Objective: Objective:

PhotosynthesisPhotosynthesis11/07/0611/07/06

Procedure:Procedure:Site of PhotosynthesisSite of PhotosynthesisLight EnergyLight EnergyChromatography DemoChromatography Demo

General Homework: Read 8.1 and answer CC questionsGeneral Homework: Read 8.1 and answer CC questionsHonors Homework: Read 7.1, 7.2, & 7.6 and answer CC questionsHonors Homework: Read 7.1, 7.2, & 7.6 and answer CC questions

stomata

veins

Stomata – gas exchange (take in CO2, take in and release O2)

Veins – carry water and nutrients throughout the plant

Chloroplasts

Site of Photosynthesis

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

Light energy contains photons which are particles that have a fixed amount of energy

This energy travels in waves

The electromagnetic spectrum

Visible LightThe pigments in our eyes cannotabsorb all the wavelengths

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

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

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