UNIT 1 ECOLOGY

STUDY GUIDE

1. Levels of Organization (Section 3-1)

A. The Biosphere-the most broad category. The thin volume of Earth that supports life.

B. Ecosystems-includes all organisms and the nonliving environment found in a particular place. (ex. a pond)

Abiotic factors- the non-living components of an ecosystem (temperature, precipitation, rocks, soil)

Biotic factors- the living components of an ecosystem (fish, birds, bacteria, predators)

C.Communities- is all the interacting organisms living in an area. (ex. all the fish, turtles, plants, algae, bacteria in a pond)

Population-all members of the same species in one place at one time.

Organism- one single living thing (studying its adaptations to survive)

2. Energy Transfer (Section 3-2)

A. Producers- autotrophs that make their own food (usually through photosynthesis) ex. plants, algae, some bacteria, plankton

Chemosynthesis-production of carbohydrates by using inorganic molecules. (some bacteria)

Gross Primary Productivity-the rate at which producers in an ecosystem capture energy. (to make sugar)

Biomass- the amount of organic material in an ecosystem.

Net Primary Productivity- the rate at which biomass accumulates in an ecosystem. (Ex. Tropical rain forest has a high net primary productivity, Desert has a low net primary productivity.)

B. Consumers- heterotrophs- consume food (ex. all animals, most protists, all fungi, and many bacteria)

Herbivores- eat producers (ex. antelope)

Carnivores-eat other consumers (ex. lions, eagles)

Omnivores-eat both producers and consumers (ex. grizzly bear)

Detrivores-feed on dead or decaying matter. (ex. vulture)

Decomposers- cause decay and breakdown of complex molecules in dead tissues and wastes into simpler molecules. (ex. bacteria)

C. Energy Flow- (Section 3-3)

whenever one organism eats another energy is transferred.

Trophic Level- indicates an organism’s position in the sequence of energy transfers.

Food Chain- a single pathway of feeding relationships among organisms in an ecosystem that results in energy transfer.

Food Web- a diagram of many food chains interlinked

  • Roughly 10 percent of the total energy consumed in one trophic level is incorporated into the next level. (Ex. Grass transfers more energy to a moose that a moose transfers to a wolf)
  • Many living things need energy to maintain body temp, move and reproduce)

4. Ecosystem Recycling (Section 3-4)

A. The Water Cycle- water is needed by all life because many chemical reactions that happen in cells need to happen in water.

Water falls to Earth’s surface as precipitation

Some water reenters the atmosphere by evaporation and transpiration (water evaporating through plants)

Some water runs into lakes, rivers and oceans

Other water seeps through the soil as ground water.

B. The Carbon Cycle

During photosynthesis, carbon dioxide is used along with water and sunlight to make sugar (glucose C6H12O6)

During cellular respiration, oxygen is used to turn glucose into ATP energy. The products are carbon dioxide and water.

Human activity has drastically increase carbon dioxide levels in the atmosphere.

C. The Nitrogen Cycle

All organisms need nitrogen to make proteins and nucleic acids.

Nitrogen Gas (N2) – is turned into nitrites and nitrates by nitrogen-fixing bacteria located in the soil and roots of legumes.

Decomposers break down dead organisms, urine, and dung by ammonification, returning more nitrogen to the ecosystem.

Nitrification-bacteria in the soil take up ammonia and turn it into nitrites (NO2-) and nitrates (NO3-)

Denitrification- anerobic bacteria break down nitrates and nitrites into nitrogen gas, returning it to the atmosphere.

Animals obtain nitrogen by eating plants and other organisms. (digestion)

Plants obtain nitrogen by absorbing it from the soil.