1. 5.3 Light-Independent Reactions
Unit 5: Cell Energy
5.3 Light-Independent Reactions

2. Light-Independent Reactions
During light-independent reactions, ATP and NADPH from light- dependent reactions are used to produce high- energy sugars
Also known as the Calvin Cycle

3. Summary No light is required ATP and NADPH are used to make sugars
Take place in the stroma
Carbon dioxide is required

4. Summary Carbon Dioxide enters the cycle Sugar Production
Six CO2 molecules from the atmosphere combine with six 5-carbon molecules
Produces twelve 3-carbon compounds
Sugar Production
Energy from ATP and NADPH are used to convert the 3-carbon molecules
Two of the twelve 3-carbon molecules are removed from the cycle to produce sugars, lipids, amino acids, etc.
Remaining ten 3-carbon molecules are converted back into 5-carbon forms that start the cycle again

5. PGA: Phosphoglyceric acid
RuBP: Rubulose Biphosphate
G3P: Glyceraldehyde-2-phosphate

6. Animation

7. Factors Affecting Photosynthesis

8. Factors that Influence the Rate of Photosynthesis
Many factors influence the rate of photosynthesis. The most important are:
Temperature
Enzymes function best at 0⁰-35⁰ C
An increase or decrease in temperature will slow the reaction

9. Factors that Influence the Rate of Photosynthesis
Light Intensity
High light intensity increases the rate of photosynthesis
At a certain level, the rate reaches its max and levels off

10. Factors that Influence the Rate of Photosynthesis
Availability of Water
Water shortage can stop photosynthesis
Water loss can damage plant tissues
Plants living in dry conditions often have waxy leaves