Chapter 46: Ecosystem Ecology

Which of the statements is true regarding atmospheric CO2 levels during the last 400,000 years? A. Atmospheric CO2 levels fluctuate periodically, with the highest levels occurring during interglacial periods. B. Correlation exists between low levels of atmospheric CO2 and high temperatures. C. Causation exists between low levels of atmospheric CO2 and high temperatures. D. Atmospheric CO2 levels have remained relatively constant and have only increased since the 1800s. E. Atmospheric CO2 levels fluctuate periodically, with the highest levels occurring during glacial periods.

A. Atmospheric CO2 levels fluctuate periodically, with the highest levels occurring during interglacial periods.

Imagine that a researcher has discovered a leaf fossil from the Cambrian Period that is 500 million years old. He notices that the leaf had very few stomata compared to present-day leaves. What does this tell the researcher about atmospheric CO2 levels during the Cambrian Period? A. Atmospheric CO2 levels were higher during the Cambrian Period than today. B. Atmospheric CO2 levels are not correlated with numbers of stomata. C. Atmospheric CO2 levels during the Cambrian Period were equal to present-day levels. D. Atmospheric CO2 levels were lower during the Cambrian Period than today.

A. Atmospheric CO2 levels were higher during the Cambrian Period than today.

Which of the answer choices would not be expected to affect primary production? A. biomass of primary consumers B. biomass of producers C. nutrients D. water E. sunlight

A. biomass of primary consumers

A researcher is measuring atmospheric CO2 levels on cloudy and sunny days. He notices that on cloudy days, CO2 levels appear slightly higher than on sunny days. This is an example of: A. correlation. B. fluctuation. C. assimilation. D. conjugation. E. causation.

A. correlation.

Organisms in an ecosystem are linked to their physical environment through the cycling of _____ and the transfer of _____. A. nutrients; energy B. energy; nutrients C. nutrients; water D. sunlight; nutrients E. nutrients; sunlight

A. nutrients; energy

The equation 6CO2 + 6H2O → C6H12O6 + 6O2 represents the process of: A. photosynthesis. B. respiration. C. None of the other answer options is correct.

A. photosynthesis.

Photosynthesis and respiration affect atmospheric CO2 levels on a _____ timescale, whereas volcanic eruptions affect atmospheric CO2 levels on a _____ timescale. A. yearly; century B. century; yearly

A. yearly; century

The carbon and nitrogen cycles are related to one another because: A. both are required to make the primary biological molecules (carbohydrates, fats, proteins, and sugars). B. All of these choices are correct. C. microorganisms have important roles in the cycling of each. D. both are liberated into the environment when organisms decompose.

B. All of these choices are correct.

Which of the statements is true regarding chemical weathering? A. It relies on bacteria to break down rocks. B. It contributes to the accumulation of CaCO3 in oceans. C. It relies on the acid SiO2. D. It releases CO2 into the atmosphere. E. It plays a major role in the short-term carbon cycle.

B. It contributes to the accumulation of CaCO3 in oceans.

Which of the statements explains how an oxygen-rich atmosphere became possible on Earth? A. The number of plants is greater than the number of animals. B. Rates of oxygen consumption are lower than rates of photosynthesis. C. Photosynthetic organisms have existed on earth longer than heterotrophs. D. Rates of carbon fixation and respiration are equal.

B. Rates of oxygen consumption are lower than rates of photosynthesis.

A researcher is measuring Earth's atmospheric CO2 levels, gathering data on CO2 levels in northern and then southern hemispheres. What do you expect that she will find? A. Atmospheric CO2 measurements will be greater in the Northern Hemisphere. B. Atmospheric CO2 measurements will be greater in the Southern Hemisphere. C. Because atmospheric CO2 measurements represent global amounts, measurements in the Northern Hemisphere and Southern Hemisphere will be approximately the same.

C. Because atmospheric CO2 measurements represent global amounts, measurements in the Northern Hemisphere and Southern Hemisphere will be approximately the same.

In terrestrial ecosystems, nitrogen is returned to the atmosphere by A. nitrifying bacteria. B. nitrogen-fixing bacteria. C. denitrifying bacteria. D. All of these choices are correct.

C. denitrifying bacteria.

Examining the relationship between primary producers, primary consumers, and secondary consumers is one way to track the flow of _____ through a system. A. energy in the form of heat B. energy contained in proteins C. energy contained in organic compounds D. energy contained in fossil fuels

C. energy contained in organic compounds

The majority of carbon stored in abiotic reservoirs is in the form of: A. CO2. B. C6H12O6. C. H2CO3. D. CaCO3. E. CH4.

D. CaCO3.

Trout and amoebas are both heterotrophs and can inhabit similar environments, such as a freshwater pond. However, these organisms are very different when it comes to their shape and size. Why? A. Trout and amoebas have different metabolic pathways. B. Trout and amoebas are exposed to different environmental conditions, even when they inhabit the same pond. C. Trout and amoebas utilize different sources of O2. D. Trout and amoebas evolved to utilize different sources of C6H12O6 (or other organic compounds). E. Trout and amoebas utilize different sources of CO2.

D. Trout and amoebas evolved to utilize different sources of C6H12O6 (or other organic compounds).

Which biogeochemical cycle does not include oxidation and reduction reactions that provide energy to microorganisms? A. nitrogen B. carbon C. None of the other answer options is correct. D. phosphorus

D. phosphorus

Please choose the correct answer from the following choices, and then select the submit answer button. A. Calvin cycle. B. food chain. C. food web. D. trophic pyramid. E. ecosystem.

D. trophic pyramid.

A scientist studying a material has determined that 12C, 13C, and 14C occur in the material in a ratio of 1000:10:1. How did he most likely differentiate between these forms of carbon? A. by the biomasses of 12C, 13C, and 14C B. by the number of protons in 12C, 13C, and 14C C. by the number of electrons in 12C, 13C, and 14C D. by the number of positrons in 12C, 13C, and 14C E. by the number of neutrons in 12C, 13C, and 14C

E. by the number of neutrons in 12C, 13C, and 14C

The rate of exchange of carbon between the atmosphere and the oceans represents a carbon: A. sink. B. reservoir. C. biomass. D. precipitation. E. flux.

E. flux.

Which of these relationships best depicts the amount of carbon stored in the atmosphere, sedimentary rocks, living organisms, and soil? A. the atmosphere < soil < living organisms < sedimentary rocks B. soil < living organisms < sedimentary rocks < the atmosphere C. sedimentary rocks < soil < living organisms < the atmosphere D. soil < the atmosphere < sedimentary rocks < living organisms E. living organisms < the atmosphere < soil < sedimentary rocks

E. living organisms < the atmosphere < soil < sedimentary rocks

T/F: An increased rate of photosynthesis is the most likely explanation as to why atmospheric CO2 levels appear lowest during glacial periods of Earth's history.

False

T/F: Glacial ice core data can provide scientists with information about atmospheric CO2 levels for the last 500 million years of Earth's history.

False

T/F: If all of the tertiary consumers were removed from an environment, the associated food web, and thus the carbon cycle, would collapse.

False

T/F: The diverse array of photosynthetic plants and microbes is the result of different sources of CO2 and has little to do with environmental conditions.

False

T/F: Phosphorus released from sedimentary rocks through chemical weathering can be immediately assimilated by primary producers and contributes to the biomass of primary producers in an ecosystem.

True

T/F: Primary consumers obtain carbon, nitrogen, and phosphorus through ingestion of primary producers.

True

T/F: The evolution of biodiversity on the planet can be linked to patterns in the carbon cycle over time.

True

T/F: The long-term and short-term carbon cycles are connected by the fact that some of the carbon contained in C6H12O6 (or other organic molecules) in plants is incorporated into sedimentary rocks or oil; carbon in sedimentary rock and oil is not immediately cycled back to the atmosphere.

True