Diatoms have cell walls composed of
a. silicon dioxide
b. carbon dioxide
c. chitin

The correct answer is a - silicon dioxide.

Diatoms are single celled algae. They have a silica - based cell wall called a frustule, which gives each diatom a particular shape.

Diatoms exist as separate single cells although some may be found in groups or colonies. The ones found in colonies create very pretty forms: leaf shaped, oval , star and even like a period.

Outer shells of diatoms are quite valuable. They are used in industry in the manufacture of toothpaste to give it grit.

answer; /// i believe that the correct answer is ( monophasic ); ethinyl estradiol- ethynodiol diacetate is a monophasic oral contraceptive agent; ///