BACE PRACTICE Comprehensive Resource To Help You Ace 2026-2027
Exams Includes Frequently Tested Questions With ELABORATED 100%
Correct COMPLETE SOLUTIONS
Guaranteed Pass First Attempt!! Current Update!!
1. Which of the following is typically measured using a spectrophotometer set at a
wavelength of 600 nm?
A. The number of DNA base pairs in a sample
B. The concentration of DNA in a sample
C. The concentration of bacteria in a suspension
D. The number of bacterial colonies on a plate of media
Rationale: OD600 (optical density at 600 nm) is the standard wavelength used to estimate
bacterial cell density/concentration in liquid culture based on light scattering.
2. Why must technicians practice aseptic technique when culturing cells?
A. To ensure they are incubating their cells at the proper temperature
B. To ensure they are adding the correct supplements to their media
C. To ensure they are growing pure cultures of their desired cells
D. To ensure they are using the correct media to grow their desired cells
Rationale: Aseptic technique specifically prevents contamination by unwanted microorganisms,
which is essential for maintaining a pure, uncontaminated culture.
3. According to the Beer-Lambert law, which of the following factors does NOT affect the
absorbance of a solution?
A. Temperature of the solution
B. Concentration of the absorbing species
C. Path length of the cuvette
D. Wavelength of light used
Rationale: The Beer-Lambert law (A = εlc) relates absorbance to concentration, path length, and
molar absorptivity (wavelength-dependent) — temperature is not a direct variable in this
equation.
,4. Salt (such as sodium chloride or sodium acetate) is commonly used in procedures to extract
plasmid DNA. What best describes the role of the salt?
A. The positively charged sodium ions dissolve cell organelles
B. The positively charged sodium ions neutralize the negative charge on the DNA
C. The positively charged sodium ions degrade the bacterial cell wall
D. The positively charged sodium ions provide a cushion allowing for faster centrifugation
Rationale: Sodium ions shield/neutralize the negatively charged phosphate backbone of DNA,
reducing electrostatic repulsion and allowing DNA to precipitate out of solution (typically with
alcohol).
5. When using an acrylamide gel for protein electrophoresis, it is best to use a higher
percentage of acrylamide to resolve smaller proteins, while large proteins are best resolved
on low-percent gels.
A. True
B. False
Rationale: Higher percentage gels have smaller pore sizes, which better resolve small proteins,
while larger pores in low-percentage gels allow larger proteins to migrate and separate more
effectively.
6. What is the purpose of staining with Coomassie Blue?
A. To coat sample proteins with a negative charge and denature them
B. To visualize proteins after PAGE
C. To determine the relative sizes of the samples run on the gel
D. To facilitate loading samples into wells and monitor sample migration during PAGE
Rationale: Coomassie Blue is a dye that binds to proteins, allowing them to be visualized as
bands on a gel after electrophoresis is complete.
7. What is the purpose of adding loading dye to protein samples?
A. To coat sample proteins with a negative charge and denature them
B. To visualize proteins after PAGE
,C. To determine the relative sizes of the samples run on the gel
D. To facilitate loading samples into wells and to monitor sample migration during PAGE
Rationale: Loading dye adds density/color/visibility to samples, helping technicians load them
into gel wells accurately and track migration progress during the run.
8. A restriction enzyme digestion reaction contains which of the following reagents?
A. DNA, Water, Restriction Enzyme
B. DNA, Water, Buffer, dNTPs
C. DNA, Water, dNTPs, Restriction Enzyme
D. DNA, Water, Buffer, Restriction Enzyme
Rationale: Restriction digestion requires an appropriate buffer to maintain optimal enzyme
activity conditions, but does not require dNTPs (which are needed for DNA synthesis, not
cutting).
9. A plasmid has three restriction sites for EcoRI. If the plasmid is treated with EcoRI, how
many fragments will be obtained?
A. 2
B. 3
C. 4
D. 5
Rationale: Since the plasmid is circular, cutting at three sites produces exactly three linear
fragments (a circular molecule with n cut sites yields n fragments).
10. What is the correct general protocol order for genetic engineering?
A. Purify gene product → Isolate gene of interest → Clone into vector → Transform host cells →
Grow recombinant cells
B. Isolate gene of interest → Paste/clone gene of interest into a vector → Transform host cells
with vector → Grow recombinant cells → Purify gene product
C. Transform host cells → Isolate gene of interest → Clone into vector → Grow recombinant
cells → Purify gene product
D. Clone into vector → Isolate gene of interest → Grow recombinant cells → Transform host
cells → Purify gene product
, Rationale: This sequence reflects the logical workflow — you must first obtain the gene, insert it
into a vector, introduce that vector into host cells, allow the cells to grow and express the gene,
and finally purify the resulting product.
11. Which of the following techniques should be used to amplify specific DNA sequences?
A. PCR
B. Bradford assay
C. PAGE
D. ELISA
Rationale: PCR (Polymerase Chain Reaction) is specifically designed to exponentially amplify
targeted DNA sequences.
12. What is the correct sequence of steps in a PCR cycle?
A. Primers hybridize → DNA polymerase extends → Mixture is heated to denature
B. The mixture is heated to denature the double-stranded DNA → The primers hybridize to
the target DNA → DNA polymerase extends the primers to make a copy of the target DNA
C. DNA polymerase extends → Mixture is heated to denature → Primers hybridize
D. Primers hybridize → Mixture is heated to denature → DNA polymerase extends
Rationale: This reflects the three core PCR steps in their correct order: denaturation (separating
strands), annealing (primer binding), and extension (new strand synthesis).
13. What is the primary advantage of using Escherichia coli for protein expression studies?
A. It is resistant to most antibiotics, making selection easier
B. It is a eukaryotic system with complex post-translational modifications
C. It can produce high yields of protein quickly and is easy to manipulate genetically
D. It grows slowly, allowing for better control of protein expression
Rationale: E. coli's fast growth rate and well-established genetic tools make it a preferred,
efficient system for producing recombinant proteins, though it lacks eukaryotic post-
translational modification capabilities.
Exams Includes Frequently Tested Questions With ELABORATED 100%
Correct COMPLETE SOLUTIONS
Guaranteed Pass First Attempt!! Current Update!!
1. Which of the following is typically measured using a spectrophotometer set at a
wavelength of 600 nm?
A. The number of DNA base pairs in a sample
B. The concentration of DNA in a sample
C. The concentration of bacteria in a suspension
D. The number of bacterial colonies on a plate of media
Rationale: OD600 (optical density at 600 nm) is the standard wavelength used to estimate
bacterial cell density/concentration in liquid culture based on light scattering.
2. Why must technicians practice aseptic technique when culturing cells?
A. To ensure they are incubating their cells at the proper temperature
B. To ensure they are adding the correct supplements to their media
C. To ensure they are growing pure cultures of their desired cells
D. To ensure they are using the correct media to grow their desired cells
Rationale: Aseptic technique specifically prevents contamination by unwanted microorganisms,
which is essential for maintaining a pure, uncontaminated culture.
3. According to the Beer-Lambert law, which of the following factors does NOT affect the
absorbance of a solution?
A. Temperature of the solution
B. Concentration of the absorbing species
C. Path length of the cuvette
D. Wavelength of light used
Rationale: The Beer-Lambert law (A = εlc) relates absorbance to concentration, path length, and
molar absorptivity (wavelength-dependent) — temperature is not a direct variable in this
equation.
,4. Salt (such as sodium chloride or sodium acetate) is commonly used in procedures to extract
plasmid DNA. What best describes the role of the salt?
A. The positively charged sodium ions dissolve cell organelles
B. The positively charged sodium ions neutralize the negative charge on the DNA
C. The positively charged sodium ions degrade the bacterial cell wall
D. The positively charged sodium ions provide a cushion allowing for faster centrifugation
Rationale: Sodium ions shield/neutralize the negatively charged phosphate backbone of DNA,
reducing electrostatic repulsion and allowing DNA to precipitate out of solution (typically with
alcohol).
5. When using an acrylamide gel for protein electrophoresis, it is best to use a higher
percentage of acrylamide to resolve smaller proteins, while large proteins are best resolved
on low-percent gels.
A. True
B. False
Rationale: Higher percentage gels have smaller pore sizes, which better resolve small proteins,
while larger pores in low-percentage gels allow larger proteins to migrate and separate more
effectively.
6. What is the purpose of staining with Coomassie Blue?
A. To coat sample proteins with a negative charge and denature them
B. To visualize proteins after PAGE
C. To determine the relative sizes of the samples run on the gel
D. To facilitate loading samples into wells and monitor sample migration during PAGE
Rationale: Coomassie Blue is a dye that binds to proteins, allowing them to be visualized as
bands on a gel after electrophoresis is complete.
7. What is the purpose of adding loading dye to protein samples?
A. To coat sample proteins with a negative charge and denature them
B. To visualize proteins after PAGE
,C. To determine the relative sizes of the samples run on the gel
D. To facilitate loading samples into wells and to monitor sample migration during PAGE
Rationale: Loading dye adds density/color/visibility to samples, helping technicians load them
into gel wells accurately and track migration progress during the run.
8. A restriction enzyme digestion reaction contains which of the following reagents?
A. DNA, Water, Restriction Enzyme
B. DNA, Water, Buffer, dNTPs
C. DNA, Water, dNTPs, Restriction Enzyme
D. DNA, Water, Buffer, Restriction Enzyme
Rationale: Restriction digestion requires an appropriate buffer to maintain optimal enzyme
activity conditions, but does not require dNTPs (which are needed for DNA synthesis, not
cutting).
9. A plasmid has three restriction sites for EcoRI. If the plasmid is treated with EcoRI, how
many fragments will be obtained?
A. 2
B. 3
C. 4
D. 5
Rationale: Since the plasmid is circular, cutting at three sites produces exactly three linear
fragments (a circular molecule with n cut sites yields n fragments).
10. What is the correct general protocol order for genetic engineering?
A. Purify gene product → Isolate gene of interest → Clone into vector → Transform host cells →
Grow recombinant cells
B. Isolate gene of interest → Paste/clone gene of interest into a vector → Transform host cells
with vector → Grow recombinant cells → Purify gene product
C. Transform host cells → Isolate gene of interest → Clone into vector → Grow recombinant
cells → Purify gene product
D. Clone into vector → Isolate gene of interest → Grow recombinant cells → Transform host
cells → Purify gene product
, Rationale: This sequence reflects the logical workflow — you must first obtain the gene, insert it
into a vector, introduce that vector into host cells, allow the cells to grow and express the gene,
and finally purify the resulting product.
11. Which of the following techniques should be used to amplify specific DNA sequences?
A. PCR
B. Bradford assay
C. PAGE
D. ELISA
Rationale: PCR (Polymerase Chain Reaction) is specifically designed to exponentially amplify
targeted DNA sequences.
12. What is the correct sequence of steps in a PCR cycle?
A. Primers hybridize → DNA polymerase extends → Mixture is heated to denature
B. The mixture is heated to denature the double-stranded DNA → The primers hybridize to
the target DNA → DNA polymerase extends the primers to make a copy of the target DNA
C. DNA polymerase extends → Mixture is heated to denature → Primers hybridize
D. Primers hybridize → Mixture is heated to denature → DNA polymerase extends
Rationale: This reflects the three core PCR steps in their correct order: denaturation (separating
strands), annealing (primer binding), and extension (new strand synthesis).
13. What is the primary advantage of using Escherichia coli for protein expression studies?
A. It is resistant to most antibiotics, making selection easier
B. It is a eukaryotic system with complex post-translational modifications
C. It can produce high yields of protein quickly and is easy to manipulate genetically
D. It grows slowly, allowing for better control of protein expression
Rationale: E. coli's fast growth rate and well-established genetic tools make it a preferred,
efficient system for producing recombinant proteins, though it lacks eukaryotic post-
translational modification capabilities.
