High School Biology : Ecology
Study concepts, example questions & explanations for High School Biology
All High School Biology Resources
Example Questions
Example Question #1 : Understanding The Nitrogen Cycle
Nitrification is the process of turning __________ into __________.
NO3- . . . N2
animal waste . . . NH3
NO3- . . . plants
N2 . . . NH3
NO2- . . . NO3-
NO2- . . . NO3-
Nitrification is the process by which nitrite (NO2-) is converted to nitrate (NO3-). This is the final step required in the processes used to oxidize nitrogen wastes (ammonia) to usable nitrate ions.
The conversion of gaseous nitrogen to ammonia (N2 to NH3) describes nitrogen fixation, and is usually done by nitrogen-fixing bacteria.
The conversion of nitrate to plant matter (NO3- to plants) describes the process of assimilation.
The conversion of nitrate to gaseous nitrogen (NO3- to N2) describes denitrification, and is performed by denitrification bacteria.
The conversion of animal waste to NH3 describes ammonification, and is accomplished by saprobiotic (decomposing) bacteria.
Example Question #3 : Understanding The Nitrogen Cycle
How do plants obtain nitrogen?
From the atmosphere
From water
From the soil using their roots
Plants do not use nitrogen
From the soil using their roots
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.
Example Question #1 : Understanding The Nitrogen Cycle
What is the largest natural reservoir nitrogen on earth?
The geosphere
The sun
The biosphere
The hydrosphere
The Earth's atomosphere
The Earth's atomosphere
The atmosphere is composed of 78% nitrogen gas and while by mass the atmosphere is less massive than the all the other choices the other choices are not primarily composed of nitrogen and contain relatively little compared to the nitrogen in the atmosphere.
Example Question #2 : Understanding The Nitrogen Cycle
Is the majority of the Earth's nitrogen immediately available for use by plants and other living organisms? Why?
No, most of it exists as inorganic nitrogen gas and is not immediately usable to most organisms.
Yes, because the nitrogen gas that composes the atmosphere is usable to most organisms.
No, because the majority of the world's nitrogen is locked in geological reservoirs
Yes, because the majority of the world's nitrogen is present in ammonium
No, because nitrogen gas is not able to be converted to other forms.
No, most of it exists as inorganic nitrogen gas and is not immediately usable to most organisms.
Since the nitrogen gas that composes 78% of the atmosphere is not immediately usable to all organisms except for nitrogen-fixing organisms the nitrogen that composes the Earth's major nitrogen reserve is not immediately usable to most organisms.
Example Question #2 : Understanding The Nitrogen Cycle
Which of the following is not a way in which nitrogen is fixed?
Deposition
Lightening
The Haber-Bosch process
Volatilization
Nitrogen-fixing bacteria
Volatilization
Volatilization is a process by which fixed nitrogen is released back into the atmosphere as 
Example Question #1 : Understanding The Nitrogen Cycle
What is the main way that fixed nitrogen is released back into the atmosphere?
Volatilization
Denitrifying microbes
Crop harvests
Erosion
Runoff
Denitrifying microbes
Only two options here actually lead to the conversion of fixed nitrogen to atmospheric nitrogen, volatilization and denitrification of which denitrification is a relatively rapid process carried out by numerous denitrifying microbes thus making it the greater contributor to the return of nitrogen to the atmosphere from fixed nitrogen.
Certified Tutor
Certified Tutor
All High School Biology Resources
