TEST BANK – FALL SEMESTER 2025 | KARP’S
CELL AND MOLECULAR BIOLOGY 2025/2026 |
310+ VERIFIED EXAM QUESTIONS WITH
CORRECT ANSWERS & DETAILED RATIONALES
| COMPLETE STUDY GUIDE & EXAM PREP
TEST BANK – FALL SEMESTER
KARP'S CELL AND MOLECULAR BIOLOGY
310+ VERIFIED EXAM QUESTIONS | COMPLETE STUDY GUIDE & EXAM PREP
Q1. What is the fundamental unit of all living organisms?
A. Tissue B. Organ C. Cell D. Molecule E. Atom
CORRECT ANSWER: C. Cell RATIONALE: The cell is the basic
structural and functional unit of all living organisms, as established by cell theory. All life
processes occur within cells or are directed by cellular activity.
Q2. Which of the following best describes prokaryotic cells?
A. They contain a membrane-bound nucleus B. They have membrane-bound organelles
C. They lack a membrane-bound nucleus D. They are only found in animals E. They
contain mitochondria
CORRECT ANSWER: C. They lack a membrane-bound nucleus
RATIONALE: Prokaryotic cells, such as bacteria and archaea, lack a membrane-
bound nucleus. Their genetic material is located in the nucleoid region, which is not
enclosed by a membrane.
Q3. Which organelle is primarily responsible for ATP synthesis in eukaryotic
cells?
A. Ribosome B. Golgi apparatus C. Endoplasmic reticulum D. Mitochondrion E.
Lysosome
, CORRECT ANSWER: D. Mitochondrion RATIONALE: The
mitochondrion is the site of aerobic respiration and oxidative phosphorylation, which
produces the majority of ATP in eukaryotic cells through the electron transport chain and
ATP synthase.
Q4. The fluid mosaic model describes which cellular structure?
A. The nuclear envelope B. The plasma membrane C. The cytoskeleton D. The Golgi
apparatus E. The cell wall
CORRECT ANSWER: B. The plasma membrane RATIONALE: The
fluid mosaic model, proposed by Singer and Nicolson in 1972, describes the plasma
membrane as a fluid phospholipid bilayer embedded with proteins that can move
laterally within the membrane.
Q5. Which of the following is a major function of the smooth endoplasmic
reticulum (SER)?
A. Protein synthesis B. Lipid synthesis C. DNA replication D. ATP production E. Protein
degradation
CORRECT ANSWER: B. Lipid synthesis RATIONALE: The smooth
endoplasmic reticulum lacks ribosomes and is primarily involved in lipid synthesis,
detoxification of drugs and poisons, and calcium ion storage, unlike the rough ER which
is involved in protein synthesis.
Q6. Which cytoskeletal element is primarily responsible for maintaining cell
shape?
A. Microfilaments B. Intermediate filaments C. Microtubules D. Centrioles E. Flagella
CORRECT ANSWER: B. Intermediate filaments RATIONALE:
Intermediate filaments (8–12 nm in diameter) provide mechanical strength and help
maintain cell shape. They are highly stable and resistant to mechanical stress, unlike
the more dynamic microfilaments and microtubules.
Q7. DNA replication is described as semiconservative, meaning:
,A. Only one strand of DNA is replicated B. Each new double helix contains one old and
one new strand C. Both strands of DNA are entirely new D. DNA replication is
incomplete E. Only the coding strand is replicated
CORRECT ANSWER: B. Each new double helix contains one old and one
new strand RATIONALE: Semiconservative replication, demonstrated by
Meselson and Stahl, means each daughter DNA molecule consists of one original
(parental) strand and one newly synthesized strand.
Q8. Which enzyme is responsible for synthesizing the RNA primer during DNA
replication?
A. DNA polymerase I B. DNA polymerase III C. Primase D. Helicase E. Ligase
CORRECT ANSWER: C. Primase RATIONALE: Primase is an RNA
polymerase that synthesizes short RNA primers complementary to the DNA template.
These primers provide the free 3'-OH group necessary for DNA polymerase to begin
synthesizing DNA.
Q9. Which of the following best describes the role of telomerase?
A. It initiates DNA replication B. It proofreads newly synthesized DNA C. It extends the
ends of chromosomes D. It unwinds the DNA double helix E. It ligates Okazaki
fragments
CORRECT ANSWER: C. It extends the ends of chromosomes
RATIONALE: Telomerase is a reverse transcriptase that adds repetitive DNA
sequences (TTAGGG in humans) to the ends of chromosomes (telomeres), preventing
chromosome shortening during replication. It is highly active in germ cells and cancer
cells.
Q10. Which type of RNA carries amino acids to the ribosome during translation?
A. mRNA B. rRNA C. tRNA D. snRNA E. miRNA
CORRECT ANSWER: C. tRNA RATIONALE: Transfer RNA (tRNA) acts
as an adaptor molecule that carries specific amino acids to the ribosome. Each tRNA
has an anticodon that base-pairs with the complementary codon on mRNA, ensuring
the correct amino acid is incorporated.
, Q11. The central dogma of molecular biology states that:
A. Proteins can be converted to DNA B. RNA can only be transcribed from DNA C.
Information flows from DNA to RNA to protein D. DNA is directly translated into protein
E. RNA is the primary genetic material in all organisms
CORRECT ANSWER: C. Information flows from DNA to RNA to protein
RATIONALE: The central dogma, proposed by Francis Crick, states that genetic
information flows from DNA → RNA → Protein. While exceptions exist (e.g., reverse
transcription in retroviruses), this remains the foundational principle of molecular
biology.
Q12. Which of the following best describes a nucleosome?
A. A segment of mRNA B. DNA wrapped around a core of histone proteins C. A
ribosomal subunit D. A nuclear pore complex E. A segment of single-stranded DNA
CORRECT ANSWER: B. DNA wrapped around a core of histone proteins
RATIONALE: A nucleosome is the basic unit of chromatin organization,
consisting of ~147 bp of DNA wrapped around an octamer of histone proteins (two
copies each of H2A, H2B, H3, and H4). This packaging compacts DNA and regulates
gene expression.
Q13. What is the role of RNA polymerase II in eukaryotic cells?
A. It transcribes ribosomal RNA B. It transcribes transfer RNA C. It transcribes
messenger RNA D. It replicates DNA E. It translates mRNA into protein
CORRECT ANSWER: C. It transcribes messenger RNA RATIONALE:
RNA polymerase II is responsible for transcribing protein-coding genes into pre-mRNA
(and also most snRNAs and miRNAs). RNA Pol I transcribes rRNA and RNA Pol III
transcribes tRNA and 5S rRNA.
Q14. Alternative splicing of pre-mRNA primarily contributes to:
A. DNA repair B. Protein diversity C. Chromosome segregation D. Lipid metabolism E.
Ribosome assembly
CELL AND MOLECULAR BIOLOGY 2025/2026 |
310+ VERIFIED EXAM QUESTIONS WITH
CORRECT ANSWERS & DETAILED RATIONALES
| COMPLETE STUDY GUIDE & EXAM PREP
TEST BANK – FALL SEMESTER
KARP'S CELL AND MOLECULAR BIOLOGY
310+ VERIFIED EXAM QUESTIONS | COMPLETE STUDY GUIDE & EXAM PREP
Q1. What is the fundamental unit of all living organisms?
A. Tissue B. Organ C. Cell D. Molecule E. Atom
CORRECT ANSWER: C. Cell RATIONALE: The cell is the basic
structural and functional unit of all living organisms, as established by cell theory. All life
processes occur within cells or are directed by cellular activity.
Q2. Which of the following best describes prokaryotic cells?
A. They contain a membrane-bound nucleus B. They have membrane-bound organelles
C. They lack a membrane-bound nucleus D. They are only found in animals E. They
contain mitochondria
CORRECT ANSWER: C. They lack a membrane-bound nucleus
RATIONALE: Prokaryotic cells, such as bacteria and archaea, lack a membrane-
bound nucleus. Their genetic material is located in the nucleoid region, which is not
enclosed by a membrane.
Q3. Which organelle is primarily responsible for ATP synthesis in eukaryotic
cells?
A. Ribosome B. Golgi apparatus C. Endoplasmic reticulum D. Mitochondrion E.
Lysosome
, CORRECT ANSWER: D. Mitochondrion RATIONALE: The
mitochondrion is the site of aerobic respiration and oxidative phosphorylation, which
produces the majority of ATP in eukaryotic cells through the electron transport chain and
ATP synthase.
Q4. The fluid mosaic model describes which cellular structure?
A. The nuclear envelope B. The plasma membrane C. The cytoskeleton D. The Golgi
apparatus E. The cell wall
CORRECT ANSWER: B. The plasma membrane RATIONALE: The
fluid mosaic model, proposed by Singer and Nicolson in 1972, describes the plasma
membrane as a fluid phospholipid bilayer embedded with proteins that can move
laterally within the membrane.
Q5. Which of the following is a major function of the smooth endoplasmic
reticulum (SER)?
A. Protein synthesis B. Lipid synthesis C. DNA replication D. ATP production E. Protein
degradation
CORRECT ANSWER: B. Lipid synthesis RATIONALE: The smooth
endoplasmic reticulum lacks ribosomes and is primarily involved in lipid synthesis,
detoxification of drugs and poisons, and calcium ion storage, unlike the rough ER which
is involved in protein synthesis.
Q6. Which cytoskeletal element is primarily responsible for maintaining cell
shape?
A. Microfilaments B. Intermediate filaments C. Microtubules D. Centrioles E. Flagella
CORRECT ANSWER: B. Intermediate filaments RATIONALE:
Intermediate filaments (8–12 nm in diameter) provide mechanical strength and help
maintain cell shape. They are highly stable and resistant to mechanical stress, unlike
the more dynamic microfilaments and microtubules.
Q7. DNA replication is described as semiconservative, meaning:
,A. Only one strand of DNA is replicated B. Each new double helix contains one old and
one new strand C. Both strands of DNA are entirely new D. DNA replication is
incomplete E. Only the coding strand is replicated
CORRECT ANSWER: B. Each new double helix contains one old and one
new strand RATIONALE: Semiconservative replication, demonstrated by
Meselson and Stahl, means each daughter DNA molecule consists of one original
(parental) strand and one newly synthesized strand.
Q8. Which enzyme is responsible for synthesizing the RNA primer during DNA
replication?
A. DNA polymerase I B. DNA polymerase III C. Primase D. Helicase E. Ligase
CORRECT ANSWER: C. Primase RATIONALE: Primase is an RNA
polymerase that synthesizes short RNA primers complementary to the DNA template.
These primers provide the free 3'-OH group necessary for DNA polymerase to begin
synthesizing DNA.
Q9. Which of the following best describes the role of telomerase?
A. It initiates DNA replication B. It proofreads newly synthesized DNA C. It extends the
ends of chromosomes D. It unwinds the DNA double helix E. It ligates Okazaki
fragments
CORRECT ANSWER: C. It extends the ends of chromosomes
RATIONALE: Telomerase is a reverse transcriptase that adds repetitive DNA
sequences (TTAGGG in humans) to the ends of chromosomes (telomeres), preventing
chromosome shortening during replication. It is highly active in germ cells and cancer
cells.
Q10. Which type of RNA carries amino acids to the ribosome during translation?
A. mRNA B. rRNA C. tRNA D. snRNA E. miRNA
CORRECT ANSWER: C. tRNA RATIONALE: Transfer RNA (tRNA) acts
as an adaptor molecule that carries specific amino acids to the ribosome. Each tRNA
has an anticodon that base-pairs with the complementary codon on mRNA, ensuring
the correct amino acid is incorporated.
, Q11. The central dogma of molecular biology states that:
A. Proteins can be converted to DNA B. RNA can only be transcribed from DNA C.
Information flows from DNA to RNA to protein D. DNA is directly translated into protein
E. RNA is the primary genetic material in all organisms
CORRECT ANSWER: C. Information flows from DNA to RNA to protein
RATIONALE: The central dogma, proposed by Francis Crick, states that genetic
information flows from DNA → RNA → Protein. While exceptions exist (e.g., reverse
transcription in retroviruses), this remains the foundational principle of molecular
biology.
Q12. Which of the following best describes a nucleosome?
A. A segment of mRNA B. DNA wrapped around a core of histone proteins C. A
ribosomal subunit D. A nuclear pore complex E. A segment of single-stranded DNA
CORRECT ANSWER: B. DNA wrapped around a core of histone proteins
RATIONALE: A nucleosome is the basic unit of chromatin organization,
consisting of ~147 bp of DNA wrapped around an octamer of histone proteins (two
copies each of H2A, H2B, H3, and H4). This packaging compacts DNA and regulates
gene expression.
Q13. What is the role of RNA polymerase II in eukaryotic cells?
A. It transcribes ribosomal RNA B. It transcribes transfer RNA C. It transcribes
messenger RNA D. It replicates DNA E. It translates mRNA into protein
CORRECT ANSWER: C. It transcribes messenger RNA RATIONALE:
RNA polymerase II is responsible for transcribing protein-coding genes into pre-mRNA
(and also most snRNAs and miRNAs). RNA Pol I transcribes rRNA and RNA Pol III
transcribes tRNA and 5S rRNA.
Q14. Alternative splicing of pre-mRNA primarily contributes to:
A. DNA repair B. Protein diversity C. Chromosome segregation D. Lipid metabolism E.
Ribosome assembly
