Chloroplasts and mitochondria are both unusual in that they have double membranes and contain their own set of DNA. Can you think of any explanations for this observation

How do accessory pigments chlorophyll?

The circles, or orbits, for electrons are called energy levels. each level can hold only a certain number of electrons. add electrons to each level until you can't add any more. how many electrons can each level hold?

Which statement describes john tuzo wilson’s contribution to the theory of plate tectonics?