Misc: what science combines botany and zoology?

Questions

Phoenix is the capital city of which US state?

What is the general name for a protein molecule which acts as a natural catalyst in the bodies of all bacteria, plants and animals?

What is the alternative name for the Galaxy?

Which gas was named after the Greek word for 'sun'?

Which substance used as a bleach, can also be used as the oxidizing agent in rocket fuel?