Semmelweis Entrance Exam Medicine Biology
Actual Exam 2026/2027 | Complete Exam-Style
Questions with Detailed Rationales | 100% Verified |
Pass Guaranteed – A+ Graded
Cell Biology, Molecular Biology, and Biochemistry
Q1: Which organelle is primarily responsible for modifying, sorting, and packaging proteins
for secretion?
A. Rough endoplasmic reticulum
B. Golgi apparatus [CORRECT]
C. Lysosome
D. Peroxisome
Correct Answer: B
Rationale: The best answer is the Golgi apparatus, as it functions as the cell's post office,
receiving proteins from the endoplasmic reticulum and modifying them for their final
destinations.
Q2: A cell is placed in a hypertonic solution. What is the most likely immediate outcome for
this cell?
A. It will swell and eventually lyse.
B. It will remain unchanged due to active transport.
C. It will shrink as water moves out of the cell. [CORRECT]
D. It will rapidly divide to increase surface area.
Correct Answer: C
Rationale: This choice is correct because water moves via osmosis from an area of lower
solute concentration inside the cell to an area of higher solute concentration in the
hypertonic solution, causing the cell to shrink.
Q3: During which phase of the cell cycle does DNA replication occur?
A. G1 phase
B. S phase [CORRECT]
C. G2 phase
D. M phase
Correct Answer: B
Rationale: This aligns with the principle that the S (synthesis) phase is specifically dedicated
to the duplication of the cell's genetic material before it enters the preparation for mitosis.
Q4: A mutation occurs that changes a single nucleotide in a DNA sequence, but the resulting
protein remains completely functional. This is most likely due to:
A. The degeneracy of the genetic code. [CORRECT]
B. A frameshift mutation correcting itself.
,C. The mutation occurring in an exon.
D. The immediate activation of DNA repair enzymes.
Correct Answer: A
Rationale: The best answer is the degeneracy of the genetic code, because multiple codons
can code for the same amino acid, meaning a silent mutation may not alter the final protein
structure.
Q5: In the process of transcription, which enzyme is responsible for synthesizing an RNA
strand complementary to the DNA template?
A. DNA polymerase
B. RNA polymerase [CORRECT]
C. Helicase
D. Ligase
Correct Answer: B
Rationale: This choice is correct because RNA polymerase is the specific enzyme that reads
the DNA template strand and links ribonucleotides together to form a messenger RNA
transcript.
Q6: A researcher measures the reaction rate of an enzyme at varying substrate
concentrations. The data shows the rate increases steadily until it plateaus at 50 µmol/min,
even when more substrate is added. What does this plateau represent?
A. The enzyme has been denatured by the high substrate concentration.
B. The enzyme has reached its maximum velocity (Vmax) because all active sites are
saturated. [CORRECT]
C. The substrate has become an inhibitor at high concentrations.
D. The reaction has reached equilibrium and stopped completely.
Correct Answer: B
Rationale: This matches the principle of enzyme kinetics where Vmax is achieved when
every enzyme molecule is actively bound to a substrate, meaning adding more substrate
cannot increase the reaction rate further.
Q7: Which of the following metabolic pathways occurs in the cytoplasm and does not
require oxygen?
A. Krebs cycle
B. Electron transport chain
C. Glycolysis [CORRECT]
D. Beta-oxidation
Correct Answer: C
Rationale: The best answer is glycolysis, as it is the initial, anaerobic breakdown of glucose
into pyruvate that takes place in the cytosol of all living cells.
Q8: During oxidative phosphorylation, the energy released by the electron transport chain is
primarily used to:
A. Directly synthesize ATP from ADP.
B. Pump protons across the inner mitochondrial membrane to create an electrochemical
gradient. [CORRECT]
C. Break down glucose into pyruvate.
, D. Convert NADH back into NAD+ without producing ATP.
Correct Answer: B
Rationale: This choice is correct because the electron transport chain uses energy from
electrons to pump protons into the intermembrane space, establishing the proton-motive
force that drives ATP synthase.
Q9: What is the primary structural difference between DNA and RNA?
A. DNA contains uracil, while RNA contains thymine.
B. DNA is typically double-stranded, while RNA is typically single-stranded. [CORRECT]
C. DNA contains ribose sugar, while RNA contains deoxyribose.
D. DNA is found only in the cytoplasm, while RNA is confined to the nucleus.
Correct Answer: B
Rationale: This aligns with the fundamental structural principle that DNA forms a stable
double helix, whereas RNA is generally single-stranded and contains ribose and uracil
instead of deoxyribose and thymine.
Q10: A patient's cells are unable to break down hydrogen peroxide, leading to toxic
accumulation. Which organelle is most likely defective?
A. Mitochondria
B. Peroxisome [CORRECT]
C. Lysosome
D. Smooth endoplasmic reticulum
Correct Answer: B
Rationale: The best answer is the peroxisome, as these organelles contain catalase, the
specific enzyme responsible for neutralizing hydrogen peroxide into water and oxygen.
Q11: Which of the following events is unique to meiosis and does not occur during mitosis?
A. Separation of sister chromatids
B. Synapsis and crossing over of homologous chromosomes [CORRECT]
C. Breakdown of the nuclear envelope
D. Alignment of chromosomes at the metaphase plate
Correct Answer: B
Rationale: This choice is correct because synapsis and crossing over are exclusive to
prophase I of meiosis, promoting genetic diversity, whereas mitosis maintains genetic
identity.
Q12: If a competitive inhibitor is added to an enzyme-catalyzed reaction, how can the
original reaction rate be restored?
A. By decreasing the temperature of the reaction.
B. By increasing the concentration of the substrate. [CORRECT]
C. By permanently altering the enzyme's active site.
D. By adding a non-competitive inhibitor.
Correct Answer: B
Rationale: This matches the principle that competitive inhibitors compete with the substrate
for the active site, so flooding the system with more substrate outcompetes the inhibitor
and restores Vmax.
Actual Exam 2026/2027 | Complete Exam-Style
Questions with Detailed Rationales | 100% Verified |
Pass Guaranteed – A+ Graded
Cell Biology, Molecular Biology, and Biochemistry
Q1: Which organelle is primarily responsible for modifying, sorting, and packaging proteins
for secretion?
A. Rough endoplasmic reticulum
B. Golgi apparatus [CORRECT]
C. Lysosome
D. Peroxisome
Correct Answer: B
Rationale: The best answer is the Golgi apparatus, as it functions as the cell's post office,
receiving proteins from the endoplasmic reticulum and modifying them for their final
destinations.
Q2: A cell is placed in a hypertonic solution. What is the most likely immediate outcome for
this cell?
A. It will swell and eventually lyse.
B. It will remain unchanged due to active transport.
C. It will shrink as water moves out of the cell. [CORRECT]
D. It will rapidly divide to increase surface area.
Correct Answer: C
Rationale: This choice is correct because water moves via osmosis from an area of lower
solute concentration inside the cell to an area of higher solute concentration in the
hypertonic solution, causing the cell to shrink.
Q3: During which phase of the cell cycle does DNA replication occur?
A. G1 phase
B. S phase [CORRECT]
C. G2 phase
D. M phase
Correct Answer: B
Rationale: This aligns with the principle that the S (synthesis) phase is specifically dedicated
to the duplication of the cell's genetic material before it enters the preparation for mitosis.
Q4: A mutation occurs that changes a single nucleotide in a DNA sequence, but the resulting
protein remains completely functional. This is most likely due to:
A. The degeneracy of the genetic code. [CORRECT]
B. A frameshift mutation correcting itself.
,C. The mutation occurring in an exon.
D. The immediate activation of DNA repair enzymes.
Correct Answer: A
Rationale: The best answer is the degeneracy of the genetic code, because multiple codons
can code for the same amino acid, meaning a silent mutation may not alter the final protein
structure.
Q5: In the process of transcription, which enzyme is responsible for synthesizing an RNA
strand complementary to the DNA template?
A. DNA polymerase
B. RNA polymerase [CORRECT]
C. Helicase
D. Ligase
Correct Answer: B
Rationale: This choice is correct because RNA polymerase is the specific enzyme that reads
the DNA template strand and links ribonucleotides together to form a messenger RNA
transcript.
Q6: A researcher measures the reaction rate of an enzyme at varying substrate
concentrations. The data shows the rate increases steadily until it plateaus at 50 µmol/min,
even when more substrate is added. What does this plateau represent?
A. The enzyme has been denatured by the high substrate concentration.
B. The enzyme has reached its maximum velocity (Vmax) because all active sites are
saturated. [CORRECT]
C. The substrate has become an inhibitor at high concentrations.
D. The reaction has reached equilibrium and stopped completely.
Correct Answer: B
Rationale: This matches the principle of enzyme kinetics where Vmax is achieved when
every enzyme molecule is actively bound to a substrate, meaning adding more substrate
cannot increase the reaction rate further.
Q7: Which of the following metabolic pathways occurs in the cytoplasm and does not
require oxygen?
A. Krebs cycle
B. Electron transport chain
C. Glycolysis [CORRECT]
D. Beta-oxidation
Correct Answer: C
Rationale: The best answer is glycolysis, as it is the initial, anaerobic breakdown of glucose
into pyruvate that takes place in the cytosol of all living cells.
Q8: During oxidative phosphorylation, the energy released by the electron transport chain is
primarily used to:
A. Directly synthesize ATP from ADP.
B. Pump protons across the inner mitochondrial membrane to create an electrochemical
gradient. [CORRECT]
C. Break down glucose into pyruvate.
, D. Convert NADH back into NAD+ without producing ATP.
Correct Answer: B
Rationale: This choice is correct because the electron transport chain uses energy from
electrons to pump protons into the intermembrane space, establishing the proton-motive
force that drives ATP synthase.
Q9: What is the primary structural difference between DNA and RNA?
A. DNA contains uracil, while RNA contains thymine.
B. DNA is typically double-stranded, while RNA is typically single-stranded. [CORRECT]
C. DNA contains ribose sugar, while RNA contains deoxyribose.
D. DNA is found only in the cytoplasm, while RNA is confined to the nucleus.
Correct Answer: B
Rationale: This aligns with the fundamental structural principle that DNA forms a stable
double helix, whereas RNA is generally single-stranded and contains ribose and uracil
instead of deoxyribose and thymine.
Q10: A patient's cells are unable to break down hydrogen peroxide, leading to toxic
accumulation. Which organelle is most likely defective?
A. Mitochondria
B. Peroxisome [CORRECT]
C. Lysosome
D. Smooth endoplasmic reticulum
Correct Answer: B
Rationale: The best answer is the peroxisome, as these organelles contain catalase, the
specific enzyme responsible for neutralizing hydrogen peroxide into water and oxygen.
Q11: Which of the following events is unique to meiosis and does not occur during mitosis?
A. Separation of sister chromatids
B. Synapsis and crossing over of homologous chromosomes [CORRECT]
C. Breakdown of the nuclear envelope
D. Alignment of chromosomes at the metaphase plate
Correct Answer: B
Rationale: This choice is correct because synapsis and crossing over are exclusive to
prophase I of meiosis, promoting genetic diversity, whereas mitosis maintains genetic
identity.
Q12: If a competitive inhibitor is added to an enzyme-catalyzed reaction, how can the
original reaction rate be restored?
A. By decreasing the temperature of the reaction.
B. By increasing the concentration of the substrate. [CORRECT]
C. By permanently altering the enzyme's active site.
D. By adding a non-competitive inhibitor.
Correct Answer: B
Rationale: This matches the principle that competitive inhibitors compete with the substrate
for the active site, so flooding the system with more substrate outcompetes the inhibitor
and restores Vmax.
