input question: What is the missing first step of the following process: - A muscle fiber gets a signal from its nerve - Proteins and chemicals release energy to either contract the muscle or relax it - When the muscles contracts the bones connected to he muscle are pulled closer together - When the muscle relaxes the bones move farther apart.???
output answer: Muscles work by expanding and contracting

input question: What is the missing first step of the following process: - The remains of the plant are buried very fast in sediment - The soft parts of the plant decay - The hard parts of the plant are replaced with minerals - The sediment turns into rock - The rock erodes - The fossil appears on the surface of the ground.???
output answer: A plant dies

input question: What is the missing first step of the following process: - Falls onto the ground - The acid rain starts scouring rocks - Destroys vegetation - The lack of vegetation alters the surrounding environment.???
output answer: Acid rain is produced by chemicals that reach into the atmosphere

input question: What is the missing first step of the following process: - Winter comes and the animal finds a place to hibernate - Over a period of days, the animal's heart rate and breathing rate drop slowly - Electrical activity in the brain almost ceases completely, though some areas remain active - The animal has entered hibernation mode -???
output answer:
The animal eats large quantities of food that will be stored as fat