Question 1

Which of the following statements about the physiological responses of plants to increasing temperatures and carbon dioxide levels is NOT true?

Accepted Answer

The answer of Which of the following statements about the...

Question 2

Human impact on the nitrogen and phosphorus cycles happens primarily through our use of:

Accepted Answer

Human impact on the nitrogen and phosphorus cycles primarily occurs through our use of fertilizers, which contain high levels of these nutrients that can runoff into waterways and cause harmful algal blooms and hypoxia (low oxygen) in aquatic ecosystems. While fossil fuels can also impact these cycles through nitrogen oxide emissions, it is less significant compared to fertilizer use. Groundwater, marine resources, and minerals do not directly impact these cycles in significant ways.

Question 3

Which of the following will help SLOW the rate of increase of atmospheric CO₂?

Accepted Answer

All the options listed contribute to reducing the rate of increase of atmospheric CO2 by either directly reducing carbon emissions (such as using solar power instead of fossil fuels, driving more fuel-efficient cars) or indirectly by conserving energy and resources (like turning off lights in an empty room and using nuclear power as an alternative to fossil fuels).

Question 4

One of the major obstacles to decreasing atmospheric CO₂ is that natural processes that sequester carbon occur at much longer time scales than human processes that add CO₂ to the atmosphere.

Accepted Answer

Natural processes for carbon sequestration, such as photosynthesis, sedimentation, and rock weathering occur over longer timescales of hundreds to thousands of years, whereas human activities like burning fossil fuels and deforestation release carbon into the atmosphere much more quickly. This makes it challenging to mitigate the increasing levels of atmospheric CO2.

Question 5

Which of the following statements about ocean acidification is NOT true?

Accepted Answer

Ocean acidification actually decreases the availability of carbonate ions in seawater, which makes it more difficult for organisms such as corals to build their skeletons.

Question 6

So-called "dead zones" in coastal oceans are associated with nutrient runoff and oxygen-depleted bottom waters. What causes the oxygen depletion?

Accepted Answer

When algae and cyanobacteria die, they are decomposed by heterotrophic bacteria, which consume oxygen during aerobic respiration, leading to oxygen depletion in the water.

Question 7

In response to global climate change, it is likely that some plant species will survive while others will go extinct. All of the following are explanations of this pattern EXCEPT:

Accepted Answer

The statement "greenhouse gases are toxic" is not true. Greenhouse gases, such as carbon dioxide, play an important role in regulating Earth's temperature, but increasing levels can lead to climate change. However, this does not make them toxic to plants.

Question 8

About how much of the nitrogen added to croplands ends up in food?

Accepted Answer

Only about 10% of the nitrogen added to croplands ends up in food. The rest can be lost to the environment through leaching, runoff, or volatilization.

Question 9

An abundance of nitrogen (N) and phosphorus (P) in an aquatic environment leads to _____ levels of dissolved oxygen due to _____.

Accepted Answer

An abundance of nitrogen and phosphorus in aquatic environments often leads to eutrophication, where excessive nutrients promote the growth of algae and aquatic plants. When these organisms die, their decomposition by aerobic bacteria increases, consuming a lot of oxygen in the process. This heightened aerobic respiration reduces the levels of dissolved oxygen in the water, which can harm aquatic life.

Question 10

Nutrients from croplands are carried by the Mississippi River into the Gulf of Mexico. If nutrients are good for growth, why are scientists concerned about this nutrient influx?

Accepted Answer

The nutrient influx can lead to eutrophication - excessive growth of phytoplankton and algae - which can result in higher respiration rates on sinking algal material, leading to depleted oxygen within the gulf waters. This can lead to the creation of dangerously low-oxygen "dead zones" where marine life struggles to survive.

Question 11

Which of the following statements about global warming is CORRECT?

Accepted Answer

Higher latitudes, particularly the Arctic, have experienced more significant warming compared to equatorial regions, a phenomenon partly due to the feedback loop involving melting ice and snow.

Question 12

What is the evidence that human activity is causing increased atmospheric CO₂ levels?

Accepted Answer

The isotopic composition of atmospheric CO2 can be measured and shows that CO2 being added to the air now comes from combustion of fossil fuels.

Question 13

The United States experienced one of the worst droughts in its history in 2012. By itself, this severe drought is strong evidence for climate change.

Accepted Answer

While the 2012 drought was severe, it cannot be used as singular evidence for climate change. Weather patterns, including droughts, have always been a natural occurrence and cannot definitively be linked to climate change without considering long-term trends and data analysis.

Question 14

Dead zones have been documented in many areas. These dead zones are increasing in size each year. Which of the following would be one of the ways to decrease the size of these dead zones?

Accepted Answer

Dead zones are caused by an excess of nutrients, particularly nitrogen, in the water. This excess nitrogen comes primarily from agricultural runoff. Therefore, decreasing the volume of nitrogen used in agricultural areas near dead zones would be the most effective way to decrease the size of these dead zones. Planting more crops might help, but only if the crops are able to take up all of the excess nitrogen. Increasing populations of cyanobacteria, which are often responsible for creating dead zones, would only make the problem worse. Increasing populations of decomposers might help to some extent, but it would not address the underlying problem of excess nitrogen in the water.

Question 15

The results of the coccolithophorid experiment done by Riebesell and colleagues showed that:

Accepted Answer

Increasing CO2 levels, which lead to ocean acidification, have been shown to result in incomplete or poorly formed calcium carbonate scales in coccolithophorids, as demonstrated by Riebesell and colleagues.

Question 16

You track aquatic coastal levels of nitrogen and phosphorus at high latitudes and notice a sharp increase in the winter and then again in the spring. What do you expect the effect of these nutrient increases will be on the plankton populations?

Accepted Answer

Plankton populations are more likely to spike in the spring when light levels are higher, as light is a critical factor for photosynthesis, which supports plankton growth. In winter, despite increased nutrients, low light levels limit plankton growth.

Question 17

The source of nitrogen in nitrogen fertilizer manufacture is:

Accepted Answer

Nitrogen gas (N2) is the source of nitrogen in nitrogen fertilizer manufacture. This gas makes up 78% of the Earth's atmosphere and can be converted into various forms of nitrogen compounds through the Haber-Bosch process.

Question 18

Potential costs associated with increasing crop area include:

Accepted Answer

Increasing crop area often requires clearing forests, which decreases the biological storage capacity for carbon, leading to increased greenhouse gas emissions and climate change. Additionally, forest conversion to cropland often leads to the loss of biodiversity as natural habitats are eliminated. Choice C may or may not be a cost associated with increasing crop area, as it depends on the specific genetically modified organisms being used and the risks associated with them. Choice D may also be a consequence of increasing crop area, but it is not necessarily a cost.

Question 19

Compared with nitrogen, do we need to be concerned that we may run out of phosphates?

Accepted Answer

Nitrogen is obtained from nitrogen gas, which makes up 78% of Earth's atmosphere. This essentially makes it an infinite supply. On the other hand, phosphate is mined from sedimentary rock and deposits are limited. While there are extensive deposits of phosphate, they are not infinite like nitrogen gas.

Question 20

Which of the following statements about global warming and the greenhouse effect is CORRECT?

Accepted Answer

The greenhouse effect is a natural process where certain gases in Earth's atmosphere trap heat from the sun, keeping the planet warm and habitable. However, when the concentration of these gases, such as carbon dioxide, increases due to human activities, this can lead to global warming. So, while global warming is a result of the greenhouse effect, they are not the same thing.

Quiz 49: The Anthropocene: Humans As a Planetary Force

Which of the following statements about the physiological responses of plants to increasing temperatures and carbon dioxide levels is NOT true?

Human impact on the nitrogen and phosphorus cycles happens primarily through our use of:

Which of the following will help SLOW the rate of increase of atmospheric CO₂?

One of the major obstacles to decreasing atmospheric CO₂ is that natural processes that sequester carbon occur at much longer time scales than human processes that add CO₂ to the atmosphere.

Which of the following statements about ocean acidification is NOT true?

So-called "dead zones" in coastal oceans are associated with nutrient runoff and oxygen-depleted bottom waters. What causes the oxygen depletion?

In response to global climate change, it is likely that some plant species will survive while others will go extinct. All of the following are explanations of this pattern EXCEPT:

About how much of the nitrogen added to croplands ends up in food?

An abundance of nitrogen (N) and phosphorus (P) in an aquatic environment leads to _ levels of dissolved oxygen due to _.

Nutrients from croplands are carried by the Mississippi River into the Gulf of Mexico. If nutrients are good for growth, why are scientists concerned about this nutrient influx?

Which of the following statements about global warming is CORRECT?

What is the evidence that human activity is causing increased atmospheric CO₂ levels?

The United States experienced one of the worst droughts in its history in 2012. By itself, this severe drought is strong evidence for climate change.

Dead zones have been documented in many areas. These dead zones are increasing in size each year. Which of the following would be one of the ways to decrease the size of these dead zones?

The results of the coccolithophorid experiment done by Riebesell and colleagues showed that:

You track aquatic coastal levels of nitrogen and phosphorus at high latitudes and notice a sharp increase in the winter and then again in the spring. What do you expect the effect of these nutrient increases will be on the plankton populations?

The source of nitrogen in nitrogen fertilizer manufacture is:

Potential costs associated with increasing crop area include:

Compared with nitrogen, do we need to be concerned that we may run out of phosphates?

Which of the following statements about global warming and the greenhouse effect is CORRECT?

Quiz 49: The Anthropocene: Humans As a Planetary Force

Which of the following statements about the physiological responses of plants to increasing temperatures and carbon dioxide levels is NOT true?

Human impact on the nitrogen and phosphorus cycles happens primarily through our use of:

Which of the following will help SLOW the rate of increase of atmospheric CO2?

One of the major obstacles to decreasing atmospheric CO2 is that natural processes that sequester carbon occur at much longer time scales than human processes that add CO2 to the atmosphere.

Which of the following statements about ocean acidification is NOT true?

So-called "dead zones" in coastal oceans are associated with nutrient runoff and oxygen-depleted bottom waters. What causes the oxygen depletion?

In response to global climate change, it is likely that some plant species will survive while others will go extinct. All of the following are explanations of this pattern EXCEPT:

About how much of the nitrogen added to croplands ends up in food?

An abundance of nitrogen (N) and phosphorus (P) in an aquatic environment leads to _____ levels of dissolved oxygen due to _____.

Nutrients from croplands are carried by the Mississippi River into the Gulf of Mexico. If nutrients are good for growth, why are scientists concerned about this nutrient influx?

Which of the following statements about global warming is CORRECT?

What is the evidence that human activity is causing increased atmospheric CO2 levels?

The United States experienced one of the worst droughts in its history in 2012. By itself, this severe drought is strong evidence for climate change.

Dead zones have been documented in many areas. These dead zones are increasing in size each year. Which of the following would be one of the ways to decrease the size of these dead zones?

The results of the coccolithophorid experiment done by Riebesell and colleagues showed that:

You track aquatic coastal levels of nitrogen and phosphorus at high latitudes and notice a sharp increase in the winter and then again in the spring. What do you expect the effect of these nutrient increases will be on the plankton populations?

The source of nitrogen in nitrogen fertilizer manufacture is:

Potential costs associated with increasing crop area include:

Compared with nitrogen, do we need to be concerned that we may run out of phosphates?

Which of the following statements about global warming and the greenhouse effect is CORRECT?

Which of the following will help SLOW the rate of increase of atmospheric CO₂?

One of the major obstacles to decreasing atmospheric CO₂ is that natural processes that sequester carbon occur at much longer time scales than human processes that add CO₂ to the atmosphere.

An abundance of nitrogen (N) and phosphorus (P) in an aquatic environment leads to _ levels of dissolved oxygen due to _.

What is the evidence that human activity is causing increased atmospheric CO₂ levels?