Bulletins for BIOL 1404

last revised:

Clicker Management

1. If your clicker number NEVER appears on the screen during a given class meeting, give me a sheet of paper with your name, full clicker number, and section number on it AT THE END of the period in which you experienced difficulty.  By the next class meeting, replace the battery and sit somewhere else in the lecture hall.  If this doesn't work, then you might replace the clicker and e-mail me your new clicker number by the next class meeting.

2. If your clicker number only sporadically appears, assure yourself that it is YOUR number that is missing.  If so, try moving around the room until you find a location where your clicker consistently gets picked-up, and/or replace the batteries. 

3. If you NEVER attend the section in which you are officially enrolled, then inform me and I will transfer your clicker number into the section that you attend.

4. If you sometimes attend one section, sometimes another then CURTAIL this activity.  On the rare days when you might attend the section in which you are not enrolled, give me a piece of paper with your name, entire clicker number, responses, and official section number on it AT THE END of the period you attended.

Strategies for success on open-note tests:

Some students cringe when an open-note test is announced; others leap for joy.  Why the divergence?  Those who cringe are focusing on the drawbacks: questions that rely on more mental sophistication than mere recall and regurgitation.  Those who leap are focusing on the benefits: the safety net offered by readily available notes.  So there are both benefits and drawbacks to such a testing format.  

The first step toward a successful outcome is knowing what the instructor expects from such a test.  In my case, I have been telling students for years that I am far more interested in their understanding the material than in their ability to remember it long enough for a test, then only to forget it.  Open-note tests emphasize student understanding over student memorization.  So I am most likely to craft questions that require understanding in order to be answered correctly.

To prepare yourself for such test questions (both essay and multiple-choice), you must already be very familiar with both your notes.  That means that you should have a complete and detailed set of notes, and that you have spent significant amounts of time reflecting about that material. 

Let's take an example from Test #4 from a previous semester in BIOL 1403.  One essay question was:

In accord with the endosymbiotic theory, make predictions about what one should expect to observe regarding (a) the process whereby mitochondria and chloroplasts reproduce themselves, (b) the kind of transcription unit found in mitochondria and chloroplasts, and (c) the proteins needed to carry out transcription in  mitochondria and chloroplasts.

The information needed to answer this question would not have been found in a good set of notes.  This question requires a student to think as a scientist thinks:  "If mitochondria and chloroplasts are descended from bacteria, then their characteristics should resemble those of prokaryotes more than they resemble those of the "host" eukaryote."  This reasoning isn't found in the textbook; it's supposed to be something that occurs in your brain.  Once this step has occurred, then you may find your text or notes helpful in determining how prokaryotes reproduce, what prokaryotic transcription units are, and what proteins are needed by prokaryotes to perform transcription.  Bottom line: the hard part of the question (the reasoning) can't be retrieved from the resources available.  Think about the question carefully, then use the notes to back up your reasoning with specific examples.

You should go into an open-note test resolved NOT to use these resources unless absolutely necessary.  Why?  Because every time you have to look something up, that's time taken away from writing or reasoning.  The test is NOT the time to study your notes.   If you find that you are spending more than 30-45 minutes on the multiple-choice part of the test, then something is wrong.  Remember that it takes 10 multiple-choice questions to equal 1 essay.  Essays require time spent reflecting and outlining before ever you start to write an answer.  If you find yourself looking up all sorts of stuff for multiple-choice items, there is every possibility that you won't have the time needed to write good essays, and this is a good way to lose lots of points.

Be aware that I am going to try to craft questions that cannot be readily answered merely by looking something up.  Your notes should be considered as last-resort "lifelines."  The correct answers are most likely to be arrived at by making the necessary mental connections in your own brain.  Notes can distract you from performing this critical process yourself.  They are not made available so that you can find all the answers you need; they are available in case your memory fails you on small details which you can then use these resources to find.

Below are a series of questions about Candida, Giardia, Streptococcus pneumoniae and herpesviruses.  You will find very little in your notes about these organisms.  The challenge in the questions connected to each paragraph is for you to apply the general principles covered in lecture or in your reading of the text to the solution of specific problems.  This application needs to take place in your brain; notes will not do it for you.

The following questions are based on the description below.  You will probably have much better success at answering these correctly if you read the assigned pages first.

Yeast infections in humans are often caused by Candida albicans.  This fungus is always present in the mouth and vagina in small populations that cause no harm.  The population is held in check by one's immune system, by the normal bacterial inhabitants of these orifices (which out-compete the fungi for nutrients), and by the relatively low pHs produced by the bacteria.  When the pH of these orifices increases for prolonged periods, when normal bacterial populations are diminished, or when one is immuno-suppressed, then the yeast population can escape from control and cause symptoms.  Yeast infections of the mouth are commonly known as thrush, and of the vagina as candidiasis.  Miconazole is often prescribed to treat such infections.  It inhibits the fungus' ability to synthesize a lipid for its plasma membranes.

1. During times of Candida outbreaks, the relationship of this fungus to its human habitat changes in what way?
(a) pathogen --> parasite            (d) mutualist --> commensal
(b) mutualist --> parasite            (e) parasite --> commensal
(c) commensal --> parasite

2. In order for miconazole to be effective against Candida, what should be true?
(a) The pH at the site of Candida's outbreak must be neutral.
(b) The miconazole must be able to somehow pass through a layer of chitin and a phospholipid bilayer to affect the cellular machinery that synthesizes lipids.
(c) The miconazole must be active in the presence of any antibiotics that have been prescribed.
(d) The environmental carrying capacity of Candida must have been exceeded.
(e) Candida's ribosomes must have been inactivated.

3. If bacteria inhibit Candida by secreting a metabolite that hinders fungal growth, then this inhibition is an example of:
(a) exploitative competition.            (d) predation.
(b) parasitism.                                   (e) intraspecific competition.
(c) interference competition.

4. Which should be most likely to develop a yeast infection? A person who is being treated with:
(a) a broad-spectrum antibiotic.
(b) a broad-spectrum anti-fungal.
(c) a vaccine against hepatitis B virus.
(d) quinine for an infection of Plasmodium falciparum.
(e) cytokines to boost immune system performance.

5. When Candida is "well-fed," it has the typical non-motile, unicellular morphology of a yeast.  When, however, Candida is nitrogen-limited, it assumes a filamentous (hyphate) morphology.  Assuming that this change in morphology has adaptive significance, which of these is the most likely explanation for the switch from unicellular to hyphate morphology?
(a) Spherical cells are better at absorbing nitrogenous compounds than are the cylindrical cells of hyphae.
(b) Speherical Candida cells can perform nitrogen-fixation, cylindrical cells cannot.
(c) Hyphae can locate untapped sources of nitrogen more effectively than can non-motile yeasts.
(d) The switch is like the blooms of dinoflagellates that occur when the correct P:N ratio occurs.

6. What should be the relationship between the incidence of dental carries (i.e. tooth cavities) which result from lactic acid secretion by mouth bacteria, and the incidence of thrush?
(a) a direct relationship
(b) an inverse relationship
(c) there can be no possible relationship
(d) the relationship depends on the pH of the vagina.

7. Which structure/substance should one observe in hyphate Candida that should not be observed among unicellular Candida?
(a) nucleus/nuclei            (d) cell wall
(b) chitin                           (e) septa
(c) plasma membrane

8. The following chart compares vaginal pH during certain drug treatments:

Based on these (hypothetical) mean vaginal pHs, which of these treatments has the greatest likelihood of causing candidiasis?

The following questions are based on the description below.  You will probably have much better success at answering these correctly if you read the assigned pages first. 

Giardia lamblia is a unicellular "protist" belonging to a lineage that is thought to have split off from the rest of the eukaryotes very early in the evolution of eukaryotes.  If it is ingested, it can cause the symptoms of giardiasis, or hiker's diarrhea.  The cells have no mitochondria, have a very simple cytoskeleton, and have two, haploid nuclei.  The nuclear DNA of Giardia contains a few genes that are clearly related to mitochondrial DNA, and it is thought that the ancestors of modern Giardia had mitochondria, but later lost them.  Modern Giardia manufacture ATP anaerobically.  

In aerobic freshwater streams, Giardia exists as dormant cysts.  If ingested, and introduced to the anaerobic small intestine of many mammal species, these cysts germinate into active cells that cause much intestinal discomfort in susceptible individuals.  Each episode of diarrhea is capable of releasing hundreds of millions of cysts into the environment.

1. Which metabolic processes should Giardia be able to perform?
(a) Kreb's cycle    (b) Glycolysis    (c) fermentation    (d) electron transport chains    (e) b & c only

2. The existence of which of the following is a clue as to the means by which the formerly mitochondrial genes became part of the nuclear genome?
(a) mobile genetic elements    (b) telomeres    (c) centromeres    (d) nucleoids    (e) nucleosomes

3. If one considers the formerly mitochondrial genes within the nuclear genome to be genes from another organism (as suggested by the endosymbiotic theory), then their presence in the nuclear genome could be considered an example of:
(a) translation    (b) transduction    (c) conjugation    (d) genetic recombination    (e) both a & b

4. If each of the chromosomes in a single nucleus has a homolog in the other nucleus, then if the two nuclei underwent karyogamy (fusion), what would subsequently be true of the nucleus?  It would be:
(a) haploid.    (b) diploid.    (c) triploid.    (d) tetraploid.

5. As a eukaryote, one should expect that Giardia possesses all of the following features, EXCEPT:
(a) linear chromosomes.                            (d) histones.
(b) introns.                                                    (e) ability to grow at temps. above 100 degrees C.
(c) multiple types of RNA polymerases.

6. In individuals who become symptomatic upon being infected by Giardia, all of the following terms are applicable to the Giardia, EXCEPT:
(a) symbiont.    (b) parasite.    (c) primary producer.    (d) chemoheterotroph.    (e) pathogen.

7. The primary treatment for giardiasis is a drug called metronidazole.  Especially among those who take alcohol during treatment with metronidazole, side effects of vomiting and nausea are common.  These side effects can be as nasty as the primary symptoms of the infection.  Why should one expect drugs used against protists, like Giardia, to have worse side effects than drugs used against bacteria?
(a) Giardia  is more similar to our cells than bacteria are to our cells.
(b) Giardia, being more advanced than bacteria, can put up a better fight against the drug than can bacteria.
(c) Protists have greater numbers of cell coverings than do bacteria, and some of these contain chemicals that, produce adverse reactions when mixed with anti-protist drugs.
(d) Protists have many more metabolic pathways than do bacteria, and some of these pathways can convert the anti-protist drugs into chemicals that are poisonous to us.

The following questions are based on the description below.  You will probably have much better success at answering these correctly if you read the assigned pages first.

In 1928, Fred Griffith was conducting research on bacterial pneumonia.  This disease can be caused by certain strains of the non-motile Streptococcus pneumoniae, of which Griffith had two different strains.  One strain, denoted the Smooth (S) strain because its colonies appear as smooth domes on agar surfaces, caused lethal pneumonia in mice.  The other strain, denoted Rough (R) because its colonies had a bumpy, irregular appearance, was non-pathogenic to mice.  When Griffith mixed heat-killed S strain pneumococcus with living R strain pneumococcus and inoculated mice with the mixture, the mice developed pneumonia and died.

1. One can derive a lot of information from this bacterium's name.  The term "diplococcus" is also applicable to this species.  Thus, the most accurate description of this species is:
(a) rod-like cells that form long chains.
(b) spherical cells that do not adhere to each other.
(c) spherical cells that form chains consisting of only two cells.
(d) spherical cells that form long chains of diploid cells.
(e) diploid, spherical cells that form grape-like clusters.

2. The appearance of colonies as either smooth or rough is due to the presence or absence, respectively, of a feature of individual bacteria.  Which of these structures is the direct cause of these colony characteristics?
(a) cell wall    (b) plasma membrane    (c) capsule    (d) pilus    (e) endospore

3. All of the daughter cells of a "smooth" cell are NOT necessarily themselves smooth.  What could account for this observation?
(a) The gene(s) that code(s) for smoothness may belong to a repressible operon.
(b) The gene(s) that code(s) for smoothness may undergo a mutation.
(c) The gene(s) that code(s) for smoothness may be located on a plasmid.
(d) all three of these.
(e) a & b only

4. The smoothness trait is easily transmitted to rough pneumococcus, thereby converting these cells into smooth cells.  If transmission can be brought about by live S cells that have not been infected by phage, then which process is most likely to have been involved in this transmission event, and what else ought to be true of the original S cell?
(a) transduction, it made a sex pilus                (d) conjugation, it possessed an F factor
(b) binary fission, it underwent crossing-over (e) transaffiliation, it was infected by provirus
(c) DNA uptake across cell coverings, it had died

5. The ability to construct sex pili is mostly limited to Gram (-) bacteria.  Based on this observation, the knowledge that live bacteria do not "leak" DNA to the environment, and on the  previous questions, what should be true of S. pneumoniae's cell wall?
(a) It has no cell wall.
(b) It has no peptidoglycan in its cell wall.
(c) It has a cell wall composed mostly of peptidoglycan.
(d) It has a cell wall with an inner layer of peptidoglycan and an outer lipopolysaccharide membrane.
(e) There is not enough information in this series of questions to say what is true of S. pneumoniae's cell wall.

6. Which of these is the most likely reason that R cells cannot cause pneumonia in mice?
(a) The pneumonia-producing toxin cannot pass through these cells' capsules to affect the mice.
(b) The mices' immune systems can eliminate the rough pneumococcus before they cause pneumonia.
(c) These cells cannot swim.
(d) These cells are vulnerable to the mices' interferons.

7. Which of these processes was/were involved in the heat-killed S cells turning the live R cells into live S cells?
                                                            1. transduction
                                                            2. genetic recombination
                                                            3. conjugation
                                                            4. meiosis
                                                            5. transformation
(a) 1 only    (b) 3 only    (c) 4 only    (d) 2 & 4    (e) 2 & 5

8. The agent that causes live R cells to become live S cells is similar to a virus insofar as the agent is:
(a) a mobile genetic element.
(b) an obligate intracellular parasite.
(c) going to integrate itself into the bacterial genophore.
(d) always delivered within a coating of protein.
(e) composed solely of DNA.

Best Answers:

Candida  questions: 1c    2b    3c    4a    5c    6b    7e    8a

Giardia questions: 1e    2a    3d    4b    5e    6c    7a

Pneumococcus questions: 1c    2c    3d    4d    5d    6b    7e    8a