How do organisms get food?

Sun (solar or light energy) Review: Heterotrophs  organisms that cannot make their own food Obtain food by: Absorption: EX: decomposition – process by which fungi and some bacteria break own organic matter into a size and form that they can absorb for food Ingestion: by mouth Autotrophs  organisms that make their own food (producers) Make food using ENERGY from… OR Sun (solar or light energy) Chemicals

Using energy from the sun to produce food is known as PHOTOSYNTHESIS. All Plants Some Bacteria Occurs in the Chloroplast Uses CO2 and H2O Produces O2 and glucose (food)

Chlorophlast

Chloroplast Only found in autotrophs Contain CHLOROPHYLL, a green pigment that traps light LIGHT-DEPENDENT REACTION: Chlorophyll traps the sun’s light, and the light energy is converted into chemical energy called ATP (adenosine triphosphate) Product: oxygen LIGHT-INDEPENDENT REACTION: ATP is then converted into glucose using carbon dioxide. Product: glucose

Factors that affect the rate of Photosynthesis Carbon dioxide Concentration Light Temperature

So What? On a global scale, photosynthesis is the most important process for the continuation of life on Earth. Each year, photosynthesis makes 160 billion tons of carbohydrates. 21% of all atmospheric O2 results from photosynthesis in plants. All the solid materials from every plant are built out of thin air…and all solid materials of every animal are built from plant materials.

Using energy from CHEMICALS to produce food is known as CHEMOSYNTHESIS Requires no sunlight Uses methane or sulfur Occurs in places that do not receive sunlight, such as the deep sea vents.