CRM 3.5 - Ecology

Why does the amount of CO₂ in the atmosphere remain relatively constant?

• Carbon dioxide is consumed by photosynthesis to produce carbohydrates.

• Carbon dioxide is consumed by decomposers.

• Carbon dioxide mostly forms rocks.

• Carbon dioxide is trapped in dead organisms’ bodies.

The diagram above shows a model of the water cycle. Which of the following arrows is incorrect?

• Runoff

• Evaportation

• Transpiration

• Condensation

Which of the above would cause an excess output in the carbon cycle?

• A reduction in the consumption of fossil fuels

• Increases in marine biota

• The destruction of terrestrial biota

• A decline in cement production

Scientists are investigating the cause of the large increase in atmospheric carbon dioxide concentration since about 1800. Which of the following provides the best explanation for the increase of carbon in our atmosphere?

• Frequent eruptions of large volcanoes

• Naturally occurring fluctuations of in the carbon cycle

• Utilization of fossil fuels by humans for industrialization

• Increased rate of photosynthesis in marine phytoplankton

The diagram above shows the flow of carbon in a terrestrial ecosystem.

Which will most likely happen if the decomposers are removed from the carbon cycle?

• The amount of carbon dioxide in the atmosphere will increase.

• The amount of carbon dioxide in the atmosphere will decrease

• The amount of carbon dioxide used by producers will increase.

• The amount of carbon dioxide needed by consumers will decrease.

Which statement best describes why the movement of energy and nutrients through living systems are different?

• Energy flows in one direction, and nutrients recycle

• Energy is limited in the biosphere, and nutrients are always available

• Nutrients flow in one direction and energy recycles

• Energy forms chemical compounds, and nutrients are lost a heat

A team of ecologists observed feeding patterns of several populations in the desert. The energy pyramid shown below depicts the feeding patterns the ecologists observed.

Which of the following best explains the difference in the amount of available energy in the trophic levels of the desert ecosystem?

• There is less energy available in the producers because their tissues are less dense than those at higher trophic levels.

• There is more energy available in the second trophic level because less energy is needed for hunting compared to the higher trophic levels.

• There is more available energy in the birds of prey because they have greater muscle mass for storing energy than organisms in lower trophic levels have.

• There is less available energy in the fourth trophic level because of the loss of energy through metabolism in each of the lower trophic levels.

Which of the following best describes how the amount of energy changes as it flows from one trophic level to the next in the marine food web shown above?

• Energy increases as it is transferred from penguins to seals, since seals are larger than penguins.

• Energy decreases as it is transferred from fish to squid, since fish are producers and squid are consumers

• When krill consume phytoplankton, about 90 percent of the phytoplankton's energy is transferred to the krill.

• When sea birds consume fish, about 10 percent of the fish’s energy is transferred to the sea birds.

When a rabbit eats a plant, nutrients from the plant become available to the tissues of the rabbit. During this process, some of the energy from these nutrients is lost. It becomes heat and unavailable chemical energy. This energy loss partly explains which of the following?

• why total energy is greater in producer populations than in consumer populations

• why total energy is greater in predator populations than in prey populations

• why total energy is greater in predator populations than in scavenger populations

• why total energy is greater in consumer populations than in producer populations

Which factor would have the greatest effect on the flow of energy into an ecosystem?

• a large increase in the number of carnivores

• a large decrease in the amount of sunlight available

• a small increase in the number of decomposers

• a small decrease in the amount of minerals available