This is a viral disease which causes the immune system to not function properly. example: can be speady by sexual contact, sharing iv needles, or by blood transfusions.

Enzymes are proteins that speed up reactions by providing an additional energy source supplying additional molecules for the reaction removing inhibitors that slow down reactions lowering the amount of energy required

What percentage of light hits earth's surface directly?

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?