Problem: - Networks of trees start forming - The trees die off - The dead material provides nutrients for more trees - The rising trees provide shelter - And more organisms begin to thrive What might be the last step of the process?

A: The ecosystem known as a forest is made.

Problem: - Humans are born as babies - Babies become infants - Infants become children - Children learn skills - Children become teenagers - Teenagers undergo puberty - Teenagers become adults - Adults have children - Adults become elderly What might be the last step of the process?

A: Elderly humans die.

Problem: - Muscles work by expanding and contracting - 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 What might be the last step of the process?

A: When the muscle relaxes the bones move farther apart.

Problem: - Air is drawn in through the mouth - The air goes down the esophagus - The air moves into the lungs - The carbon dioxide is removed - The remaining oxygen enters the body What might be the last step of the process?

A:
The remaining carbon dioxide is expelled through the mouth.