Explain the similarities and differences between direct and indirect methods of measuring microbial growth, and give examples of each.
What will be an ideal response?
Direct methods of measuring microbial growth involve quantifying the number of microbes in a specimen through actual counting of cells in a microscope or cytometer, or counting the numbers of colonies produced from the plating of a specimen. The advantage of these techniques lies in their usefulness for counting very large and very small populations of bacteria. Indirect methods, by contrast, seek to quantify cells by measuring some characteristic related to the number of cells present. For example, spectrophotometry measures the amount of light transmitted through a culture; the less light that is transmitted, the more cells are present. The amount of light transmitted gives an approximation of the number of cells present. Indirect methods are useful for quantifying microbes, such as filamentous microbes, that are hard to count directly. Both direct and indirect methods seek to arrive at an approximation of the actual number of cells present. Because that number is changing even during the measurement process, neither technique can give an exact number of cells.
You might also like to view...
On a road trip in the American West, you see a prairie dog town – a colony of related animals. There are hundreds of prairie dogs, but only a subset are scanning for predators at any time. If a predator is spotted, a prairie dog barks to warn the rest of the colony, who dart into their burrows. Prairie dogs have a complex vocabulary of alarm calls, which differ to indicate hawks, coyotes, or humans. What feature of group living is best illustrated by the prairie dog alarm system?
A. the many-eyes hypothesis B. the geometry of the selfish herd C. reciprocal altruism D. haplodiploidy E. optimality theory
Members of the lineage ____ include octopuses, squids, and nautiluses. Their fused head-foot body
has the "foot" modified into a set of arms and tentacles.
a. Cephalopoda b. Polyplacophora c. Bivalvia d. Gastropoda e. Scaphopoda
Reuse
What will be an ideal response?
A male human somatic cell has 22 pairs of autosomes and one pair of sex chromosomes.
a. true b. false