Answer:
In a research there are two variables independent and dependent variable. independent variable is defined as the variable which is controlled and changed in a scientific experiment and evaluate the effects on the dependent variable while the variable which are tested and measured in experiment are called dependent variable.
When antibiotic is sprayed at one side of the petri dish, the bacterial growth on that side will eventually decrease in comparison to other side.
So, the independent variable in this experiment will be antibiotic because it is used to understand the growth of bacteria by decreasing their numbers and the dependent variable in this experiment will be bacteria as they vary according to the change in independent variable that is antibiotic.
Answer:
8900 CFU/mL
Explanation:
Colony Forming Units (CFU) is a value that indicates the degree of microbiological contamination of an environment. It expresses the relative number of microorganisms of a given taxon in a volume of one cubic meter of water.
UFC is the minimum number of separable cells on the surface, or inside, of a semi-solid agar medium that results in the development of a visible colony of the order of tens of millions of descending cells. The CFUs can be pairs, chains or clusters, as well as individual cells. Colony forming unit.
Calculation
Colonies * Dilution = CFU/mL
89 * (100/ 1 mL) = CFU/mL
8900 CFU/mL
Answer:
B, A fossil found in rocks from one time period
Explanation:
Fossils are used to determine the ages of rock layers. Index fossils are the most useful for this. Index fossils are of organisms that lived over a wide area. They lived for a fairly short period of time. An index fossil allows a scientist to determine the age of the rock it is in. Hope that this helps you :)
