The of a trna molecule determines the type of amino acid that bonds with the trna

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

all these collisions do one thing, and that thing is explained in the last option. when dusst, rocks and ice collide, they harden and form giant layers of rocks or hard ice.

d)   to harden materials to form different parts of earth’s layers

hope it ,

bioteacher101