In this task, you are given a paragraph, and your task is to construct a question from the given passage. Construct question in such a way that (i) it is well explained in the paragraph, (ii) the words may/may not be present in the paragraph, (iii) it should start with what/how/describe. Avoid creating a question that (i) is just relevant to one or two sentences, and (ii) not relevant to passage. 

Q: Bacteria changes nitrogen into ammonium through fixation. The nitrification process is where ammonium gets changed into nitrates by bacteria. Plants absorb the nitrates from soil into their roots through assimilation. When plants die, fungi and bacteria turn nitrogen back into ammonium through ammonification. The denitrification process pushes extra nitrogen from soil into the air. The cycle repeats from step 1. 

A: Describe the nitrogen cycle
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Q: Movements of tectonic plates causes the creation of volcanoes. These volcanoes erupt. Volcanic mountains are formed from the eruption. Sometimes tectonic plates crash into one another or ride over one another. These plates sometimes fold and buckle, which forms Fold Mountains. Sometimes fault blocks are raised or tilted, and they form Block Mountains. 

A: How are mountains formed?
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Q: The cornea and lens refract light into a small image. Shine it on the retina. The retina's rods and cones convert it to electrical pulses. The optic nerve carries electrical pulses through the optic canal. Nerve fibers end in the lateral geniculate nucleus and the visual cortex. 

A:
How does the human vision system work?
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