1. Chapter 8 Miss Colabelli Biology CPA
Photosynthesis
Chapter 8
Miss Colabelli
Biology CPA

2. Obtaining Energy Autotroph: energy (glucose) from sunlight.
6CO2 + 6H2O + sunlight  C6H12O6 + 6O2
Heterotroph: energy from food

3. Why is Photosynthesis important?
Makes organic molecules out of inorganic materials
It begins all food chains & webs
All life is supported by this process
It also makes oxygen gas!
Organic molecules = glucose
Inorganic = CO2 + water

4. Photosynthesis-starts ecological food webs!

5. Photo-synthesis
= "putting together with light."
Plants use sunlight to turn water and carbon dioxide into glucose
Plants use glucose as food
Autotrophs make glucose and heterotrophs are consumers of it

6. Overview of Photosynthesis
Light Reactions
Sunlight is absorbed and converted to chemical energy
Chemical energy is temporarily stored in plants as ATP and NADPH
Calvin Cycle
CO2, ATP, and NADPH make organic compounds
6CO2 + 6H2O C6H12O6 + 6O2

7. Photosynthesis 6CO2 + 6H2O + energy  C6H12O6 + 6O2 sunlight
Carbon dioxide + water glucose + oxygen
absorbed by chlorophyll
6CO2 + 6H2O + energy  C6H12O6 + 6O2
As can be seen from the equation for photosynthesis, the wood, bark, and root came from water and carbon dioxide

8. Plants in Action

9. Capturing Light Energy
During light reactions, the plant’s chloroplasts absorb the sunlight
Chloroplasts have two membranes. In the inner membrane there are flat sacs called thylakoids. Thylakoids that are bunched together are called granum. The stroma is the space between the grana.

10. Elodea
Same plant that we used for transport. The green circular organelles are the chloroplasts!

11. Elodea using photosynthesis What gas do you think is in the bubbles that the plant made?

12. Why are plants green?
The light we see from the sun is white light, but its way more than white!
Colors that we see are reflected from the object

13. Pigment in Plants Why do we see green?
Green color from white light reflected NOT absorbed by the chlorophyll in the chloroplast

14. Visible light is only a small part of the electromagnetic spectrum (all forms of light).

15. Converting Light Energy to Chemical Energy
Absorbing light energy to make chemical energy
Pigments: Absorb different colors of white light (ROY G BIV)
Main pigment: Chlorophyll a
Accessory pigments: Chlorophyll b and Carotenoids
These pigments absorb all wavelengths (light) EXCEPT green!

16. Light Reactions

17. Light Reactions Reactants used Products made
Require sunlight in order to occur
Light reactions take place in two parts
Photosystems I and II
Occurs in the thylakoid of the chloroplasts
Reactants used
Water
Products made O2
NADPH (form of energy used in plants)
Some ATP

18. H2O
Sunlight
Light Reactions O2
ATP
NADPH

19. Making ATP! The thylakoid has its membrane and proteins throughout
Facilitated
Diffusion!!
The thylakoid has its membrane and proteins throughout
H+ ions are higher concentration in the cell
ATP synthase: protein in membrane that transports H+ ions via facilitated diffusion
This process make ATP

21. Calvin Cycle Named after American biochemist Melvin Calvin
Most commonly used pathway by most plants
Calvin cycle is used by plants that are called C3 because of the 3-Carbon molecules that are made

22. Calvin Cycle Light-independent reaction (Dark Reaction)
Does not require light
Occurs in stroma of chloroplast
Reactants used
CO2
Uses ATP and NADPH
Products made
Glucose sugar

23. Calvin Cycle
Uses products from the light reactions + CO2 to make sugars and other compounds
What are the products of the light reactions?
Where does the CO2 come from?

24. O2
ATP
NADPH
Glucose
ATP
Calvin Cycle

25. Overview

26. Stoma This opening how plants exchange gases! Stoma Open Stoma Closed
CO2 can increase
O2 will decrease and leave cells
Stoma Closed
CO2 decrease
O2 increases

27. C4 Pathway
Plants that use this are called C4 plants and have stomata closed during hot part of day
Enzyme fixes CO2 to a 4-carbon compound when CO2 is low and O2 is high
Corn, sugar cane, & crab grass
Usually tropical climates

28. CAM Pathway Water conserving pathway Hot dry climates
Stoma closed during day & open at night
Opposite of ordinary plants
Pineapples & cacti

29. CAM Pathway During the day During the night Stoma are closed
CO2 is released from compounds and enters Calvin cycle
During the night
Stoma are open
Take in CO2 and fix into carbon compounds

30. PHOTOSYNTHESIS What affects photosynthesis?
Light intensity: as light increases, rate of photosynthesis increases until it reaches a certain point

31. PHOTOSYNTHESIS
Carbon Dioxide: As CO2 increases, rate of photosynthesis increases until it reaches a certain point

32. PHOTOSYNTHESIS Temperature:
Temperature Low = Rate of photosynthesis low
Temperature Increases = Rate of photosynthesis increases
If temperature is too hot, rate drops