List the two main sources of renewable energy used in the United States.

Use this diagram of an animal cell to answer the question. where does the first stage of cellular respiration occur? w x y z

Read the following scenario to answer the following question. in some zoos, rare crosses between a male lion and a female tiger have produced hybrid offspring called "ligers." male ligers are sterile but some female ligers are fertile. in the wild, lion and tiger ranges do not naturally overlap, making such a cross unlikely. furthermore, the solitary behavior of tigers and the social organizations of lions create behavioral differences. applying the biological species concept, the sterility of ligers reveals that a. lions are probably a subspecies of tigers b. tigers and lions are the same species c. a new species called "ligers" is forming d. tigers and lions are separate species

Which of the following statements about protists are true? a. they are typically found in moist environments. b. they are all unicellular. c. they have a nucleus. d. they are all multicellular.