The comparison between a virus and a unicellular organism can be summarized as follows:
1. Viruses need energy; unicellular organisms also need energy: Both viruses and unicellular organisms require energy to carry out their biological functions, although they obtain energy in different ways. Viruses rely on the host cell's machinery for energy, while unicellular organisms generate energy through various metabolic processes.
2. Viruses reproduce through asexual reproduction; unicellular organisms usually reproduce through cell division: Viruses replicate by taking over the cellular machinery of a host cell and producing multiple copies of themselves. Unicellular organisms, on the other hand, typically reproduce through cell division or other forms of asexual reproduction.
3. Neither unicellular organisms nor viruses respond to stimuli: Although both viruses and unicellular organisms carry out various functions, neither of them possesses complex sensory or response mechanisms like multicellular organisms.
4. Unicellular organisms have a cell membrane made from a lipid bilayer; viruses have a protein coat: Unicellular organisms possess a cell membrane composed of a lipid bilayer that separates their internal cellular components from the external environment. In contrast, viruses have a protein coat, known as a capsid, which surrounds their genetic material.
It is important to note that while unicellular organisms are considered living organisms due to their cellular structure, viruses are often regarded as non-living or acellular entities that can only replicate within a host cell.