[Q]: What is the final step of the following process: - 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
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[A]: Opposing pairs of muscles exist in order to provide the necessary range of motion.

[Q]: What is the final step of the following process: - An owl leaves his nest - The owl flys out into the night - The owl looks down at the ground - The owls keen eyesight allows him to see in the dark - The owls sensitive hearing allows him to locate hidden prey - The owl swoops down
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[A]: The owl catches a mouse in his talons.

[Q]: What is the final step of the following process: - Pollution enters natural water sources such as rivers and lakes - The pollution negatively affects the water quality - The pollution negatively affects the health of plants and animals - The plants and animals have shorter, less healthy lives - The plants and animals do not reproduce very well - The number of plants and animals decreases over time - The quality of water gets worse and worse as there are no plants or animals to clean it
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[A]: Eventually there is nothing living in the water and it is unusable

[Q]: What is the final step of the following process: - Water seeps into rocks - The water freezes and thaws - Cracks form in the rocks - Cracks also form when rocks heat up
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[A]:
The rocks slowly break down.