BIOD210
DNA & Chromosomes
Comprehensive Test Review (Qns & Ans)
2025
1. Which of the following best describes the structure of DNA?
- A) Single-stranded helix
- B) Double-stranded helix
- C) Triple-stranded helix
- D) Quadruple-stranded helix
- ANS: B) Double-stranded helix
- Rationale: DNA is composed of two strands that form a
double helix structure, held together by hydrogen bonds between
complementary base pairs.
©/2025
,2. What is the primary role of histone proteins in DNA
packaging?
- A) To catalyze DNA replication
- B) To unwind the DNA helix
- C) To help package DNA into nucleosomes
- D) To repair DNA damage
- ANS: C) To help package DNA into nucleosomes
- Rationale: Histone proteins help package DNA into
nucleosomes, which are the basic units of chromatin structure,
aiding in DNA compaction and organization.
3. Which enzyme is responsible for unwinding the DNA double
helix during replication?
- A) DNA polymerase
- B) DNA ligase
- C) Helicase
- D) Topoisomerase
- ANS: C) Helicase
- Rationale: Helicase is the enzyme responsible for
unwinding the DNA double helix during replication, allowing the
replication machinery to access the DNA strands.
©/2025
, Fill-in-the-Blank Questions
4. The __________ is the region of a chromosome that contains
the genetic material responsible for the synthesis of ribosomal
RNA (rRNA).
- ANS: Nucleolus
- Rationale: The nucleolus is the region of a chromosome that
contains the genetic material responsible for the synthesis of
ribosomal RNA (rRNA) and the assembly of ribosomes.
5. In eukaryotic cells, DNA is organized into linear structures
called __________.
- ANS: Chromosomes
- Rationale: In eukaryotic cells, DNA is organized into linear
structures called chromosomes, which contain the genetic
information necessary for cell function and inheritance.
6. During DNA replication, the __________ strand is
synthesized continuously, while the __________ strand is
synthesized in short fragments.
- ANS: Leading, lagging
- Rationale: During DNA replication, the leading strand is
synthesized continuously in the direction of the replication fork,
while the lagging strand is synthesized in short fragments called
Okazaki fragments.
©/2025
, True/False Questions
7. True or False: The telomere is a repetitive DNA sequence at
the ends of chromosomes that protects them from degradation.
- ANS: True
- Rationale: Telomeres are repetitive DNA sequences at the
ends of chromosomes that protect them from degradation and
prevent the loss of genetic information during replication.
8. True or False: DNA methylation is a process that involves the
addition of a methyl group to the adenine base of DNA.
- ANS: False
- Rationale: DNA methylation involves the addition of a
methyl group to the cytosine base of DNA, typically at CpG sites,
and plays a role in gene regulation.
9. True or False: The genetic code is universal, meaning it is the
same in all living organisms.
- ANS: True
- Rationale: The genetic code is universal, meaning that the
same codons specify the same amino acids in nearly all living
organisms, highlighting the shared evolutionary history of life.
Multiple Response Questions
©/2025
DNA & Chromosomes
Comprehensive Test Review (Qns & Ans)
2025
1. Which of the following best describes the structure of DNA?
- A) Single-stranded helix
- B) Double-stranded helix
- C) Triple-stranded helix
- D) Quadruple-stranded helix
- ANS: B) Double-stranded helix
- Rationale: DNA is composed of two strands that form a
double helix structure, held together by hydrogen bonds between
complementary base pairs.
©/2025
,2. What is the primary role of histone proteins in DNA
packaging?
- A) To catalyze DNA replication
- B) To unwind the DNA helix
- C) To help package DNA into nucleosomes
- D) To repair DNA damage
- ANS: C) To help package DNA into nucleosomes
- Rationale: Histone proteins help package DNA into
nucleosomes, which are the basic units of chromatin structure,
aiding in DNA compaction and organization.
3. Which enzyme is responsible for unwinding the DNA double
helix during replication?
- A) DNA polymerase
- B) DNA ligase
- C) Helicase
- D) Topoisomerase
- ANS: C) Helicase
- Rationale: Helicase is the enzyme responsible for
unwinding the DNA double helix during replication, allowing the
replication machinery to access the DNA strands.
©/2025
, Fill-in-the-Blank Questions
4. The __________ is the region of a chromosome that contains
the genetic material responsible for the synthesis of ribosomal
RNA (rRNA).
- ANS: Nucleolus
- Rationale: The nucleolus is the region of a chromosome that
contains the genetic material responsible for the synthesis of
ribosomal RNA (rRNA) and the assembly of ribosomes.
5. In eukaryotic cells, DNA is organized into linear structures
called __________.
- ANS: Chromosomes
- Rationale: In eukaryotic cells, DNA is organized into linear
structures called chromosomes, which contain the genetic
information necessary for cell function and inheritance.
6. During DNA replication, the __________ strand is
synthesized continuously, while the __________ strand is
synthesized in short fragments.
- ANS: Leading, lagging
- Rationale: During DNA replication, the leading strand is
synthesized continuously in the direction of the replication fork,
while the lagging strand is synthesized in short fragments called
Okazaki fragments.
©/2025
, True/False Questions
7. True or False: The telomere is a repetitive DNA sequence at
the ends of chromosomes that protects them from degradation.
- ANS: True
- Rationale: Telomeres are repetitive DNA sequences at the
ends of chromosomes that protect them from degradation and
prevent the loss of genetic information during replication.
8. True or False: DNA methylation is a process that involves the
addition of a methyl group to the adenine base of DNA.
- ANS: False
- Rationale: DNA methylation involves the addition of a
methyl group to the cytosine base of DNA, typically at CpG sites,
and plays a role in gene regulation.
9. True or False: The genetic code is universal, meaning it is the
same in all living organisms.
- ANS: True
- Rationale: The genetic code is universal, meaning that the
same codons specify the same amino acids in nearly all living
organisms, highlighting the shared evolutionary history of life.
Multiple Response Questions
©/2025
