The layer of air that lies closest to earth is called the

stratosphere
thermosphere
mesosphere
troposphere

Which term refers to a group or community that forms the focal point of a study and consists of all the people considered for evaluation in the research? a. sample b. population c. variable d. mean

Which was not a part of the compromise of 1850? a. california was admitted to the u.s. as a free state. b. slavery was banned in western territories. c. slave trade was banned in washington d.c. d. the strict fugitive slave law was passed.

For 50 points.. some organisms feed on other organisms without immediately killing them. what term describes this act? a. predation b. commensalism c. mutualism d. parasitism