PAX Science NLN Exam Collection 2026/2027
Actual Practice Questions: Comprehensive
Assessment with Verified Solutions
BIOLOGY SECTION (Questions 1-32)
Cell Biology & Biochemistry
Q1: Which cellular organelle is responsible for producing ATP through aerobic cellular
respiration?
A. Nucleus
B. Mitochondria
C. Ribosomes
D. Golgi apparatus
Correct Answer: B
Rationale: Mitochondria are the "powerhouses" of the cell, producing ATP through the
Krebs cycle (citric acid cycle) and oxidative phosphorylation (electron transport chain).
The inner mitochondrial membrane contains the protein complexes necessary for
chemiosmosis and ATP synthesis. The nucleus (A) houses genetic material and
controls cell activities. Ribosomes (C) synthesize proteins through translation. The
Golgi apparatus (D) modifies, packages, and distributes proteins and lipids.
,Pre-Nursing Connection: Understanding cellular energy production is fundamental to
physiology, pharmacology (how medications affect cellular metabolism), and
pathophysiology (cellular hypoxia in shock, cyanide poisoning affecting mitochondria).
Q2: During which phase of mitosis do the sister chromatids separate and move toward
opposite poles of the cell?
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase
Correct Answer: C
Rationale: Anaphase is characterized by the separation of sister chromatids at the
centromere, pulled toward opposite poles by spindle fibers. Prophase (A) involves
chromosome condensation and nuclear envelope breakdown. Metaphase (B) aligns
chromosomes at the metaphase plate. Telophase (D) involves nuclear envelope
reformation and cytokinesis beginning.
Pre-Nursing Connection: Cell division knowledge applies to understanding cancer
(uncontrolled mitosis), tissue repair, and embryonic development.
Q3: The diagram shows a cell in a solution. The cell membrane has separated from the
cell wall, and the cytoplasm has shrunk. What type of solution is the cell immersed in?
(Diagram description: Plant cell with plasma membrane pulling away from cell wall,
indicating plasmolysis)
,A. Hypotonic
B. Isotonic
C. Hypertonic
D. Osmotic
Correct Answer: C
Rationale: The described phenomenon is plasmolysis, which occurs when a cell is
placed in a hypertonic solution (higher solute concentration outside the cell). Water
moves out of the cell by osmosis, causing the cytoplasm to shrink and the membrane to
pull away from the cell wall. In hypotonic solutions (A), water enters the cell, causing
swelling or lysis. Isotonic solutions (B) result in no net water movement. Osmotic (D)
describes the process, not the solution type.
Pre-Nursing Connection: Critical for understanding fluid and electrolyte balance, IV
therapy (why we use isotonic solutions like 0.9% NaCl), and cellular responses to
dehydration.
Q4: Which biomolecule is primarily responsible for storing genetic information and
transmitting it from one generation to the next?
A. Protein
B. Carbohydrate
C. Lipid
D. Nucleic acid
Correct Answer: D
, Rationale: Nucleic acids (DNA and RNA) store and transmit genetic information. DNA
contains the genetic code in its nucleotide sequence (adenine, thymine, guanine,
cytosine). Proteins (A) perform enzymatic, structural, and regulatory functions.
Carbohydrates (B) provide energy and structural support. Lipids (C) store energy, form
membranes, and serve as signaling molecules.
Pre-Nursing Connection: Genetics is fundamental to understanding inherited diseases,
pharmacogenomics (how genetic variations affect drug response), and cancer biology.
Genetics & Heredity
Q5: In Mendelian genetics, if two heterozygous parents (Tt) for a single trait cross, what
percentage of their offspring would be expected to express the recessive phenotype?
A. 0%
B. 25%
C. 50%
D. 75%
Correct Answer: B
Rationale: Using a Punnett square for Tt × Tt:
● TT (homozygous dominant): 25% - express dominant phenotype
● Tt (heterozygous): 50% - express dominant phenotype (T is dominant)
● tt (homozygous recessive): 25% - express recessive phenotype
Only the tt genotype expresses the recessive phenotype = 25%.
Actual Practice Questions: Comprehensive
Assessment with Verified Solutions
BIOLOGY SECTION (Questions 1-32)
Cell Biology & Biochemistry
Q1: Which cellular organelle is responsible for producing ATP through aerobic cellular
respiration?
A. Nucleus
B. Mitochondria
C. Ribosomes
D. Golgi apparatus
Correct Answer: B
Rationale: Mitochondria are the "powerhouses" of the cell, producing ATP through the
Krebs cycle (citric acid cycle) and oxidative phosphorylation (electron transport chain).
The inner mitochondrial membrane contains the protein complexes necessary for
chemiosmosis and ATP synthesis. The nucleus (A) houses genetic material and
controls cell activities. Ribosomes (C) synthesize proteins through translation. The
Golgi apparatus (D) modifies, packages, and distributes proteins and lipids.
,Pre-Nursing Connection: Understanding cellular energy production is fundamental to
physiology, pharmacology (how medications affect cellular metabolism), and
pathophysiology (cellular hypoxia in shock, cyanide poisoning affecting mitochondria).
Q2: During which phase of mitosis do the sister chromatids separate and move toward
opposite poles of the cell?
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase
Correct Answer: C
Rationale: Anaphase is characterized by the separation of sister chromatids at the
centromere, pulled toward opposite poles by spindle fibers. Prophase (A) involves
chromosome condensation and nuclear envelope breakdown. Metaphase (B) aligns
chromosomes at the metaphase plate. Telophase (D) involves nuclear envelope
reformation and cytokinesis beginning.
Pre-Nursing Connection: Cell division knowledge applies to understanding cancer
(uncontrolled mitosis), tissue repair, and embryonic development.
Q3: The diagram shows a cell in a solution. The cell membrane has separated from the
cell wall, and the cytoplasm has shrunk. What type of solution is the cell immersed in?
(Diagram description: Plant cell with plasma membrane pulling away from cell wall,
indicating plasmolysis)
,A. Hypotonic
B. Isotonic
C. Hypertonic
D. Osmotic
Correct Answer: C
Rationale: The described phenomenon is plasmolysis, which occurs when a cell is
placed in a hypertonic solution (higher solute concentration outside the cell). Water
moves out of the cell by osmosis, causing the cytoplasm to shrink and the membrane to
pull away from the cell wall. In hypotonic solutions (A), water enters the cell, causing
swelling or lysis. Isotonic solutions (B) result in no net water movement. Osmotic (D)
describes the process, not the solution type.
Pre-Nursing Connection: Critical for understanding fluid and electrolyte balance, IV
therapy (why we use isotonic solutions like 0.9% NaCl), and cellular responses to
dehydration.
Q4: Which biomolecule is primarily responsible for storing genetic information and
transmitting it from one generation to the next?
A. Protein
B. Carbohydrate
C. Lipid
D. Nucleic acid
Correct Answer: D
, Rationale: Nucleic acids (DNA and RNA) store and transmit genetic information. DNA
contains the genetic code in its nucleotide sequence (adenine, thymine, guanine,
cytosine). Proteins (A) perform enzymatic, structural, and regulatory functions.
Carbohydrates (B) provide energy and structural support. Lipids (C) store energy, form
membranes, and serve as signaling molecules.
Pre-Nursing Connection: Genetics is fundamental to understanding inherited diseases,
pharmacogenomics (how genetic variations affect drug response), and cancer biology.
Genetics & Heredity
Q5: In Mendelian genetics, if two heterozygous parents (Tt) for a single trait cross, what
percentage of their offspring would be expected to express the recessive phenotype?
A. 0%
B. 25%
C. 50%
D. 75%
Correct Answer: B
Rationale: Using a Punnett square for Tt × Tt:
● TT (homozygous dominant): 25% - express dominant phenotype
● Tt (heterozygous): 50% - express dominant phenotype (T is dominant)
● tt (homozygous recessive): 25% - express recessive phenotype
Only the tt genotype expresses the recessive phenotype = 25%.
