Question How is growth measured in microbial populations? How do eukaryotes... How is growth measured in microbial populations? How do eukaryotes and bacteria/archaea differ in their reproductive methods? In what situation would the VBNC occurrence benefit cells? How could this pose a public health threat? Answer & Explanation 1. Microbial growth is determined is a lot of different ways:  If for example, it is being measured in the laboratory, then they can be reported in CFUs or Colony Forming Units. In this method, an inoculating loop can be used, and the number of colonies is multiplied depending on the calibration of the loop. This is particularly useful when determining the presence of bacteria in a urine culture, and for the diagnosis of UTI.  Bacterial growth can also be measured by using a spectrophotometer. In this equipment, the optical density of a solution containing the bacteria is determined; it is based on the amount of light transmitted and amount of light absorbed. The amount of light absorbed is directly proportional to the concentration of bacteria, while the amount of light transmitted is indirectly proportional to the population of bacteria.  If however a liquid culture needs to be determined of its microbial growth, directly counting the cells present or by diluting the original sample (and then counting cell numbers) can be done.  Indirect method include measuring the turbidity or cloudiness of a solution. This may be subjective, however.  2. Reproductive methods of eukaryotes and bacteria Eukaryotes reproduce both asexually and sexually. While bacteria/Archaea reproduce asexually only.  ASEXUAL REPRODUCTION: This type of reproduction whereby one parent produces offspring by cell division or without the fusion of two gametes is called asexual reproduction. This type of reproduction is commonly found among lower forms of organisms. One advantage of reproducing asexually is that an organism can produce many offspring in a short period of time without exerting much energy to either produce the gametes or to find a mate SEXUAL REPRODUCTION: Most animals especially in higher forms reproduce sexually - a process in which new individuals form from sex cells or gametes produced by the parents in their sexual organs. The testes produce the male gametes, while the ovaries produce the female gametes. The primary goal of sexual reproduction is to merge the sperm and egg (fertilization) of an animal to make a baby. 3. VBCN means viable but nonculturable cells. Normally, a bacterial cell can be cultured in the laboratory with the use of particular media that supports their growth. Performing a bacterial culture is useful in determining the specific pathogen present in a sample that causes disease to a person.  However, in the case of VBCNs, they cannot be cultured, which means that they cannot be grown in a laboratory. This is very important to known because VBCNs are metabolically active and still can cause infections to plants and animals. Examples of VBCNs are Legionella pneumophila and Vibrio cholerae. Being in VBCN state is advantageous for them because in enables to to "hide" and continue further infection. Lastly, this poses a health threat in a way because we are unable to actually grow and detect them in the laboratory, this makes them invisible as they invade an animal's body.