1. AP Biology Discussion Notes Monday 01/11/2015

2. Goals for the Day 1.Be able to describe the importance of pigments in a plant and the different types of pigments present 2.Be able to describe how/why leaves change color in the fall 3.Be able to describe and interpret an absorption spectrum 4.Be prepared for a photosynthesis lab

3. 1/11 Question of the Day What are the 2 major stages of photosynthesis? Give the reactants & products of each.

4. Light Reactions Light + H 2 O  NADPH + ATP + O 2 Water supplies Electrons and Hydrogen ions that will power chemiosmosis and Phosyphorylation of ADP to ATP.

5. Calvin Cycle CO 2 Carbohydrate Recycles ADP/NADP+ The MIRACLE OF LIFE! Inorganic Organic

6. What is light energy? The electromagnetic spectrum is the entire range of electromagnetic energy, or radiation Visible light consists of wavelengths (including those that drive photosynthesis) that produce colors we can see Light also behaves as though it consists of discrete particles, called photons

7. Figure 10.7 Gamma rays X-rays UV Infrared Micro- waves Radio waves Visible light Shorter wavelength Longer wavelength Lower energy Higher energy 380 450500 550600650 700 750 nm 10  5 nm 10  3 nm 1 nm 10 3 nm 10 6 nm (10 9 nm) 10 3 m 1 m

8. Pigments: The Light Receptors Pigments are substances that absorb visible light – Different pigments absorb different wavelengths – Wavelengths that are not absorbed are reflected or transmitted= reflected wavelengths are what we see Why do leaves appear green? Leaves appear green because chlorophyll reflects and transmits green light

9. Chloroplast Light Reflected light Absorbed light Transmitted light Granum Figure 10.8

10. Absorption Spectrum

11. Pigments Absorption spectrum is a graph plotting a pigment’s light absorption versus wavelength Where does the absorption spectrum of chlorophyll a suggest would work best for photosynthesis? Action spectrum profiles the relative effectiveness of different wavelengths of radiation in driving a process

12. (b) Action spectrum (a) Absorption spectra Chloro- phyll a Chlorophyll b Carotenoids Wavelength of light (nm) Absorption of light by chloroplast pigments Rate of photosynthesis (measured by O 2 release) 400 500600700 400 500600700 RESULTS Figure 10.10

13. Chlorophyll a is the main photosynthetic pigment Accessory pigments, such as chlorophyll b, broaden the spectrum used for photosynthesis Accessory pigments called carotenoids absorb excessive light that would damage chlorophyll Pigments

14. Absorption Spectrum

15. Figure 10.11 Hydrocarbon tail (H atoms not shown) Porphyrin ring CH 3 CH 3 in chlorophyll a CHO in chlorophyll b

17. What would the evolutionary reason be for differences in pigments of photosynthetic Algae? Decreased competition argument – Decreased competition = increased available energy = increased survival & reproduction!

18. How do we find these things out? How do we come to know these thing?

19. Experiments The action spectrum of photosynthesis was first demonstrated in 1883 by Theodor W. Engelmann In his experiment, he exposed different segments of a filamentous alga to different wavelength Areas receiving wavelengths favorable to photosynthesis produced excess O 2 He used the growth of aerobic bacteria clustered along the alga as a measure of O 2 production

20. Engelmann’s Experiment

21. http://www.phschool.com/science/biology_p lace/biocoach/photosynth/action.html

22. (b) Action spectrum (a) Absorption spectra Engelmann’s experiment (c) Chloro- phyll a Chlorophyll b Carotenoids Wavelength of light (nm) Absorption of light by chloroplast pigments Rate of photosynthesis (measured by O 2 release) Aerobic bacteria Filament of alga 400 500600700 400 500600700 400 500600700 RESULTS Figure 10.10

23. Photosynthesis Pre-lab

24. #5 – Factors that you think affect the rate of photosynthesis CO 2 + H 2 O  C 6 H 12 O 6 + O 2

25. Work Order for Today 1.Photosynthesis Pre-lab 2.Photosynthesis Video Guide 3.Pre-reading #5! – Next discussion MONDAY 1/18