Question 1

Figure 42.2 Diagram of a food web (arrows represent energy flow and numbers represent species)
-If Figure 42.2 represents a terrestrial food web,the combined biomass of 3 + 4 would probably be

Accepted Answer

In a food web, the biomass tends to decrease as you move up trophic levels. 
Option 1 includes only plants (primary producers) and so has the highest biomass among all other options. 
Option 8 is a tertiary predator that feeds on both herbivores (Option 3) and secondary predators (Option 7), hence it has relatively lower biomass compared to primary consumers (Options 2, 3, and 4) and secondary predators (Option 7). 
Options 2 and 6 have the same trophic position and so cannot be compared. 
Therefore, the combined biomass of Options 1 and 2 (primary producers and primary consumers) would be greater than the biomass of Options 3 and 4 (herbivores and primary carnivores) but less than the biomass of Option 1 alone. Thus, the correct answer is Option D (less than the biomass of 1 + 2).

Question 2

Which of the following locations is the main reservoir for nitrogen in Earth's nitrogen cycle?

Accepted Answer

The atmosphere is the main reservoir for nitrogen, as approximately 78% of the atmosphere is made up of nitrogen gas (N2). This nitrogen gas is converted into different forms through various processes, such as nitrogen fixation by certain bacteria and lightning, and is then utilized by living organisms before being returned to the atmosphere through denitrification and other processes.

Question 3

Corn production can be limited by nitrogen levels in the soil.Some farmers reduce the need to apply ammonia to their fields by rotating corn crops with nitrogen-fixing soybean crops.Using soybeans to add nitrogen to degraded soils is an example of

Accepted Answer

Biological augmentation refers to the use of living organisms to improve or restore an ecosystem, which is exactly what is happening when farmers use nitrogen-fixing soybean crops to add nitrogen to the soil for corn production. This reduces the need for synthetic fertilizers and promotes a more sustainable farming practice.

Question 4

Nitrogen can be used by plants in the form of

Accepted Answer

Nitrate ions (NO3-) are the most commonly used form of nitrogen by plants. They are easily absorbed by roots and can be converted into organic compounds within the plant. Other forms of nitrogen, such as ammonia and nitrite ions, can be toxic to plants in high concentrations. Uric acid is not a commonly used form of nitrogen by plants.

Question 5

How does phosphorus normally enter ecosystems?

Accepted Answer

Phosphorus normally enters ecosystems through rock weathering, as it is released from rocks and minerals as they break down over time. It can also be released through volcanic activity, but this is a less common source.

Question 6

The flow of energy in an arctic ecosystem goes through a simple food chain: phytoplankton to zooplankton to fish to seals to polar bears.Which of the following is most correct about this food chain?

Accepted Answer

The energy transfer is greater from zooplankton to fish than from fish to seals, as there is a greater loss of energy between trophic levels in a food chain. This means that less energy is available for transfer to the next level. Therefore, the total biomass of fish is higher than that of seals. Additionally, the energy transfer from seals to polar bears would also be lower than that from seals to fish. Finally, there is not necessarily equal energy transfer between all organisms at all levels of the food chain.

Question 7

After Hurricane Katrina,sunflowers and other plants were planted to selectively remove contaminants from the soil.Once the plants matured,they were pulled up by the roots and safely stored with other contaminated wastes.This is an example of

Accepted Answer

This is an example of phytoremediation, a process that uses plants to remove pollutants from the soil or water. The plants selectively absorb the contaminants, which are then stored in their tissues or converted into less harmful forms. In this case, sunflowers were used to remove contaminants from the soil, and once mature, they were pulled up and safely stored, effectively detoxifying the soil.

Question 8

Which of the following statements about biogeochemical cycling is correct?

Accepted Answer

The phosphorous cycle involves the weathering of rocks of marine origin, as marine sedimentary rocks contain phosphorous that can be weathered and released into the soil and water. The other statements are incorrect: atmospheric phosphorus gas is not a significant component of the phosphorous cycle, photosynthesis produces oxygen and glucose rather than carbon dioxide, and the carbon cycle does not maintain a constant level of atmospheric carbon dioxide.

Question 9

Why do logged tropical rain forests typically have nutrient-poor soils?

Accepted Answer

Most of the nutrients in a tropical rain forest are stored within the biomass, including the trees. When these trees are logged and removed, the nutrients contained within them are also removed from the ecosystem, leading to nutrient-poor soils.

Question 10

Which of the following is an example of bioremediation?

Accepted Answer

Bioremediation involves using living organisms, such as microorganisms, to break down and remove pollutants from the environment. Option D is the only choice that involves using microorganisms to eat oil in marine waters after a tanker oil spill, making it the best example of bioremediation. The other choices involve different methods of managing or repairing the environment but do not directly involve the use of living organisms to remove pollutants.

Question 11

Figure 42.3
-In the diagram of the nitrogen cycle in Figure 42.3,which number represents nitrogen gas?

Accepted Answer

The answer of  Figure 42.3
-In the diagram of the...

Question 12

In Japan,seaweed and seagrass bed reconstruction included constructing a seafloor habitat,transplanting seaweeds and seagrasses,and hand seeding.Which of the following correctly pairs the specific task with the restoration strategy?

Accepted Answer

Biological augmentation involves adding living organisms to an ecosystem to restore or enhance its function. Transplanting seaweeds and seagrasses is a form of biological augmentation because it involves adding these organisms to the seafloor habitat to restore the ecosystem.

Question 13

In the nitrogen cycle,which step depends exclusively on bacteria?

Accepted Answer

Nitrogen fixation is the process where nitrogen gas is converted into a form that can be used by plants, which is only carried out by certain types of bacteria. The other steps mentioned in the question do not exclusively depend on bacteria.

Question 14

Consider the food chain grass → grasshopper → mouse → snake → hawk.How much of the chemical energy fixed by photosynthesis of the grass (100%)is available to the hawk?

Accepted Answer

In a typical food chain, about 10% of the energy is transferred from one trophic level to the next. Starting with 100% energy in grass, only 10% of that energy is transferred to the grasshopper, then 10% of that to the mouse, 10% of that to the snake, and finally 10% of that to the hawk. This results in 0.01% of the original energy being available to the hawk (0.1% of 0.1% of 0.1% of 0.1% = 0.01%).

Question 15

Figure 42.2 Diagram of a food web (arrows represent energy flow and numbers represent species)
-If Figure 42.2 represents a marine food web,the simplest organism might be

Accepted Answer

The simplest organism in this food web would be represented by the number 1, which is likely a primary producer, such as a type of phytoplankton.

Question 16

What is the first step in the restoration of an extremely degraded ecosystem?

Accepted Answer

The answer of What is the first step in the...

Question 17

Which of the following locations is the largest reservoir for carbon in the carbon cycle?

Accepted Answer

Sedimentary rocks are the largest reservoir for carbon in the carbon cycle, storing approximately 99% of Earth’s carbon. These rocks are formed over millions of years from the accumulation of organic matter and the remains of marine organisms that settle on the ocean floor. The other choices listed are important parts of the carbon cycle, but they do not function as large-scale reservoirs for carbon like sedimentary rocks.

Question 18

In the nitrogen cycle,the organisms that convert nitrate to atmosphere N₂ are

Accepted Answer

Denitrifying bacteria use nitrate as a source of oxygen, converting it back to atmospheric nitrogen.

Question 19

Rain falls on a fertilized agricultural field after a farmer has harvested the corn.Which biogeochemical cycles are involved when runoff from the field flows into a nearby stream?

Accepted Answer

When runoff from the fertilized field flows into a nearby stream, it can carry nitrogen and phosphorus from the fertilizer into the water, leading to eutrophication. Carbon is not a major component of this process, therefore carbon cycle is not involved here.

Question 20

What is the goal of restoration ecology?

Accepted Answer

The goal of restoration ecology is to initiate or accelerate the restoration of a degraded ecosystem by implementing techniques such as introducing native species, controlling invasive species, and repairing damaged landscapes. While complete restoration to a former state may be ideal, it is often not feasible and restoration is focused on improving the current state of the ecosystem. Park status and managing competition are not the main goals of restoration ecology.

Quiz 42: Ecosystems and Energy

Figure 42.2 Diagram of a food web (arrows represent energy flow and numbers represent species) -If Figure 42.2 represents a terrestrial food web,the combined biomass of 3 + 4 would probably be

Which of the following locations is the main reservoir for nitrogen in Earth's nitrogen cycle?

Corn production can be limited by nitrogen levels in the soil.Some farmers reduce the need to apply ammonia to their fields by rotating corn crops with nitrogen-fixing soybean crops.Using soybeans to add nitrogen to degraded soils is an example of

Nitrogen can be used by plants in the form of

How does phosphorus normally enter ecosystems?

The flow of energy in an arctic ecosystem goes through a simple food chain: phytoplankton to zooplankton to fish to seals to polar bears.Which of the following is most correct about this food chain?

After Hurricane Katrina,sunflowers and other plants were planted to selectively remove contaminants from the soil.Once the plants matured,they were pulled up by the roots and safely stored with other contaminated wastes.This is an example of

Which of the following statements about biogeochemical cycling is correct?

Why do logged tropical rain forests typically have nutrient-poor soils?

Which of the following is an example of bioremediation?

Figure 42.3 -In the diagram of the nitrogen cycle in Figure 42.3,which number represents nitrogen gas?

In Japan,seaweed and seagrass bed reconstruction included constructing a seafloor habitat,transplanting seaweeds and seagrasses,and hand seeding.Which of the following correctly pairs the specific task with the restoration strategy?

In the nitrogen cycle,which step depends exclusively on bacteria?

Consider the food chain grass → grasshopper → mouse → snake → hawk.How much of the chemical energy fixed by photosynthesis of the grass (100%) is available to the hawk?

Figure 42.2 Diagram of a food web (arrows represent energy flow and numbers represent species) -If Figure 42.2 represents a marine food web,the simplest organism might be

What is the first step in the restoration of an extremely degraded ecosystem?

Which of the following locations is the largest reservoir for carbon in the carbon cycle?

In the nitrogen cycle,the organisms that convert nitrate to atmosphere N₂ are

Rain falls on a fertilized agricultural field after a farmer has harvested the corn.Which biogeochemical cycles are involved when runoff from the field flows into a nearby stream?

What is the goal of restoration ecology?

Quiz 42: Ecosystems and Energy

Figure 42.2 Diagram of a food web (arrows represent energy flow and numbers represent species) -If Figure 42.2 represents a terrestrial food web,the combined biomass of 3 + 4 would probably be

Which of the following locations is the main reservoir for nitrogen in Earth's nitrogen cycle?

Corn production can be limited by nitrogen levels in the soil.Some farmers reduce the need to apply ammonia to their fields by rotating corn crops with nitrogen-fixing soybean crops.Using soybeans to add nitrogen to degraded soils is an example of

Nitrogen can be used by plants in the form of

How does phosphorus normally enter ecosystems?

The flow of energy in an arctic ecosystem goes through a simple food chain: phytoplankton to zooplankton to fish to seals to polar bears.Which of the following is most correct about this food chain?

After Hurricane Katrina,sunflowers and other plants were planted to selectively remove contaminants from the soil.Once the plants matured,they were pulled up by the roots and safely stored with other contaminated wastes.This is an example of

Which of the following statements about biogeochemical cycling is correct?

Why do logged tropical rain forests typically have nutrient-poor soils?

Which of the following is an example of bioremediation?

Figure 42.3 -In the diagram of the nitrogen cycle in Figure 42.3,which number represents nitrogen gas?

In Japan,seaweed and seagrass bed reconstruction included constructing a seafloor habitat,transplanting seaweeds and seagrasses,and hand seeding.Which of the following correctly pairs the specific task with the restoration strategy?

In the nitrogen cycle,which step depends exclusively on bacteria?

Consider the food chain grass → grasshopper → mouse → snake → hawk.How much of the chemical energy fixed by photosynthesis of the grass (100%) is available to the hawk?

Figure 42.2 Diagram of a food web (arrows represent energy flow and numbers represent species) -If Figure 42.2 represents a marine food web,the simplest organism might be

What is the first step in the restoration of an extremely degraded ecosystem?

Which of the following locations is the largest reservoir for carbon in the carbon cycle?

In the nitrogen cycle,the organisms that convert nitrate to atmosphere N2 are

Rain falls on a fertilized agricultural field after a farmer has harvested the corn.Which biogeochemical cycles are involved when runoff from the field flows into a nearby stream?

What is the goal of restoration ecology?

In the nitrogen cycle,the organisms that convert nitrate to atmosphere N₂ are