1. Biology – Exploring Life - Chapter 8
Energy from Sunlight
Biology – Exploring Life - Chapter 8

2. The Carbon Cycle

3. Human CO2 emissions
Photosynthesis Overview
A different kind of fuel

4. As in cellular respiration, the chemical equation for photosynthesis summarizes several reaction steps

5. Overall equation for
photosynthesis
CHLOROPLAST

8. The two main stages of photosynthesis are: the light reactions, which occur in the thylakoids, and the Calvin cycle (light independent reactions), which occurs in the stroma

9. Different forms of electromagnetic energy have different wavelengths
Different forms of electromagnetic energy have different wavelengths. Shorter wavelengths have more energy than longer wavelengths

10. Absorbed light
A substance’s color is due to chemical compounds called pigments

11. Types of pigments in plants
Chlorophyll a: Absorbs mainly blue-violet and red light and reflects mainly green light
Chlorophyll b: Absorbs mainly blue and orange light and reflects yellow-green
Carotenoids: Absorb mainly blue-green light and reflect yellow-orange.

12. Harvesting Light Energy - Photosystems

13. Photosystem model Chlorophyll 1 Chlorophyll 2
Chlorophyll 3 (Reaction-center Chlorophyll)
Primary Electron Acceptor
Water Molecule
Light source

15. The light energy boosts the electrons up to their excited states

16. The Calvin Cycle

17. By converting light energy to chemical energy, photosynthesis is the first step in the flow of energy through an ecosystem.

18. Photosynthesis Table Stages Location INPUT OUTPUT Light Reactions
Calvin Cycle

19. Photosynthesis Table CO2 Stages Location INPUT OUTPUT Light Reactions
THYLACOIDS
LIGTH
H2O
ATP
NADPH
Calvin Cycle
STROMA
CO2
SUGAR
NADP+
ADP + P

20. Snail & elodea Investigation
Bromylthymol blue is blue in the absence of CO2 and is yellow to clear when CO2 is present.
Do snails give off CO2?
Do snails give off CO2 in the dark?
Does elodea give off CO2?
Does elodea give off CO2 in the dark?

21. ELODEA, SNAILS, & CO2
DARK
LIGHT

22. Analysis questions
How do snails affect the level of CO2 in the test tubes?
How does Elodea affect the level of CO2 in the test tubes?
What is the purpose of test tube #4?
Which of the test tubes is an example of a balance system? Why?
How do you explain the difference in color (if any) between the test tubes kept under the light, and the ones in the dark? (Compare #1in the light with #1in the dark, and so on)

23. Hypothesis: What color do you think the tube will be after 24 hours?
IN THE LIGHT
IN THE DARK
Tube contents
Hypothesis: What color do you think the tube will be after 24 hours?
Observations: Actual color of tube after 24 hours.
1. ELODEA+
SNAILS
2. SNAILS
3. ELODEA
4. NOTHING