PHOTOSYNTHESIS The purpose of photosynthesis is to convert light energy into chemical energy.

DRAW THIS DIAGRAM, LEAVING ROOM FOR EQUATION

PHOTOSYNTHESIS BALANCED EQUATION 6 CO2 + 6 H20 C6H12O6 + 6 O2 enzymes light energy Waste product ENTERS THROUGH STOMA IN THROUGH ROOTS SUGAR = CHEMICAL ENERGY

PHOTOSYNTHESIS OCCURS IN 2 STAGES

STEP ONE: The Light Reactions Light energy is absorbed by chlorophyll and then used to make ATP ATP is used to split water (photolysis) H2O H AND O To break apart light Used to make sugar Released as a waste product

Step Two: The Calvin Cycle (AKA: “The Dark Reactions”) CO2 and H combine to form simple sugars From water, which was split during the light reactions Enters through leaves

Chloroplast! Grana –(Stacks of thylakoid membranes. Site of light reactions) Stroma (NOT STOMA!) – Site of Calvin Cycle

Leaf Cross-Section Waxy layer(cutin):prevents water loss Epidermis: Protection Palisade Layer- Tightly packed photosynthetic cells Veins:Xylem(top) transports water, phloem (botton) food Spongy Layer – Loosely arranged photosynthetic cells Stoma – Opening for gas exchange Guard Cells: Control opening/closing of stoma

Guard cells

Visible spectrum: Portion of electromagnetic spectrum that we can see. Least Energetic (longest wavelength) Most energetic (shortest wavelength)

Why do objects appear colored? The color that you see is being reflected, all other colors are being absorbed. White: Reflects all colors Black: Absorbs all colors

Pigments give plants their specific color. Function: Absorb maximum amount of light energy while at the same time protecting plant from too much energy. Examples: Chlorophyll: Reflects green. Chlorophyll is the dominant photosynthetic pigment. Carotenoids : Reflect orange, like carrots Xanthophylls : Reflects yellow

Why do leaves change color in the fall?

Length of day decreases Less light = less energy = less photosynthesis Chlorophyll, being used less and begins to break down Other accessory pigments become visible

If a plant appears green, how do we know that other pigments are present?

CHROMATOGRAPHY! A process that separates all of the pigments present in a solution.