Which system is responsible for breaking down food to provide cellular energy?

What percentage of light hits earth's surface directly?

The double bond between a carbon atom and two oxygen atoms (a molecule of carbon dioxide) has two characteristics. what are they? a. an ionic bond is formed between the oxygen and carbon atoms. b. four valence electrons are shared. c. two valence electrons are shared. d. valence electrons are shared between oxygen atoms.

As a result of these processes the single celled organism accomplishes