Faculty Topics addressed: Membranes, Mendelian Genetics, Enzymes, Cellular Respiration,
Evolution dealing with topics other than natural selection. In red are the published post-test
scores from hundreds of students—these are topics that faculty want questions on, and that
students still struggle on post-instruction
>>>IMCA; Q9 (A) (~70%)
A phospholipid molecule is diagrammed at the right, and the four diagrams A-D below represent cross
sections of spherical structures composed of phospholipids. Which of these structures is most likely to
form when a phospholipid is vigorously dispersed in water?
The incorrect answers represent two common
misconceptions: reversing polar and non-polar portions
of a phospholipid (b), as well as thinking the membrane
is comprised of one layer of phospholipids (c,d).
>>>IMCA; Q15 (A) (~60%)
Which of the following substances will be least likely to diffuse through a pure phospholipid bilayer
membrane that contains no proteins?
a) Na+
b)
c)
d)
The student must demonstrate a
knowledge of the types of small molecules
that are able to pass through a membrane,
and must understand exactly why ions are
less likely than a large non-polar molecule to
travel through a membrane, even though
both are not likely to pass through.
>>>IMCA; Q12 (B) (~70%)
If the intracellular reaction A + B →C proceeds in the presence of a specific enzyme and no other
components, you can conclude that:
a) the reaction would not proceed in the absence of the enzyme.
b) the reaction would proceed in the absence of the enzyme but at a slower rate.
c) the reverse reaction C → A + B would not proceed in the presence of the enzyme.
d) the reaction in the presence of the enzyme will not proceed any faster if the temperature is
raised a few degrees.
The student must understand how an enzyme works, and the role it plays in a chemical reaction. By
lowering activation energy, the enzyme speeds up a chemical reaction, making “b” the correct answer.
The incorrect answers address student misconception about the nature of enzymes, bring in related
topics such as temperature (d) and directionality of the reaction (c), while “a” addresses the
misconception that enzymes are always necessary for a reaction that utilizes them.
>>>IMCA Q20 (C) (~15%)
The replicated chromosome shown at the right (from a cell undergoing mitosis)
contains:
a) DNA from one of your parents in the sister chromatid on the left and DNA
from the other parent in the sister chromatid on the right.
b) DNA contributions from both parents, resulting from recombination (crossing
over).
c) DNA from only one of your parents.
>>>GCA Q9 (B) (59%)
A population of buffalos is isolated such that no new buffalos can come into their territory. Which of the
following is primarily responsible for the appearance of new alleles in this population?
a) Reassortment of chromosomes during the process of creating sperm or eggs.
b) Mutations in cells that will become sperm or eggs.
c) Changes in the environment that favor some buffalo traits over others.
d) Random mating between the buffalos in the population.
>>>GCA Q15 (C) (55%)
You have identified a previously unknown human gene that appears to have a role in autism. It is similar
enough in DNA sequence to a known mouse gene that you believe the two genes may be evolutionarily
related. You determine and compare the DNA sequences, the predicted mRNA sequences, and the
predicted amino acid sequences corresponding to the two genes. You would expect to find the greatest
sequence similarity from comparisons of the two:
a) DNA sequences.
b) mRNA sequences.
c) amino acid sequences.
d) All three comparisons are likely to show the same degree of sequence similarity.
>>>GCA Q3 (C) (56%)
An inherited disease that affects women and not men is likely to be caused by:
a) a mutation in a gene on the X chromosome, which is a sex chromosome.
b) a mutation in a gene on a non-sex chromosome (autosome).
c) without additional information, either answer (a) or (b) is possible.
>>>GCA Q20 (C) (58%)
Sue’s chromosome #18 pair looks like this (first picture):
Bob’s chromosome #18 pair looks like this (second picture):
Bob and Sue have a stillborn son with three copies of
chromosome #18 that look like this (third picture):
In which parent did the chromosome separation
problem occur?
a) Sue
b) Bob
c) You need additional information to determine which parent.