Chapter 44 Learning Curve\

Many organisms make up a food web. If snakes are removed from the food web, then: -tertiary consumers will eat fewer birds. -tertiary consumer population sizes will decrease. -small mammal populations will decrease. -primary productivity will increase.

tertiary consumer population sizes will decrease.

Which of the statements is true regarding the carbon cycle? -It was based on microbes during the early stages of Earth's history. -It evolved before plants appeared on Earth. -It involves both long- and short-term processes. -It cycles both carbon and H2O. -All of these choices are correct.

All of these choices are correct

Which of these factors likely contributed to the accumulation of O2 within Earth's atmosphere? -All of these choices are correct. -the fact that there is a slight "de-coupling" between photosynthesis and respiration -the fact that O2 is also cycled during the carbon cycle -the fact that photosynthesis releases O2 as a product -the evolution of cyanobacteria

All of these choices are correct.

If N-fixing bacteria were eliminated, the flux of N through the nitrogen cycle would: -decrease because more N2 would remain in the atmosphere. increase because bacteria-performing denitrification would -increase their metabolic activity in anoxic environments. stay the same. -decrease because more nitrogen would be converted to ammonia. -increase because more N2 would remain in the atmosphere.

decrease because more N2 would remain in the atmosphere.

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

denitrifying bacteria.

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

energy contained in organic compounds

By eating primary producers, primary consumers are able to obtain _____ for making nucleic acids. -magnesium -phosphorous -glucose -oxygen

phosphorus

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

phosphorus

To which group do herbivores belong in a food web? -tertiary consumers -primary consumers -primary producers -decomposers -secondary consumers

primary consumers

Consider the figure shown. Which organism would have the least effect if removed from the food web? -grasshopper -fox -duck -raccoon

racoon

Photosynthesis _____ the atmosphere, whereas respiration _____ the atmosphere. -introduces CO2 to; removes CO2 from -removes CO2 from; introduces CO2 to

removes CO2 from; introduces CO2 to

Energy flow through ecosystems can be depicted using a(n): -food chain. -trophic pyramid. -food web. -ecosystem. -Calvin cycle.

trophic pyramid

Following the 10% rule for energy moving through a trophic pyramid, an increase of 10% at the level of primary producer would increase the biomass supported in the secondary producer trophic level by: -0.1% -1% -10% -0.01%

0.1%

If all volcanic activity were to stop tomorrow, there would be a _____ reduction in carbon flux into the atmosphere. -99% -66% -33%

99%

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

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

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

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

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

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

Why does the burning of fossil fuels have such a large impact on atmospheric carbon concentrations? -The impact is minimal rather than large because volcanic activity has been raising CO2 levels in the atmosphere at a constant rate since Earth formed. -Burning fossil fuels results in the release of carbon held in sinks for over 350 million years, and there is no other reservoir capable of holding that amount of carbon. -Burning fossil fuels does not have a large impact because current plant biomass can absorb the CO2 through photosynthesis. -The impact is large because the CO2 rises to a level in the atmosphere that cannot be utilized by or absorbed by plants through photosynthesis.

Burning fossil fuels results in the release of carbon held in sinks for over 350 million years, and there is no other reservoir capable of holding that amount of carbon.

Consider the graph shown. Studies using isotopic CO2 ratios have shown that the ratio of 13C /12C in the atmosphere has declined. What would it indicate if the ratio of 13C /12C had remained constant? -It would suggest that plants have started incorporating more 13C into their tissues. -It would suggest that volcano activity was responsible for rising CO2 levels -There would be a change in CO2 levels in ice cores. -Detecting an increase in CO2 emissions from the burning of fossil fuels would be less likely.

Detecting an increase in CO2 emissions from the burning of fossil fuels would be less likely.

Which of the answer choices is a form of nitrogen that can be utilized by plants? -N2 -NH4+ -NO2— -None of the other answer options is correct. -NO3—

NO3—

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 -false

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.

Imagine that scientists have discovered a new planet that is apparently devoid of life but has ice caps located at the poles. These ice caps reveal that the planet's atmospheric O2 levels sharply increased about 1,000,000 years ago but then quickly dropped 50,000 years ago. What could account for these changes in atmospheric O2 levels? -Photosynthetic organisms evolved on the planet 50,000 years ago. -Photosynthetic organisms evolved on the planet 100,000 years ago but went extinct 50,000 years ago. -Oxygen-based mammalian life evolved on the planet 100,000 years ago. -Oxygen-based mammalian life evolved on the planet 100,000 years ago, and photosynthetic organisms evolved 50,000 years ago.

Photosynthetic organisms evolved on the planet 100,000 years ago but went extinct 50,000 years ago.

Carbon moves through ecosystems on both short- and long-term scales. Which of the statements best describes the movement of carbon through short-term time scales of the food chain? -Partially reduced carbon compounds from primary producers are completely reduced by decomposers. -Once carbon is fixed by primary producers, it will not enter the atmosphere again until broken down by decomposers. -Primary producers oxidize carbon compounds that were previously reduced by decomposers. -Primary producers fix atmospheric carbon into compounds that will be oxidized by secondary consumers.

Primary producers fix atmospheric carbon into compounds that will be oxidized by secondary consumers.

If we were able to restore the forests in the Northern Hemisphere that have been clear-cut in the past 300 years, what changes to the data shown in the graph would you expect? -There would be no change in atmospheric CO2 levels because the amount released to the atmosphere is too great to be absorbed through photosynthesis. -The year-to-year oscillation in CO2 levels would be more pronounced in that more CO2 could be absorbed each season. -The oscillation would increase because respiration levels would increase.

The year-to-year oscillation in CO2 levels would be more pronounced in that more CO2 could be absorbed each season.

Why isn't the point for CO2 concentration the same for April 2015 and April 2016? -There are seasonal fluctuations in CO2 levels during different seasons in the Northern Hemisphere. -There is variation in the instruments that collect CO2 data. -There is a continual rise from one year to the next in CO2 levels on the planet. -Respiration levels remain constant over time, but there is variation in the amount of CO2 produced through respiration.

There is a continual rise from one year to the next in CO2 levels on the planet.

As shown in the graph, we see decreases in CO2 that follow an annual pattern. This pattern is attributed to seasonal fluctuations in photosynthesis from large forests in the Northern Hemisphere. There are no large deciduous temperate forests in the Southern Hemisphere. How would you predict the CO2 concentration figure to change if there were deciduous temperate forests in the Southern Hemisphere as well ? -There would still be an increase year over year, but the magnitude of change in CO2 levels would be greater. -There would no longer be fluctuations, and the curve would be closer to a flat line. -There would still be fluctuations throughout the year, but the concentration levels for any one month on the graph would be the same from one year to the next. -There would still be an increase year over year, but the magnitude of change in CO2 levels would be smaller.

There would still be an increase year over year, but the magnitude of change in CO2 levels would be greater.

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? -Trout and amoebas utilize different sources of CO2. -Trout and amoebas evolved to utilize different sources of C6H12O6 (or other organic compounds). -Trout and amoebas have different metabolic pathways. -Trout and amoebas utilize different sources of O2. -Trout and amoebas are exposed to different environmental conditions, even when they inhabit the same pond.

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

A team of scientists studying a material have determined that 12C, 13C, and 14C occur in the material in a ratio of 1000:10:1. How did they most likely differentiate between these forms of carbon? -by the number of neutrons in 12C, 13C, and 14C -by the biomasses of 12C, 13C, and 14C -by the number of electrons in 12C, 13C, and 14C -by the number of positrons in 12C, 13C, and 14C -by the number of protons in 12C, 13C, and 14C

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

A(n) _____ is a community of organisms and the physical environment it occupies. -interaction -metapopulation -population -community -ecosystem

ecosystem

Currently, atmospheric CO2 levels are the highest they have ever been in Earth's 4.6 billion-year history. -true -false

false

If all of the tertiary consumers were removed from an environment, the associated food web, and thus the carbon cycle, would collapse. -true -false

false

Photosynthesis and respiration were the main causes of fluctuations in atmospheric CO2 levels over the last 500 million years. -true -false

false

The diverse array of photosynthetic plants and microbes is the result of different sources of CO2 and has little to do with environmental conditions. -true -false

false

An examination of geologic processes that drive the long-term carbon cycle shows that: -more carbon is moved from the atmosphere into geologic reservoirs than is released from geologic reservoirs into the atmosphere. -less carbon is moved from the atmosphere into geologic reservoirs than is released from geologic reservoirs into the atmosphere. -the same amount of carbon is moved from the atmosphere into geologic reservoirs as the amount released from geologic reservoirs into the atmosphere.

more carbon is moved from the atmosphere into geologic reservoirs than is released from geologic reservoirs into the atmosphere.

The movement of Earth's crust, plate tectonics, contributes to the long-term carbon cycle through all of the answer choices except: -volcanic activity. -photosynthesis. -mountain lifting. -None of the other answer options is correct. -subduction.

photosynthesis

The Olympic Mountain Range is an actively growing mountain range, where two tectonic plates are continuing to move each other, exposing more sedimentary rock. This movement of one tectonic plate contributing to the growth of the mountain chain will primarily: -return carbon to the ocean through weathering. -return carbon to the atmosphere through volcanic activity. -return carbon to sedimentary rocks through sedimentation of shells and skeletons. -return carbon to the atmosphere through oxidation of ancient organic matter.

return carbon to the ocean through weathering.

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 -false

true