"what percentage of radiation exposure is a result of man made sources"

Compare and contrast the relative importance of the sporophyte vs gametophyte generation between nonvascular plants (bryophytes), seedless vascular plants and seed plants, and explain the ecological significance of a larger sporophyte generation

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 must be kept in mind when determining if an explanation is correct? check all that apply.which must be kept in mind when determining if an explanation is correct? check all that apply.