Energy releasing equation

Which of these serves as a reference for comparison during a scientific investigation? a)outcome variable (dependent variable) b) test variable (independent variable) c)control group d)hypothesis

This is the amino acid cysteine. circle the amine group, put a box aroundthe carboxylic acid group and use a different colored pencil/pen to circle the sidechain (r group). h o | ||nh2— c- c-oh | ch2 | sh

When analyzing tree rings, what do scientists assume a thin ring indicates?