How do genes make evolution possible?

One of the reasons that stars are so large is because

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.

This is an active transport mechanism by which cells pump sodium and potassium ions against the concentration gradient