Why doesn't an onion have any chloroplast?

Question

Why doesn't an onion have any chloroplast?

Answer 1

The part you eat (which really are leaves) is not exposed to the sun, so it is useless to build chloroplasts in those cells.  Have you ever seen a sprout that has been growing in the dark?  It will be white too (it's protoplasts won't develop into chloroplasts because it's a waste of energy without sunlight).

Answer 2

The onion is an underground stucture (a bulb or corm).  An onion does have chloroplasts in its leaves though (the above ground part of the plant).