Need the answers to this so I can fill out the work sheet with the key above

Elephants in the savanna regions of africa dig holes in dried up river beds to reach water lying just below the surface. these holes provide drinking water for other animals as well. so, without the elephants, many animals might otherwise die from lack of water during the dry season. the location in which the elephants live is an example of a/n and the role they play in creating water holes is an example of a a) ecosystem; habitat b) community; niche c) habitat; niche d) niche; habitat

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

What would most likely happen to a unicellular organism if it was exposed to a hypotonic solution for an extended period of time?