The original source of energy in most ecosystems is a) water. b) the sun. c) carbon in the carbon cycle. d) the products of photosynthesis.

Which of the following statements best describes the relationship between the environment and human health? a. the environment is the only factor that affects human health. b. many aspects of the environment can have an impact on human health. c. human health is impacted by changes in climate. d. the environment has no impact on human health. select the best answer from the choices provided

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?

In the desert, saguaro cacti, owls, horned lizards, and fire ants all share the same space. which of the following can be considered a population? question 9 options: all plants in the same area all cacti in the same area all species in the same area the lizards and the ants