HESI A2 BIOLOGY SUMMER 2026/2027 | Complete
Solutions | Already Graded A | Nursing Entrance Exam
Prep | Pass Guaranteed - A+ Graded
SECTION 1: CELL BIOLOGY (Questions 1-12)
Q1. A nurse is reviewing a patient's lab report showing elevated liver enzymes (AST
and ALT). Which organelle in hepatocytes is primarily responsible for the
detoxification processes that, when overworked, can lead to increased enzyme
release?
A. Rough endoplasmic reticulum B. Smooth endoplasmic reticulum C. Golgi
apparatus D. Lysosomes
Correct Answer: B. Smooth endoplasmic reticulum [CORRECT]
Rationale: The smooth endoplasmic reticulum (SER) is the primary site of
detoxification reactions in liver cells, including drug metabolism and alcohol
breakdown via cytochrome P450 enzymes. When hepatocytes are damaged, SER
membrane integrity is compromised, releasing AST and ALT into the bloodstream.
The rough ER (A) synthesizes proteins for secretion, not detoxification. The Golgi
apparatus (C) modifies and packages proteins. Lysosomes (D) contain hydrolytic
enzymes for intracellular digestion, not detoxification of external substances.
Q2. A student observes human cheek cells under a microscope and notes they lack
cell walls and chloroplasts. These cells are classified as:
A. Prokaryotic and autotrophic B. Prokaryotic and heterotrophic C. Eukaryotic and
autotrophic D. Eukaryotic and heterotrophic
Correct Answer: D. Eukaryotic and heterotrophic [CORRECT]
,Rationale: Human cheek cells are eukaryotic because they possess a membrane-
bound nucleus and organelles such as mitochondria. They are heterotrophic because
they cannot produce their own food and must obtain energy by consuming organic
molecules. Prokaryotic cells (A, B) lack a nucleus and membrane-bound organelles.
Autotrophic cells (A, C) can synthesize their own food via photosynthesis or
chemosynthesis, which human cells cannot do.
Q3. During cell division, spindle fibers attach to chromosomes and pull them apart.
These spindle fibers are composed of:
A. Actin filaments B. Intermediate filaments C. Microtubules made of tubulin D.
Myosin proteins
Correct Answer: C. Microtubules made of tubulin [CORRECT]
Rationale: Spindle fibers are composed of microtubules, which are polymers of alpha
and beta tubulin dimers. They originate from centrosomes and attach to
kinetochores on chromosomes to ensure proper segregation during mitosis and
meiosis. Actin filaments (A, microfilaments) are involved in muscle contraction and
cytokinesis. Intermediate filaments (B) provide structural support. Myosin (D) is a
motor protein that interacts with actin, not a structural component of spindle fibers.
Q4. A red blood cell is placed in a solution with a solute concentration of 0.9% NaCl.
The cell maintains its normal biconcave shape. This solution is best described as:
A. Hypotonic B. Hypertonic C. Isotonic D. Osmotic
Correct Answer: C. Isotonic [CORRECT]
Rationale: An isotonic solution has the same solute concentration as the cell's
cytoplasm, resulting in no net water movement across the membrane. Normal saline
(0.9% NaCl) is isotonic to human red blood cells, which is why it is used clinically for
IV fluid replacement. A hypotonic solution (A) would cause water to enter the cell,
leading to swelling and potential lysis. A hypertonic solution (B) would cause water to
, leave the cell, resulting in crenation (shriveling). "Osmotic" (D) describes a process,
not a solution type.
Q5. A patient with cystic fibrosis has a defective CFTR protein, a channel protein that
normally transports chloride ions across the cell membrane. This defect primarily
impairs which type of transport?
A. Simple diffusion B. Facilitated diffusion C. Active transport D. Osmosis
Correct Answer: B. Facilitated diffusion [CORRECT]
Rationale: The CFTR protein is a channel protein that allows chloride ions to passively
diffuse down their concentration gradient, which is facilitated diffusion—passive
transport that requires a membrane protein but no ATP. Simple diffusion (A) does
not require proteins. Active transport (C) requires ATP and moves substances against
their gradient. Osmosis (D) refers specifically to water movement, not ion transport.
Q6. A nurse administers an antibiotic that targets bacterial ribosomes. The antibiotic
is effective because bacterial ribosomes are:
A. 80S, while human ribosomes are 70S B. 70S, while human ribosomes are 80S C.
Free in the cytoplasm, while human ribosomes are bound to the ER D. Bound to the
nuclear membrane, while human ribosomes are free
Correct Answer: B. 70S, while human ribosomes are 80S [CORRECT]
Rationale: Prokaryotic (bacterial) ribosomes are 70S (composed of 50S and 30S
subunits), whereas eukaryotic (human) ribosomes are 80S (composed of 60S and 40S
subunits). This structural difference allows antibiotics like tetracycline and macrolides
to selectively inhibit bacterial protein synthesis without affecting human cells. Both
bacterial and human cells have free and membrane-bound ribosomes (C is incorrect).
Bacterial ribosomes are not bound to the nuclear membrane (D) because bacteria
lack a nucleus.
Solutions | Already Graded A | Nursing Entrance Exam
Prep | Pass Guaranteed - A+ Graded
SECTION 1: CELL BIOLOGY (Questions 1-12)
Q1. A nurse is reviewing a patient's lab report showing elevated liver enzymes (AST
and ALT). Which organelle in hepatocytes is primarily responsible for the
detoxification processes that, when overworked, can lead to increased enzyme
release?
A. Rough endoplasmic reticulum B. Smooth endoplasmic reticulum C. Golgi
apparatus D. Lysosomes
Correct Answer: B. Smooth endoplasmic reticulum [CORRECT]
Rationale: The smooth endoplasmic reticulum (SER) is the primary site of
detoxification reactions in liver cells, including drug metabolism and alcohol
breakdown via cytochrome P450 enzymes. When hepatocytes are damaged, SER
membrane integrity is compromised, releasing AST and ALT into the bloodstream.
The rough ER (A) synthesizes proteins for secretion, not detoxification. The Golgi
apparatus (C) modifies and packages proteins. Lysosomes (D) contain hydrolytic
enzymes for intracellular digestion, not detoxification of external substances.
Q2. A student observes human cheek cells under a microscope and notes they lack
cell walls and chloroplasts. These cells are classified as:
A. Prokaryotic and autotrophic B. Prokaryotic and heterotrophic C. Eukaryotic and
autotrophic D. Eukaryotic and heterotrophic
Correct Answer: D. Eukaryotic and heterotrophic [CORRECT]
,Rationale: Human cheek cells are eukaryotic because they possess a membrane-
bound nucleus and organelles such as mitochondria. They are heterotrophic because
they cannot produce their own food and must obtain energy by consuming organic
molecules. Prokaryotic cells (A, B) lack a nucleus and membrane-bound organelles.
Autotrophic cells (A, C) can synthesize their own food via photosynthesis or
chemosynthesis, which human cells cannot do.
Q3. During cell division, spindle fibers attach to chromosomes and pull them apart.
These spindle fibers are composed of:
A. Actin filaments B. Intermediate filaments C. Microtubules made of tubulin D.
Myosin proteins
Correct Answer: C. Microtubules made of tubulin [CORRECT]
Rationale: Spindle fibers are composed of microtubules, which are polymers of alpha
and beta tubulin dimers. They originate from centrosomes and attach to
kinetochores on chromosomes to ensure proper segregation during mitosis and
meiosis. Actin filaments (A, microfilaments) are involved in muscle contraction and
cytokinesis. Intermediate filaments (B) provide structural support. Myosin (D) is a
motor protein that interacts with actin, not a structural component of spindle fibers.
Q4. A red blood cell is placed in a solution with a solute concentration of 0.9% NaCl.
The cell maintains its normal biconcave shape. This solution is best described as:
A. Hypotonic B. Hypertonic C. Isotonic D. Osmotic
Correct Answer: C. Isotonic [CORRECT]
Rationale: An isotonic solution has the same solute concentration as the cell's
cytoplasm, resulting in no net water movement across the membrane. Normal saline
(0.9% NaCl) is isotonic to human red blood cells, which is why it is used clinically for
IV fluid replacement. A hypotonic solution (A) would cause water to enter the cell,
leading to swelling and potential lysis. A hypertonic solution (B) would cause water to
, leave the cell, resulting in crenation (shriveling). "Osmotic" (D) describes a process,
not a solution type.
Q5. A patient with cystic fibrosis has a defective CFTR protein, a channel protein that
normally transports chloride ions across the cell membrane. This defect primarily
impairs which type of transport?
A. Simple diffusion B. Facilitated diffusion C. Active transport D. Osmosis
Correct Answer: B. Facilitated diffusion [CORRECT]
Rationale: The CFTR protein is a channel protein that allows chloride ions to passively
diffuse down their concentration gradient, which is facilitated diffusion—passive
transport that requires a membrane protein but no ATP. Simple diffusion (A) does
not require proteins. Active transport (C) requires ATP and moves substances against
their gradient. Osmosis (D) refers specifically to water movement, not ion transport.
Q6. A nurse administers an antibiotic that targets bacterial ribosomes. The antibiotic
is effective because bacterial ribosomes are:
A. 80S, while human ribosomes are 70S B. 70S, while human ribosomes are 80S C.
Free in the cytoplasm, while human ribosomes are bound to the ER D. Bound to the
nuclear membrane, while human ribosomes are free
Correct Answer: B. 70S, while human ribosomes are 80S [CORRECT]
Rationale: Prokaryotic (bacterial) ribosomes are 70S (composed of 50S and 30S
subunits), whereas eukaryotic (human) ribosomes are 80S (composed of 60S and 40S
subunits). This structural difference allows antibiotics like tetracycline and macrolides
to selectively inhibit bacterial protein synthesis without affecting human cells. Both
bacterial and human cells have free and membrane-bound ribosomes (C is incorrect).
Bacterial ribosomes are not bound to the nuclear membrane (D) because bacteria
lack a nucleus.
