1. Photosynthesis
Biology B

2. Overview 1. SUN 2. LIGHT ENERGY 3. PHOTOSYNTHESIS 5. RESPIRATION
6. ATP
(CELL ENERGY)
4. CHEMICAL ENERGY

3. Energy Formation in Cells
Organic Compounds & Oxygen
ATP
Energy for Life
Carbon Dioxide & Water
ADP and P

4. What is Photosynthesis?
The process of photosynthesis is where organisms convert light energy into chemical energy to create products such as carbohydrates, sugars, and starches.

5. Where does it occur?
In plants that are able to capture sunlight to make their own food (aka autotrophs.)
The actual process occurs inside a cell’s chloroplasts.

6. What does it need?
CARBON DIOXIDE (CO2)
WATER  (H20)
SUNLIGHT

7. What happens? (photosynthesis equation)
Water
Carbohydrates
6CO2 +
6H2O +
ENERGY
C6H12O6 +
6O2
Sunlight
Carbon Dioxide
Oxygen

8. How does it happen?
The process of photosynthesis does not happen all at once. It is a very long process that is broken into 3 stages.

9. Stage 1 – Light Reactions
Light is absorbed from the sun by the chloroplasts.
H2O is taken into the cell as well.
The light energy is used to split H20 into 3 separate parts (H, O2, and electrons.)

10. How does it work?
Inside the chloroplasts are disk-shaped structures called thylakoids that contain different pigments.

11. How does it work? Pigments do the actual absorbing of light.
a) Chlorophylls absorb red and blue light
(produce green colors)
b) Carotenoids absorb other colors
(produce yellow and orange colors)

13. How does it work?
Once the sunlight is captured it is used to split water (H20) into Hydrogen (H), Oxygen gas (O2), and free electrons.
Oxygen gas (O2) is free to leave the plant and this is what animals use to breathe.

14. Stage 2 – Energy Storage
Free electrons are passed from thylakoid to thylakoid until they reach an ADP molecule and turn it into an ATP.
Hydrogen (H) molecules are passed from protein to protein until they reach a NADP+ molecule and then they become an NADPH.

15. How does it work?
As electrons continuously get passed on this process is known as the electron transport chain.

16. Stage 3 – Dark Reactions
The newly formed ATP and NADPH power the formation of carbohydrates, sugars, and starches.
This is done by using CO2 as the starting material.

17. How does it work?
Carbon Dioxide (CO2) enters the cell from the atmosphere and undergoes a process called the Calvin Cycle which creates simple sugars.

18. Summary of Stages Things used: Things made: Stage 1 Light and H2O
O2, H, and electrons
Stage 2
H and electrons
ATP and NADPH
Stage 3
ATP, NADPH, and CO2
Carbohydrates, sugars, starches

19. Factors that affect it? Light intensity Amount of CO2 available
Temperature
If any of these factors increase the photosynthesis process also increases and vice versa.

20. Photosynthesis H2O C6H12O6 CO2 + O2 + Calvin Cycle ATP ADP Energy
Which splits
water
Calvin Cycle
Light is Adsorbed By
Chlorophyll
ADP
Chloroplast
C6H12O6 O2 +
Light Reaction
Dark Reaction

21. * Light Independent Reactions
Photosynthesis
Capturing Energy from the Sun*
Using energy to make ATP and NADPH*
Using ATP and NADPH to make carbohydrates, sugars, and starches *
* Light Dependent Reactions
* Light Independent Reactions
(Calvin Cycle)

22. Any Questions? Education is light, lack of it darkness.
--Russian Proverb
Education is the movement from darkness to light. --Bloom