How do trophic levels change in a trophic level pyramid?

How can scientists test their ideas about the origin of the universe if they can't physically interact with or study?

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

Indicate the coat color and the proportion of offspring with that color for each of the following crosses of rabbits. assume all are homozygous. chinchilla x chinchilla 1/2 agouti, 1/2 chinchilla 3/4 agouti, 1/4 chinchilla all chinchilla