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]: Blood enters the kidney. The blood travels into the neophrons. Waste is expelled via the neophrons. The waste goes to the bladder in the form of urine. The clean blood exits the kidneys. 
[A]: How do kidneys filter blood?


[Q]: Magma rises through surrounding rock. Gas bubbles form and expand, causing lots of pressure. This pressure pushes the magma through weak spots in the earth's surface,. Magma flows out as lava. This can happen slowly or in a huge explosion. 
[A]: What happens during a vocanic eruption?


[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