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. 
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Question: Electrical signals in the brain travel through nerves to muscles. Two types of proteins exist in filaments in the muscles. The filaments move when the brain instructs them to. The motion of the filaments cause the muscle to shorten and contract. Opposing pairs of muscles exist in order to provide the necessary range of motion. 

Answer: How do muscles work?


Question: Solar panels are made up of two types of silicon. Sun shines on solar panels. Sunlight goes into the top half of the solar panel. Sunlight travels into the bottom half of the solar panel. The "jump" between the two halves can be used to make direct current. A solar "inverter" changes the direct current to alternating current. Alternating current can be used to power things in your house. 

Answer: How do solar panels generate electricity?


Question: Fluid. Waste enters the kidneys. A processing moment in the kidneys let waste and fluid pass. Prevents larger molecules to pass. Fluid goes back to the bloodstream. Bad waste is removed. The final product is turned into urine. 

Answer:
Describe how kidneys work