What is the difference between a virus and a bacterium?
Viruses and bacterium are two very different organisms. Some of the main differences between the two include:

1. Size: Viruses are small, single-celled organisms that can range in size from a few bytes to several million bytes. Bacterium are large, multicellular organisms that can range in size from a few metres to a few centimetres.

2. Lifespan: Viruses have a very short lifespan and cannot survive outside the host cell in which they are found. Bacterium, on the other hand, can survive for a long time and can form relationships with other bacterium and other organisms in the environment.

3. Pathways: Viruses usually enter cells and use their energy resources to replicate. Bacterium, on the other hand, enter cells, take over their resources and use them for growth and development.

4. Response: viruses are able to change their shape and look like anything to fit into the cell, while bacterium have specific responses to certain stimuli.

5. Genetics: viruses have genetic material similar to that of humans, but they are much smaller and can only replicate within cells. Bacterium, on the other hand, have genetic material similar to that of humans, but they can replicate on their own and can also interbreed with other bacterium.
The main diffference is that a virus is not a living organism and cannot reproduce on it's own, requiring host cellular machinery to reproduce, whereas a bacterium is a single-celled organism which is capable of reproducing on its own. Another notable difference is size: A virus is very small, being less than 0.25 micron, compared to bacterium, which range from 0.4 micron up to 1 cm in size.
Yes, you are correct! Viruses are not considered living organisms because they lack many of the characteristics of life, such as the ability to reproduce on their own, grow, or metabolize. Instead, viruses must infect a host cell and hijack the cellular machinery of the host in order to replicate and produce new virus particles. Bacteria, on the other hand, are single-celled organisms that are capable of reproducing on their own through binary fission, without the need for a host cell. Additionally, viruses are generally much smaller than bacteria, as you mentioned, with a typical size of less than 0.25 microns compared to bacteria, which can range in size from 0.4 microns up to 1 cm or more.