Practice test Laboratory

Question 1

In the reverse transcriptase PCR, the cDNA is synthesized by:

a. reverse transcriptase
b. DNA polymerase
c. Oligo dT primers
d. RNAse H

Answer 1

DNA polymerase

Question 2

One of the disadvantages of using a nested PCR is

Answer 2

susceptible to contamination

Question 3

What is the relationship of the fluorescent dye to the single stranded DNA in every PCR cycle?

a. direct relationship
b. inverse relationship
c. no relationship
d. none of these options

Answer 3

no relationship

Question 4

What will happen to the target DNA sequence if the annealing temperature is too high?
1. No hybridization takes place
2. Primers and templates remains dissociated
3. Production of mismatch hybrids
4. Amplification is more likely to occur at nontarget sites in the template molecule

a. 1 and 2
b. 2 and 3
c. 3 and 4
d. 2 and 4
e. 1 and 4

Answer 4

1 and 2

Question 5

What will happen to the target DNA sequence if the annealing temperature is too low?
1. No hybridization takes place
2. Primers and templates remains dissociated
3. Production of mismatch hybrids
4. Amplification is more likely to occur at nontarget sites in the template molecule
a. 1 and 2
b. 2 and 3
c. 3 and 4
d. 2 and 4
e. 1 and 4

Answer 5

3 and 4

Question 6

What would be the effect to the amplicons, if the denaturation temperature is too low?

Answer 6

the DNA will not completely denature and amplification efficiency will be low

Question 7

Which of the following are correct when using a Multiplex PCR?
1. A minimum of three primer sets designed for amplification of different targets are
included in the same PCR reaction.
2. More than one target sequence in a clinical specimen can be amplified in a single
tube.
3. The primers used must be selected carefully to have similar annealing temperatures
should be complementary to each other.
4. The amplicon sizes should be different enough to form distinct bands when visualized
by gel electrophoresis.

a. 1 and 2
b. 1 and 3
c. 2 and 3
d. 2 and 4

Answer 7

2 and 4

Question 8

A type of purification you would use if the sample is for diagnostic analysis.

Answer 8

Proteinase K in low salt buffer

Question 9

Addition of this component can make the DNA pellet stable for long period of time
a. Sterile distilled H2O
b. Heparin
c. EDTA
d. Both sterile distilled water and EDTA

Answer 9

Sterile distilled H2O

Question 10

Any material composed of, containing, or that may contain microbial entities and/or their
harmful products such as toxins and allergens.

Answer 10

Biological Material

Question 11

In a COVID-19 Molecular Biology Laboratory, the main hazard handled is the SARS-COV 2 virus. Which among the following has a potential to cause a laboratory acquired infection
risk?
a. Leak in primary container or viral transport medium
b. DNA extraction inside a Biosafety Cabinet
c. Spillage in the Reagent Preparation Room
d. Non-functional PCR machine

Answer 11

Leak in primary container or viral transport medium

Question 12

Purification of DNA includes removal of proteins, carbohydrates, lipids and cell debris. TRUE OR FALSE

Answer 12

TRUE

Question 13

Ratio of phenol:chloroform:isoamyl alcohol.

Answer 13

25:24:1

Question 14

Staff trained and proficient in techniques is under which basic principle of biosafety?
a. Practices and Procedures
b. Equipment Safety
c. Facility Design and construction
d. Increasing Levels of Protection
e. Material Control
f. None of the above

Answer 14

Practices and Procedures

Question 15

Which among the following about Risk Characterization is NOT TRUE?

a. A hazard cannot pose a risk without a specific situation. Conversely, a situation also does
not represent a risk without a hazard.
b. Both a changing hazard and a changing situation will independently alter the scenario
being assessed, and thus change the risk.
c. The hazard or threat can affect both the likelihood and consequences of a risk, the
situation will usually affect only the likelihood.
d. If an institution finds a particular risk unacceptable, it will either cease the work resulting in
that unacceptable risk, or it will find ways to mitigate that risk to a more acceptable level
e. The actual process of determining the likelihood and consequence of a particular risk
within a Risk Assessment
f. None of the above

Answer 15

If an institution finds a particular risk unacceptable, it will either cease the work resulting in
that unacceptable risk, or it will find ways to mitigate that risk to a more acceptable level

Question 16

Which among the following practices is NOT considered as a security measure designed
to prevent the international release of pathogens.

a. Access control
b. Proper decontamination / disposal of waste material
c. Fences and border lines
d. Personal protective equipment
e. Personnel management
f. None of the above

Answer 16

Personnel management

Question 17

Which of the following evidences must be presented to the Department of Health during
initial monitoring to ensure that the COVID-19 Molecular Laboratory has policies on STAFF
RECRUITMENT, SELECTION, APPOINTMENT AND RESPONSIBILITIES.

a. Written policies and procedures for staff development and training.
b. Proof of training through relevant certificates, memos, written reports, budgetary
allocations.
c. Written policies and procedures on hiring, orientation and promotion of personnel at all
levels
d. Updated organizational chart structured. indicating the names with latest pictures

Question 18

It is used to catch nucleotides
I. Glass particles
II. Magnetic beads
III. Silica membrane
IV. Diatomaceous earth

a. I only
b. II and III
c. I, II, IV
d. I, III, IV
e. All of the above

Question 19

Which of the following is/are considered as lysing agent?

I. Detergent
II. Zymolyse
III. Lysozyme
IV. Phylase
V. None of the above

a. I only
b. I, II, III
c. I, II, IV
d. V

Answer 19

I, II, III

Question 20

Isolation of DNA from whole blood via Ficoll-Directed gradient method what would be the
correct arrangement of the product (top to bottom)

Answer 20

Plasma > WBC > Ficoll reagent >
Erythrocytes

Question 21

A 75µL total volume of sample of dsDNA was diluted in 1:5. The diluted sample gave a
reading of 0.451 on a spectrophotometer at OD260. Determine the yield of DNA in the
original sample.

Answer 21

8.46 µg DNA

Question 22

Give the DNA concentration in µg/µL.
Dilution: 1:100
Blank reading: 0.680
A260 reading: 1.580
A280 reading: 1.180
a. 0.079 µg/µL
b. 0.79 µg/µL
c. 7.90 µg/µL
d. 79.0 µg/µL
e. 790.0 µg/µL

Answer 22

7.90 µg/µL

Question 23

Calculate the yield of DNA in the sample using the following data:
Total volume of DNA sample was 200 mL
The DNA sample was diluted in 1:5
Absorbance at 260 nm of the diluted solution was 0.25

a. 0.0125 µg of DNA
b. 0.125 µg of DNA
c. 1.25 µg of DNA
d. 12.5 µg of DNA
e. 125.0 µg of DNA

Answer 23

12.5 µg of DNA

Question 24

Which of the following is true about the length of a primer?

Answer 24

If the primers are too short,
they might hybridize to nontarget sites and give undesired amplification products

Question 25

Which of the following troubleshooting procedures must be performed when the annealing
time is too short?

Answer 25

use an annealing time of at least 30 seconds.

Question 26

In qPCR, regardless of starting point, all reactions will end at the same, or similar,
concentration. qPCR involves gathering of information during the reaction, when
different reactions are still in the exponential phase.

Question 27

Cycle threshold is the number of PCR cycles required to exceed the background
fluorescence. It is also the number of which the fluorescence of the given sample
crosses the threshold value

Question 28

Cycle threshold is the number of PCR cycles required to exceed the background
fluorescence. It is also the number of which the fluorescence of the given sample
crosses the threshold value.

Question 29

If the denaturation time is too short, the DNA will completely denature and
amplification efficiency will be low. For the initial denaturation, use 3 min to
activate the polymerase and to denature the template during cycling, use 30 sec.

Question 30

If the annealing temperature is too high, primers are unable to bind to the
template. The rule of thumb is to use an annealing temperature that is 5°C higher
than the melting point of the primer.

Question 31

All of the following are considered pre-analytical standards in Molecular Biology
Diagnostic Laboratories, EXCEPT?

Answer 31

Quality Assessment

Question 32

All of the following are principles of Binding of nucleic acid into the membrane except:

Answer 32

Number of carbon rings

Question 33

In organic type of purification what part of the solution contains the DNA

a. Upper
b. Lower
c. Middle

Answer 33

Upper

Question 34

In Salting out of DNA, what solution you will add in order to further purify the DNA.
a. 100% ethanol
b. Chilled absolute ethanol
c. Saturated NaCl
d. Proteinase K
e. Both a and c

Answer 34

Chilled absolute ethanol

Question 35

Is elimination a proper mitigation control for the main hazard (SARS-COV 2 virus) in a
COVID-19 laboratory? Why? Why not?

a. Yes, because elimination is the most efficient mitigation control.
b. Yes, eliminating the main hazard would ensure that the risk of laboratory acquired
infection would be removed.
c. No, substitution is a better mitigation control measure than elimination because you
cannot fully remove handling the virus in the laboratory
d. No, elimination is not possible because the main purpose of the laboratory is to test for the
virus

Answer 35

No, elimination is not possible because the main purpose of the laboratory is to test for the
virus

Question 36

Organic type of purification of nucleic acid uses

a. Proteinase K: chloroform: isoamyl alcohol
b. Phenol
c. Absolute alcohol
d. Both a and b

Question 37

Other term for Spin column.

Answer 37

Solid phase

Question 38

Risk characterization will depend on the likelihood that the risk will happen and the
consequences of the exposure to that risk. Which among the following statements regarding
risk characterization in a COVID-19 molecular laboratory is FALSE?

a. Risk characterization with regards to likelihood will also depend on the frequency of a risk
happening. Because of the high number of samples being submitted to a COVID-19
molecular laboratory, there is a higher possibility of the laboratory to receive viral transport
mediums with leaks. therefore, risk characterization would veer to a higher level of risk.
b. Risk characterization will also depend on the severity of the risk once it occurs. In a
COVID-19 molecular laboratory, exposure of the laboratory staff to the virus while handling it
inside a biosafety cabinet constitutes to a high risk because of the severity of exposure.
c. Risk characterization depicts the mitigation control measure to be applied to a certain
procedure.
d. In a COVID-19 laboratory, the risk of chemical injuries is low. Although exposure to
hazardous chemicals may have severe consequences, it very unlikely to happen because
the molecular laboratory does not handle chemical hazards often.

Answer 38

Risk characterization will also depend on the severity of the risk once it occurs. In a
COVID-19 molecular laboratory, exposure of the laboratory staff to the virus while handling it
inside a biosafety cabinet constitutes to a high risk because of the severity of exposure.

Question 39

The following statements regarding equipment maintenance are true, except?

Answer 39

Adjustable
and fixed-volume automatic pipettors must be checked for volumetric accuracy and
reproducibility, and recalibrate as necessary before placing in service initially and at specific
defined intervals, at least once every 2 months

Question 40

What would be the sequence in order to get the pure DNA. Cell lysis > affinity via
magnetic beads > elution

Answer 40

Cell lysis & affinity via
magnetic beads ; elution

Question 41

Which among the following engineering mitigations is not a recommendation of the
Interim Biosafety Guidelines for Laboratories Handling and Testing SARS-COV 2
(COVID-19) samples.
a. The air must flow from an area of higher contamination to an area of lower contamination.
b. Biosafety Cabinets must be located away from areas where movements that affects
airflow pattern could disrupt the fragile air curtain at the front of the cabinet.
c. There must be a sink with adequate supply for clean water for hand washing located near
the exit door.
d. Access must be restricted to laboratory personnel and support service providers only.

Answer 41

he air must flow from an area of higher contamination to an area of lower contamination.

Question 42

Which of the following is used in an Inorganic type of purification?

Answer 42

Saturated NaCl