[Q]: What is the missing first step of the following process: - 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 - Eventually there is nothing living in the water and it is unusable -
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[A]: Pollution enters natural water sources such as rivers and lakes

[Q]: What is the missing first step of the following process: - Over time, more sediment piles on top - The resulting heat and pressure transforms the organic layer into a dark and waxy substance known as kerogen - Left alone, the kerogen molecules eventually crack - The molecules break up into shorter and lighter molecules composed almost solely of carbon and hydrogen atoms - It will turn into either petroleum or natural gas -
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[A]: Dead organic material accumulates on the bottom of oceans, riverbeds or swamps, mixing with mud and sand

[Q]: What is the missing first step of the following process: - 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.
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[A]: Blood enters the kidney

[Q]: What is the missing first step of the following process: - The liver uses enzymes to clean the blood - The cleaned blood is expelled - The liver creates bile from the items filtered - The liver takes energy and stores it as glycogen - The bile is sent to the intestines.
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[A]:
The liver takes in blood from the rest of the body