Review (8L.3.2 & 8L3.3)6-

Which organisms contribute MOST to the decomposition of dead organisms?

• snakes

• viruses

• insects

• bacteria

The diagrams show different ways to represent energy flow. Although very different, both diagrams are acceptable because

• different energy diagrams require different organization.

• both diagrams show the information accurately.

• the numbers of animals in the diagrams are different.

• the energy levels change between diagrams.

The picture shows the effect that wind can have on water movement. As the wind blows water away from shore, cold water moves up toward the surface bringing nutrients to the shallow waters. Which statement BEST identifies the relationship taking place in this example?

• Abiotic factors can influence energy flow in an ecosystem.

• Biotic interactions control the movement of nutrients in the ocean.

• Abiotic parts of an environment make up parts of marine food webs.

• Biotic interactions are causing an increase in food sources for marine life.

4. In which process is nitrogen from the air put into a form that plants can use?

• nitrification

• denitrification

• nitrogen saturation

• nitrogen fixation

The nitrogen cycle is an important cycle found in ecosystems. Nitrogen is used by living organisms to produce a number of complex organic molecules. Most of the nitrogen is found in the atmosphere, where it exists as a gas. Nitrogen is made available in a useful form for animals in the

• plants they eat.

• air they breathe.

• rainwater they drink.

• fertilizers they absorb.

A salt marsh has a variety of animals and plants. The pyramid represents the amount of energy transferred between organisms in a salt marsh. Which trophic level would lose the MOST useful energy as heat when organisms at that level feed on other organisms?

• 5

• 4

• 3

• 2

Which factor BEST explains why biomass decreases as trophic level increases in a food pyramid?

• Some of the energy is converted to heat.

• The survival rate of organisms gradually decreases

• The availability of space decreases as feeding levels increase.

• Toxic chemicals get concentrated as they move up the food web.

How does the energy in each trophic level of an energy pyramid compare to the energy in the preceding level?

• It has about 5% of the energy from the level below it.

• It has about 10% of the energy from the level below it.

• It has about 15% of the energy from the level below it.

• It has about 20% of the energy from the level below it.

Meadows are grassland areas, usually low-lying with moist soil. Meadows support a rich variety of animal life. A food web for a meadow is shown. The removal of which populations of organisms would have the greatest impact on the food web?

• grasses and shrubs

• seed-eating birds

• rabbits

• snakes

Food webs are used to identify the feeding relationships between organisms. Which statement can be logically concluded about the food web shown?

• Organism 1 is most likely a type of bacteria.

• Organism 2 is definitely an omnivore.

• Organism 5 is most likely a plant eater.

• Organism 8 is definitely a carnivore.