Ionic bond is a compound made up of a meta and a non-metal eg NaCl (sodium chloride)
covalent bond is made up of two non-metals eg H2O (water)
Plants go through a process called photosynthesis where they take in carbon dioxide from the atmosphere (as well as water and sunlight), and they turn it into oxygen (so we can breathe) and glucose (sugar)!
Your answer is going to be Hydrolysis