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Portage Learning BIOD 101 Actual Exam
Questions and Answers with Rationales
2026/2027 | Essential Biology I Module 3 |
Genetics & Evolution | Pass Guarantee
Q001: In a monohybrid cross between two heterozygous pea plants (Tt × Tt), what
is the expected phenotypic ratio of tall to short plants in the F₁ generation?
Options:
A. 1:1
B. 2:1
C. 3:1 - CORRECT
D. 4:1
ANSWER: C
Q002: Which nitrogenous base pair is held together by three hydrogen bonds in a
DNA double helix?
Options:
A. Adenine–Thymine
B. Cytosine–Guanine - CORRECT
C. Uracil–Adenine
D. Guanine–Thymine
ANSWER: B
Q003: During DNA replication, which enzyme is responsible for joining Okazaki
fragments on the lagging strand?
Options:
A. DNA polymerase III
, 2
B. Helicase
C. DNA ligase - CORRECT
D. Primase
ANSWER: C
Q004: A couple both have type AB blood. What is the probability that their child
will have type O blood?
Options:
A. 0 % - CORRECT
B. 25 %
C. 50 %
D. 75 %
ANSWER: A
Q005: In protein synthesis, which RNA molecule carries the amino acid to the
ribosome?
Options:
A. mRNA
B. rRNA
C. tRNA - CORRECT
D. snRNA
ANSWER: C
Q006: Which of the following is an example of incomplete dominance in genetics?
Options:
A. Pea plant height
B. Human ABO blood groups
C. Four-o’clock flower petal color - CORRECT
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D. Huntington disease
ANSWER: C
Q007: A missense mutation results in which of the following outcomes?
Options:
A. Premature stop codon
B. Silent change with no amino acid change
C. Substitution of one amino acid - CORRECT
D. Frameshift after the mutation point
ANSWER: C
Q008: Which evolutionary mechanism involves the random change in allele
frequency in a small population?
Options:
A. Gene flow
B. Natural selection
C. Genetic drift - CORRECT
D. Mutation
ANSWER: C
Q009: The Hardy-Weinberg equation assumes that no evolutionary forces are
acting on a population. Which condition is NOT required for this equilibrium?
Options:
A. Random mating
B. No mutation
C. No gene flow
D. Directional selection - CORRECT
ANSWER: D
Portage Learning BIOD 101 Actual Exam
Questions and Answers with Rationales
2026/2027 | Essential Biology I Module 3 |
Genetics & Evolution | Pass Guarantee
Q001: In a monohybrid cross between two heterozygous pea plants (Tt × Tt), what
is the expected phenotypic ratio of tall to short plants in the F₁ generation?
Options:
A. 1:1
B. 2:1
C. 3:1 - CORRECT
D. 4:1
ANSWER: C
Q002: Which nitrogenous base pair is held together by three hydrogen bonds in a
DNA double helix?
Options:
A. Adenine–Thymine
B. Cytosine–Guanine - CORRECT
C. Uracil–Adenine
D. Guanine–Thymine
ANSWER: B
Q003: During DNA replication, which enzyme is responsible for joining Okazaki
fragments on the lagging strand?
Options:
A. DNA polymerase III
, 2
B. Helicase
C. DNA ligase - CORRECT
D. Primase
ANSWER: C
Q004: A couple both have type AB blood. What is the probability that their child
will have type O blood?
Options:
A. 0 % - CORRECT
B. 25 %
C. 50 %
D. 75 %
ANSWER: A
Q005: In protein synthesis, which RNA molecule carries the amino acid to the
ribosome?
Options:
A. mRNA
B. rRNA
C. tRNA - CORRECT
D. snRNA
ANSWER: C
Q006: Which of the following is an example of incomplete dominance in genetics?
Options:
A. Pea plant height
B. Human ABO blood groups
C. Four-o’clock flower petal color - CORRECT
, 3
D. Huntington disease
ANSWER: C
Q007: A missense mutation results in which of the following outcomes?
Options:
A. Premature stop codon
B. Silent change with no amino acid change
C. Substitution of one amino acid - CORRECT
D. Frameshift after the mutation point
ANSWER: C
Q008: Which evolutionary mechanism involves the random change in allele
frequency in a small population?
Options:
A. Gene flow
B. Natural selection
C. Genetic drift - CORRECT
D. Mutation
ANSWER: C
Q009: The Hardy-Weinberg equation assumes that no evolutionary forces are
acting on a population. Which condition is NOT required for this equilibrium?
Options:
A. Random mating
B. No mutation
C. No gene flow
D. Directional selection - CORRECT
ANSWER: D
