Problem: What is the missing first step of the following process:  -  Is trapped - Plant also takes in water and carbon dioxide from the environment - The plant forms glucose - The plant releases oxygen into the atmosphere.

A: Sunlight strikes the chlorophyll molecules in the plant


Problem: What is the missing first step of the following process:  -  The liver uses chemicals and proteins to treat the blood - The blood is cleaned - Energy is produced - The blood leaves the liver cleaned.

A: Blood is sent to the liver


Problem: What is the missing first step of the following process:  -  The water combines with carbon dioxide in the air to form carbonic acid - As the acid is formed, the iron starts to dissolve - Some of the water breaks down into hydrogen and oxygen - The free oxygen and dissolved iron bond together - They form iron oxide, which is rust -

A: Water comes into contact with something made of iron


Problem: What is the missing first step of the following process:  -  The bat makes sounds with their mouth or nose - The sound waves travel away from the bat - The sound waves hit objects - The sound waves bounce off the objects back towards the bat - The bat hears the sound waves echoing off the objects - The bat knows where the objects are because of where the sound echoed from - The bat doesn't hurt itself by hitting the objects.

A:
Bats fly through an area