Sample Lab Test Questions
The test questions will cover objectives (posted on the Web page) for the experiments to be covered for that test (see syllabus for schedule). There will be ten questions covering a range of levels of thinking skills. They will not all be knowledge and comprehension questions. Here are some examples:
1. Which quantity describing the distribution of a sample
indicates the precision of the measurements in the sample?
A. mean
B. standard error
C. 95% confidence interval
D. standard deviation
Answer: D
Level: Knowledge (simple recall of information, in this
case the definition of standard deviation)
Objective covered: "Distinguish between accuracy and precision and state
the statistical quantity that describes each"
2. What does a colony represent when a bacterial culture is
plated on agar?
A. the offspring of a single bacterium in the original culture
B. the offspring of multiple bacteria in the original culture
C. the entire titer of the the original culture
D. one of the locations colonized by a single bacterium from the original
culture
Answer: A
Level: Comprehension (requires you to understand how a
colony arises on a plate)
Objective covered: "describe the origin of a bacterial colony and explain why a plate count provides a measure of the titer of the culture used to innoculate
the plate"
3. A sample of red blood cells was placed in a solution of NaCl.
The sample produced an absorbance of 0.045 when placed in a spectrophotometer
set on 600nm. The absorbance of another sample of red blood cells having
the same titer placed in PBS had an absorbance of 0.78 . How would you
describe the solution of NaCl into which the first sample was placed?
A. crenate
B. lysed
C. isotonic
D. hypotonic
E. hypertonic
Answer: D
Level: Application (You must know that a hypotonic
solution will lyse cells and that the lysing of cells causes a solution to
become clear and have a lowered absorbance. Note: the term lysed describes
what happens to the cells, but is not descriptive of the solution.)
Objective covered: "describe the changes that may occur to a cell
when placed in a hypotonic or hypertonic solution"
4. A student makes a lot of Spec 20 absorbance
measurements, but suspects that they are unreasonably low. When she puts
the blank in, the absorbance is 0. When she removes the cuvette it reads
1.0 . What is the likely problem?
A. The lamp of the spectrophotometer was probably burned out.
B. The blank adjustment (right knob) was probably not done or done wrong.
C. The 0% transmittance adjustment (left knob) was probably not done or done
wrong.
D. The cuvette is probably very dirty.
Answer: C
Level:
Analysis (You must be able to recognize the relevant information given, i.e.
that the reading is 1.0 when there is no cuvette, and apply your knowledge of
how a spectrophotometer works and is adjusted to determine which problem is
likely)
Objective covered: "recognize common mistakes made using the Spec20
spectrophotometer and diagnose Spec20 problems based on the condition of the
spectrophotometer"
5. A student performs the regular/antibacterial soap experiment
that we did in lab and records the following plate counts:
no soap - 2578 colonies
regular soap - 679 colonies
antibacterial soap - 652 colonies
Which counts should he compare to assess whether antibacterial compounds had an
effect in decreasing the number of bacteria surviving?
A. 652 vs. 679
B. 652 vs. 2578
C. 679 vs. 2578
D. all three must be compared
Answer: A
Level: Application
Objective covered: select the appropriate data from an experiment
that can be used to evaluate the effect of an experimental variable