Answer:
All of the above are true.
Explanation:
Microbial cells are surrounded by the plasma membrane or cytoplasmic membrane. It serves as a selective barrier allowing materials in and out of the cell e.g. allowing nutrients in and waste out.
Microbial cells grow independently, in that they are unicellular, and so do not depend on the other cells to carry out the process. However, they rely on nutrients, and in some environments, these may be nutrients produced by other organisms.
Microbial cells are unicellular, although some microorganisms are multi-cellular. Microorganisms such as bacteria are unicellular, that is, exist as single cells.
Bacteria and viruses are microorganisms.
