When You Eat a Hamburger, You Get Energy from the Sun!

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Chapter 5 Section 2

•Photosynthesis

•Energy from the Sun

•When you eat a hamburger, you get energy from the sun!

•Energy from the Sun

•With few exceptions, you end up with energy from plants whenever you trace your food back to its origin.

•Photosynthesis

•Its the process that provides energy for almost all life.

•We represent photosynthesis by:

•6CO2 + 6 H20 → C6H12O6 + O2

•Photosynthesis

•Plants use pigments to capture light from the sun to produce carbohydrates.

•Sunlight contains a mixture of all wavelengths (colors) of visible light.

•Three Kinds of Pigments & Colors absorbed

•Chlorophyll a - Indigo, red, violet, orange

•Chlorophyll b –Blue, indigo, violet, orange

•Carotenoids - Blue, dark green

•Why all the different pigments?

•The reason that there are so many pigments is that each absorbs light more efficiently in a different part of the spectrum.

•Where are pigments found?

•Pigments involved in plant photosynthesis are located in the chloroplasts of leaf cells.

•Within the chloroplasts, pigments are embedded in disk-shaped structures called thylakoid.

•How do pigments work?

•Pigments attract light.

•In the pigments, electrons freely float around until light strikes it.

•When light strikes the electrons, the electrons capture the energy.

•How do pigments work?

•The electrons then use the captured energy in the photosynthetic process.

•Why is water used in photosynthesis?

•Water is absorbed by the plants to be broken down and used in the photosynthetic process.

•Uses of H2O in photosynthesis:

When water splits, the electrons are taken from the hydrogen atoms.

Electrons replace those lost from the pigment when light is absorbed.

The hydrogenions is used to produce NADPH – used in producing glucose.

The oxygen atom combines with another oxygen atom and is released as a by-product (waste).

•Why is carbon dioxide used in photosynthesis?

•The carbon in carbon dioxide is used to build the glucose molecule (C6H12O6).

•The two oxygen atoms are released as a by-product.

•2 Phases of Photosynthesis

•Light cycle

–Light energy is captured

–Water molecules are split

•Dark cycle (Calvin cycle)

–Carbon dioxide is split

–Captured light energy is converted into stored energy with the carbon from CO2 to make glucose.

•3 Factors that Affect Photosynthesis

•Amount of Light – Increases until all the pigments are used.

•Amount of CarbonDioxide

•Temperature