This document discusses photosynthesis and the process by which plants convert light energy to chemical energy. It explains that chloroplasts in plant cells contain chlorophyll, which absorbs light for photosynthesis. Different pigments like chlorophyll a, chlorophyll b, and carotenoids absorb different wavelengths of light and reflect different colors, which determines the color we see in leaves. In fall, leaves change color as chlorophyll production decreases and carotenoid pigments become visible.

1. Objective: Photosynthesis 11/07/06 Procedure: Site of Photosynthesis Light Energy Chromatography Demo General Homework: Read 8.1 and answer CC questions Honors Homework: Read 7.1, 7.2, & 7.6 and answer CC questions

2. stomata veins Stomata – gas exchange (take in CO 2 , take in and release O 2 ) Veins – carry water and nutrients throughout the plant

3. Chloroplasts

4. Site of Photosynthesis

5. Photosynthesis Photosynthetic organisms transform light energy into chemical energy (glucose) Pigment molecules absorb the light energy Photosynthetic pigment molecules are found in chlorophyll Chlorophyll is stored in the thylakoids of the chloroplasts

6. Light energy contains photons which are particles that have a fixed amount of energy This energy travels in waves The electromagnetic spectrum

7. Visible Light The pigments in our eyes cannot absorb all the wavelengths

8. When light meets matter, it may be Reflected – bounced back OR Transmitted – passed though OR Absorbed The light that is reflected or transmitted determines what color you see When light is absorbed, the energy in light is transferred to the atoms in the molecules of the object absorbing it

10. In order to maximize energy absorption , different pigment molecules are used: 1. Chlorophyll a – reflect green, primary pigment 2. Chlorphyll b – reflect green (some yellow), accessory pigment 3. Carotenoids – reflect red, yellow and orange, accessory pigment (ex. Beta carotene – orange) The reflected green color of the primary pigment, chlorophyll a, masks the accessory pigment colors This is why leaves look green! The light-absorbing pigment molecules found in chlorophyll are only able to absorb light within a narrow range of wavelengths

11. Why do leaves change color in the fall? When days get shorter (less light) and there is less precipitation, plants go into dormant stage Chlorophyll a & b is no longer produced Carotenoid pigment molecules begin to show through and determine color