CNIH Entrance Exam: Your Complete Guide to Admission Requirements and Preparation

CNIH Entrance Exam: Your Complete
Guide to Admission Requirements and
Preparation


Section 1: Cell Biology (Questions 1–10)

Question 1: Which organelle is responsible for modifying, sorting, and packaging proteins for
secretion or delivery to other organelles? A) Lysosome B) Golgi apparatus C) Mitochondrion D)
Rough endoplasmic reticulum

Correct Answer: B Rationale: The Golgi apparatus modifies proteins (e.g., glycosylation) and
packages them into vesicles for transport. Lysosomes (A) degrade cellular waste;
mitochondria (C) produce ATP; the rough ER (D) synthesizes proteins but does not package
them for secretion.



Question 2: What is the primary function of the sodium-potassium pump in animal cells? A) To
generate ATP via ion gradients B) To maintain resting membrane potential by exchanging 3 Na⁺
out and 2 K⁺ in per ATP C) To facilitate oxygen transport across the membrane D) To synthesize
sodium and potassium ions

Correct Answer: B Rationale: The Na⁺/K⁺ pump actively transports 3 Na⁺ out and 2 K⁺ in per
ATP, maintaining electrochemical gradients critical for membrane potential. It does not
generate ATP (A), transport oxygen (C), or synthesize ions (D).



Question 3: Which of the following is a prokaryotic cell feature? A) Membrane-bound nucleus
B) 80S ribosomes C) Circular DNA chromosome D) Mitochondria

Correct Answer: C Rationale: Prokaryotes (e.g., bacteria) have a single circular DNA
chromosome and lack membrane-bound organelles. Eukaryotes have a nucleus (A), 80S
ribosomes (B; prokaryotes have 70S), and mitochondria (D).

,Question 4: During mitosis, which phase is characterized by the alignment of chromosomes at
the cell’s equatorial plane? A) Prophase B) Metaphase C) Anaphase D) Telophase

Correct Answer: B Rationale: In metaphase , chromosomes align at the metaphase plate
(equatorial plane). Prophase (A) involves chromatin condensation; anaphase (C) is
chromosome separation; telophase (D) is nuclear reformation.



Question 5: Which type of cellular transport requires no energy and moves substances down
their concentration gradient? A) Active transport B) Endocytosis C) Facilitated diffusion D)
Exocytosis

Correct Answer: C Rationale: Facilitated diffusion uses transport proteins to move
molecules (e.g., glucose) down their gradient without ATP. Active transport (A) requires
energy; endocytosis (B) and exocytosis (D) involve vesicle movement.



Question 6: What is the primary component of the cell membrane? A) Phospholipid bilayer B)
Chitin C) Cellulose D) Glycogen

Correct Answer: A Rationale: The phospholipid bilayer forms the membrane’s structure,
with hydrophobic tails inward and hydrophilic heads outward. Chitin (B) is in fungal cell walls;
cellulose (C) in plant walls; glycogen (D) is a carbohydrate storage molecule.



Question 7: Which organelle contains digestive enzymes like acid hydrolases? A) Peroxisome
B) Lysosome C) Ribosome D) Centriole

Correct Answer: B Rationale: Lysosomes contain acid hydrolases (e.g., proteases, lipases)
for breaking down waste. Peroxisomes (A) detoxify H₂O₂; ribosomes (C) synthesize proteins;
centrioles (D) organize microtubules.



Question 8: What is the function of the rough endoplasmic reticulum? A) Lipid synthesis B)
Protein synthesis and folding C) Detoxification of drugs D) Energy production

Correct Answer: B Rationale: The rough ER (studded with ribosomes) synthesizes and folds
proteins (e.g., secretory proteins, membrane proteins). Lipid synthesis (A) occurs in the
smooth ER; detoxification (C) in peroxisomes/liver; energy production (D) in mitochondria.

, Question 9: Which of the following is not a function of the cytoskeleton? A) Maintaining cell
shape B) DNA replication C) Organelle positioning D) Cell motility

Correct Answer: B Rationale: The cytoskeleton (microfilaments, intermediate filaments,
microtubules) maintains shape (A), positions organelles (C), and enables motility (D) but does
not replicate DNA.



Question 10: What is the role of chloroplasts in plant cells? A) Protein synthesis B)
Photosynthesis C) Lipid storage D) Waste degradation

Correct Answer: B Rationale: Chloroplasts contain chlorophyll and conduct
photosynthesis, converting light energy to chemical energy. Protein synthesis (A) occurs in
ribosomes; lipid storage (C) in oil bodies; waste degradation (D) in lysosomes.




Section 2: Genetics & DNA (Questions 11–20)

Question 11: Which nitrogenous base is not found in DNA? A) Adenine B) Thymine C) Uracil D)
Guanine

Correct Answer: C Rationale: DNA contains adenine (A), thymine (T), guanine (G), and
cytosine (C). Uracil (U) replaces thymine in RNA.



Question 12: During DNA replication, which enzyme is responsible for unwinding the double
helix? A) DNA polymerase B) Helicase C) Ligase D) Topoisomerase

Correct Answer: B Rationale: Helicase breaks hydrogen bonds to unwind the DNA at the
replication fork. DNA polymerase (A) adds nucleotides; ligase (C) seals nicks; topoisomerase
(D) relieves supercoiling.



Question 13: A frameshift mutation occurs when: A) A single nucleotide is substituted B) One
or more nucleotides are inserted or deleted C) A codon changes to a stop codon D) A
chromosome breaks and rejoins incorrectly

Correct Answer: B Rationale: Frameshift mutations shift the reading frame due to
insertions/deletions of nucleotides. Substitutions (A) are point mutations; nonsense mutations
(C) create premature stops; chromosomal breaks (D) are large-scale mutations.