Pg:- 84,85

Ch:- 6

Photosynthesis is the process by which green plants, algae, and some bacteria make their own food using sunlight.

What is Photosynthesis:

• Plants take in carbon dioxide (CO₂) from the air through tiny pores on their leaves called stomata. They absorb water (H₂O) from the soil through their roots. Using sunlight as an energy source, they convert CO₂ and H₂O into glucose (a type of sugar) and oxygen (O₂).This reaction happens in the chloroplasts, which contain a green pigment called chlorophyll. Chlorophyll captures sunlight.

The Chemical Equation:

• The overall reaction can be summarized as:

  6CO2 + 6H2O → C6H12O6 + 6O2​

  • Reactants: Carbon dioxide and water

  • Products: Glucose and oxygen

Steps of Photosynthesis:

• Photosynthesis occurs in two main stages:

  • Light-dependent reactions: These take place in the chloroplasts when sunlight is available. Sunlight splits water into oxygen and energy molecules (ATP and NADPH).

  • Light-independent reactions (Calvin Cycle): These use the energy molecules from the first step to convert carbon dioxide into glucose. This happens even in the absence of light.

  
  

  Importance:

  • It provides oxygen, which is essential for the survival of most living organisms.

  • It creates glucose, which plants use for energy and growth. This energy is transferred to other organisms when they eat plants.