Which of the following is not a characteristic of bacteria? A. It contains a protective cell wall
B. It has a cell membrane
C. It lacks a nucleus
D. It is a multicelled organism

How are gene and protein sequences used to classify organisms?

Why is it important to study each branch of earth science?

Amino acids contain the elements carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. of the 20 amino acids found in humans, 11 are called "nonessential" because they can be manufactured by the body when needed. which elements in these 11 amino acids are commonly obtained from the metabolism of sugar molecules?