Chapter 8 Notes

Energy Flows Between Living Things

• Photosynthesis-process by which light energy is converted to chemical energy.

• Autotrophs-organisms that use energy from sunlight or inorganic substances to make organic substances (ex: sugar)

• Heterotrophs—organisms that must get their energy from food instead of directly from sunlight or other inorganic substances

Cellular Respiration

• Metabolic process that uses food and oxygen to make energy (ATP)

ATP

• a portable form of energy “currency” inside the cells. The energy released from ATP powers chemical reactions in your cells.

• ATP releases energy when the bond between one of the 3 phosphates breaks, forming ADP (diphosphate). As the bond breaks, energy is released that the cell can use.

Photosynthesis- Light Reactions

1. Sunlight strikes the chlorophyll located in the chloroplast in the plant.

2. This activates a system that splits H2O into hydrogen and oxygen; oxygen is released.

Light Reactions continued

3. “Excited” electrons move through the electron transport chain and produce molecules of ATP and NADPH.

Photosynthesis- Dark Reactions (Calvin Cycle)

1. CO2 is “fixed” to a compound to form a simple sugar

2. Two of these simple sugars combine to form glucose.

3. Glucose is stored in the plant in many ways:

• Chemical energy for plant

• Fruits• Vegetables

• The Equation for Photosynthesis

• Reactants: CO2(carbon dioxide) + H2O (water)

• Products: C6H12O6(glucose) + O2 (oxygen)

CO2H2O

SUNLIGHT

Fig. 7-6c, p.111

O2

light-dependent reactions

light-independent

reactions

sugars

CHLOROPLAST

NADPH, ATP

NADP+, ADP

Summary of PhotosynthesisSummary of Photosynthesis