Biochemical Cycles

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AP Environmental Science › Biochemical Cycles

Questions 1 - 10
1

Which biogeochemical cycle is the only one without an atmospheric component?

The phosphorus cycle

The sulfur cycle

The nitrogen cycle

The carbon cycle

Explanation

All of the other cycles have at least one atmospheric component in their systems. The carbon cycle incorporates carbon dioxide in the photosynthesis portion of its cycle. The sulfur cycle incorporates gaseous sulfur dioxide when it is released by volcanic eruptions. The water cycle has the condensation of clouds in the atmosphere and the precipitation of those clouds as well. The nitrogen cycle incorporates atmospheric nitrogen gas before it is fixed by cyanobacteria. Only the phosphorus cycle does not have a phosphorus containing compound in the atmosphere that is essential for life on Earth.

2

Which biogeochemical cycle is the only one without an atmospheric component?

The phosphorus cycle

The sulfur cycle

The nitrogen cycle

The carbon cycle

Explanation

All of the other cycles have at least one atmospheric component in their systems. The carbon cycle incorporates carbon dioxide in the photosynthesis portion of its cycle. The sulfur cycle incorporates gaseous sulfur dioxide when it is released by volcanic eruptions. The water cycle has the condensation of clouds in the atmosphere and the precipitation of those clouds as well. The nitrogen cycle incorporates atmospheric nitrogen gas before it is fixed by cyanobacteria. Only the phosphorus cycle does not have a phosphorus containing compound in the atmosphere that is essential for life on Earth.

3

Which answer choice a pair of terms that are the most similar in reference to the water cycle?

Transpiration and evaporation

Condensation and percolation

Precipitation and percolation

Precipitation and runoff

Explanation

Transpiration is the evaporation of water from plants. Both terms can be defined as the conversion of liquid water on Earth into atmospheric water vapor. Condensation is the formation of clouds from water vapor. Precipitation is the release of water from clouds down towards the earth in the form of rain, hail, sleet or snow. Percolation is the seeping of water through the ground into groundwater sources like aquifers. Runoff is excess water on the superficial soil layers that cannot percolate into the ground.

4

Which answer choice a pair of terms that are the most similar in reference to the water cycle?

Transpiration and evaporation

Condensation and percolation

Precipitation and percolation

Precipitation and runoff

Explanation

Transpiration is the evaporation of water from plants. Both terms can be defined as the conversion of liquid water on Earth into atmospheric water vapor. Condensation is the formation of clouds from water vapor. Precipitation is the release of water from clouds down towards the earth in the form of rain, hail, sleet or snow. Percolation is the seeping of water through the ground into groundwater sources like aquifers. Runoff is excess water on the superficial soil layers that cannot percolate into the ground.

5

Which of the following is the major reservoir of nitrogen in the nitrogen cycle?

Atmoshpere

Bacteria

Soil

Plants

Animals

Explanation

Although all of the above are part of the nitrogen cycle, the major reservoir for nitrogen is the atmosphere. The atmosphere contains nitrogen gas which cannot be extracted by plants or animals from the atmosphere. From its reservoir in the atmosphere, nitrogen gas is combined with oxygen to form nitrate and carried to Earth dissolved in rain. Nitrogen-fixing bacteria produce ammonia. This is absorbed by plants and other producers and incorporated into biological molecules that are passed through the trophic levels. Nitrate and ammonia are released by excretion or by decomposer bacteria. Other bacteria convert these molecules back to atmoshperic nitrogen, completing the cycle.

6

Which of the following is the major reservoir of nitrogen in the nitrogen cycle?

Atmoshpere

Bacteria

Soil

Plants

Animals

Explanation

Although all of the above are part of the nitrogen cycle, the major reservoir for nitrogen is the atmosphere. The atmosphere contains nitrogen gas which cannot be extracted by plants or animals from the atmosphere. From its reservoir in the atmosphere, nitrogen gas is combined with oxygen to form nitrate and carried to Earth dissolved in rain. Nitrogen-fixing bacteria produce ammonia. This is absorbed by plants and other producers and incorporated into biological molecules that are passed through the trophic levels. Nitrate and ammonia are released by excretion or by decomposer bacteria. Other bacteria convert these molecules back to atmoshperic nitrogen, completing the cycle.

7

Which of the following steps is not part of the carbon cycle?

Transpiration

Photosynthesis

Combustion

Extraction

Respiration

Explanation

Transpiration concerns the process through which water is carried through plants from roots to small pores in leaves, where it evaporates into the atmosphere. Thus transpiration is not a part of the carbon cycle, which concerns the biochemical exchange of carbon.

8

Which of the following steps is not part of the carbon cycle?

Transpiration

Photosynthesis

Combustion

Extraction

Respiration

Explanation

Transpiration concerns the process through which water is carried through plants from roots to small pores in leaves, where it evaporates into the atmosphere. Thus transpiration is not a part of the carbon cycle, which concerns the biochemical exchange of carbon.

9

Which of these is a type of biogeochemical cycles?

Carbon cycle

Phosphorous cycle

Nitrogen cycle

Hydraulic cycle

All of these

Explanation

All of these are biogeochemical cycles:

Carbon cycle - plants and animals consume carbon dioxide and release carbon dioxide during decomposition or respiration, then the carbon dioxide returns to the atmosphere.

Phosphorus cycle - similar to the carbon cycle, plants and animals consume phosphorous and release it during decomposition. Then the phosphorous returns to the ground and waterways by way of bacteria and processes such as mineralization.

Nitrogen cycle - this is the most complicated biogeochemical cycles. This is because it takes place in multiple situations, including: nitrogen fixation, nitrification, denitrification, and ammonification.

Hydraulic cycle - the water cycle. Water evaporates, wind moves air (and water), precipitation occurs.

10

Which of these is a type of biogeochemical cycles?

Carbon cycle

Phosphorous cycle

Nitrogen cycle

Hydraulic cycle

All of these

Explanation

All of these are biogeochemical cycles:

Carbon cycle - plants and animals consume carbon dioxide and release carbon dioxide during decomposition or respiration, then the carbon dioxide returns to the atmosphere.

Phosphorus cycle - similar to the carbon cycle, plants and animals consume phosphorous and release it during decomposition. Then the phosphorous returns to the ground and waterways by way of bacteria and processes such as mineralization.

Nitrogen cycle - this is the most complicated biogeochemical cycles. This is because it takes place in multiple situations, including: nitrogen fixation, nitrification, denitrification, and ammonification.

Hydraulic cycle - the water cycle. Water evaporates, wind moves air (and water), precipitation occurs.

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