A granum is a stack of thylakoid discs. "Grana" is Latin for "stacks of coins". Grana are connected by intergrana or stroma thylakoids, which join granum stacks together as a single functional compartment.
Yes. The atmosphere contains 78% nitrogen, 21% oxygen, and the rest is made up of carbon dioxide, hydrogen, water vapor, argon, helium, and other noble gases.