Exam with Solution - Fundamentals of Microbiology | MBIO 3813 | Exams Biology

Exam 1 Copy 1 MBIO 3813-001 Spring 2014

MBIO 3813-001 Fundamentals of Microbiology ANNOTATED KEY KEY KEY KEY ANNOTATED

Lecture Exam 1 WHITE VERSION 7 February 2014 WHITE VERSION

Annotated – Fairly thorough explanations – this ANNOTATED KEY may be a helpful review at the end

of the semester

Q 13, Q 14,Q. 29, Q 43, Q 46, White Version. Alternative Answers are being accepted. Check

out these questions. Wait for corrected exam scores to be posted.

Question 8 and Question 29: please refer to APPENDIX. A brief introduction to current work on

human gut microbiome.

GREEN VERSION Q 1 = WHITE VERSION Q 26. Questions are identical, displaced by 25 spots

1. On Answer Sheet: NAME: Print Last Name [space] First Name; IDENTIFICATION NUMBER: OU ID. No.

a. Fill-in the corresponding circles with No. 2 pencil. (b. No Birthdate, Gender, or Special Code)

3. Answer the exam questions. Fill in the circles corresponding to your answers. Do this before 9:20. No additional time will be given to do this.

4. Cell Phone Penalty: Mandatory 10 (te n) point penalty if your cell phone is heard ringing or vibrating during the exam. If you expect an urgent call,

identify yourself to the instructor.

5. No electronic devices of any kind are permitted during the exam. No books or notes are permitted.

Backpacks and books must placed at front of classroom. Hats must be worn with the brim at the back.

You may not leave the exam room and come back into it during the exam period.

6. Academic Misconduct: Submission of the Scantron form of your exam indicates agreement with the statement “I have neither given nor received

inappropriate aid in completing this exam .” Using crib sheets, electronic communication, looking at anothe r person’s paper, or other ac tivities which

compromise the integrity of the exam are unacceptable and will be penalized.

7. Versions of Exam: there are two or more versions of this exam. You must answer Question 51 correctly or lose 10 points from the raw score of your

exam.

MULTIPLE CHOICE QUESTIONS. Choose the letter of the best response for each question and darken the corresponding

circle on the Scantron Sheet (No. 2 Pencil!). You may write on these pages; only the Scantron Sheet is graded.

Questions 1 to 3 refer to Figure I on page 1.

1. The organism in Fig. I is a:_______________

A. bacillus B. coccus C. bacilli D. spirochete E. vibrio

Bacillus is a singular word, meaning rod-shaped. Bacilli is plural; there is only one bacillus in the

figure. Coccus is a spherical-shaped microbe, a spirochete is a corkscrew-shaped bacterium, a

vibrio is slightly curved, rather like a comma “,”

2. The organism in Fig. I is a(n):________________ .

A. Protozoan B. “Prokaryote” C. Eukaryote D. Pathogen E. Organelle

A “Prokaryote” is a single-celled microorganism, lacking internal membrane-surrounded organelles

such as the nucleus and mitochondrion/chloroplast and having “loose” DNA, not organized into the

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MBIO 3813- 001 Fundamentals of Microbiology ANNOTATED KEY KEY KEY KEY ANNOTATED

Lecture Exam 1 WHITE VERSION 7 February 201 4 WHITE VERSION

Bacillus is a singular word, meaning rod-shaped. Bacilli is plural; there is only one bacillus in the

figure. Coccus is a spherical-shaped microbe, a spirochete is a corkscrew-shaped bacterium, a

vibrio is slightly curved, rather like a comma “,”

A “Prokaryote” is a single-celled microorganism, lacking internal membrane-surrounded organelles

such as the nucleus and mitochondrion/chloroplast and having “loose” DNA, not organized into the

I II

familiar Eukaryotic cell chromosomes in the mitotic apparatus. The quotation marks are to remind

us that “Prokaryote” is an organism defined by what it does not have.

A bit challenging, this question requires, first, an idea how big the cell is (remember, on order of 1 μm),

and second, a calculation that 0.01 μm is the same as 10 x 10-^9 m; 5 and 50 μm are too big

(although the flagellum of a Eukaryotic cell may be 5 μm or wider in diameter (remember, that

flagellum has microbubles inside and a membrane surrounding it, and it moves in a whip-like

fashion, not a rotary fashion).

1 Angstrom is approximately the size of an atom, much too small for a molecular structure.

The principles behind some of these size-based questions are worth keeping in mind. A red blood cell

is about 8 μm in diameter; a ribosome is about 10 nm in diameter.

This response is correct because the phase-contrast principle relies upon refraction of the light beam

by particles (structures) inside the cells, rendering a 3-D effect and a transparent cell structure.

The SSU RNA, is the 16S rRNA in Archaea and Bacteria, 18S rRNA in Eukaryotes.

SSU is the small subunit. SSU rDNA refers to the gene for the SSU RNA.

Key word here is “Nucleus”, which Archaea do not possess.

The root “Litho” means rock or mineral, “troph” refers to nutrition, and here means the source of

chemical energy. B is a Heterotroph; C has to do with biofilms, D, is a particular type of

heterotroph.

A challenging question.

Will give 1 point for B and C. But look at slides of WInogradsky column and textbook

description: C, O, S cycles occur in a functioning column and the microbiologists had a good

handle on these critical environmental pathways.

Challenging question: Aerobic photosynthesis on the top. Carbon cycle throughout the column.

Sulfur cycle in anaerobic zone (H2S à SO 4 -^2 à H2S , oxidation via light-driven processes,

reduction by sulfate-reducing heterotrophs).

The N cycle isnʼt demonstrated in his column system, although he did work on the ammonia-

using lithotrophs.

A was the Turks, or Lady Montague, and could be the cowpox vaccination developed by Jenner

B was determined by botanists with the lead provided by anaerobic microbiologists, and it was

in mid 1900s before this reaction was recognized.

C YES

D This was Alexander Fleming, although folk-medicine suggested something was produced by

fungi that protected against infection long before his breakthrough.

From reading at very beginning of Ch 3. Protein, 55%, RNA, 20%, Lipids, 10% or so, DNA, 3%

or so, E, 1 to 3% or so. Important point. The largest investment for the cell is to produce protein

A. True B. False almost everybody got this. Stay tuned.

Bright-field, TEM, give 2 D images, and size may not be X-Ray,

The SSU RNA sequence of mitochondrion places it squarely in the group known as Proteobacteria.

A. the tagged antibodies may absorb photons, but cannot be detected unless they emit light of second

wavelength (absorbance wonʼt resolve the very small dimensions required here). About 1/3 chose this

one. Remember that light emission is whatʼs important.

B. Emission from a point source can be readily detected and localized.

C. They are not used in the animal system for this purpose, but native antibodies (not tagged) of course

do this

D. not typically why fluorescent antibodies are used.

PG from the reading and brief statements in class. A and B and C are in Gram-neg cells, but are not

the cell wall,

C is found in a few Archaea

SubSection heading in Sec 3.4. One molecule at any given instant. It is dynamically changing, by

expanding in area as cell grows, before cell division, at the site of septation.

This is another challenging question, but we have to become practical chemists. Reaction C is

important in many anaerobic organisms, represents anaerobic respiration, which we will be covering

and which some pathogens utilize.

A refers to what happens to N2.

B. NO 3 -^ is an oxidized substance, has no electrons to be used by lithotrophs. He showed NH 3 - utilizers.

C. TRUE. Last step of N cycle where N 2 is formed from nitrate.

D. again, not electrons available.

A high percentage of us do not have a good understanding of the N cycle and that it has direction.

Also, Nitrogen in animal and plant tissue is part of the nutritional cycle

A refers to size of image, but still cannot resolve structures below a certain size (200 nm in light

microscopy based on absorbance).

Majority got E. A fair number picked D, but B. anthracis is from the Firmicutes.

This is a question in the real world. Note that Iodine Solution was not used in the staining procedure.

Both Gram-pos and Gram-neg would be decolorized without the use of the Iodine mordant, which

makes a complex with CV which binds to the Gram-pos wall tightly enough not to be removed during

the ethanol treatment.

People tell me this is an example of the kind of close-reading one must do on the MCAT.