Question

The step in Koch's postulates that most critically enabled him to determine that a particular microbe was the cause, and not an effect, of a particular disease was __________.

Answer 1

Cells from the pure culture can cause disease in healthy individual after infecting it with the pure culture.

Explanation:

Koch postulates says that microbes are the cause of every disease. These microbes can be isolated from the infected host and can be grown outside the host in a pure culture. Then this pure culture is able to cause disease in a healthy host after infecting the host with pure culture. Then this same microbe can again be isolated from the second host.

So Koch postulates which proves that cells from the pure culture can cause disease in healthy individuals after infecting it with the pure culture was the step that enabled Koch to determine that a particular microbe is the cause of the disease because it was causing disease in healthy individual also.