Photosynthesis Converts light energy into chemical energy What organisms uses photosynthesis? 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2

Why do plants look green? Chlorophyll, found in the chloroplasts of many plant cells. What other pigments are found in plant cells? Red anthocyanins, Yellow xanthophyll Orange carotenoids

Why do plants have chlorophyll? To absorb light wavelengths (energy) to start the photosynthetic process Why do plants have other pigments? They absorb the wavelengths that chlorophyll cannot and pass the energy to chlorophyll.

The Electromagnetic Spectrum

Light is electromagnetic energy The shorter wavelengths of light have more energy than the longer wavelengths. The different pigments absorb different wavelengths

The absorption spectrum of a plant is the combination of all of the absorption spectra of all of its pigments

% of light absorbed Oxygen production Absorption spectrum Action Spectrum The rate of photosynthesis at particular wavelengths is called the action spectrum Correlations?

The photosynthetic process produces sugar molecules. It requires energy to make the covalent bonds of the glucose. (glucose)

Where does this energy come from?

Photosynthesis occurs in two stages: 1. A set of reactions “traps light” energy and converts it to chemical energy (ATP) 2. A set of reaction, then bonds CO2 to H2O to make glucose

1. The first stage of photosynthesis: Also called the light dependent reactions Chlorophyll (and other pigments) absorb light. Light energy splits water into oxygen and hydrogen (photolysis) Light energy makes ATP

Oxygen is released as a waste product ATP and Hydrogen move to the second stage of photosynthesis: /08/guest-blog-bre...

2. The second stage of photosynthesis also called the light-independent reactions Carbon dioxide and the hydrogen from light reactions form glucose using ATP for energy (also from the light reactions) Called Carbon fixation (inorganic molecule to organic molecule)

Therefore, photosynthesis can be described as a series of reactions in which carbon dioxide and water are fixed into glucose, and oxygen is produced as a by-product

6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Absorption of CO 2 Photosynthesis can be measured by: Absorption of H 2 O Production of Glucose Production of O 2

Keeping in mind the plant also has a small but constant rate of respiration. and water absorption is influenced by transpiration CO 2 O2O2 H2OH2O C 6 H 12 O 6

Photosynthesis depends on many environmental factors: Light intensity Temperature Carbon Dioxide concentration

The term ‘limiting factor’ is used to describe the factor that controls a process at a minimum rate. from Heinemann Baccalaureate In photosynthesis many factors could be limiting (light, CO 2, temp, etc.) The one that alters the rate of photosynthesis, is the limiting factor.

Change in the other factors will not change the rate of photosynthesis Because photosynthesis is such a complex reaction, a lack of one factor will slow down the whole process.

Look at the pigments found on your chromatography paper. Draw an absorption spectrum for the pigments and an action spectrum for the leaf you got. Tape the chromatography paper to the bottom.

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