A cat thinks that you are opening a can of cat food when it hears the can opener.
A dog shying away from a magazine or newspaper, if the owner has used one to swat the dog as punishment.
If humans are ok to use as examples, A child learning that a stove is hot by touching it.
MRNA (Messenger RNA)
rRNA (Ribosomal RNA)
tRNA (Transfer RNA)
A quadrilateral has 4 sides and each angle is 90 degrees therefore the sum would be 360 degrees