I need help please !!

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?

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important

Dan made the table shown to describe two different relationships between animals. organism interactions relationship a relationship b one organism lives inside the organism it feeds off no organism is harmed which of the following statements is most likely correct?