Science 6 A-4

The function of a decomposer in an ecosystem is to

• recycle materials
• break down starches
• combine light and carbon dioxide
• remove water

An energy pyramid shows

• how much energy green plants take
• which animals eat green plants
• how much energy is available
• which animals are producers and consumers

The most important materials in an ecosystem are sunlight, water, 

• nitrogen, and sugar
• carbon dioxide, and oxygen
• glucose, and bacteria
• bacteria, and carbon dioxide

Nitrogen is returned to the atmosphere when

• lightning strikes
• bacteria converts nitrogen
• lightning converts nitrogen
• bacteria decomposes wastes

Populations of organisms change when

• animals move away
• conditions change
• organisms get older
• animals eat seeds

Which is an example of competition?

• Two snakes hunt for scarce prey
• A bird feeds on insects  while another feeds on berries
• Male and female cardinals feed their babies
• A bluebird nests in a tree while a robin  builds a nest on the same tree.

Plants that are introduced often spread rapidly because they

• have stronger roots
• produce more seeds
• have no natural defenses
• have no natural pests

The kinds of plants that live in a biome determine the kind of

• climate
• landforms
• animals
• latitude

The most common types of plants in the tundra are

• deciduous trees
• ferns and vines
• coniferous trees
• mosses and lichens

Which biome covers most of the Earth?

• saltwater
• freshwater
• tropical rain forest
• taiga