Solution:

• Coenzymes are the enzymes that catalyze biochemical reactions. For example, NAD and NADP act as coenzymes, these are derived from niacin.
• NAD and NADP are the coenzymes with enzymes of the electron transport chain to initiate the transfer of an electron from the substrate to products.
• FAD acts as a coenzyme which catalyzes the splitting of ultraviolet-induced thymine dimers.
• ATP is not a coenzyme because it does not have any property to initiate an enzyme-catalyzed reaction.
• ATP can be an allosteric modulator, a product, or a substrate, a signaling molecule for an enzyme but not a coenzyme.