photosynthesis notes

Photosynthesis Notes

1.  Definition of Photosynthesis:

Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll. It generally involves the green pigment chlorophyll and generates oxygen as a by-product.

2.  Photosynthesis Equation:

6CO2 + 6H2O + light energy -> C6H12O6 + 6O2

3.  Process of Photosynthesis:

a) Light-dependent Reactions:

-  Occur in the thylakoid membranes of the chloroplasts.

-  Require sunlight.

-  Water molecules are split (photolysis), releasing oxygen.

-  ATP and NADPH are produced.

b) Light-independent Reactions (Calvin Cycle):

-  Occur in the stroma of the chloroplasts.

-  Do not require light directly.

-  Use ATP and NADPH to fix carbon dioxide into glucose.

4. Chloroplast Structure:

-  Outer membrane

-  Inner membrane

-  Stroma (fluid-filled space)

-  Thylakoids (flattened sacs containing chlorophyll)

-  Grana (stacks of thylakoids)

5. Factors Affecting Photosynthesis:

-  Light intensity

-  Carbon dioxide concentration

-  Temperature

-  Availability of water

6. Importance of Photosynthesis:

-  Produces oxygen necessary for respiration.

-  Provides the primary source of energy for all living organisms.

-  Basis of the food chain.

-  Removes carbon dioxide from the atmosphere.