A
Which organisms play the most important role in returning nutrients to an ecosystem by breaking down dead organisms?
A. Producers
B. Herbivores
C. Decomposers
D. Carnivores
C. Decomposers
Which process returns carbon dioxide directly to the atmosphere?
A. Photosynthesis
B. Cellular respiration
C. Nitrogen fixation
D. Transpiration
B. Cellular respiration
Which organisms are especially important in nitrogen fixation?
A. Fungi
B. Nitrogen-fixing bacteria
C. Herbivores
D. Carnivores
B. Nitrogen-fixing bacteria
Water vapor cools and changes into tiny liquid water droplets. This process is called:
A. Evaporation
B. Condensation
C. Transpiration
D. Infiltration
B. Condensation
Excess phosphorus entering lakes and ponds can contribute to:
A. Eutrophication
B. Nitrogen fixation
C. Condensation
D. Cellular respiration
A. Eutrophication
A tree absorbs carbon dioxide from the atmosphere and uses it to produce glucose. Which process is responsible?
A. Decomposition
B. Photosynthesis
C. Cellular respiration
D. Combustion
B. Photosynthesis
Carbon can be stored for millions of years in which reservoir?
A. Clouds
B. Fossil fuels
C. Grasslands
D. Animals
B. Fossil fuels
If nitrogen-fixing bacteria disappeared from an ecosystem, what would most likely happen?
A. More atmospheric nitrogen would become immediately available to plants.
B. Plants would have less access to usable nitrogen.
C. Photosynthesis would completely stop.
D. Carbon dioxide would no longer be produced.
B. Plants would have less access to usable nitrogen.
Which process releases water vapor from plant leaves?
A. Respiration
B. Transpiration
C. Precipitation
D. Infiltration
B. Transpiration
The ultimate source of energy for most ecosystems is:
A. Soil
B. Decomposers
C. The Sun
D. Oxygen
C. The Sun
6. Which process removes carbon dioxide from the atmosphere?
A. Combustion
B. Cellular respiration
C. Photosynthesis
D. Decomposition
C. Photosynthesis
Why is nitrogen important to living organisms?
A. It is the main source of energy for cells.
B. It is a component of proteins and nucleic acids.
C. It is used directly to produce sunlight.
D. It prevents water from evaporating.
B. It is a component of proteins and nucleic acids.
Which process occurs when liquid water changes into water vapor?
A. Condensation
B. Precipitation
C. Evaporation
D. Infiltration
C. Evaporation
Rain, snow, sleet, and hail are all forms of:
A. Condensation
B. Evaporation
C. Precipitation
D. Transpiration
C. Precipitation
Which organisms capture light energy and convert it into chemical energy?
A. Consumers
B. Producers
C. Decomposers
D. Carnivores
B. Producers
Which sequence correctly represents an important part of the carbon cycle?
A. Carbon dioxide → photosynthesis → glucose → cellular respiration → carbon dioxide
B. Carbon dioxide → nitrogen fixation → glucose → transpiration
C. Oxygen → photosynthesis → nitrogen → decomposition
D. Water → combustion → glucose → nitrogen fixation
A. Carbon dioxide → photosynthesis → glucose → cellular respiration → carbon dioxide
Most atmospheric nitrogen exists in a form that most organisms cannot use directly. Which process converts atmospheric nitrogen into usable nitrogen compounds?
A. Photosynthesis
B. Nitrogen fixation
C. Transpiration
D. Cellular respiration
B. Nitrogen fixation
What is the primary role of decomposers in the nitrogen cycle?
A. Convert nitrogen gas directly into oxygen
B. Return nitrogen compounds from dead organisms and waste to the soil
C. Remove all nitrogen from the atmosphere
D. Convert glucose into nitrogen gas
B. Return nitrogen compounds from dead organisms and waste to the soil
A scientist observes that an area has experienced extensive deforestation. Which change in the water cycle would be most likely?
A. Increased transpiration
B. Decreased transpiration
C. Increased photosynthesis
D. Elimination of evaporation
B. Decreased transpiration
As energy moves from one trophic level to the next, generally:
A. All energy is transferred.
B. More energy becomes available.
C. Less energy is available.
D. Energy is converted back into sunlight.
C. Less energy is available.
. Which statement best describes the difference between matter and energy in an ecosystem?
A. Both matter and energy are continuously recycled.
B. Matter cycles through ecosystems, while energy flows through ecosystems.
C. Energy cycles through ecosystems, while matter flows in one direction.
D. Neither matter nor energy is transferred between organisms.
B. Matter cycles through ecosystems, while energy flows through ecosystems.
Why are biogeochemical cycles essential to ecosystems?
A. They prevent energy from being lost as heat.
B. They allow essential elements and compounds to be reused.
C. They eliminate the need for producers.
D. They increase the amount of sunlight reaching Earth.
B. They allow essential elements and compounds to be reused.
A large increase in deforestation would most likely have which effect on the carbon cycle?
A. Increased carbon dioxide removal from the atmosphere
B. Decreased atmospheric carbon dioxide
C. Reduced photosynthesis and potentially increased atmospheric carbon dioxide
D. Increased nitrogen fixation
C. Reduced photosynthesis and potentially increased atmospheric carbon dioxide
Unlike carbon and nitrogen, phosphorus does not normally have a significant gaseous phase in the atmosphere. Where is most phosphorus stored?
A. Rocks and sediments
B. Clouds
C. The atmosphere
D. Oxygen molecules
A. Rocks and sediments
Why is less energy available at higher trophic levels?
A. Energy is destroyed by consumers.
B. Much energy is used for metabolism and released as heat.
C. Producers consume all the energy.
D. Decomposers prevent energy transfer.
B. Much energy is used for metabolism and released as heat.