The Five Kingdom classification system was used until the invention of: A. the microscope.
B. the scientific method.
C. DNA sequencing.
D. genes.

What was the land like over 500 million years ago? what was under the sea?

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?

What substance is the most acidic. lemon juice. tomato juice. sodium hydroxide. water