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BIOD 210 GENETICS FINAL EXAM Actual
Exam 2026/2027 Complete Questions and
Verified Answers with Detailed Rationales
Portage Learning Pass Guaranteed - A+ Graded
Section 1: BIOD 210 Genetics Final Exam
Q1: In a monohybrid cross between two heterozygous parents (Aa × Aa), what is the expected
phenotypic ratio in the offspring assuming complete dominance?
A. 1:1
B. 1:2:1
C. 3:1 [CORRECT]
D. 9:3:3:1
Correct Answer: C
Rationale: In a monohybrid cross between two heterozygous parents (Aa × Aa), the Punnett
square yields genotypic ratios of 1 AA : 2 Aa : 1 aa. With complete dominance, both AA and Aa
genotypes express the dominant phenotype, while aa expresses the recessive phenotype, resulting
in a 3:1 phenotypic ratio of dominant to recessive traits.
Q2: A pedigree shows a trait that appears in every generation, affects both sexes equally, and is
transmitted by affected parents to approximately half of their offspring. What is the most likely
inheritance pattern?
A. Autosomal recessive
B. Autosomal dominant [CORRECT]
C. X-linked recessive
D. Y-linked inheritance
Correct Answer: B
Rationale: Autosomal dominant inheritance is characterized by appearance in every generation
(no skipping), equal affectation of both sexes, and transmission from affected parents to
approximately 50% of offspring regardless of sex. These features distinguish it from recessive
patterns (which often skip generations) and sex-linked patterns (which show sex-biased
transmission).
,2
Q3: Which nitrogenous base in DNA pairs with guanine through three hydrogen bonds?
A. Adenine
B. Thymine
C. Cytosine [CORRECT]
D. Uracil
Correct Answer: C
Rationale: In DNA, guanine (a purine) pairs specifically with cytosine (a pyrimidine) through
three hydrogen bonds. This G-C pairing, along with A-T pairing (two hydrogen bonds),
maintains the complementary base pairing essential for DNA structure, replication, and genetic
information storage.
Q4: During DNA replication, which enzyme synthesizes the new DNA strand by adding
nucleotides in the 5' to 3' direction?
A. DNA ligase
B. DNA helicase
C. DNA polymerase [CORRECT]
D. Topoisomerase
Correct Answer: C
Rationale: DNA polymerase is the primary enzyme responsible for synthesizing new DNA
strands during replication. It reads the template strand in the 3' to 5' direction and adds
complementary nucleotides to the growing new strand exclusively in the 5' to 3' direction,
catalyzing phosphodiester bond formation between nucleotides.
Q5: In codominance, what is observed in the phenotype of heterozygous individuals?
A. Only the dominant phenotype is expressed
B. Only the recessive phenotype is expressed
C. Both alleles are fully and distinctly expressed [CORRECT]
D. A blended intermediate phenotype is observed
Correct Answer: C
Rationale: Codominance occurs when both alleles in a heterozygous individual are fully and
distinctly expressed in the phenotype, with neither being dominant over the other. A classic
, 3
example is the ABO blood group system, where individuals with genotype IAIB express both A
and B antigens on their red blood cells.
Q6: What is the term for an individual who carries one copy of a recessive allele for a genetic
disorder but does not express the disease phenotype?
A. Affected homozygote
B. Carrier (heterozygote) [CORRECT]
C. Dominant expressor
D. Nullizygote
Correct Answer: B
Rationale: A carrier is a heterozygous individual who possesses one normal allele and one
recessive disease-causing allele. The presence of the normal dominant allele prevents disease
expression, but the individual can transmit the recessive allele to offspring, potentially producing
affected offspring if the other parent is also a carrier.
Q7: Which process converts the genetic information in mRNA into a sequence of amino acids
during protein synthesis?
A. Transcription
B. Replication
C. Translation [CORRECT]
D. Splicing
Correct Answer: C
Rationale: Translation is the process by which the genetic code carried by messenger RNA
(mRNA) is decoded by ribosomes to produce a specific polypeptide chain. Transfer RNA
(tRNA) molecules bring amino acids to the ribosome, where they are joined together according
to the codon sequence in the mRNA.
Q8: A dihybrid cross between two heterozygous parents (AaBb × AaBb) produces offspring with
what expected phenotypic ratio assuming independent assortment and complete dominance?
A. 1:1:1:1
B. 9:3:3:1 [CORRECT]
C. 1:2:1
D. 3:1
BIOD 210 GENETICS FINAL EXAM Actual
Exam 2026/2027 Complete Questions and
Verified Answers with Detailed Rationales
Portage Learning Pass Guaranteed - A+ Graded
Section 1: BIOD 210 Genetics Final Exam
Q1: In a monohybrid cross between two heterozygous parents (Aa × Aa), what is the expected
phenotypic ratio in the offspring assuming complete dominance?
A. 1:1
B. 1:2:1
C. 3:1 [CORRECT]
D. 9:3:3:1
Correct Answer: C
Rationale: In a monohybrid cross between two heterozygous parents (Aa × Aa), the Punnett
square yields genotypic ratios of 1 AA : 2 Aa : 1 aa. With complete dominance, both AA and Aa
genotypes express the dominant phenotype, while aa expresses the recessive phenotype, resulting
in a 3:1 phenotypic ratio of dominant to recessive traits.
Q2: A pedigree shows a trait that appears in every generation, affects both sexes equally, and is
transmitted by affected parents to approximately half of their offspring. What is the most likely
inheritance pattern?
A. Autosomal recessive
B. Autosomal dominant [CORRECT]
C. X-linked recessive
D. Y-linked inheritance
Correct Answer: B
Rationale: Autosomal dominant inheritance is characterized by appearance in every generation
(no skipping), equal affectation of both sexes, and transmission from affected parents to
approximately 50% of offspring regardless of sex. These features distinguish it from recessive
patterns (which often skip generations) and sex-linked patterns (which show sex-biased
transmission).
,2
Q3: Which nitrogenous base in DNA pairs with guanine through three hydrogen bonds?
A. Adenine
B. Thymine
C. Cytosine [CORRECT]
D. Uracil
Correct Answer: C
Rationale: In DNA, guanine (a purine) pairs specifically with cytosine (a pyrimidine) through
three hydrogen bonds. This G-C pairing, along with A-T pairing (two hydrogen bonds),
maintains the complementary base pairing essential for DNA structure, replication, and genetic
information storage.
Q4: During DNA replication, which enzyme synthesizes the new DNA strand by adding
nucleotides in the 5' to 3' direction?
A. DNA ligase
B. DNA helicase
C. DNA polymerase [CORRECT]
D. Topoisomerase
Correct Answer: C
Rationale: DNA polymerase is the primary enzyme responsible for synthesizing new DNA
strands during replication. It reads the template strand in the 3' to 5' direction and adds
complementary nucleotides to the growing new strand exclusively in the 5' to 3' direction,
catalyzing phosphodiester bond formation between nucleotides.
Q5: In codominance, what is observed in the phenotype of heterozygous individuals?
A. Only the dominant phenotype is expressed
B. Only the recessive phenotype is expressed
C. Both alleles are fully and distinctly expressed [CORRECT]
D. A blended intermediate phenotype is observed
Correct Answer: C
Rationale: Codominance occurs when both alleles in a heterozygous individual are fully and
distinctly expressed in the phenotype, with neither being dominant over the other. A classic
, 3
example is the ABO blood group system, where individuals with genotype IAIB express both A
and B antigens on their red blood cells.
Q6: What is the term for an individual who carries one copy of a recessive allele for a genetic
disorder but does not express the disease phenotype?
A. Affected homozygote
B. Carrier (heterozygote) [CORRECT]
C. Dominant expressor
D. Nullizygote
Correct Answer: B
Rationale: A carrier is a heterozygous individual who possesses one normal allele and one
recessive disease-causing allele. The presence of the normal dominant allele prevents disease
expression, but the individual can transmit the recessive allele to offspring, potentially producing
affected offspring if the other parent is also a carrier.
Q7: Which process converts the genetic information in mRNA into a sequence of amino acids
during protein synthesis?
A. Transcription
B. Replication
C. Translation [CORRECT]
D. Splicing
Correct Answer: C
Rationale: Translation is the process by which the genetic code carried by messenger RNA
(mRNA) is decoded by ribosomes to produce a specific polypeptide chain. Transfer RNA
(tRNA) molecules bring amino acids to the ribosome, where they are joined together according
to the codon sequence in the mRNA.
Q8: A dihybrid cross between two heterozygous parents (AaBb × AaBb) produces offspring with
what expected phenotypic ratio assuming independent assortment and complete dominance?
A. 1:1:1:1
B. 9:3:3:1 [CORRECT]
C. 1:2:1
D. 3:1
