Nitrogen Cycle Questions: Quiz!
Questions and Answers
- 1.
What is the most common way that nitrogen fixation occurs?
- A.
Lighting
- B.
Nitrogen-fixing bacteria
- C.
Fossil fuel combustion
- D.
Forest fires
Correct Answer
B. Nitrogen-fixing bacteriaExplanation
Microorganisms, particularly bacteria, play major roles in all of the principal nitrogen transformations. Nitrogen-fixing bacteria often form symbiotic relationships with host plants. In fact, most nitrogen-fixing is carried out by bacteria.Rate this question:
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- 2.
Atmospheric nitrogen (N2 gas) is easily taken up and used by plants and animals.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Although the majority of the air we breathe is N2, most of the nitrogen in the atmosphere is unavailable for use by organisms. In order for plants and animals to be able to use nitrogen, N2 gas must first be converted to a different form, such as ammonium (NH4+), nitrate (NO3-), or organic nitrogen.Rate this question:
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- 3.
Organic nitrogen is converted back to inorganic nitrogen like ammonium through the process:
- A.
Nitrogen fixation
- B.
Decay
- C.
Answer not here
- D.
Birth
Correct Answer
A. Nitrogen fixationExplanation
After nitrogen is incorporated into organic matter, it is often converted back into inorganic nitrogen by decay. When organisms die, bacteria and fungi consume organic matter. During decomposition, a significant amount of the nitrogen contained within the dead organism is converted to ammonium.Rate this question:
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- 4.
Ammonium (NH4) stays in the soil, while nitrate (NO3) is easily leached out. Why do they behave so differently?
- A.
NO3 is broken down by bacteria, so it is easily carried away
- B.
NH4has a positive charge and sticks to soil particles
- C.
NH4 is unavailable to organisms, so it remains unchanged in the soil.
- D.
NO3 is only produced when water is flowing through soil.
Correct Answer
A. NO3 is broken down by bacteria, so it is easily carried awayExplanation
Correct! In nitrification, some positively charged ammonium ions are converted to negatively charged nitrate. The positive charge prevents ammonium nitrogen from being leached out of the soil by rainfall. In contrast, the negatively charged nitrate ion is not held by soil particles and so can be washed out of the soil and into surface and groundwater.Rate this question:
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- 5.
Which process releases dinitrogen gas (N2) back into the atmosphere?
Correct Answer
denitrificationExplanation
Correct! In the process of denitrification, bacteria convert nitrate to dinitrogen (N2), a gas that is rapidly lost to the atmosphere.Rate this question:
- 6.
Once bacteria have fixed nitrogen, it can be taken up by plants and animals, where it is used in the production of
Correct Answer
proteinsExplanation
Correct! Nitrogen (N) is an essential component of DNA, RNA, and proteins. In the process of nitrogen fixation, bacteria convert N2 from the atmosphere into ammonium, a form that plants and animals can use. The ammonia produced by nitrogen fixing bacteria is used to make protein.Rate this question:
- 7.
Legumes host nitrogen fixing bacteria, and thus are good crops to plant to replenish the soil.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Correct! Burning fossil fuels, using synthetic nitrogen fertilizers, and cultivating legumes all fix nitrogen. Through these activities, humans have more than doubled the amount of fixed nitrogen that is pumped into the biosphere every year.Rate this question:
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- 8.
What is the chemical formula for the nitrogen gas that is in the atmosphere?
Correct Answer
N2Explanation
The chemical formula for nitrogen gas in the atmosphere is N2. This means that nitrogen gas consists of two nitrogen atoms bonded together. This formula is commonly used to represent the nitrogen gas that makes up about 78% of Earth's atmosphere.Rate this question:
- 9.
Click all the living organisms that play an important role in changing nitrogen when it gets to the soil.
- A.
Bacteria
- B.
Reptiles
- C.
Whales
- D.
Plants
Correct Answer
A. BacteriaExplanation
Bacteria play an important role in changing nitrogen when it gets to the soil. They are responsible for the process of nitrogen fixation, where they convert atmospheric nitrogen into a form that can be used by plants. This is a crucial step in the nitrogen cycle as it allows plants to obtain the necessary nitrogen for their growth and development. Reptiles, whales, and plants do not have the ability to change nitrogen in this way, making bacteria the correct answer.Rate this question:
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- 10.
Which process in the nitrogen cycle turns dead plants and animals to ammonium?
- A.
Nitrogen fixation
- B.
Nitrification
- C.
Ammonification
- D.
Deacidification
Correct Answer
C. AmmonificationExplanation
Ammonification is the process in the nitrogen cycle that converts dead plants and animals into ammonium. This occurs through the decomposition of organic matter by bacteria and fungi. During ammonification, these decomposers break down the proteins and other nitrogen-containing compounds present in dead organisms, releasing ammonium as a byproduct. This ammonium can then be further transformed into other nitrogen compounds through processes like nitrification and denitrification.Rate this question:
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- 11.
What process in the nitrogen cycle turns ammonium into nitrates?
- A.
Nitrogen fixation
- B.
Nitrification
- C.
Denitrification
- D.
Decayification
Correct Answer
B. NitrificationExplanation
Nitrification is the correct answer because it is the process in the nitrogen cycle that converts ammonium into nitrates. This process involves two steps: the first step is the oxidation of ammonium to nitrite by nitrifying bacteria, and the second step is the oxidation of nitrite to nitrate by different nitrifying bacteria. Nitrates are an important form of nitrogen that plants can easily absorb and use for growth, making nitrification a crucial step in the nitrogen cycle.Rate this question:
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- 12.
What percent of the air around you is made of nitrogen gas, N2?
Correct Answer
78, 78%Explanation
Approximately 78% of the air around us is made up of nitrogen gas, N2. Nitrogen is the most abundant gas in the Earth's atmosphere and is essential for many biological processes. This high percentage of nitrogen in the air is crucial for the survival of living organisms and plays a significant role in maintaining the balance of gases in the atmosphere.Rate this question:
- 13.
What process turns nitrogen into ammonium?
- A.
Nitrogen fixation
- B.
Ammonification
- C.
Denitrification
- D.
Yea
Correct Answer
A. Nitrogen fixationExplanation
Nitrogen fixation is the process that converts nitrogen gas (N2) into ammonium (NH4+), which is a form of nitrogen that can be utilized by plants and other organisms. This process is carried out by certain bacteria and archaea, either in the soil or in the root nodules of leguminous plants. These microorganisms have the ability to convert atmospheric nitrogen into a form that can be incorporated into organic compounds. Ammonification, on the other hand, is the process by which organic nitrogen compounds are converted into ammonium, while denitrification is the process that converts nitrate (NO3-) back into nitrogen gas.Rate this question:
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- 14.
Why is nitrogen important to live on Earth?
- A.
It is used to make DNA
- B.
It is used to make chlorophyll in plants
- C.
It is used to make proteins
- D.
It is used to make amino acids
- E.
It creates mud
Correct Answer(s)
A. It is used to make DNA
B. It is used to make chlorophyll in plants
C. It is used to make proteins
D. It is used to make amino acidsExplanation
Nitrogen is important for life on Earth because it is used to make DNA, chlorophyll in plants, proteins, and amino acids. DNA is the genetic material that carries the instructions for the development and functioning of all living organisms. Chlorophyll is the pigment that allows plants to photosynthesize and convert sunlight into energy. Proteins are essential for the structure, function, and regulation of cells, tissues, and organs. Amino acids are the building blocks of proteins. Therefore, nitrogen plays a crucial role in the fundamental processes of life and is necessary for the existence and functioning of living organisms.Rate this question:
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- 15.
Why can plants not utilize naturally occurring nitrogen gas?
- A.
Plants cannot break the triple bond between the two nitrogen atoms
- B.
Lack of nitrogen-fixing bacteria
- C.
There are insufficient amounts available in the atmosphere
- D.
Most of the nitrogen is stored as nitrate (NO3-)
Correct Answer
A. Plants cannot break the triple bond between the two nitrogen atomsExplanation
Plants cannot utilize naturally occurring nitrogen gas because they are unable to break the triple bond between the two nitrogen atoms. Nitrogen gas is composed of two nitrogen atoms tightly bonded together, and plants do not possess the enzymes necessary to break this strong bond. Instead, they rely on nitrogen-fixing bacteria to convert nitrogen gas into a usable form, such as nitrate (NO3-), which can be taken up by plants and used for growth and development.Rate this question:
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- 16.
Which of the following is most directly responsible for nitrogen fixation?
Correct Answer
bacteriaExplanation
Nitrogen fixation is mostly done by bacteria living in the soil. Plants need nitrogen to grow, but they cannot use it straight from the atmosphere or as ammonia from the soil.
Humans and animals largely obtain their necessary nitrogen by consuming plants, and do not fix nitrogen or rely directly on bacteria for the process.Rate this question:
- 17.
How do plants obtain nitrogen?
- A.
Plants do not use nitrogen
- B.
From water
- C.
From the soil using their roots
- D.
From the atmosphere
Correct Answer
C. From the soil using their rootsExplanation
The nitrogen in plants comes from the soil. Bacteria in the soil take nitrogenous wastes and convert it into forms of nitrogen that plants can use. Plants then take up nitrogen through their roots.Rate this question:
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- 18.
What is the largest natural reservoir nitrogen on earth?
- A.
Atomosphere
- B.
Sun
- C.
Ocean
- D.
Dirt
Correct Answer
A. AtomosphereExplanation
The atmosphere is the largest natural reservoir of nitrogen on Earth. Nitrogen makes up about 78% of the Earth's atmosphere and is crucial for many biological processes. It is an essential element for the formation of proteins and DNA in living organisms. Nitrogen is constantly cycled through the atmosphere, land, and water through various processes like nitrogen fixation, nitrification, and denitrification. The other options, such as the sun, ocean, and dirt, do not contain as much nitrogen as the atmosphere.Rate this question:
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