IV. Nutrient Sources; How organisms obtain energy A. Autotrophs; Organisms that are able to produce their own food. 1. Photosynthetic; organisms that use sunlight to produce food. These contain chlorophyll. a. plants; multi-cellular, with chloroplasts b. cyanobacteria; known as blue-green algae, single celled c. some protists; single celled, and multi-celled algae.

2. Chemosynthetic; use chemical compounds for metabolism. a. bacteria at ocean thermal vents (black smokers) metabolize hydrogen sulfide.

b. bacteria in the Gulf of Mexico metabolize frozen methane. B. Heterotrophs; Use other organisms for food. 1. herbivores; feed only on plants ex. Cattle and deer 2. carnivores; eat other animals ex. Lions killing and eating gazelles

a. scavengers eat dead animals ex. turkey vultures 3. omnivores; eat plants and animals ex. Bears will eat fish and berries 4. decomposers; break down dead and decaying plants and animals into simple molecules. Molecules are absorbed by organism. ex. many bacteria, some protozoans most fungi.

Herbivore Primary consumer eats plants V. Energy Flow through Ecosystem; each feeding step is a trophic level. Tertiary consumer- eats secondary consumers Carnivores Secondary consumer- eats herbivores Herbivore Primary consumer eats plants Producer Autotrophs Omnivores can feed from different trophic levels in different food chains.

A. Food chain; simple linear representation. ex. grass → mouse → hawk B. Food web; more realistic representation than a food chain. Shows all possible feeding relationships at each trophic level in a biological community.

C. ecological pyramid; shows energy flow through an ecosystem. Illustrates that the amount of available energy decreases at each succeeding trophic level.

Biomass is the total amount of mass of organisms in an ecosystem.

VI. Cycles in nature; Conservation of mass. applied VI. Cycles in nature; Conservation of mass applied. Matter is constantly recycled, but it is never lost. A. Water Cycle; there is a finite amount of water in the environment. 1. evaporation; occurs at the surface of bodies of water. Water turns to vapor (gas), and moves into the atmosphere. a. transpiration; water leaving the soil and the leaves of plants. b. respiration; water given off during process of exhaling.

2. Condensation; Water molecules turn from a vapor, to a liquid. a. formation of water droplets. b. formation of dew. 3. Precipitation; Water in the atm. gets too heavy to stay suspended in the air, and returns to Earth as rain, sleet, snow or hail. a. may soak into the ground as ground water. b. may move along Earth’s surface as runoff.

B. Carbon Cycle; Carbon is used and produced. by almost every organism B. Carbon Cycle; Carbon is used and produced by almost every organism. It is present in CO2 in the atm. and dissolved in water.

C. Nitrogen cycle; necessary for the formation of amino acids. 1. lightning strikes 2. decay of organic matter by bacteria 3. Nitrogen fixing bacteria (rhizobia) in the root nodules of legumes.

D. phosphorus cycle 1. short term cycle; Animals obtain phosphorus by eating plants. Animals die, then decompose returning the phosphorus to the soil for plant use again. 2. long term cycle; phosphates washed into the water become incorporated into rock. Over time, as rock is exposed to weathering and erosion, phosphorous is made available for plant use again.