Energy

A. Producers- make food in a community 1. The lowest trophic level 2. Autotrophs 3. Make their own food through the process of photosynthesis 4. Includes: a. plants b. algae c. bacteria

B. Photosynthesis-plants use the sun’s energy to convert water and carbon dioxide into sugars (glucose)

C. Consumers- organisms that eat other organisms 1. All heterotrophs that can’t make their own food 2. Depend on the producers to supply energy

D. Cellular Respiration-a chemical process that uses oxygen to convert the chemical energy stored in organic molecules into another form of chemical energy-ATP!

1. Plants and animals use ATP as their main energy supply

E. Photosynthesis and Cellular Respiration Recycle a common set of chemicals

1. Water 2. Carbon Dioxide

3. Oxygen 4. Glucose

A. Is Water the Source of Energy in Plants? 1. Jan Baptista van Helmont, Flemish physician,

chemist, and physicist, in the 1600s carried out a famous experiment a. Planted a willow tree weighing 5 kg in a pot for

5 years b. The tree increased in mass by 74kg but the

mass of the soil had changed little. c. Van Helmont believed that water was the source

of the extra mass and the plant's source of life.

B. The Interaction of Plants With Air 1. August of 1771, Joseph Priestley, an English

Chemist a. put a sprig of mint into a transparent closed

space with a candle that burned out the air (oxygen was not discovered yet) until it soon went out.

b. After 27 days, he relit the extinguished candle again and it burned perfectly well in the air that previously would not support it.

C. Plants and Light1. Jan Ingenhousz 1779 2. Put a plant and a candle into a transparent closed space.

3. He allowed the system to stand in sunlight for two or three days.

4. Then, he covered the closed space with a black cloth and let it remain covered for several days.

5. When he tried to light the candle it would not light. 6. He concluded that somehow the plant must have

breathed, fouling the air; in order to purify the air plants need light.

III. Food Stores Chemical Energy A. Energy- the ability to do work B. Kinetic Energy- the energy of motion C. Potential Energy- Stored energy D. Energy cannot be created or destroyed, it

merely changes form.

E. Chemical Energy is a form of potential energy. 1. Due to the arrangement of the atoms

within molecules 2. Organic molecules that store chemical

energy include a. Carbohydrates b. Lipids

c. Proteins

3. Rearranging the atoms in these molecules releases the potential energy and changes it into kinetic energy so work can be done

a. Muscle contraction4. Glucose reacts with oxygen to produce carbon

dioxide, water and ENERGY!

IV. ATP Provides Energy For Cellular Work A. Cells need energy for 1. Mechanical Work (Movement) 2. Transport Work (Active Transport) 3. Chemical Work (Building

Macromolecules)

B. ATP (Adenosine Triphosphate) 1. The cells energy molecule 2. Has three parts a. sugar b. adenine c. three phosphates 3. When a phosphate is broken off a. a lot of energy is released b. ADP c. AMP 4. ATP is continuously recycled

V. Photosynthesis Uses Light Energy to Make Food

A. Occurs inside the chloroplasts 1. Thylakoids- flattened sacs 2. Grana- stacks of thylakoids 3. Stroma- semiliquid substance 4. Photosystem- groups of chlorophyll

pigments stored in thylakoids

• B. Formula for photosynthesis6 CO2 + 6H2O + LIGHT C6H12O6 + 6 O2

C. Light-Dependent Reactions- light is needed 1. Occurs inside of the thylakoid 2. Photoevent-capturing energy from sunlight (photosystem one= the water splitting photosystem) a. a photon of white light excites an electron within the chlorophyll pigment b. Chloroplasts use the energy to remove electrons from

water2 H2O O2 + 4H+ + 4 e-

c. Oxygen is a waste product of photosynthesis!

3. Electron Transport-the excited electron is used to make

ATP (photosystem II=the NADPH producing system) a. The excited electron travels from one electron carrier to another, losing energy until it arrives at a transmembrane proton pump b. H+ ions are pumped into the thylkoid (opposites

attract) c. Proton transport drives the synthesis of ATP by

diffusion

d. The electron, which now has half the energy, passes to another chlorophyll molecule

e. The electron obtains more energy from light and becomes highly energized again

f. The electron is passed along another electron chain producing NADPH (the energy coupon to be cashed in later)

4. To summarize a. The energy of light is captured by

chlorophyll and passed on to electrons b. This energy is used to - make ATP - make NADPH - generate oxygen by splitting water

D. Light-Independent Reactions-can occur in the dark without light

1. Occurs inside the stroma 2. Called the Calvin Cycle 3. Makes sugar using carbon dioxide and NADPH