Types of Energy: Although energy may be classified in a number of different ways and as a number of different types, two forms of energy are of particular interest to biologists: SOLAR and CHEMICAL
I.
Solar Energy: Energy emitted from the Sun (essentially a nuclear fusion reactor) in the form of LIGHT and HEAT . Light can be described by its WAVELENGTH .
Wavelength is the distance between two identical points on a repeating wave, in this case peak (crest) to peak, however any repeating points could be used (for example, trough [bottom] to trough)
Wavelength directly relates to the energy carried by light, with shorter wavelengths carrying more energy than longer wavelengths.
Below is the Electromagnetic Spectrum of light—a useful tool in visualizing the different forms light can take. REMEMBER SHORTER WAVELENGTH=MORE
ENERGY!!
Reds---------Oranges----Yellows—Greens-----Blues--------Violets
***Note: the units of length are in nanometers which are one billionth of a meter!!

II.
Chemical Energy: Type of potential energy where the energy is stored in the chemical bonds that form molecules. When certain chemical reactions takes place, bonds are broken and energy is released. Chemical reactions can be represented using a chemical equation in the form: Reactants

Products . The Law of Conservation of
Mass dictates that all matter that enters a chemical reaction must leave (although in different forms), so this helps in that we can see and track everything going in and everything going out. SOMETIMES YOU WILL SEE SOMETHING WRITTEN
ABOVE THE ARROW (an enzyme, light, ATP, etc.) THIS MEANS THAT IT
PLAYED A ROLE IN THE REACTION BUT DID NOT DIRECTLY
PARTICIPATE. (EX. An enzyme helps a reaction take place but is not chemically altered in the process; light is essential for photosynthesis but is not matter and cannot, therefore, be accounted for in the reaction; the energy to produce ATP is provided by a chemical reaction, but the reaction itself does not involve ATP)
What we think of as food is chemical energy! Where does it come from?
photo means “light” and synthesis means “putting together”, so photosynthesis means “putting together with light”. What is being put together?
Molecules  FOOD. Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy (in the form of molecular bonds) that can be later released to fuel the organisms' activities.


Pigment: A chemical/substance that absorbs certain wavelengths of light and reflects others. o Absorbance: A wavelength, or series of wavelengths, of light is/are trapped by a pigment along with energy it/they contain(s)

the visible light wavelengths absorbed never reach your eye and, thus, are not seen.
o Reflection: A wavelength, or series of wavelengths, of light is/are scattered by a substance

the visible light wavelengths reflected are the ones that enter your eye and are seen.
o Example: A leaf that appears green absorbs all wavelengths except for green, and reflects it in all directions (some of this light enters your eye and causes you to perceive the leaf as green); something that appears black absorbs all wavelengths of visible light and appears to have no color (because no visible light is reflected into your eye); something that appears white reflects ALL wavelengths and appears to have every color (light of all visible wavelengths is reflected into the eye and the brain perceives this as “white”)
**Now you know why light colors keep you cooler in the summer and dark colors get hot faster…dark colors ABSORB more light and ENERGY (which dissipates as heat)!!**

I.
Chlorophyll- pigment with strong absorbance in the blue and violet wavelengths, and moderate absorbance in the orange-red wavelengths. There are two types
Chlorophyll-α (A) and Chlorophyll-β (B) CAUSES THE GREEN APPEARANCE
OF PHOTOSYNTHESIZING PLANTS

REFLECTS GREEN LIGHT!!
II.
Carotenoids- pigment with moderate absorbance in the blue and green wavelengths.
Causes the orange-yellow-red appearance of photosynthesizing plants. Typically seen in the Fall when plants stop replenishing their chlorophyll (absorbs orange-red wavelengths) concentrations in preparation for winter (decreased sunlight).
Thylakoid: Site of the LIGHT-
DEPENDENT REACTIONS
Granum (plural Grana): Stack of thylakoids surrounded by the stroma
Stroma: Watery fluid (like the cytoplasm, but thicker), site of the LIGHT-INDEPENDENT
REACTIONS

I.
The Light-Dependent Reaction (aka Light Reaction)
II.
The Light-Independent Reaction (aka Dark Reaction aka Calvin Cycle)

Inputs (what goes in): o Light energy(from the Sun) In photosynthesis equation as reactant o Water (H
2
O) In photosynthesis equation as reactant o NADP+ o ADP + P

Outputs (what comes out): o Oxygen gas (O
2
) In photosynthesis equation as product o ATP o NADPH

Inputs (what goes in): o Carbon Dioxide gas
(CO
2
) In photosynthesis equation as reactant o NADPH o ATP

Outputs (what comes out): o Glucose (C
6
H
12
O
6
) In photosynthesis equation as product