Most of the amino acids are coded for by more than one codon. What are the two amino acids that are coded by only one codon?

This is the diveristy of ecosystems natural communites and habits it is the variety of ways that species interact with each other and their environment

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

What are the student's observations and inferences before he starts his investigation?