Missed questions from past exams

Question 1

Besides the nucleoid, two other kinds of DNA molecules that may be present in the cytoplasm of a bacterial cell are ________ and ________.

Answer 1

plasmids; bacteriophages genome

Question 2

Which of the following mutation types are possible with a deletion or insertion of 1 or 2 nucleotides?

Answer 2

Nonsense mutation and Frameshift mutation

Question 3

Genes that are part of plasmids are not essential for cell growth.

Answer 3

TRUE

Question 4

Genetic change in bacteria can be brought about by all of the following EXCEPT
- mutation
- conjugation
- transformation
- replication

Answer 4

replication

Question 5

During what process do you see ringed catenanes form?

Answer 5

End of DNA replication

Question 6

Both leading and lagging strands are synthesized 5’ to 3’ direction.

Answer 6

TRUE

Question 7

All of the following are TRUE about DNA gyrase EXCEPT
- relieves DNA supercoils
- is a type 1 topoisomerase
- introduces negative supercoil
- it is capable of making double strand cut

Answer 7

it is a type 1 topoisomerase

Question 8

Which of the following molecules will initiate chain termination after they have been incorporated to the growing strand of nucleotides by a polymerase.
- Zidovudine
- Robonucleotide
- 2’,3’ - Dideoxyribonucleotide
- 2’ - Deoxyribonucleotdie

Answer 8

Zidovudine and 2’,3’-Dideoxyribonucleotide

Question 9

RNA primer is required in rolling circle replication of plasmids

Answer 9

TRUE

Question 10

Which is NOT TRUE about bacterial transcription?
- Bacterial transcription is different from archaeal transcription
- Can be affected by Actinomycin D
- Can be affected by Rifamycin B
- Requires a separate Helicase enzyme

Answer 10

Requires a separate Helicase enzyme

Question 11

Antibiotic Streptomycin is designed to inhibit protein synthesis and it is bacteriostatic agent.

Answer 11

FALSE

Question 12

The following image is a result from Kirby-Bauer Disk Susceptibility test of Staphylococcus aureus against three antibiotics. What can be concluded from the result below?

Answer 12

Staphylococcus aureus is resistant to antibiotic A (no clearing around antibiotic)

Question 13

Assume that your lab partner swabs the side of his face and uses the swab to inoculate a nutrient agar plate. The next day, he performs a Gram stain on the colonies. They are Gram positive cocci. He is worried that he might be affected by a MRSA. You advise him that he should next look for?

Answer 13

Antimicrobial sensitivity

Question 14

The best target for development of a new antibiotic against Mycobacterium species would be

Answer 14

mycolic acids

Question 15

Consider an MIC result of 5 μg/ml of vancomycin for bacterial strain A, 10 μg/ml for strain B, 15 μg/ml for strain C, and 20 μg/ml for strain D. Which bacterial strain can be interpreted as the most resistant to vancomycin?

Answer 15

D

Question 16

These are some of the antimicrobial agents used to treat human infections. Answer the following question based on the information listed below.
1. Aminoglycosides
2. Cephalosporins
3. Penicillin G
4. Gramicidin
Which of the above numbered antimicrobials can also destroy human cells

Answer 16

only antibiotic number 4

Question 17

Square planar arrangement of cells that forms when round bacteria remain attached to each other during reproduction are called ________.

Answer 17

Tetrads

Question 18

The majority of nitrogen in soil and marine environments is fixed by:

Answer 18

Free living bacteria and archaea

Question 19

After you transferred 1mL from a 10-6 dilution tube into a plate, you counted 207 colonies. How many CFU are present in 1 mL?

Assuming all cells remain viable and in log phase.

Answer 19

2.07 x 108

Question 20

Longest lag period would most likely be observed if a culture is transferred ___________.

Answer 20

From a complex medium to a minimal medium

Question 21

You feed #. coli 3 glucose molecules. How many ATP are created ONLY through substrate level phosphorylation?

Answer 21

12

Question 22

In cultures without oxygen, if S.pyogenes decided to undergo fermentation, what happens to the electrons carried by NADH from glycolysis?

Answer 22

Will be donated to pyruvates

Question 23

Fermentation produces more energy than anaerobic respiration

Answer 23

FALSE

Question 24

Which of the following pathways would be fully operational ONLY in respiring bacteria?

Answer 24

TCA

Question 25

When chemoorganotrophs oxidize an organic energy source, the electrons released are accepted by electron carriers such as NAD+ and FAD. When these reduced electron carriers (NADH and FADH2) in turn donate the electrons to an electron transport chain, the metabolic process is called __________.

Answer 25

Respiration

Question 26

The significance of the thermophile Thermus aquaticus in microbiology is, due to its ability to ferment different sugars at a very high temperature.

Answer 26

FALSE

Question 27

Which of the following determines if microorganisms are going to use oxygen or not?

Answer 27

• their ability to use oxygen as a terminal electron acceptor
• their ability to have enzymes that deals with ROS

Question 28

Invisible living creatures were thought to exist and cause disease long before they were ever observed.

Answer 28

TRUE

Question 29

All of the following are arguments the support the classification of archaea as a third domain of life apart from bacteria, EXCEPT?
- Archaea are larger in size when compared to bacteria
- archaea rDNA is different from bacterial rDNA
- Microscopic characteristics of archaea are different from bacteria
- Unlike bacteria, archaea cannot cause disease

Answer 29

Unlike bacteria, archaea cannot cause disease

Question 30

In Griffin’s experiment of transformation, he concluded that protein was the biological molecule that must be “transferring” information to the nonvirulent strain of Streptococcus.

Answer 30

FALSE

Question 31

Light rays are refracted when they cross the interface between materials with different refractive indices.

Answer 31

TRUE

Question 32

Prior to staining, smears of microorganisms must be heat fixed in order to __________.

Answer 32

attach them firmly to the slide

Question 33

The instrument that produces a bright image of the specimen against a dark background is called a

Answer 33

dark-field microscope

Question 34

Which of the following antibiotics target the peptidoglycan cell wall of bacteria.

Answer 34

Both penicillin and vancomycin

Question 35

Which of the following is FALSE about bacterial outer membrane?
- It contains a toxic component
- It contains a lipopolysaccharide layer
- It is composed of a phospholipid bilayer
- It is found only in Gram negative bacteria

Answer 35

It is composed of a phospholipid bilayer

Question 36

Bacteria rotate their flagella clockwise when they try to change direction.

Answer 36

TRUE