1. Photosynthesis

2. Photosynthesis
Photosynthesis is the process of converting light energy from the sun into chemical energy in the form of organic compounds (glucose)
There are two stages of photosynthesis
Light Reactions
Calvin Cycle

3. Obtaining Energy
Autotrophs use energy from sunlight or chemical bonds to make organic compounds such as glucose (photosynthesis and cell respiration)
Heterotrophs must get energy from food (cell respiration)

4. Linking Photosynthesis and Cell Respiration

5. 1st Stage of Photosynthesis: Light Reactions
Light energy is converted to chemical energy
Temporarily stored in ATP and NADPH (energy carrier molecule)
Equation of photosynthesis:
6CO2 + 6H2O + light energy  C6H12O6 (Glucose) + 6O2

6. 1st Stage of Photosynthesis: Light Reactions
The light reactions begin with the absorption of light in the chloroplasts – organelles found in the cells of plants and algae
Pigments found in the thylakoids attract light to begin the process of photosynthesis

7. The Role of Light
The Visible Light Spectrum is an array of colors splitting a beam of white light coming from the sun.
Pigments absorb certain colors of light and reflect/transmit the other colors.
The inner membrane of the thylakoids contain the pigments chlorophyll and carotenoids.
Chlorophyll reflects green-blue light
Carotenoids are accessory pigments reflecting orange, red, and yellow lights

8. 2nd Stage of Photosynthesis: Calvin Cycle
Chemical Energy stored in ATP and NADPH is converted into organic compounds with the use of CO2.
Equation of photosynthesis:
6CO2 + 6H2O + light energy  C6H12O6 (Glucose) + 6O2

9. 2nd Stage of Photosynthesis: Calvin Cycle
The Calvin cycle occurs in the stroma of the chloroplast where chemical energy made in the light reactions (ATP & NADPH) drive the Calvin Cycle
Through carbon fixation, glucose is produced

10. Circle of Life of Cell Energy

11. Different Carbon Fixation Pathways of Plants
Most plants fix carbon through the Calvin Cycle through the C3 Pathway where these plants typically lose water through their open stomata.
Some plants that are evolved in hot, dry climates fix carbon through the C4 pathway where these plants close their stomata at the hottest part of the day.
Other plants go through the CAM pathway where they bring in CO2 at night to store so they can photosynthesize during the day and minimize water loss.

12. Factors that Influence Photosynthesis
Light Intensity
Increase in light = increase in photosynthesis
Carbon Dioxide Levels
Increase in CO2 = increase stimulation of photosynthesis
Temperature
Increase in temperature = increase in photosynthesis
However, too high of heat = closing of stomata = decrease in photosynthesis

13. Factors that Influence Photosynthesis
Water Levels
Increase of water = Increase of photosynthesis
pH Levels
Increase or decrease in pH = decrease of photosynthesis