detailed experiments related to photosynthesis can be found in specific textbooks for further study.