Which of these are common theories that explain how the First Americans came to North and South America? Check all that are true.

They traveled across the ocean on boats.

They built a land bridge.

They rode across the ocean on large animals.

They migrated across Beringia.

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

At which location in earth’s interior does the top density continue to increase as thickness decreases?

Most animal cells membranes have proteins that pump ions out of the cell and potassium ions into the cell