Ecosystems & Biomes Review
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Ecologists study feeding patterns to learn how energy flows within a(n) ecosystem
Organisms that use the sun’s energy to turn water and carbon dioxide into food molecules are
called producers
A diagram that shows the amount of energy that moves from one feeding level to another in an
ecosystem is called a(n) energy pyramid
The processes of evaporation, condensation, and precipitation make up the water cycle
“Free” nitrogen gas is changed into a usable form of nitrogen in the process called nitrogen
fixation
Wind, water, and living things are three means of dispersal
The type of biome that exists in an area is determined by its climate conditions
The biome that receives less than 25 cm of precipitation a year is the desert
An extremely cold, dry biome is the tundra
Succession is the series of predictable changes that occur over time in a community
A(n) scavenger is a carnivore that feeds on the bodies of dead organisms
Plants, algae, and some microorganisms make food molecules in the process of photosynthesis
The very slow motion of huge blocks of Earth’s crust is called continental drift
Physical barriers, competition, and climate conditions can limit the dispersal of species
A(n) biome is a group of ecosystems with similar climates and organisms
Scavengers break down wastes and dead organisms and return raw materials to the
environment (F; decomposers)
Matter is not recycled in ecosystems (F; energy)
Species that have been carried into a new location by people are known as exotic species (T)
The study of where organisms live is called biogeology (F; biogeography)
Wolves, foxes, and caribou are typical animals in the tropical rain forest biome (F; Tundra)
Essay
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How can competition limit the dispersal of a species
o When a species moves into a new area, it must compete for resources with the species
that are already there. It the new species does not find its own unique niche, it will be
outcompete by the existing species
Describe the major differences between a tropical rain forest and a desert
o The major differences include the large number of species that inhabit the tropical rain
forest compared to the desert; the constant temperature of the rain forest and the
extremes of the desert; and the different amounts of rainfall in the biomes
The grassland biome has few trees. The tundra has no trees at all. What conditions in each of
the two biomes cause this similarity
o The grassland does not receive enough rainfall for many trees to grow. In addition,
large, grazing herbivores keep young trees from growing. In the tundra, the lack of rain
and cold, short growing season do not allow young trees to grow
What is shown in the diagram above: the nitrogen cycle
What should the labels be for Steps 1, 2, 3, & 4: 1. Free nitrogen in the air, 2. Bacteria fix nitrogen, 3.
Decomposers breakdown remains, & 4. Bacteria release free nitrogen
Why is Step 2 so important: most organisms cannot use free nitrogen in the air; the nitrogen must be
combined with other elements to form nitrogen compounds. Nitrogen fixation by bacteria provides
these compounds for other organisms to use