Best hard riddles with simple answers

The front of me is the source of a song Or to kiss with a fervor of love lifelong. My back is a plant fit for a queen, Crafted by needle, chemical, or machine.

What goes up and doesn’t come back down?

What's green and loud?

While I am in air, I am not in oxygen. I am also in water, but not in hydrogen. I am necessary in all animals, but you won't find me in the zoo. Look in all brains and you'll find me there too. What am I?

I have keys but no locks. I have a space but no room. You can enter, but can't go outside. What am I?

Where can you find rivers with no water, cities with no buildings and forests with no trees?

What has one head, one foot and four legs?

What is represented by this BrainBat Pattern? EST EST EST EST

I visit you every night even if you don't call me. I'm lost every day. What Am I?

What do you call an asian vegatable?