BIOD 210 Genetics Comprehensive Final Exam 2026/2027 UPDATE
1. Which of Gregor Mendel’s laws states that the two alleles for a heritable
character separate during gamete formation and end up in different gametes?
A. Law of Segregation
B. Law of Independent Assortment
C. Law of Dominance
D. Law of Recombination
Answer: A
Rationale: The Law of Segregation describes the separation of allele pairs during meiosis
so that each gamete carries only one allele for each gene.
2. In a cross between two individuals heterozygous for a single trait (Aa x Aa),
what is the expected genotypic ratio?
A. 3:1
B. 1:2:1
C. 9:3:3:1
D. 1:1
Answer: B
Rationale: The genotypic ratio for a monohybrid cross of heterozygotes is 1 (AA) : 2 (Aa) :
1 (aa).
,3. Which nitrogenous base is found in RNA but not in DNA?
A. Adenine
B. Uracil
C. Thymine
D. Cytosine
Answer: B
Rationale: RNA contains Uracil instead of Thymine, which is found in DNA.
4. What type of bond holds the two strands of the DNA double helix together
between nitrogenous bases?
A. Phosphodiester bonds
B. Covalent bonds
C. Ionic bonds
D. Hydrogen bonds
Answer: D
Rationale: Hydrogen bonds form between complementary base pairs (A-T and C-G) to
stabilize the double helix.
5. DNA replication is considered ‘semi-conservative’ because:
A. Each new double helix consists of one old strand and one new strand
B. The daughter molecule consists of two newly synthesized strands
C. One strand is DNA and the other is RNA
D. The original double helix remains intact
Answer: A
Rationale: Semi-conservative replication means each parental strand serves as a template
for a new strand, resulting in hybrids of old and new.
, 6. Which enzyme is responsible for unwinding the DNA double helix at the
replication fork?
A. Helicase
B. DNA Ligase
C. DNA Polymerase III
D. Topoisomerase
Answer: A
Rationale: Helicase breaks the hydrogen bonds between bases to unzip the DNA molecule.
7. What is the role of DNA Ligase during replication?
A. Joining Okazaki fragments on the lagging strand
B. Synthesizing RNA primers
C. Adding nucleotides to the 3’ end
D. Proofreading the DNA sequence
Answer: A
Rationale: DNA Ligase ‘glues’ the sugar-phosphate backbones of DNA fragments,
particularly Okazaki fragments, together.
8. Transcription occurs in the ________ of eukaryotic cells.
A. Cytoplasm
B. Ribosome
C. Nucleus
D. Endoplasmic Reticulum
Answer: C
Rationale: In eukaryotes, DNA is located in the nucleus, so transcription (DNA to mRNA)
must happen there.
1. Which of Gregor Mendel’s laws states that the two alleles for a heritable
character separate during gamete formation and end up in different gametes?
A. Law of Segregation
B. Law of Independent Assortment
C. Law of Dominance
D. Law of Recombination
Answer: A
Rationale: The Law of Segregation describes the separation of allele pairs during meiosis
so that each gamete carries only one allele for each gene.
2. In a cross between two individuals heterozygous for a single trait (Aa x Aa),
what is the expected genotypic ratio?
A. 3:1
B. 1:2:1
C. 9:3:3:1
D. 1:1
Answer: B
Rationale: The genotypic ratio for a monohybrid cross of heterozygotes is 1 (AA) : 2 (Aa) :
1 (aa).
,3. Which nitrogenous base is found in RNA but not in DNA?
A. Adenine
B. Uracil
C. Thymine
D. Cytosine
Answer: B
Rationale: RNA contains Uracil instead of Thymine, which is found in DNA.
4. What type of bond holds the two strands of the DNA double helix together
between nitrogenous bases?
A. Phosphodiester bonds
B. Covalent bonds
C. Ionic bonds
D. Hydrogen bonds
Answer: D
Rationale: Hydrogen bonds form between complementary base pairs (A-T and C-G) to
stabilize the double helix.
5. DNA replication is considered ‘semi-conservative’ because:
A. Each new double helix consists of one old strand and one new strand
B. The daughter molecule consists of two newly synthesized strands
C. One strand is DNA and the other is RNA
D. The original double helix remains intact
Answer: A
Rationale: Semi-conservative replication means each parental strand serves as a template
for a new strand, resulting in hybrids of old and new.
, 6. Which enzyme is responsible for unwinding the DNA double helix at the
replication fork?
A. Helicase
B. DNA Ligase
C. DNA Polymerase III
D. Topoisomerase
Answer: A
Rationale: Helicase breaks the hydrogen bonds between bases to unzip the DNA molecule.
7. What is the role of DNA Ligase during replication?
A. Joining Okazaki fragments on the lagging strand
B. Synthesizing RNA primers
C. Adding nucleotides to the 3’ end
D. Proofreading the DNA sequence
Answer: A
Rationale: DNA Ligase ‘glues’ the sugar-phosphate backbones of DNA fragments,
particularly Okazaki fragments, together.
8. Transcription occurs in the ________ of eukaryotic cells.
A. Cytoplasm
B. Ribosome
C. Nucleus
D. Endoplasmic Reticulum
Answer: C
Rationale: In eukaryotes, DNA is located in the nucleus, so transcription (DNA to mRNA)
must happen there.
