Lab Technology Microscopy

Question 1

Which of the following usually cannot be viewed with light microscopy?
A. Fruit fly
B. Bacteria
C. Virus
D. Blood cell
E. Mitochondria

Answer 1

C. Virus
A virus can be viewed using a scanning electron microscope (SEM).

A light microscope, also known as a stereomicroscope, is used to view the surfaces of live objects using visible light. These microscopes are unable to view objects smaller than half the wavelength of visible light (which ranges from 380-700 nm). Viruses are significantly smaller, typically ranging from about 20-200 nm in size.

Question 2

From smallest to largest, order the relative sizes of the biological matter listed below.
I. Virus
II. Protein
III. Mitochondria
IV. Red blood cell
V. Animal cell

Answer 2

. 2,1,3,4,5
Protein,Virus,Mitochondria,IV. Red blood cell,Animal cell
Most proteins are generally smaller than 10 nm. Viruses typically range from about 20-200 nm in size. Mitochondria are about 1000 nm in size. Red blood cells are anuclear and lack organelles, and are therefore a little smaller than a regular animal cell, which is around 10,000 nm in size.

Question 3

Which of the following uses visible light to create a 3D image of a sample’s surface?
A. Stereomicroscopy
B. Compound Microscopy
C. Phase-Contrast Microscopy
D. Scanning Electron Microscopy
E. Dark Field Microscopy

Answer 3

A. Stereomicroscopy
Stereomicroscopy, also known as light microscopy, uses visible light to view the surface of an object. The light waves emitted by the light microscope are bent to form a cone-like shape around the object, which enables the lens to focus on the object. Light microscopes have low magnification and resolution.

Question 4

Which of the following uses visible light to create a 2D image of a single cell layer?
A. Stereomicroscopy
B. Phase-Contrast Microscopy
C. Dark Field Microscopy
D. Electron Tomography
E. Compound Microscopy

Answer 4

E. Compound Microscopy
A compound microscope is very similar to a light microscope in that it uses visible light to view a sample. The difference is that a compound microscope uses multiple lenses. This kind of microscope allows one to view a single cell layer with its internal structures. Compound microscopy usually requires staining to best visualize the sample.

Question 5

Which of the following uses light phase changes and contrast to create a 2D image of a thin sample?
A. Dark Field microscopy
B. Cryo Scanning Electron Microscopy
C. Phase-Contrast Microscopy
D. Stereomicroscopy
E. Electron Tomography

Answer 5

A phase-contrast microscope is used to view thin live cells, as well as their internal structures if the cell is thin enough. This kind of microscope creates a phase shift that leads to the high contrast between the sample and the surrounding field. A downside to this type of microscopy is the production of the “halo effect,” in which rings form around the sample.

Question 6

Which of the following uses a laser light to display and a fluorescent marker to tag specific 2D structures within a specimen?
A. Stereomicroscopy
B. Phase-Contrast Microscopy
C. Dark Field Microscopy
D. Confocal Laser Scanning and Fluorescence Microscopy
E. Compound Microscopy

Answer 6

D. Confocal Laser Scanning and Fluorescence Microscopy
Confocal laser scanning and fluorescence microscopy are used to view thin slices of live tissue and are commonly used during mitosis. Fluorescence tagging utilizes fluorophores to track specific cell components. Artifacts are distortions in the sample and commonly arise during fluorescence microscopy.

Question 7

Which of the following uses the contrast of light between the background field and sample to view living samples?
A. Dark Field microscopy
B. Phase-Contrast microscopy
C. Compound Microscopy
D. Stereomicroscopy
E. Transmission Electron Microscopy

Answer 7

A dark field microscope is used to view unstained live cells by creating a high contrast of light between the cells and the background. The high contrast results in the surrounding field appearing extremely dark.

Question 8

Which of the following is a disadvantage of using the stereomicroscope compared to an electron microscope?
A. Low light resolution
B. Need to stain the sample
C. Produces the “Halo Effect”
D. Can cause artifacts
E. Need to freeze the living sample

Answer 8

A. Low light resolution
A stereomicroscope, also known as a light microscope, uses visible light to view the surface of an object. However, since it has only one lens, it has a low resolution (i.e. it cannot distinguish detail very well). In contrast, an electron microscope bombards a sample with electrons and produces images with extremely high resolution.

Question 9

Which of the following is performed to better view cell structures when microscopy is used?
A. Staining
B. Heat fixation
C. Freezing
D. Centrifugation
E. Gel electrophoresis

Answer 9

A. Staining
Most cells do not produce enough pigments, which prevents us from being able to view them properly. Staining cells with dyes will allow us to visualize them underneath a microscope.

Question 10

Which of the following best describes heat fixation?
A. Adding color or dye to cells
B. Freezing cells using liquid nitrogen
C. Using chemicals to preserve cells on a slide
D. Homogenizing the cell
E. Heating cells to preserve cells on a slide

Answer 10

E. Heating cells to preserve cells on a slide
Heat fixation is a laboratory process necessary for killing and preserving cells and eliminating contaminants. After bacteria are smeared on a slide, the slide is heated over a Bunsen burner; the extreme heat kills the bacteria. Heating also results in the sample sticking to the slide, preventing it from moving around.

Question 11

Due to a lab error, harvested cells are still alive while observed under an electron microscope. Which of the following lab protocols was most likely not performed correctly?
A. Gel electrophoresis
B. Heat fixation
C. Polymerase Chain Reaction
D. Flow cytometry
E. Centrifugation

Answer 11

B. Heat fixation
Heat fixation is a laboratory process necessary for killing and preserving cells and eliminating contaminants. After bacteria are smeared on a slide, the slide is heated over a Bunsen burner; the extreme heat kills the bacteria. Heating also results in the sample sticking to the slide, preventing it from moving around.

Question 12

Which of the following is necessary when performing electron microscopy?
A. Preserved cells
B. Living cells
C. Visible light
D. Low resolution
E. Absence of magnetic field

Answer 12

A. Preserved cells
An electron microscope bombards a sample with electrons and produces images with extremely high resolution. Objects that are viewed using electron microscopy are placed into a vacuum. A living sample cannot exist vacuum, and the cells must therefore be killed and preserved.

Question 13

Which of the following can produce the “Halo Effect” on the imaging sample?
A. Compound Microscopy
B. Stereomicroscopy
C. Cryo Scanning Electron Microscopy
D. Confocal Laser Scanning and Fluorescence Microscopy
E. Phase-Contrast Microscopy

Answer 13

E. Phase-Contrast Microscopy
A phase-contrast microscope is used to view thin live cells, as well as their internal structures if the cell is thin enough. This kind of microscope creates a phase shift that leads to a high contrast between the sample and the surrounding field. A downside to this type of microscopy is the production of the “halo effect,” in which rings form around the sample.

Question 14

Which of the following can produce artifacts or distortions on the imaging of a sample?
A. Fluorescence Microscopy
B. Phase-Contrast Microscopy
C. Dark Field Microscopy
D. Compound Microscopy
E. Stereomicroscopy

Answer 14

Fluorescence microscopy is used to view thin slices of live tissue and is commonly used during mitosis. Fluorescence tagging utilizes fluorophores to track specific cell components. Artifacts are distortions in the sample and commonly arise during fluorescence microscopy.

Question 15

Which of the following is used routinely to view chromosomes during mitosis?
A. Stereomicroscopy [4%]
B. Compound Microscopy [7%]
C. Phase-contrast Microscopy [6%]
D. Fluorescence and Confocal Laser Scanning Microscopy [70%]
E. Transmission Electron Microscopy [13%]

Answer 15

Fluorescence and Confocal Laser Scanning Microscopy
Confocal laser scanning and fluorescence microscopy are used to view thin slices of live tissue and are commonly used during mitosis. Fluorescence tagging utilizes fluorophores to track specific cell components. During mitosis, fluorophores bind to the major and minor grooves of the chromosomes.

Question 16

What is the major difference between Cryo scanning electron microscopy (Cryo SEM) and conventional scanning electron microscopy (SEM)?
A. Cryo SEM is used on living samples
B. Cryo SEM is used on dehydrated samples
C. Cryo SEM is used on frozen samples
D. SEM is used on wet samples
E. SEM is used on frozen samples

Answer 16

C. Cryo SEM is used on frozen samples
Both types of electron microscopes bombard a nonliving sample with electrons and produce images with extremely high resolution. A conventional SEM uses dehydrated samples. When using a Cryo SEM, samples are frozen in liquid nitrogen instead of dehydrating them.

Question 17

Which of the following can be used to view internal cell organization in great detail?
A. Electron Tomography
B. Scanning Electron Microscopy
C. Cryo Scanning Electron Microscopy
D. Transmission Electron Microscopy
E. Phase Contrast Microscopy

Answer 17

D. Transmission Electron Microscopy
A transmission electron microscope (TEM) is used to obtain extremely high-resolution 2D images of cells’ internal structures. A TEM works best when observing thin cross-sections.

Question 18

Which of the following is used to generate a 3D model of a sample?
A. Cryo Scanning Electron Microscopy
B. Phase-Contrast Microscopy
C. Electron Tomography
D. Scanning Electron Microscopy
E. Fluorescence and Confocal Laser Scanning Microscopy

Answer 18

C. Electron Tomography

Question 19

Which of the following is a drawback of using electron microscopy compared to light microscopy?
A. Poor resolution
B. Can only use living samples
C. Costly
D. Short preparation period
E. Can only display 2D images of samples

Answer 19

C. Costly

Question 20

Which microscopy technique was most likely used to take this image below of the Orpheo Virus particles’ exocytosis?
A. Scanning Electron Microscopy
B. Fluorescence and Confocal Laser Scanning Microscopy
C. Compound Light Microscopy
D. Phase-Contrast Microscopy
E. Transmission Electron Microscopy

Answer 20

A. Scanning Electron Microscopy
An electron microscope bombards a nonliving sample with electrons and produces extremely high-resolution 3D images. The samples are coated with a thin layer of a non-conducting metal prior to scanning.

Question 21

This high-resolution photo was taken of the internal structure of cotton phloem tissue. Which of the following microscopy techniques was used to take this?
A. Compound Microscopy
B. Phase-Contrast Microscopy
C. Scanning Electron Microscopy
D. Cryo-SEM
E. Transmission Electron Microscopy

Answer 21

A transmission electron microscope (TEM) is used to obtain extremely high-resolution images of cells’ internal structures. A TEM works best when observing thin cross-sections.

Question 22

This low-resolution photo was taken of the internal structure of cotton phloem tissue. Which of the following microscopy techniques was used to take this?

A. Dark Field Microscopy
B. Fluorescence and Confocal Laser Scanning Microscopy
C. Compound Microscopy
D. Scanning Electron Microscopy
E. Cryo-SEM

Answer 22

C. Compound Microscopy
A compound microscope is very similar to a light microscope in that it uses visible light to view a sample. The difference is that a compound microscope uses multiple lenses. This kind of microscope allows one to view a single cell layer with its internal structures. Compound microscopy usually requires staining to best visualize the sample.

Question 23

This image was taken with electron microscopy. Which animal cell organelle is this?

A. Nucleus
B. Rough ER
C. Smooth ER
D. Lysosome
E. Mitochondria

Answer 23

E. Mitochondria
Mitochondria are easily distinguishable due to their cristae (infoldings of the inner membrane). Cristae increase the surface area of the mitochondria’s inner membrane, allowing for greater ATP production by the electron transport chain during cellular respiration.

Question 24

This image was taken with electron microscopy. Which animal cell organelle is this?

A. Golgi Apparatus
B. Rough ER
C. Smooth ER
D. Peroxisome
E. Mitochondria

Answer 24

B. Rough ER
The rough endoplasmic reticulum (ER) is a membranous network continuous with the nuclear membrane and is studded with ribosomes (black dots in the photo). The ribosomes synthesize polypeptides within the rough ER, and polysaccharides are bonded to nascent polypeptides to form glycoproteins.

Question 25

This image was taken with electron microscopy. Which animal cell organelle is this?

A. Golgi Apparatus
B. Smooth ER
C. Nucleus
D. Mitochondria
E. Rough ER

Answer 25

B. Smooth ER
The smooth endoplasmic reticulum (ER) is a membranous network and is free of ribosomes. The smooth ER functions in lipid and steroid biosynthesis and detoxification.

Question 26

This image was taken with electron microscopy. Which animal cell organelle is this?

A. Rough ER
B. Smooth ER
C. Golgi Apparatus
D. Mitochondria
E. Vacuole

Answer 26

C. Golgi Apparatus
The Golgi apparatus is composed of flattened membranous sacs (cisternae). This organelle functions in modifying and packaging products from the endoplasmic reticulum. Vesicles pinch off from the Golgi and carry their products to their specific destinations.

Question 27

What is the difference between Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM)?
A. SEM creates a 2D image
B. TEM creates a 3D image
C. SEM looks at living cells
D. TEM creates a 2D image
E. SEM looks at internal structures

Answer 27

D. TEM creates a 2D image
A scanning electron microscope (SEM) bombards a nonliving sample with electrons and produces extremely high-resolution 3D images of the sample’s surface. A transmission electron microscope (TEM) is used to obtain extremely high-resolution 2D images of cells’ internal structures.

Question 28

This microscopy technique was created to reduce the artifacts produced by fluorescent microscopy.
A. Confocal Laser Scanning Microscopy
B. Scanning Electron Microscopy
C. Stereomicroscopy
D. Compound Microscopy
E. Dark Field Microscopy

Answer 28

A. Confocal Laser Scanning Microscopy
Confocal laser scanning and fluorescence microscopy are commonly used together to view thin slices of live tissue. Fluoresce can produce artifacts, or distortions, in the sample. The confocal laser focuses light directly on the substrate and controls the depth of focus, thereby preventing artifacts from occurring.

Question 29

A scientist needs to observe the internal structure of an animal cell with high resolution. Which microscopy technique should she use?
A. Scanning Electron Microscopy
B. Transmission Electron Microscopy
C. Stereomicroscopy
D. Dark Field Microscopy
E. Electron Tomography

Answer 29

B. Transmission Electron Microscopy
A transmission electron microscope (TEM) is used to obtain extremely high-resolution 2D images of cells’ internal structures. A TEM works best when observing thin cross-sections.

Question 30

A scientist needs to follow an expensive sample preparation to develop a high-resolution 3D photo of a dehydrated cell. Which microscopy technique should he use?
A. Transmission Electron Microscopy
B. Scanning Electron Microscopy
C. Cryo Scanning Electron Microscopy
D. Fluorescence and Confocal Laser Scanning Microscopy
E. Compound Microscopy

Answer 30

B. Scanning Electron Microscopy
A scanning electron microscope bombards a nonliving sample with electrons and produces extremely high-resolution 3D images. The preparation of samples is very expensive and also requires dehydration.

Question 31

A dentist would like to see the living bacteria in dental plaque under a microscope. Which microscopy technique could he use?
A. Phase-Contrast Microscopy
B. Cryo SEM
C. Transmission Electron Microscopy
D. Scanning Electron Microscopy
E. Electron Tomography

Answer 31

A. Phase-Contrast Microscop
A phase-contrast microscope is used to view thin live cells, as well as their internal structures. This kind of microscope creates a phase shift that leads to the high contrast between the sample and the surrounding field. Therefore, the dental plaque will not interfere with viewing the living bacteria.y

Question 32

A researcher has an unstained living sample he would like to observe under a microscope with good contrast. Which microscopy technique best fits his needs?
A. Compound Microscopy
B. Dark Field Microscopy
C. Stereomicroscopy
D. Cryo Scanning Electron Microscopy
E. Electron Scanning Electron Microscopy

Answer 32

B. Dark Field Microscopy
A dark field microscope is used to view unstained live cells by creating a high contrast of light between the cells and the background. The high contrast results in the surrounding field appearing extremely dark.
A scientist performed electron tomography to form a

Question 33

A scientist performed electron tomography to form a 3D model of their microscopy images. Which microscope was used to produce these microscopy images?
A. Transmission Electron Microscopy
B. Stereomicroscopy
C. Cryo Scanning Electron Microscopy
D. Scanning Electron Microscopy
E. Phase-Contrast Microscopy

Answer 33

A. Transmission Electron Microscopy
Electron tomography is an analytical lab technique that stitches together many 2D photos to create a 3D model of a sample. The 2D images are obtained using a transmission electron microscope. This technique cannot be used on living samples.

Note: Electron tomography is an analytical lab technique and not a type of microscopy.

Question 34

Why is Cryo Scanning Electron Microscopy sometimes favored over other electron microscopy techniques?
A. Can view internal structures
B. Can view cell in a more natural form
C. High resolution
D. Can be used on living cells
E. Not as costly

Answer 34

B. Can view cell in a more natural form
Electron microscopes bombard a nonliving sample with electrons and produce images with extremely high resolution. The conventional scanning electron microscope uses dehydrated samples. When using a Cryo SEM, however, samples are frozen in liquid nitrogen instead of dehydrating them, which keeps them in their more natural forms.

Question 35

When is Phase-Contrast microscopy ineffective as an imaging technique?
A. Sample is too thick
B. Sample is living
C. Sample is thin
D. Sample is not intact
E. Sample is not dehydrated

Answer 35

A. Sample is too thick
A phase-contrast microscope is used to view thin live cells, as well as their internal structures if the cell is thin enough. This kind of microscope creates a phase shift that leads to a high contrast between the sample and the surrounding field. The sample is generally prepared by freezing or treating it with chemicals.

Question 36

If a scientist would like to use visible light on a stained sample, which microscopy technique should he use?
A. Compound Microscopy
B. Phase-Contrast Microscopy
C. Stereomicroscopy
D. Dark field Microscopy
E. Scanning Electron Microscopy

Answer 36

A. Compound Microscopy
A compound microscope is very similar to a light microscope in that it uses visible light to view a sample. The difference is that a compound microscope uses multiple lenses. This kind of microscope allows one to view a single cell layer with its internal structures and usually requires staining to best visualize the sample.

Question 37

Which of the following microscopy techniques has the lowest resolution?
A. Cryo Scanning Electron Microscopy
B. Phase-Contrast Microscopy
C. Stereomicroscopy
D. Dark Field Microscopy
E. Scanning Electron Microscopy

Answer 37

C. Stereomicroscopy
Stereomicroscopy, also known as light microscopy, uses visible light to view the surface of an object. Light microscopes have low magnification and resolution.

Question 38

Which of the following microscopy techniques has the highest resolution?
A. Dark Field Microscopy
B. Transmission Electron Microscopy
C. Phase-Contrast Microscopy
D. Stereomicroscopy
E. Compound Microscopy

Answer 38

B. Transmission Electron Microscopy
A transmission electron microscope (TEM) is used to obtain extremely high resolution 2D images of cells’ internal structures. A TEM works best when observing thin cross-sections.

Question 39

What is the first step of differential centrifugation?
A. Centrifugation
B. Pelleting out nucleus
C. Homogenization
D. Filtration
E. Isolating supernatant

Answer 39

C. Homogenization
Before differential centrifugation, cells must be lysed in a process known as homogenization, and cellular contents are released. Differential centrifugation is a lab technique that separates macromolecules on the basis of density and shape.

Question 40

What is the best definition of “pellet” in centrifugation?
A. Most dense layer in the centrifuge tube
B. Less dense layer in the centrifuge tube
C. Liquid layer above the sedimented layer
D. Sedimented layer above the liquid layer
E. Cellular homogenate

Answer 40

A. Most dense layer in the centrifuge tube

Question 41

What is the best definition of “supernatant” in centrifugation?
A. Liquid layer below the sedimented layer
B. Precipitate
C. Sedimented layer below the liquid layer
D. Less dense layer in the centrifuge tube
E. Most dense layer in the centrifuge tube

Answer 41

D. Less dense layer in the centrifuge tube

Question 42

During centrifugation, which will pellet out first?
A. ER fragments
B. Ribosome
C. Mitochondria
D. Chloroplast
E. Nuclei

Answer 42

E. Nuclei

Question 43

List the order of the cell organelles below from most to least dense.
I. ER fragments
II. Ribosomes
III. Mitochondria/Chloroplast
IV. Nuclei

A. 4,3,1,2
B. 4,1,3,2
C. 3,4,1,2
D. 3,1,4,2
E. 2,1,3,4

Answer 43

List the order of the cell organelles below from most to least dense.
I. ER fragments
II. Ribosomes
III. Mitochondria/Chloroplast
IV. Nuclei
A. 4,3,1,2
The nucleus is the most dense component of a cell as it is composed of the nuclear envelope and chromatin. Mitochondria and chloroplasts are similar in density and have greater density than the endoplasmic reticulum. Ribosomes are small and the least dense of these choices.

Question 44

If a cell homogenate is centrifuged, which of the following will pellet out last?
A. Nuclei
B. Ribosome
C. Mitochondria
D. Chloroplast
E. ER fragments

Answer 44

B. Ribosome
Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. The least dense particles will pellet out last.

The nucleus is the most dense component of a cell, composed of the nuclear envelope and chromatin. Mitochondria and chloroplasts are similar in density and have greater density than the endoplasmic reticulum. Ribosomes are small and the least dense of these choices.

Question 45

If a pellet with the nuclei is discarded, then which of the following will pellet out of the supernatant first if it is centrifuged?
A. ER fragments
B. Mitochondria
C. Ribosome
D. Cytosol
E. Viruses

Answer 45

B. Mitochondria
Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. The most dense particles will pellet out first.

The nucleus is the most dense component of a cell, followed by mitochondria/chloroplasts. If the pellet with the nuclei is discarded, the mitochondria and chloroplasts will then be first to pellet out of the supernatant.

Question 46

A scientist performs differential centrifugation. They spin the tube once and discard the pellet layer. They spin the tube again and isolate the pellet layer. Which molecule is produced in significant amounts by the organelle that would be found in this layer?
A. Tubulin
B. ATP
C. Chromatin
D. Glycogen
E. Flagellin

Answer 46

B. ATP
Differential centrifugation is a common procedure used to separate organelles and other sub-cellular particles based on their sedimentation rate. Particles of different densities or sizes in a suspension will sediment at different rates, with the larger and denser particles sedimenting faster. The nucleus is the most dense component of a cell, followed by mitochondria/chloroplasts, and the very last components seen would be ribosomes (and other small particles that may be present such as viruses).

Given that the tube has gone through two cycles of centrifugation, we would expect to find mitochondria/chloroplast in this pellet layer. Finally, ATP would be produced in significant amounts by mitochondria found in this layer because it is the major ATP-producing organelle in the cell.

Question 47

If centrifugation is performed on proteins, then which of the following will appear in the pellet?
A. Insoluble proteins
B. Soluble proteins

Answer 47

A. Insoluble proteins
Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. Proteins can also be separated by centrifugation according to their solubility. An insoluble protein will appear in the pellet, and a soluble protein will remain dissolved in the supernatant.

Question 48

If differential centrifugation is performed, then which of the following will pellet out last?
A. Nuclei
B. Mitochondria
C. Ribosomes
D. ER fragments
E. Cytosol

Answer 48

E. Cytosol
Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. The cytosol is the least dense cellular component and will therefore pellet out last.

Question 49

Which of the following best describes differential centrifugation?
A. Separation of cell contents with one spin step
B. Creation of multiple layers in one centrifuge tube
C. Separation of cell contents with multiple spin steps
D. Separation of cell contents based only on the density
E. Separation of cell contents based only on the size

Answer 49

Separation of cell contents with multiple spin steps

Question 50

Which of the following is most likely to appear in the precipitate if a cell homogenate is centrifuged?
A. Nuclei
B. Chloroplast
C. Mitochondria
D. Ribosome
E. ER fragments

Answer 50

A. Nuclei
During centrifugation, the most dense particles will pellet out of the cell homogenate first. The nucleus is the most dense component of a cell, as it is composed of the nuclear envelope and chromatin, and is, therefore, most likely to appear in the precipitate.

Question 51

If a cell homogenate is centrifuged for the first time during differential centrifugation, and the scientist would like to study the chloroplast, he should __________.
A. Keep the pellet
B. Keep the supernatant
C. Keep the precipitate
D. Discard the supernatant
E. Homogenize the pellet and supernatant

Answer 51

B. Keep the supernatant

Question 52

If differential centrifugation is performed, then which of the following will pellet out first?
A. Soluble proteins
B. Ribosomes
C. Viruses
D. Nuclei
E. ER Fragments

Answer 52

D. Nuclei

Question 53

While centrifuging homogenized cell components, the scientist accidentally shakes the tube, and the supernatant and pellet homogenize together again. What should he do?
A. Discard the tube
B. Centrifuge the tube again
C. Try his best to remove the precipitate with a pipette
D. Shake the tube manually
E. Heat the tube up

Answer 53

B. Centrifuge the tube again
Centrifuging the tube again will separate the homogenized supernatant and pellet. The pellet will reform and be separate from the supernatant.

Question 54

Which of the following appears as one of the last homogenates after differential centrifugation?
A. Mitochondria
B. Chloroplast
C. Nuclei
D. Cytosol
E. Ribosomes

Answer 54

D. Cytosol
Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. The cytosol is the least dense cellular component and will therefore pellet out last.

Question 55

If a scientist would like to separate all the cell components into individual tubes, then which of the following steps must occur?
A. Heat fixation
B. Density centrifugation
C. Differential centrifugation
D. Only one cycle of centrifugation
E. Staining

Answer 55

C. Differential centrifugation

Question 56

If a scientist performs only one centrifugation cycle, then which form of centrifugation is he most likely performing?
A. Density centrifugation
B. Differential centrifugation
C. Homogenization
D. Heat fixation
E. Karyotyping

Answer 56

A. Density centrifugation

Question 57

Which of the following is the best definition of centrifugation?
A. Spinning cell components at high speeds
B. Heating cell components to separate them
C. Homogenizing cell components
D. Killing cells
E. Removing soluble cell components

Answer 57

A. Spinning cell components at high speeds
Centrifugation is a lab technique that separates macromolecules suspended in a liquid matrix on the basis of density. The centrifuge spins test tubes containing cell components at extremely high velocities which force denser components to form a pellet at the bottom of the tube.

Question 58

Which of the following is typically used to homogenize cells?
A. Centrifuge
B. Laboratory mixer
C. Heat shock
D. Flow cytometry
E. Polymerase Chain Reaction

Answer 58

B. Laboratory mixer
Before centrifugation, cells should be mixed together to form a liquified cell homogenate. A laboratory mixer is the proper piece of lab equipment to homogenize cells.

Question 59

Which of the following best describes recombinant DNA?
A. DNA summated from different organisms
B. DNA from the same source
C. DNA found naturally in the genome
D. DNA generated through mutations
E. DNA homogenized with a laboratory mixer

Answer 59

A. DNA summated from different organisms

Question 60

Recombinant DNA segments can combine with each other in all the following ways EXCEPT one. Which of the following is the EXCEPTION?
A. Viral transduction
B. Bacterial transfection
C. Bacterial conjugation
D. Transposons
E. Artificial recombinant DNA technology

Answer 60

B. Bacterial transfection
Transfection is a form of horizontal gene transfer in which foreign DNA is introduced into a eukaryotic cell without the use of a virus. Physical and/or chemical methods are employed that enable DNA to easily enter the eukaryotic cell.

Question 61

Which of the following is used to accurately slice segments of DNA?
A. Restriction endonucleases
B. Polymerase Chain Reaction
C. Vector
D. Bacterial conjugation
E. Electroporation

Answer 61

A. Restriction endonucleases
When DNA from different organisms is combined in vitro, recombinant DNA is formed. Restriction endonucleases are used to cut the DNA at specific palindromic sequences, and the fragments are then ligated together.

Question 62

When DNA is cut, what are the cut ends of DNA called?
A. Sticky ends
B. Short tandem repeats
C. Restriction fragment length polymorphisms
D. Vectors
E. Telomeres

Answer 62

A. Sticky ends

Question 63

Restriction enzymes or endonucleases are usually used by bacteria to __________.
A. Protect itself from invading RNA
B. Reproduce sexually
C. Protect itself from invading DNA
D. Accept infecting organisms for conjugation
E. Infect host organisms

Answer 63

C. Protect itself from invading DNA
Restriction endonucleases cut DNA at specific palindromic sequences. In bacteria, these enzymes work like an immune system; they recognize and cut foreign DNA to prevent it from integrating into the bacterial genome.

Question 64

Which of the following is used to identify DNA fingerprinting to identify possible suspects in criminal cases?
A. Restriction fragment length polymorphisms
B. EcoRI
C. Restriction enzymes
D. Recombinant DNA
E. Vector

Answer 64

A. Restriction fragment length polymorphisms
Different individuals have variations within homologous DNA sequences at the sites recognized by restriction enzymes; these variations are referred to as restriction fragment length polymorphisms. These variations result in differences in DNA fragment length which can be used in identifying individuals utilizing gel electrophoresis in a process known as DNA fingerprinting.

Question 65

Which of the following is similar to restriction fragment length polymorphisms in that they can be used as a form of identification?
A. BamHI
B. Short tandem repeats
C. Sticky ends
D. Recombinant DNA
E. Expression vectors

Answer 65

B. Short tandem repeats
DNA fingerprinting is a lab technique used to identify individuals based on specific DNA fragments. Restriction fragment length polymorphisms and short tandem repeats are common DNA segments used in DNA fingerprinting.

Question 66

What is the major difference between the analysis of restriction fragment length polymorphisms and short tandem repeats?
A. Short tandem repeats are analyzed using restriction enzymes
B. Restriction fragment length polymorphisms are not analyzed using restriction enzymes
C. Restriction fragment length polymorphisms are analyzed using probes and PCR amplification
D. Short tandem repeats are analyzed using probes and PCR amplification
E. There is no analytical difference between the two

Answer 66

D. Short tandem repeats are analyzed using probes and PCR amplification
Short tandem repeats (STRs) are repeats of DNA sequences about 2-5 nucleotides in length. Analysis of STRs includes probing and PCR amplification.

Restriction fragment length polymorphisms (RFLPs) are the DNA variations among individuals at restriction sites. Restriction enzymes are used for analysis since they will cut RFLPs differently among individuals and produce DNA fragments of varying lengths.

Question 67

Which of the following best describes short tandem repeats?
A. Fragments of different sizes
B. Repeats of nucleotides that is inherited identically in all humans
C. Repeats of nucleotides that vary between humans
D. Fragments of DNA created from different sources
E. Cannot be used in paternity or criminal cases

Answer 67

C. Repeats of nucleotides that vary between humans
Short tandem repeats (STRs) are repeats of DNA sequences about 2-5 nucleotides in length. STRs are different among every individual except identical twins.

Question 68

Short tandem repeats differ in humans except for __________.
A. Siblings
B. Identical twins
C. Fraternal twins
D. Cousins
E. Direct relatives

Answer 68

B. Identical twins
Short tandem repeats (STRs) are repeats of DNA sequences about 2-5 nucleotides in length. STRs are different among every individual except identical twins.

Note: Identical twins are monozygotic and result from indeterminate cleavage, and therefore are genetically identical.

Question 69

Which of the following best describes restriction fragment length polymorphisms?
A. Short repeats of nucleotides that differ between individuals
B. Uninheritable
C. Different fragment lengths depending on individual specific differences in DNA
D. Analyzed using probes
E. Analyzed without restriction enzymes

Answer 69

C. Different fragment lengths depending on individual specific differences in DNA
Restriction fragment length polymorphisms (RFLPs) are the DNA variations among individuals at restriction sites. When cut by restriction enzymes, fragment lengths will differ among individuals due to these different DNA sequences.

Question 70

Which of the following best describes polymorphisms in restriction fragment length polymorphisms?
A. Fragments of the same length
B. Short nucleotide repeats
C. Fragments of different lengths
D. Different short nucleotide changes
E. Same DNA sequence between individuals

Answer 70

C. Fragments of different lengths
Restriction fragment length polymorphisms (RFLPs) are the DNA variations among individuals at restriction sites. When cut by restriction enzymes, fragment lengths will differ among individuals due to the different DNA sequences. The fragments of different lengths are observed due to polymorphisms, which occur when there are multiple phenotypes that exist within a population.

Question 71

What is the purpose of a DNA vector?
A. Transfer foreign DNA into another cell
B. Remove genetic material
C. Protect bacteria from viral infection
D. Identify polymorphisms
E. Cut DNA into unique fragments

Answer 71

A. Transfer foreign DNA into another cell
In order to express a eukaryotic gene in a bacterium, it must be transferred in some way. A vector is an agent used to transfer the foreign DNA into another cell. A vector can be either a plasmid or a bacteriophage.

Question 72

Which of the following is a common example of a DNA vector?
A. Restriction enzymes
B. Plasmid
C. Peroxisome
D. Ribosomes
E. DNA probe

Answer 72

B. Plasmid
In order to express a eukaryotic gene in a bacterium, it must be transferred in some way. A vector is an agent used to transfer foreign DNA into another cell. A vector can be either a plasmid or a bacteriophage.

Question 73

D. Expression vectors contain a very active promoter of the restriction site Which of the following is required to add foreign DNA into a plasmid?
A. Transformation
B. Translation
C. Conjugation
D. Transduction
E. Transfection

Answer 73

A. Transformation

Question 74

What is the difference between a cloning vector and an expression vector?
A. Cloning vectors are used to ensure the gene inserted in the plasmid has significant gene production
B. Cloning vectors contain a very active promoter of the restriction site
C. Expression vectors inhibit the gene of interest from expressing
D. Expression vectors contain a very active promoter of the restriction site
E. Expression vectors transfer foreign DNA into a host cell

Answer 74

D. Expression vectors contain a very active promoter of the restriction site
Cloning vectors contain the DNA segments that contain the gene of interest, the origin of replication, and restriction sites. An expression vector consists of the same elements, but also contains a very active promoter and other regulatory sites.

Question 75

To introduce the plasmid to the bacterium or make the bacterium competent, which of the following needs to be performed?
A. Transformation
B. Conjugation
C. PCR Amplification
D. Electroporation
E. Antibiotic resistance screen

Answer 75

D. Electroporation

Question 76

Answer 76

A

Question 77

Answer 77

Question 78

Instead of electroporation, which of the following can also be used to make the cell competent?
A. Centrifugation
B. Heat shock + CaCl2
C. Heat shock + hot water
D. Antibiotic treatment
E. DNA probe

Answer 78

B. Heat shock + CaCl2

Question 79

Which of the following is used to test if bacteria successfully took in the plasmid?
A. Electroporation
B. Heat shock + CaCl2
C. Expression vectors
D. Antibiotic resistance screen
E. Transformation

Answer 79

D. Antibiotic resistance screen
Plasmids commonly carry genes that confer antibiotic resistance to bacteria. In order to test if bacteria successfully took in the plasmid, an antibiotic resistance screen is performed. The bacteria that did not take up the plasmid will die since they do not have antibiotic-resistance genes, and those that did take up the plasmid will survive.

Question 80

If a bacteria did not take in plasmid successfully during the antibiotic resistance screen, then which of the following will occur?
A. Die
B. Survive
C. Turn red
D. Change color
E. Develop multiple colonies

Answer 80

A. Die

Plasmids commonly carry genes that confer antibiotic resistance to bacteria. In order to test if bacteria successfully took in the plasmid, an antibiotic resistance screen is performed. The bacteria that did not take up the plasmid will die since they do not have antibiotic-resistance genes, and those that did take up the plasmid will survive.

Question 81

What is the purpose of gel electrophoresis?
A. Shock the bacterium to accept the plasmid
B. Separate RNA molecules
C. Separate DNA molecules
D. Tag specific DNA sequences
E. Synthesize RNA molecules

Answer 81

C. Separate DNA molecules
Gel electrophoresis is a laboratory technique that uses an electric current to separate DNA fragments or proteins in agarose gel. DNA fragments or proteins are separated on the basis of size; smaller molecules migrate furthest.

DNA is negatively charged due to its phosphate groups. Therefore, DNA is placed by the negatively charged cathode and will migrate toward the positively charged anode.

Question 82

In gel electrophoresis, the DNA fragments move toward the __________.
A. Agarose gel
B. Positive end
C. Negative end
D. Closest neighbor DNA fragment
E. SDS page

Answer 82

B. Positive end
DNA is negatively charged due to the phosphate groups. Therefore, DNA is placed by the negatively charged cathode and will migrate toward the positively charged anode.

Question 83

In gel electrophoresis, which of the following will move the farthest?
A. Small molecules
B. Large molecules
C. Proteins
D. RNA fragments
E. Positively charged molecules

Answer 83

A. Small molecules
Gel electrophoresis is a laboratory technique that uses an electric current to separate DNA fragments or proteins in agarose gel on the basis of size. Smaller molecules will migrate the furthest because they can easily fit through the pores in the gel.

Question 84

Which facet of DNA allows it to move towards the positive end during gel electrophoresis?
A. Hydrogen bonding between DNA
B. Negative charge of the phosphate backbone
C. Large size
D. DNA is negatively charged unlike RNA
E. DNA probes present

Answer 84

B. Negative charge of the phosphate backbone

Question 85

To perform gel electrophoresis on proteins, which of the following must be added?
A. SDS
B. Magnetic field
C. DNA probe
D. Fluorescence
E. Electroporation

Answer 85

A. SDS
Due to the presence of their R groups, proteins have different charges that will affect their migration patterns during gel electrophoresis. SDS (sodium dodecyl sulfate) is a chemical that denatures proteins and gives them all a uniform negative charge.

Question 86

What does SDS do to proteins during gel electrophoresis?
A. Adds a positive charge to the protein
B. Adds a negative charge to the protein
C. Coils the protein
D. Promote protein folding
E. Maintain the hydrophobic areas

Answer 86

B. Adds a negative charge to the protein
Due to the presence of their R groups, proteins have different charges that will affect their migration patterns during gel electrophoresis. SDS (sodium dodecyl sulfate) is a chemical that denatures proteins and gives them all a uniform negative charge.

Question 87

How do DNA probes work for gel electrophoresis?
A. Complementarily bind to the gene of interest
B. Denature the DNA
C. Add a negative charge to the DNA
D. Introduce DNA to the agarose gel
E. Linearize protein present

Answer 87

A. Complementarily bind to the gene of interest
A DNA probe is a radioactively labeled single-stranded DNA molecule used to locate and identify specific DNA sequences during gel electrophoresis. DNA probes have complementary sequences for the sequence of interest. The radioactive label will identify wherever that specific sequence is among the DNA fragments.

Question 88

What is the purpose of DNA probes after gel electrophoresis?
A. Identify the specific DNA sequence
B. Identify the specific RNA sequence
C. Aid the DNA in migrating to the positive end
D. Synthesize RNA template
E. Create cDNA based on RNA present in the agarose gel

Answer 88

A. Identify the specific DNA sequence
A DNA probe is a radioactively labeled single-stranded DNA used to locate and identify specific DNA sequences during gel electrophoresis. DNA probes have complementary sequences for the sequence of interest. The radioactive label will identify wherever that specific sequence is among the DNA fragments.

Question 89

Which of the following are used by DNA probes to identify the DNA fragment of interest?
A. SDS
B. Electroporation
C. Nucleic acid hybridization
D. Short tandem repeats
E. Transformation

Answer 89

C. Nucleic acid hybridization
DNA probes have complementary sequences for a sequence of interest. During nucleic acid hybridization, the DNA (or RNA) and DNA probe are denatured and then hybridize with each other. The result is two double-stranded DNA molecules with strands from a different sources.

Question 90

Which technique allows the observation of gene expression in intact organisms like embryos or tissue?
A. In situ hybridization
B. Reverse transcriptase
C. Electroporation
D. Scanning Electron Microscopy
E. Next-generation sequencing

Answer 90

A. In situ hybridization
A nucleic acid probe is a fluorescently labeled single-stranded DNA molecule used to locate and identify specific DNA sequences. Probes have complementary sequences for the sequence of interest. In situ hybridization uses nucleic acid probes to measure gene expression in intact organisms by identifying specific mRNA molecules.

Question 91

Which of the following is used to establish the specific sequence of base pairs in a DNA molecule?
A. Next-generation sequencing
B. Nucleic acid hybridization
C. Edman degradation
D. Electroporation
E. Short tandem repeats

Answer 91

A. Next-generation sequencing
Next generation sequencing is the current method used to sequence a DNA molecule and utilizes PCR.

Question 92

Which of the following is used to create DNA molecules based on an RNA template?
A. Polymerase Chain Reaction
B. Reverse transcriptase
C. Next-generation sequencing
D. Nucleic acid hybridization
E. Gel electrophoresis

Answer 92

B. Reverse transcriptase
Reverse transcriptase is an enzyme that synthesizes a DNA copy complementary to an RNA template. This enzyme can be used to create cDNA (complementary DNA). cDNA is extremely useful as it lacks introns and is composed of exons only; this enables the insertion of human DNA into bacteria for experimentation.

Reverse transcriptase is also found in retroviruses, such as HIV.

Question 93

Human Immunodeficiency Virus (HIV) naturally uses which of the following to create complementary DNA off of an RNA template?
A. Reverse transcriptase
B. Polymerase Chain Reaction
C. Restriction enzymes
D. DNA probes
E. Nucleic acid hybridization

Answer 93

A. Reverse transcriptase
Reverse transcriptase is an enzyme that synthesizes a DNA copy complementary to an RNA template. HIV is a retrovirus; within the host cell, its RNA genome is transcribed into DNA by reverse transcriptase and then inserted into the host cell’s DNA genome.

Question 94

Unlike normal DNA translation, complementary DNA created by reverse transcriptase has __________.
A. No exons
B. No introns
C. Mutations
D. To perform RNA processing
E. Negatively charged phosphate groups

Answer 94

B. No introns
Reverse transcriptase is an enzyme that synthesizes a DNA copy complementary to an RNA template. This enzyme can be used to create cDNA (complementary DNA). cDNA is extremely useful as it lacks introns and is composed of exons only; this enables the insertion of human DNA into bacteria for experimentation.

Question 95

DNA probes can be __________.
A. Double-stranded RNA fragments
B. Double-stranded DNA
C. Single-stranded DNA
D. Intron
E. Proteins

Answer 95

C. Single-stranded DNA
A DNA probe is a radioactively labeled single-stranded DNA molecule used to locate and identify specific DNA sequences during gel electrophoresis. DNA probes have complementary sequences for the sequence of interest. The radioactive label will identify wherever that specific sequence is among the DNA fragments.

Question 96

If a plasmid is successfully taken up by bacteria, then which of the following cannot occur during the antibiotic resistance screen?
A. Death
B. Color change
C. Colony formation
D. Multiplication
E. Successful growth

Answer 96

A. Death
Plasmids commonly carry genes that confer antibiotic resistance to bacteria. In order to test if bacteria successfully took in the plasmid, an antibiotic resistance screen is performed. The bacteria that did not take up the plasmid will die since they do not have antibiotic-resistance genes, and those that did take up the plasmid will survive.

Question 97

Why are plasmids that are successfully taken up by the bacteria able to survive the antibiotic resistance screen?
A. Absence of antibiotic resistance gene
B. Antibiotic resistance gene present in plasmid
C. Bacteria already contains the antibiotic resistance gene
D. Bacteria that take up plasmid is considered antibiotic-resistant
E. Antibiotics cannot penetrate bacteria naturally

Answer 97

B. Antibiotic resistance gene present in plasmid
Plasmids commonly carry genes that confer antibiotic resistance to bacteria. In order to test if bacteria successfully took in the plasmid, an antibiotic resistance screen is performed. The bacteria that did not take up the plasmid will die since they do not have antibiotic-resistance genes, and those that did take up the plasmid will survive.

Question 98

While performing the lab procedure to insert a plasmid into a bacterium, the scientist forgets the step of creating holes into the plasma membrane. Which step did he miss?
A. Gel electrophoresis
B. Electroporation
C. Transformation
D. Ligation
E. Polymerase Chain Reaction

Answer 98

B. Electroporation
A competent cell is one that is capable of taking up exogenous DNA from the environment. There are two main methods of making bacterial cells competent. The first method is electroporation, in which the cell is given a quick electrical pulse that creates pores in the plasma membrane. The other method is to heat shock and treat with CaCl2.

Question 99

Which of the following is required to create the sticky ends that allow DNA fragments to bind to a plasmid?
A. Restriction enzymes
B. DNA ligase
C. Expression vector
D. Electroporation
E. Transformation

Answer 99

A. Restriction enzymes

Question 100

This is used to stabilize the connecting parts of DNA sticky ends and the plasmid.
A. Reverse transcriptase
B. Electroporation
C. Restriction enzymes
D. DNA ligase
E. Cloning vector

Answer 100

D. DNA ligase
Restriction enzymes cut DNA at specific sequences and can generate sticky ends (staggered cuts) or blunt ends (straight cuts). DNA ligase is an enzyme that stabilizes the interaction between the plasmid and DNA by catalyzing the covalent bonding between the molecules.

Question 101

What is the difference between sticky and blunt ends in DNA?
A. Blunt ends have an overhang
B. Blunt ends have no nucleotides with complementary pairing
C. Sticky ends have an overhang
D. Sticky ends have nucleotides with complementary pairing
E. Sticky ends are not cut with restriction enzymes

Answer 101

C. Sticky ends have an overhang

Question 102

What does the absence of introns in cDNA aid with?
A. Effective transcription and translation of gene
B. Inhibition of transcription and translation of gene
C. Inhibition of gene product expression
D. Overexpression of exons
E. Overexpression of bacterial DNA

Answer 102

A. Effective transcription and translation of gene
cDNA (complementary DNA) lacks introns and is composed of exons only. Because there are no introns, splicing is not required and enables effective transcription and translation of genes. cDNA is extremely useful for when we wish to express eukaryotic genes in bacteria which lack splicing activity.

Question 103

Which of the following lab techniques amplifies a specific DNA sequence?
A. Centrifugation
B. Polymerase Chain Reaction
C. Electroporation
D. Western Blotting
E. Gel electrophoresis

Answer 103

. Polymerase Chain Reaction

The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. There are three steps of PCR: (1) denaturation, (2) annealing, and (3) elongation.

Question 104

List the steps of PCR in the correct order below.
A. Annealing, Denaturation, Elongation
B. Elongation, Denaturation, Annealing
C. Denaturation, Annealing, Elongation
D. Denaturation, Elongation, Annealing
E. Annealing, Elongation, Denaturation

Answer 104

C. Denaturation, Annealing, Elongatio
The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. During step 1, denaturation, DNA is heated to separate the double-stranded DNA. Step 2, annealing, involves DNA primers annealing the single-stranded DNA. Step 3 is the elongation of the strands in which Taq polymerase adds nucleotides to the 3` ends.

Question 105

Which of the following is not needed to perform PCR?
A. Taq Polymerase
B. Buffer/Cofactors
C. Human DNA polymerase
D. Nucleotides
E. Primer

Answer 105

C. Human DNA polymerase
The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. The reactions reach almost 100 ˚C which requires a heat-resistant enzyme to be used. Unlike human DNA polymerase, Taq polymerase (derived from the thermophilic bacterium Thermus aquaticus) is extremely heat-stable.

Question 106

Why must Taq polymerase be used in PCR?
A. Denatured easily
B. Heat resistant
C. Unstable
D. Harder to isolate
E. Heat sensitive

Answer 106

B. Heat resistant
The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. The reactions reach almost 100 ˚C which requires a heat-resistant enzyme to be used. Unlike human DNA polymerase, Taq polymerase (derived from the thermophilic bacterium Thermus aquaticus) is extremely heat-stable.

Question 107

What is the direct purpose of denaturation during PCR?
A. Attach primers to individual strands
B. Synthesize complementary strands
C. Separate the double-stranded DNA molecule
D. Replicate the separated DNA strands
E. Denature the Taq polymerase

Answer 107

C. Separate the double-stranded DNA molecule
The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. In order for the DNA to be replicated, the strands must first be separated by denaturation. Once denatured, a primer is added and then the strands are elongated using Taq polymerase.

Question 108

If the denaturation step were to fail during PCR, which of the following would be seen?
A. DNA would be broken down entirely into individual nucleotides
B. DNA strands would all be double-stranded and unable to separate
C. RNA would be present rather than DNA
D. Polymerase would be unable to synthesize after binding to the DNA
E. The phosphodiester backbone of DNA would be unable to separate from the nucleotides

Answer 108

B. DNA strands would all be double-stranded and unable to separate

Question 109

What is the direct purpose of annealing during PCR?
A. Separate the double-stranded DNA molecule
B. Replicate the separate DNA strands
C. Allow primers to bind to separated strands of DNA
D. Denature the DNA
E. Allow Taq polymerase to bind in the absence of primers

Answer 109

C. Allow primers to bind to separated strands of DNA
During the annealing phase of PCR, the temperature is lowered to 55 ˚C. At this temperature, primers are able to bind to the separated strands of DNA.

Question 110

During PCR, why are polymerases from bacteria and archaea found in extremely hot environments often used?
A. Prokaryotic polymerases in hot environments lack introns and are therefore more efficient
B. The polymerases are less likely to denature when the temperature is raised during PCR
C. Bacteria and archaea in extremely hot environments are easier to isolate than cold ones
D. Eukaryotic polymerases are more expensive while prokaryotic polymerases are cheaper
E. The hotter the environment a polymerase functions in, the more accurate its output

Answer 110

B. The polymerases are less likely to denature when the temperature is raised during PCR

PCR (shown in the image below) requires thermostable or heat-stable DNA polymerases to carry out synthesis because high temperatures are used to separate the template DNA strands in each cycle during the denaturation step. ​Because DNA polymerases are (protein) enzymes, they are susceptible to becoming denatured when exposed to these high temperatures. Certain bacteria and archaea are adapted to extremely hot environments, so their enzymes are more resistant to heat destabilization, making these polymerases an ideal fit for PCR.

Question 111

What most likely is occurring due to the high temperature during the denaturation step of PCR?
A. Hydrogen bonds are breaking between the DNA strands
B. Hydrogen bonds are forming between the DNA strands
C. Phosphodiester bonds are breaking between the DNA strands
D. Ester bonds are breaking between the DNA strands
E. Single DNA strands are complementary binding

Answer 111

A. Hydrogen bonds are breaking between the DNA strands

Question 112

What will most likely happen if the temperature was not maintained during the denaturation step of PCR?
A. Premature stop of DNA separation
B. Completed DNA separation
C. Nothing
D. DNA complementary binding
E. Primer binding

Answer 112

A. Premature stop of DNA separation
The denaturation step of PCR is performed at 95 ˚C in order to separate the two strands of double-stranded DNA. If the temperature was not maintained during this step, the separation of the DNA would stop prematurely and the DNA will only be partially denatured.

Question 113

During the annealing step of PCR, the primers will __________.
A. Ester bond to the separated DNA strands
B. Covalent bond to the separated DNA strands
C. Phosphodiester bond to the separated DNA strands
D. Hydrogen bond to the separated DNA strands
E. Metallically bond to the separated DNA strands

Answer 113

Hydrogen bond to the separated DNA strands
During the annealing phase of PCR, the temperature is lowered to 55 ˚C. At this temperature, primers are able to bind to the separated strands of DNA. Primers are the nucleotides that begin the complementary strand of DNA and they form hydrogen bonds with the template strand.

Question 114

What is the direct purpose of elongation during PCR?
A. Separate the double-stranded DNA
B. Synthesize complementary strand using Taq polymerase
C. Allow the primer to bind to the separated DNA strands
D. Convert DNA to RNA
E. Denature the DNA strands into nucleotides

Answer 114

Allow the primer to bind to the separated DNA strands
The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. In order for the DNA to be replicated, the strands must first be separated by denaturation. Once denatured, a primer is added and then the strands are elongated using Taq polymerase.

Question 115

Polymerase Chain Reaction is performed __________.
A. In multiple cycles
B. In one cycle
C. In a temperature negligent setting
D. To produce primers
E. To amplify RNA

Answer 115

In multiple cycles
The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. During each cycle, the total number of DNA strands doubles as each DNA strand is replicated to give two daughter strands. After one cycle, there are two strands of DNA; after two cycles, there are four strands of DNA, and so on. Multiple cycles are performed during PCR in order to obtain millions of copies.

Question 116

Nucleotide differences in the human genome are called __________.
A. Single nucleotide polymorphisms
B. Short tandem repeats
C. Primers
D. Restriction fragment length polymorphisms
E. Plasmids

Answer 116

A. Single nucleotide polymorphisms
Different individuals have single-nucleotide variations within homologous DNA sequences; these variations are referred to as single nucleotide polymorphisms (SNPs). For example, at homologous sequences, one person can have the sequence AAAAAA, and another person can have the sequence AAAAAT. SNPs are responsible for many diseases and much of the genetic variation we see.

Question 117

A geneticist would like to create a genetic marker for an allele linked to Parkinson’s Disease. Which of the following would be the most helpful for his research?
A. Primers
B. PCR
C. Single nucleotide polymorphisms
D. Short tandem repeats
E. Whole human genome

Answer 117

C. Single nucleotide polymorphisms
Different individuals have single-nucleotide variations within homologous DNA sequences; these variations are referred to as single nucleotide polymorphisms (SNPs). For example, at homologous sequences, one person can have the sequence AAAAAA, and another person can have the sequence AAAAAT. SNPs are responsible for many diseases and much of the genetic variation we see.

Question 118

Polymerase chain reaction can be used to discover all the following EXCEPT one. Which of the following is the EXCEPTION?
A. Single nucleotide polymorphisms
B. Short tandem repeats
C. Restriction fragment length polymorphisms
D. Specific DNA sequences
E. Mutation detection

Answer 118

C. Restriction fragment length polymorphisms
Restriction fragment length polymorphisms (RFLPs) are the DNA variations among individuals at restriction sites. Restriction enzymes are used to discover RFLPs since they will cut the RFLPs differently in each individual and produce DNA fragments of varying lengths. Polymerase chain reaction (PCR) cannot be used to discover RFLPs.

Question 119

Which of the following will most likely be used to study the expression of a large sample of genes in the genome?
A. Northern blot
B. Western blot
C. DNA microarray assay
D. PCR
E. Next-generation sequencing

Answer 119

C. DNA microarray assay
The DNA microarray assay consists of thousands of DNA probes that represent different genes. Fluorescence during the assay indicates the level of expression of specific genes and where in the organism the genes are expressed.

Question 120

A scientist would like to study multiple mutation hot spots in the genome of a patient suffering from breast cancer. Which DNA technology should he use to do so?
A. Southern Blot
B. Western Blot
C. PCR
D. Sanger Sequencing
E. DNA microarray assay

Answer 120

E. DNA microarray assay
The DNA microarray assay consists of thousands of DNA probes that represent different genes. Fluorescence during the assay indicates the level of expression of specific genes and where in the organism the genes are expressed.

Question 121

In DNA microarray assays, which of the following is used to make cDNA bind to the DNA microarray?
A. Taq polymerase
B. DNA polymerase
C. Reverse transcriptase
D. RNA polymerase
E. Buffer salts

Answer 121

Reverse transcriptase
The DNA microarray assay consists of thousands of DNA probes that represent different genes. Reverse transcriptase is an enzyme that synthesizes cDNA from an mRNA template. cDNA is then fluorescently labeled and will hybridize with the DNA probes.

Question 122

For a DNA microarray assay, the cDNA of cancerous tissue was tagged with red fluorescence. During DNA microarray analysis, one of the wells lights up as red fluorescence. This means __________.
A. The gene in the DNA microarray is only expressed in the healthy tissue
B. The gene in the DNA microarray is only expressed in the cancerous tissue
C. The gene in the DNA microarray is not dormant in pathogenic tissue
D. The gene in the DNA microarray is not expressed in either healthy or pathogenic tissue
E. The gene in the DNA microarray is expressed in both healthy and pathogenic tissue

Answer 122

The gene in the DNA microarray is only expressed in the cancerous tissue

The DNA microarray assay consists of thousands of DNA probes that represent different genes. Fluorescence during the assay indicates the level of expression of specific genes and where in the organism the genes are expressed. Because this well lights up as red fluorescence, the gene contained in the well must be expressed only in cancerous tissue.

Question 123

For a DNA microarray assay, the cDNA of cancerous tissue was tagged with red fluorescence and the cDNA of healthy tissue was tagged with blue fluorescence. During DNA microarray analysis, one of the wells lights up as purple. This means ___________.
A. The gene in the DNA microarray is only expressed in the healthy tissue
B. The gene in the DNA microarray is only expressed in the cancerous tissue
C. The gene in the DNA microarray is not dormant in pathogenic tissue
D. The gene in the DNA microarray is not expressed in either healthy or pathogenic tissue
E. The gene in the DNA microarray is expressed in both healthy and pathogenic tissue

Answer 123

E. The gene in the DNA microarray is expressed in both healthy and pathogenic tissue
The DNA microarray assay consists of thousands of DNA probes that represent different genes. Fluorescence during the assay indicates the level of expression of specific genes and where in the organism the genes are expressed. Because this well lights up as purple fluorescence, the gene contained in the well must be expressed in both healthy (blue) and pathogenic (red) tissue.

Question 124

A scientist is performing a DNA microarray assay and uses red fluorescence for healthy tissue cDNA and blue fluorescence for malignant tissue cDNA. During analysis, he notices one of the wells has no fluorescence. This means ___________.
A. The gene in the DNA microarray is only expressed in the healthy tissue
B. The gene in the DNA microarray is only expressed in the cancerous tissue
C. The gene in the DNA microarray is not dormant in pathogenic tissue
D. The gene in the DNA microarray is not expressed in either healthy or malignant tissue
E. The gene in the DNA microarray is expressed in both healthy and pathogenic tissue

Answer 124

D. The gene in the DNA microarray is not expressed in either healthy or malignant tissue
The DNA microarray assay consists of thousands of DNA probes that represent different genes. Fluorescence during the assay indicates the level of expression of specific genes and where in the organism the genes are expressed. Because there is no fluorescence, the gene contained in the well is not being expressed in any type of tissue.

Question 125

Blotting techniques in research can be used to identify all of the following EXCEPT one. Which of the following is the EXCEPTION?
A. DNA
B. Protein
C. RNA
D. Cell density
E. Fragments of the gene

Answer 125

Cell density
Blotting is a laboratory technique that involves the transfer of DNA, RNA, or proteins from an agarose gel onto a blotting membrane for the purposes of identification and diagnostics. Cell density is commonly identified using a spectrophotometer.

Question 126

Which step is needed to start a Southern blot?
A. Antibody attachment
B. Gel electrophoresis
C. RNA molecules PCR
D. Protein PCR
E. Karyotyping

Answer 126

Gel electrophoresis
Blotting is a laboratory technique that involves the transfer of DNA, RNA, or proteins from an agarose gel onto a blotting membrane for the purposes of identification and diagnostics. The first step of a Southern blot is to run the molecules of interest in gel electrophoresis to separate DNA fragments.

Question 127

Which of the following is a Southern blot used for?
A. RNA identification
B. Density division of a cell
C. DNA identification
D. Protein identification
E. RNA duplication

Answer 127

DNA identification
The mnemonic to remember the different blotting techniques is SNoW DRoP:

S(outhern) – DNA

N(orthern) – RNA

W(estern) – protein

Question 128

Which of the following is a Northern blot used for?
A. DNA replication
B. RNA identification
C. Separation of cell homogenate
D. Protein identification
E. DNA identification

Answer 128

B. RNA identification
The mnemonic to remember the different blotting techniques is SNoW DRoP:

S(outhern) – DNA

N(orthern) – RNA

W(estern) – protein

Question 129

Which of the following is a Western blot used for?
A. Protein identification
B. DNA identification
C. RNA identification
D. RNA processing
E. Antibody identification

Answer 129

Protein identification
The mnemonic to remember the different blotting techniques is SNoW DRoP:

S(outhern) – DNA

N(orthern) – RNA

W(estern) – protein

Question 130

A scientist would like to study a single and specific DNA sequence extracted from Dolly, the cloned sheep. Which laboratory technique should she use for identifying this DNA sequence?
A. Western Blotting
B. DNA microarray assay
C. Southern Blotting
D. Northern Blotting
E. Centrifugation

Answer 130

Southern Blotting
The mnemonic to remember the different blotting techniques is SNoW DRoP:

S(outhern) – DNA

N(orthern) – RNA

W(estern) – protein

Question 131

A scientist would like to study a specific DNA sequence in HIV, an RNA virus. Which laboratory technique should she use?
A. Southern Blotting
B. Western Blotting
C. Northern Blotting
D. DNA microarray assay
E. Polymerase chain reaction

Answer 131

Northern Blotting
The mnemonic to remember the different blotting techniques is SNoW DRoP:

S(outhern) – DNA

N(orthern) – RNA

W(estern) – protein

Question 132

A difference between western and southern blotting is that ___________.
A. Western blotting uses antibodies
B. Western blotting uses probes
C. Southern blotting uses antibodies
D. Southern blotting does not use probes
E. Both use the same technique

Answer 132

A. Western blotting uses antibodies
A Western blot is used to identify proteins, and therefore uses tagged antibodies (or antibody-based probes) that will bind to the protein of interest. The tagged antibodies will change color when the blotting paper is treated with a color development solution. A Southern blot is used to identify DNA fragments, and a DNA probe is used to hybridize and mark the DNA.

The mnemonic to remember the different blotting techniques is SNoW DRoP:

S(outhern) – DNA

N(orthern) – RNA

W(estern) – protein

Question 133

A scientist would like to confirm the presence of mad cow prions, a misfolded protein, in a diseased cow’s brain tissue. Which blotting technique could he use to determine this?
A. Northern Blot
B. Western Blot
C. Southern Blot
D. Centrifugation
E. Polymerase chain reaction

Answer 133

B. Western Blot
The mnemonic to remember the different blotting techniques is SNoW DRoP:

S(outhern) – DNA

N(orthern) – RNA

W(estern) – protein

Question 134

Which of the following is used by both Southern and Northern Blotting?
A. DNA or RNA probes
B. Primary and secondary antibodies
C. mRNA
D. Taq polymerase
E. cDNA

Answer 134

A. DNA or RNA probes
Southern and Northern blotting use DNA and RNA probes, respectively.

Note: The mnemonic to remember the different blotting techniques is SNoW DRoP:

S(outhern) – DNA

N(orthern) – RNA

W(estern) – protein

Question 135

Which of the following is the best definition of a genomic library?
A. Aggregation of cloned DNA fragments from a genome
B. Collection of all human mutations
C. Summation of DNA probes
D. All blotting techniques
E. All organism vectors

Answer 135

A. Aggregation of cloned DNA fragments from a genome
A genomic library contains a copy of an organism’s complete genome. By screening a genomic library, specific genes can be located within the genome.

Question 136

Which of the following correctly describes a step in the formation of a gene library?
A. Genes of interest are inserted into mitochondria
B. PCR is performed after northern blotting
C. Centrifugation of all cell fragments
D. DNA microarray assay of all cell fragments
E. Genes of interest are inserted into plasmids

Answer 136

E. Genes of interest are inserted into plasmids
Genes of interest are plasmids, which are small, circular pieces of DNA that can replicate independently of the genome of the organism that they are taken from. The plasmids containing the inserted genes of interest are then introduced into host cells, where they can be replicated and stored in large numbers. The resulting collection of plasmids containing the genes of interest is known as a gene library.

Question 137

What is the first step of gene cloning?
A. Restriction enzymes are used to cut plasmid
B. Sticky ends of restriction fragments join together
C. Plasmids are removed from bacterial cells to be used as vectors
D. Plasmids are removed from animal cells to be used as vectors
E. DNA ligase seals nucleotides together

Answer 137

C. Plasmids are removed from bacterial cells to be used as vectors
During gene cloning, a gene is inserted into a plasmid and then replicated. The plasmid must first be removed from the bacterial cells in order to add the gene of interest. After insertion of the gene and replication of the plasmid, it can now serve as a vector to be inserted into bacteria to express the gene.

Question 138

After plasmids are removed from bacteria cells, which step needs to follow in the process of gene cloning?
A. PCR of bacterial plasmids
B. Extraction of the gene of interest from cell
C. Attachments of nucleotides by DNA ligase
D. Mixing of plasmids with competent bacteria
E. An antibiotic screening test is performed

Answer 138

B. Extraction of the gene of interest from cell
During gene cloning, a gene is inserted into a plasmid and then replicated. The plasmid must first be removed from the bacterial cells in order to add the gene of interest. The gene of interest from another cell must then be extracted and inserted into the plasmid. The plasmid is replicated and can now serve as a vector to be inserted into bacteria to express the gene.

Question 139

To ensure the gene of interest is incorporated in the plasmid during gene cloning, which of the following is used?
A. DNA ligase
B. Reverse
C. Antibiotic screening
D. Color change test
E. Reverse transcriptase

Answer 139

DNA ligase
DNA ligase is an enzyme that stabilizes the interaction between the plasmid and DNA by catalyzing the covalent bonding between the two DNA molecules.

Question 140

Which of the following is best suited for the examination of a gene function?
A. Western blotting
B. DNA microarray assay
C. Centrifugation
D. In situ hybridization
E. In vitro mutagenesis

Answer 140

In vitro mutagenesis
If a mutation occurs within a gene, its function can be altered. In vitro mutagenesis takes advantage of this by introducing mutations into a cloned gene. Phenotypic changes are observed and can be used to determine the function of the gene of interest.

Question 141

Which of the following best describes the basic procedure of in vitro mutagenesis?
A. Introduce the gene of another organism to the organism of interest
B. Observing plasmids in a test tube
C. Cloning random mutations
D. Mutating the whole genome of the organism of interest
E. Introduction of mutations to a cloned gene

Answer 141

E. Introduction of mutations to a cloned gene
If a mutation occurs within a gene, its function can be altered. In vitro mutagenesis takes advantage of this by introducing mutations into a cloned gene. Phenotypic changes are observed and can be used to determine the function of the gene of interest.

Question 142

“Knockout” mice are a classic example of ___________.
A. Karyotyping
B. In vivo mutagenesis
C. In vitro mutagenesis
D. In situ hybridization
E. Western blotting

Answer 142

In vitro mutagenesis
In vitro mutagenesis is a procedure in which mutations are introduced into a cloned gene which will result in phenotypic changes. These changes can be used to determine the function of the gene of interest. In knockout mice, the gene of interest is “knocked out” (i.e. inactivated) and phenotypic changes are observed.

Question 143

What gene technology can a researcher use to determine the presence of a gene sequence in an individual’s genome?
A. Primer specific PCR
B. In vitro mutagenesis
C. Western blotting
D. Karyotyping
E. Electron Microscopy

Answer 143

Primer specific PCR
The polymerase chain reaction (PCR) is a lab technique that can create millions of copies of DNA in a short period of time. The presence of a gene sequence in an individual’s genome can be identified by using a specific primer that will hybridize to the sequence of interest.

Question 144

By introducing the human oncogene, oncomice have their oncogene inactivated and are a strain used to further study how cancer develops. Which term best describes oncomice?
A. Transgenic mice
B. Knockout mice
C. Wild-type mice
D. Immune-competent mice
E. Karyotyped mice

Answer 144

Transgenic mice
Oncomice are transgenic because they have a gene from a different species introduced into their genome. Transgenic animals are often studied to understand the function of a gene.

Question 145

Which of the following is a major difference between transgenic and knockout mice?
A. Both mice are identical mouse models
B. Knockout mice are more specifically targeted
C. Transgenic mice are more specifically targeted
D. Knockout mice are used only to examine proteins
E. Knockout mice carry the whole genome of a different species

Answer 145

Knockout mice are more specifically targeted
In transgenic mice, the gene of interest is removed and replaced with a gene from another organism. In knockout mice, the gene of interest is “knocked out” (i.e. inactivated). The method used in knockout mice specifically targets the gene of interest and inactivates it, whereas by transgenic mice, the gene that is removed may be randomly selected.

Question 146

Which of the following best describes the study of genomics?
A. Examination of the genome and its interdisciplinary function
B. Examination of a specific mutation in a plasmid
C. Examination of experimentation on lab rodents
D. Examination of only the coding DNA
E. Examination of only the noncoding DNA

Answer 146

Examination of the genome and its interdisciplinary function

Genomics is the branch of biology concerned with the study and examination of the entire genome and its interdisciplinary function.

Question 147

What is the difference between genomics and genetics?
A. Genomics specifically studies heredity
B. Genomics only looks at a specific gene
C. Genomics looks at the whole genetic data of an organism
D. Genomics looks at only the phenotype of a gene
E. Genomics was introduced by Gregor Mendel

Answer 147

Genomics looks at the whole genetic data of an organism
Genomics is the branch of biology concerned with the study and examination of the entire genome and its interdisciplinary function. Genetics only looks at specific genes and heredity.

Question 148

What did Pasteur’s swan neck flask experiment reveal?
A. Survival of the fittest
B. Natural selection
C. Spontaneous development of organisms is not possible without life already present
D. Genetic traits can be transferred via bacterial transformation
E. DNA is heritable

Answer 148

Spontaneous development of organisms is not possible without life already present
Louis Pasteur’s swan neck flask experiment proved that organisms cannot develop spontaneously without life already being present.

In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. One flask’s neck was kept intact and dust particles containing microorganisms could not reach the broth and no growth occurred. When he tilted the flask to allow dust to mix with the broth, growth occurred.

Another flask’s neck was broken off which allowed dust particles containing microorganisms to settle in the broth; this broth became cloudy, indicating microbial growth.

Question 149

When the curved neck was removed during Pasteur’s swan neck flask experiment, which of the following occurred?
A. No bacteria formed in the broth
B. Bacteria formed in the broth
C. No microorganisms entered the flask
D. The flask was unviable to microorganisms
E. The broth combusted

Answer 149

Bacteria formed in the broth
In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. One flask’s neck was kept intact and dust particles containing microorganisms could not reach the broth and no growth occurred. When he tilted the flask to allow dust to mix with the broth, growth occurred.

Another flask’s neck was broken off which allowed dust particles containing microorganisms to settle in the broth; this broth became cloudy, indicating microbial growth.

Question 150

If the curved neck was not removed during Pasteur’s swan neck flask experiment, then which of the following occurred?
A. Microorganisms could not form
B. Microorganisms could form
C. Air pressure was not maintained, and the flask cracked
D. Broth boiled out of the flask
E. Broth could not be boiled

Answer 150

Microorganisms could not form
In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. One flask’s neck was kept intact and dust particles containing microorganisms could not reach the broth and no growth occurred. Growth was only able to occur once he tilted the flask to allow dust to mix with the broth.

Another flask’s neck was broken off which allowed dust particles containing microorganisms to settle in the broth; this broth became cloudy, indicating microbial growth.

Question 151

What was the main purpose of the curved neck on Pasteur’s swan neck flask experiment?
A. Maintain air pressure
B. Maintain volume
C. Prevent the entry of microorganisms
D. Trap heat in the broth
E. Prevent broth from spilling

Answer 151

Prevent the entry of microorganisms
In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. The curved neck of the flask prevented dust particles containing microorganisms from reaching the broth and therefore no microbial growth occurred.

Question 152

List the steps of Pasteur’s swan neck flask experiment in a logical order.
1. Bacteria formed
2. Flask was left to sit
3. Bacteria did not form
4. Heat applied to the flask with curved neck
5. The curved neck was removed

A. 4,2,5,1
B. 4,2,5,3
C. 2,4,5,1
D. 2,4,5,3
E. 5,4,2,1

Answer 152

List the steps of Pasteur’s swan neck flask experiment in a logical order.
1. Bacteria formed
2. Flask was left to sit
3. Bacteria did not form
4. Heat applied to the flask with curved neck
5. The curved neck was removed
A. 4,2,5,1

In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. The flasks were left to sit initially. One of the flask’s necks was then broken off which allowed dust particles containing microorganisms to settle in the broth; this broth became cloudy, indicating microbial growth.

The other flask’s neck was kept intact and no growth occurred as microorganisms could not reach the broth.

Question 153

What was the purpose of boiling the broth solution in Pasteur’s swan neck flask experiment?
A. Increase microorganism growth
B. Increase volume of the broth
C. Increase air bubbles in the broth
D. Kill off all existing microorganisms in broth
E. Evaporate the salt in the broth

Answer 153

. Kill off all existing microorganisms in broth
In his experiment, Pasteur boiled nutrient broth in swan neck flasks to kill all microorganisms. The curved neck of the flask prevented dust particles containing microorganisms from reaching the broth.

Question 154

Which strains did Griffith use in his experiment to demonstrate bacterial transformation?
A. HIV strains
B. COVID-19 strains
C. Pneumonia strains
D. Lactobacillus strains
E. Salmonella strains

Answer 154

Pneumonia strains
Griffith’s transformation experiment showed that bacteria can transfer genetic traits to each other by transformation. In his experiment, Griffith mixed living non-virulent pneumoniae with inactivated virulent pneumoniae. Some of the non-virulent bacteria became virulent after being mixed with the virulent strain.

The non-virulent bacteria was the rough (R) strain, and the virulent bacteria was the smooth (S) strain.

Question 155

What did Griffith’s experiment on bacterial strains directly reveal?
A. Genetic traits can be transferred using bacterial transfection
B. Genetic traits can be transferred using bacterial conjugation
C. Genetic traits can be transferred using bacterial transformation
D. Spontaneous development of organisms is not possible without life already present
E. DNA is heritable

Answer 155

Genetic traits can be transferred using bacterial transformation

Griffith’s transformation experiment showed that bacteria can transfer genetic traits to each other by transformation. In his experiment, Griffith mixed living non-virulent S. pneumoniae with inactivated virulent S. pneumoniae. Some of the non-virulent bacteria became virulent after being mixed with the virulent strain.

The non-virulent bacteria was the rough (R) strain, and the virulent bacteria was the smooth (S) strain.

Question 156

What is the difference between the smooth (S) pneumonia strain and the rough (R) pneumonia strain in Griffith’s experiment on bacterial strains?
A. Rough strain has a protective capsule
B. Rough strain is virulent
C. Rough strain can kill a mouse
D. Smooth strain is not virulent
E. Smooth strain has a protective capsule

Answer 156

Smooth strain has a protective capsule

Question 157

What does the protective capsule of the smooth (S) pneumonia strain do in Griffith’s experiment on bacterial strains?
A. Make the strain non-virulent
B. Protect it from the immune system
C. Prevent pneumonia in the host
D. Aid in bacterial transfection
E. Cause immune system detection

Answer 157

. Protect it from the immune system

Question 158

If a pneumonia strain is rough (R) and injected into a mouse in Griffith’s experiment on bacterial strains, then which will most likely happen?
A. Mouse dies
B. Mouse lives
C. Virulently spread
D. Avoid immune detection
E. Forms protective capsule

Answer 158

B. Mouse lives

Question 159

If heat-killed smooth (S) pneumonia strain is injected into a mouse in Griffith’s experiment on bacterial strains, then which will most likely happen?
A. Mouse lives
B. Mouse dies
C. Anaphylactic shock
D. Metamorphosis

Answer 159

A. Mouse lives

Question 160

If both heat-killed smooth (S) pneumonia strain and rough (R) pneumonia are injected into a mouse in Griffith’s experiment on bacterial strains, then which will most likely happen?
A. Mouse lives
B. Mouse dies
C. Anaphylactic shock
D. Metamorphosis

Answer 160

Mouse dies

Question 161

Why did the mouse in the Griffith experiment on pneumonia strains die despite being introduced to both rough and heat-killed smooth strain?
A. The rough strain DNA was transferred to the smooth strain
B. The smooth strain DNA was transferred to the rough strain
C. The heat-killed smooth strain can independently still kill the mouse
D. The rough strain independently is virulent enough
E. The rough strain can evade the immune system naturally

Answer 161

The smooth strain DNA was transferred to the rough strain

Question 162

Which of the following occurred in the Griffith experiment on pneumonia strains?
A. The rough strain injection killed the mouse
B. The smooth strain injection could not kill the mouse
C. The heat-killed smooth strain injection killed the mouse
D. The rough strain and heat-killed smooth strain injection killed the mouse
E. The rough strain and heat-killed smooth strain injection could not kill the mouse

Answer 162

The rough strain and heat-killed smooth strain injection killed the mouse

Question 163

What did the Avery-MacLeod-McCarty experiment reveal?
A. DNA is heritable in bacterial transformation
B. RNA is heritable in bacterial transformation
C. Protein is heritable in bacterial transformation
D. Fats are heritable in bacterial transformation
E. Genetic information cannot be inherited

Answer 163

DNA is heritable in bacterial transformation
The Avery-MacLeod-McCarty experiment was conducted to discover what was the cause of bacterial transformation in Griffith’s experiment. They revealed that DNA was the heritable material that causing the bacterial transformation.

Question 164

Which digestive enzyme led to the survival of pneumonia-infected mice in the Avery-MacLeod-McCarty experiment?
A. DNase
B. Proteinase
C. Lipase
D. Protease
E. Ribosomes

Answer 164

DNase
The Avery-MacLeod-McCarty experiment revealed that DNA was the heritable material that caused the bacterial transformation. In their experiment, they treated cell lysate from heat-killed S strains (virulent) with various enzymes. The mixtures were then mixed with R strains (nonvirulent). The mixture with DNase was the only one that did not result in R strains becoming transformed into S strains because DNase digested the virulent S strain DNA.

Question 165

What did DNase do that prevented the pneumonia-infected mice from dying?
A. DNase replicated the virulent DNA from the smooth strain of pneumonia
B. DNase transformed the virulent DNA from the smooth strain of pneumonia
C. DNase digested the virulent DNA from the smooth strain of pneumonia
D. DNase inhibited protease function
E. DNase activated the production of the protective capsule

Answer 165

DNase digested the virulent DNA from the smooth strain of pneumonia
The Avery-MacLeod-McCarty experiment revealed that DNA was the heritable material that caused the bacterial transformation. In their experiment, they treated cell lysate from heat-killed S strains (virulent) with various enzymes. The mixtures were then mixed with R strains (nonvirulent). The mixture with DNase was the only one that did not result in R strains becoming transformed into S strains because DNase digested the virulent S strain DNA.

Question 166

What did Hershey & Chase demonstrate concerning Phage T2?
A. Protein is the genetic material
B. Lipid is the general material
C. DNA is the genetic material
D. RNA is the genetic material
E. There is no genetic material present

Answer 166

DNA is the genetic material
The Hershey-Chase experiment demonstrated that DNA, and not proteins, are the genetic material. They used radioactive phosphorus and sulfur to track DNA and proteins, respectively.

Question 167

Phage T2 is a bacteriophage, which means it is a __________.
A. Bacterium that infects bacteria
B. Protein that infects bacteria
C. Type of bacteria
D. Virus that infects bacteria
E. Bacterial infection

Answer 167

Virus that infects bacteria

Question 168

Which radioactive labels were used in the Hershey & Chase experiment on Phage T2?
A. Oxygen and nitrogen
B. Phosphorus and nitrogen
C. Phosphorus and sulfur
D. Nitrogen and sulfur
E. Oxygen and sulfur

Answer 168

Phosphorus and sulfur
The Hershey-Chase experiment demonstrated that DNA, and not proteins, are the genetic material. They used radioactive phosphorus and sulfur to track DNA and proteins, respectively.

Question 169

In the Hershey & Chase experiment on Phage T2, the radioactive label of phosphorus was put on the __________.
A. DNA of the virus
B. RNA of the virus
C. Protein of the virus
D. Capsule of the virus
E. Protein coat of the virus

Answer 169

DNA of the virus
The Hershey-Chase experiment demonstrated that DNA, and not proteins, are the genetic material. They used radioactive phosphorus to track DNA as it contains phosphorus in its phosphate groups. They used radioactive sulfur to track proteins as sulfur is contained in two of the amino acids (methionine and cysteine).

Question 170

In the Hershey & Chase experiment on Phage T2, the radioactive label of sulfur was put on the __________.
A. Protein of the virus
B. Capsule of the virus
C. Host bacterial cell wall
D. RNA of the virus
E. DNA of the virus

Answer 170

Protein of the virus
The Hershey-Chase experiment demonstrated that DNA, and not proteins, are the genetic material. They used radioactive phosphorus to track DNA as it contains phosphorus in its phosphate groups. They used radioactive sulfur to track proteins as sulfur is contained in two of the amino acids (methionine and cysteine).

Question 171

In the Hershey & Chase experiment on Phage, the __________.
A. Radioactively labeled sulfur appeared inside the bacteria
B. Radioactively labeled phosphorus appeared inside the bacteria
C. Radioactively labeled sulfur and phosphorus appeared inside the bacteria
D. No radioactive labels appeared
E. T2 Phage could not infect the bacteria

Answer 171

Radioactively labeled phosphorus appeared inside the bacteria
The Hershey-Chase experiment demonstrated that DNA, and not proteins, are the genetic material. They used radioactive phosphorus and sulfur to track DNA and proteins, respectively. The radioactively labeled phosphorus (contained in DNA) appeared inside the bacteria after the phage infected it, proving that DNA is the genetic material that is being transferred. The radioactively labeled sulfur (contained in proteins) was not found to be transferred to the bacteria.

Question 172

Who developed the photo that aided Watson and Crick to determine the double helix structure of DNA?
A. Charles Darwin
B. Hershey and Chase
C. George Mendel
D. Rosalind Franklin
E. Georges Cuvier

Answer 172

Rosalind Franklin
Rosalind Franklin used X-ray diffraction to capture a photo of DNA. This photo assisted Watson and Crick in discovering that DNA has a double helical structure.

Question 173

Which experiment proved that DNA replicates semi-conservatively?
A. Pavlov’s dog experiment
B. Meselson-Stahl experiment
C. Miller-Urey experiment
D. Oparin-Haldane experiment
E. Hershey-Chase experiment

Answer 173

Meselson-Stahl experiment

Question 174

DNA replication is __________.
A. Semiconservative
B. Conservative
C. Dispersive

Answer 174

Semiconservative

Question 175

Meselson and Stahl grew which bacteria to determine the replication model of DNA?
A. E-Coli
B. Norovirus
C. Salmonella
D. Measles
E. Hepatitis B

Answer 175

E-Coli

Question 176

Meselson and Stahl labeled which element isotope to determine the replication model of DNA?
A. Oxygen
B. Phosphorus
C. Sulfur
D. Nitrogen
E. Carbon

Answer 176

Nitrogen

Question 177

Which of the following best describes the semiconservative model of DNA replication?
A. Parental strand stays intact and directs the creation of a new double-stranded daughter DNA
B. Parental strand intertwines intermittently with daughter DNA to create hybrids strands
C. Parental strand attaches to the end of the daughter strand to elongate it
D. Parental strand serves as the template for the formation of a daughter DNA with one newly synthesized and one original parental strand
E. Parental strand inhibits DNA replication

Answer 177

Parental strand serves as the template for the formation of a daughter DNA with one newly synthesized and one original parental strand

Question 178

Who was the first to isolate nucleic acids or nuclein?
A. Watson and Crick
B. Rosalind Franklin
C. Jean-Baptiste Lamarck
D. Johann Friedrich Miescher
E. Meselson and Stahl

Answer 178

Johann Friedrich Miescher
Johann Friedrich Miescher was the first to isolate DNA along with its associated proteins in 1869. He referred to this isolated product as nuclein.

Question 179

What did Gurdon’s experiment on frog cells reveal?
A. Differentiated cells lose genetic information
B. Differentiated cells have spliced genetic information
C. Differentiated cells have altered gene expression
D. Egg cells lose genetic information
E. Cells contain different genetic information depending on their bodily location

Answer 179

Differentiated cells have altered gene expression

Gurdon transplanted the nuclei of frog embryos (undifferentiated) and tadpoles (fully differentiated) into enucleated eggs. He discovered that the less differentiated the cell was, the more likely it was to develop into a tadpole. This experiment revealed that differentiated cells have altered gene expression since they cannot differentiate into other cell types.

Question 180

When the nucleus from a somatic frog cell was inserted into an egg cell that was missing its nucleus, which of the following occurred?
A. The altered egg cell formed into a tadpole
B. The altered egg cell developed into more somatic cells
C. The altered egg cell went through apoptosis
D. The altered egg cell continued to further differentiate
E. The altered egg cell lysed

Answer 180

The altered egg cell formed into a tadpole

Gurdon transplanted the nuclei of frog embryos (undifferentiated) and tadpoles (fully differentiated) into enucleated eggs. He discovered that the less differentiated the cell was, the more likely it was to develop into a tadpole.

Question 181

Dolly the sheep is a prime example of __________.
A. Gel electrophoresis
B. Reproductive cloning
C. In situ hybridization
D. In vitro mutagenesis
E. Therapeutic cloning

Answer 181

Reproductive cloning
The first successful reproductive cloning of a mammal produced Dolly the sheep in 1996. A mammary cell and an enucleated egg cell from two separate sheep were fused and grown in culture. Once it was at the early embryo stage, it was placed into a surrogate. The embryo (Dolly) was genetically identical to the mammary cell donor sheep.

Question 182

What is the pulse-chase experiment primarily used for?
A. To track the movement of organelles in a cell
B. To track DNA replication in a cell
C. To track RNA replication in a cell
D. To track protein movement in a cell
E. To track mutations in a cell

Answer 182

To track protein movement in a cell
The pulse-chase experiment uses radioactively labeled amino acids to track protein movement in a cell. During the “pulse” part of the experiment, radioactively labeled amino acids are incorporated into the cell’s proteins. During the “chase” part of the experiment, nonradioactive amino acids are added to the cell and are incorporated into proteins.

Question 183

Which of the following is used to separate proteins based on their size?
A. Southern blotting
B. Northern blotting
C. Size exclusion chromatography
D. Pulse-chase experiment
E. DNA microarray assay

Answer 183

Size exclusion chromatography

Question 184

Which of the following occurs in the “pulse” part of the pulse-chase experiment?
A. Excess labeling substance is introduced into the cell
B. An electric field is introduced to the cell
C. A magnetic field is introduced to the cell
D. Radioactive amino acids are incorporated into the cell’s protein
E. Monitoring the movement of the cell

Answer 184

D. Radioactive amino acids are incorporated into the cell’s protein

The pulse-chase experiment uses radioactively labeled amino acids to track protein movement in a cell. During the “pulse” part of the experiment, radioactively labeled amino acids are incorporated into the cell’s proteins. During the “chase” part of the experiment, nonradioactive amino acids are added to the cell and incorporated into proteins.

Question 185

Which of the following occurs in the “chase” part of the pulse-chase experiment?
A. Radioactive amino acids are incorporated into the cell’s protein
B. Nonradioactive amino acids are added to the cell
C. Cellular movement is watched with a stereomicroscope
D. An electric field is introduced to the cell
E. Bacterial transformation occurs

Answer 185

Nonradioactive amino acids are added to the cell

The pulse-chase experiment uses radioactively labeled amino acids to track protein movement in a cell. During the “pulse” part of the experiment, radioactively labeled amino acids are incorporated into the cell’s proteins. During the “chase” part of the experiment, nonradioactive amino acids are added to the cell and incorporated into proteins.

Question 186

What is the difference between centrifugation and chromatography?
A. Centrifugation separates mixtures of gas
B. Centrifugation separates by evaporation
C. Chromatography separates mixtures using a rotating tube
D. Chromatography separates a mixture of liquid
E. Chromatography separates by phase change

Answer 186

Chromatography separates a mixture of liquid

Chromatography separates a mixture of liquid in a column in which components migrate at different speeds. Centrifugation is a lab technique that separates liquids of different densities or solids from liquids. Centrifugation uses a tube that rotates at extremely high velocities to separate components.

Question 187

Which of the following can be used to best observe the diffusion mobility of a cell membrane?
A. Pulse-chase experiment
B. Centrifugation
C. Chromatography
D. Light microscopy
E. Fluorescence recovery after photobleaching

Answer 187

Fluorescence recovery after photobleaching
Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine whether a membrane protein can move freely around the membrane or if it is a structural component. The entire cell is fluorescently tagged. To remove fluorescence from a specific location, a high-intensity light is directed there and ultimately causes photobleaching.

Question 188

In Fluorescence recovery after photobleaching, what is fluorescently tagged?
A. The nucleus
B. The whole cell
C. The mitochondria
D. The cytosol
E. The Golgi apparatus

Answer 188

B. The whole cell
Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine whether a membrane protein can move freely around the membrane or if it is a structural component. The entire cell is fluorescently tagged. To remove fluorescence from a specific location, a high-intensity light is directed there and ultimately causes photobleaching.

Question 189

Which of the following best describes what occurs when a light is directed to a specific location to remove fluorescence in fluorescence recovery after photobleaching?
A. Bright spot formation
B. Cell apoptosis
C. Halo Effect
D. Photobleaching
E. Artifact development

Answer 189

Photobleaching
Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine whether a membrane protein can move freely around the membrane or if it is a structural component. The entire cell is fluorescently tagged. To remove fluorescence from a specific location, a high-intensity light is directed there and ultimately causes photobleaching.

Question 190

A scientist would like to determine if a protein is mobile or bound to the cellular membrane. He could use which of the following to determine this?
A. Chromatography
B. Centrifugation
C. Fluorescence recovery after photobleaching
D. Pulse-chase experiment
E. Reproductive cloning

Answer 190

Fluorescence recovery after photobleaching

Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine whether a membrane protein can move freely around the membrane or if it is a structural component. The entire cell is fluorescently tagged. To remove fluorescence from a specific location, a high-intensity light is directed there and ultimately causes photobleaching.

A mobile protein will have a high percent recovery and fast motility, and an immobile protein will have a low percent recovery and slow motility.

Note: Percent recovery refers to the amount of light that returns to the photobleached area relative to the amount present prior to photobleaching.

Question 191

During fluorescence recovery after photobleaching, if a protein is mobile, it would have __________.
A. Low percent recovery and slow mobility
B. Low percent recovery and fast mobility
C. High percent recovery and fast mobility
D. High percent recovery and slow mobility
E. High percent recovery and no mobility

Answer 191

High percent recovery and fast mobility

Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine membrane protein mobility. A mobile protein will have a high percent recovery and fast motility, and an immobile protein will have a low percent recovery and slow motility.

Note: Percent recovery refers to the amount of light that returns to the photobleached area relative to the amount present prior to photobleaching.

Question 192

Which of the following best describes percent recovery in fluorescence recovery after photobleaching?
A. The speed of fluorescent molecule migration to the photobleached area
B. The amount of photobleaching in one location
C. The light return relative to the light present before photobleaching
D. The size of the cell
E. The elution rate of the cellular contents

Answer 192

The light return relative to the light present before photobleaching

Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine membrane protein mobility. Percent recovery refers to the amount of light that returns to the photobleached area relative to the amount present prior to photobleaching.

Note: A mobile protein will have a high percent recovery and fast motility, and an immobile protein will have a low percent recovery and slow motility.

Question 193

During fluorescence recovery after photobleaching, if a protein is immobile, it would have __________.
A. High percent recovery and fast mobility
B. No percent recovery and fast mobility
C. High percent recovery and slow mobility
D. Low percent recovery and fast mobility
E. Low percent recovery and slow mobility

Answer 193

Low percent recovery and slow mobility

Fluorescence recovery after photobleaching (or FRAP exam) is a lab technique that is used to determine membrane protein mobility. A mobile protein will have a high percent recovery and fast motility, and an immobile protein will have a low percent recovery and slow motility.

Note: Percent recovery refers to the amount of light that returns to the photobleached area relative to the amount present prior to photobleaching.

Question 194

In reproductive cloning, the embryo is identical to the __________.
A. Egg donor
B. Somatic cell nucleus donor
C. Sperm donor
D. Egg nucleus donor
E. Both the egg and somatic cell nucleus donor

Answer 194

Somatic cell nucleus donor

Question 195

Reproductive cloning requires a(n) __________.
A. Nucleated egg
B. Enucleated somatic cell
C. Enucleated egg
D. Dedifferentiated somatic cell
E. Dedifferentiated egg cell

Answer 195

Enucleated egg

Question 196

Which of the following is used to fuse the enucleated egg cell with the somatic cell nucleus in reproductive cloning?
A. Electric pulse
B. Centrifugation
C. Heat shock
D. Staining
E. Homogenization

Answer 196

Electric pulse