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

A. Silicon dioxide

Diatoms are unicellular algae that are found in the freshwater, brackish and marine water. These organisms exhibit cell wall that are made up of silica that is hydrated silicon dioxide. This type of cell wall is called as frustule. The cell wall is divided into two valves called as thecae.

explanation:

plz give me the characteristics.

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.