Thu18November0303AM 10

A graph representing bacterial growth (y) with respect to time (x) is an exponential relationship.

Which one of the following statements is most specific for this type of exponential relationship?

(Please select 1 option)

As x increases the increase in y is proportional to y

The y intercept is 0, 1

The negative x axis is a horizontal asymptote

y = ex This is the correct answer

Is an example of a build-up exponential Incorrect answer selected

Explanation

Bacterial growth is an example of a tear-away exponential. Mathematically the relationship between y and x is:

y = ex

Where x is the power and e is the base.

Euler's number (e) is a mathematical constant = 2.718

The first answer option reflects the change in y with respect to x in any exponential relationship.

The second answer option incorrect as a build-up or wash-in exponential is represented mathematically as y = 1 - e-kt

Examples include:

Rate of rise of plasma concentration of an intravenous induction agent given by infusion

Volume change in lung during inspiration using a constant pressure generator

Rate of fall of alveolar partial pressure of volatile anaesthetic agents, and

Potential difference across a capacitor when charging.

The third and fourth answer options are true of tearaway exponentials but neither describe an exponential process.

Answer Statistics

1

13%

2

6%

3

6%

4

55%

5

22%

Times answered: 236