Carbon dioxide is a greenhouse gas that helps to trap heat in Earth's atmosphere. We need some CO2 in the atmosphere to maintain a warm planet, but excess
carbon can cause considerable warming of the planet.
A What fossil fuel usage will result in no change in atmospheric CO2 each year?
B. What percentage decrease in fossil fuel usage is required to achieve this goal?

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 group of algae is characterized by unicellular organisms and includes some members that would be better classified as zooflagellates? euglenophytes red algae sporozoans green algae

What are 3 reasons that natural selection occurs