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Experiment: Antibiotic sensitivity
There is well understood documentation of the effect of Tetracycline on the microorganism E. col. Scientist have synthesised a new antibiotic and have devised an experiment to see if E. coli is as sensitive to the new antiiotic as it is to the Tetracycline. They soak a sterile disc in tetracycline, another in the new antibiotic, and a third in sterile Dl water. On the bottom of the plate, using a sharple, they divide the plate into three sections. They flipped the plate over and then cover the surface of a nutrient agar (petri dish) with a solution containing E.Coli, In one section of the plate they place the disc soaked in Tetracycline, in the adjacent section they place the disc soaked in new antibiotic, and on the third section they place the disc soaked in Dl water. They oincubate the plates overnight and observe the growth the following day. Effective antibiotics inhibit bacterial growth around the disc. This area is known as the zone of inhibition. The diameter of the zones of inhibition will be measured for each disc and compared. Identify the parts of the experiment.
a. Disc soaked in Tetracycline
b. Diameter of the zone of inhibition
c. Disc soaked in the new antibiotic
d. The discs soaked in their respective solutions
e. Disc soaked in Dl water
1. Independent variable
2. Dependent variable
3. Positive control
4. Negative control
5. Experimental

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Oseni

The different parts of the experiment to test if E. coli is as sensitive to a new antibiotic as it is to tetracycline would be as follows:

  • Disc soaked in tetracycline - positive control
  • Diameter of zone on inhibition - dependent variable
  • Disc soaked in the new antibiotic - experimental
  • The discs soaked in their respective solutions - independent variable
  • Discs soaked in Dl water - negative control

In experiments, positive controls are groups that are given treatments with already established results while negative controls are groups given the placebo but subject to the same experimental conditions.

The experimental groups are those that receive treatment whose outcome is yet to be known or about to be determined.

  • In this case, tetracycline is already known to have certain effects on E. coli, hence the discs soaked in tetracycline act as the positive control.
  • Dl water produces no effect and hence act as the negative control.
  • The effects that the new antibiotic would have on E. coli is not known yet, hence, it acts as the experimental.

Dependent variables are the actual variables to be measured in the course of experiments while independent variables are those supplied and manipulated by the researcher.

Dependent variables are results of 'effects' of the independent 'causal' variables. Hence, in this case, the supplied variables are the discs soaked in their respective solutions. They cause an effect that is measurable as zone of inhibition, the dependent variable.

More on various experimental groups can be found here: https://brainly.com/question/17602354