Portage Learning BIOD 101 Module 5 Exam / BIOD 101
Essential Biology Module 5 Problem Set Questions and Correct
Answers/ BIOD 101 Module 5/ Biology 101/ Essential Biology
This module exam assesses mastery of cell division (mitosis and meiosis), the cell cycle, DNA structure and
replication, gene expression and protein synthesis, Mendelian and chromosomal inheritance, and mutations.
Questions require multi-step reasoning, data interpretation, and synthesis across molecular and organismal
levels. It contains 59 multiple-choice questions, each with four distractors and a fully worked rationale that
explains why the keyed answer is correct. Questions are organized into clearly labelled sections that mirror the
major content areas of the course. Targeted learning outcomes include: Differentiate the phases and regulatory
checkpoints of the cell cycle and predict consequences of their dysregulation.; Analyze the molecular mechanisms
of DNA replication, transcription, and translation, and infer outcomes of specific errors.; Apply Mendelian and
chromosomal inheritance principles to solve complex genetic crosses and interpret pedigrees.; Evaluate how
mutations and chromosomal alterations generate genetic variation and phenotypic change.. Every item has been
reviewed for clinical accuracy, current guidelines, and clarity so that students can study with confidence and
self-correct as they work through the bank. Use it as a high-yield review immediately before the exam, or as a
structured practice tool during the unit - the rationales double as concise teaching notes. The recommended
writing time is 3 hours, with a passing score of 70%. Aligned with Aligned with US university introductory biology
standards (AAAS Vision and Change core concepts) and Portage Learning BIOD 101 Module 5 learning
Section 1: General (Questions 1-59)
1 Which event uniquely defines anaphase of mitosis versus anaphase I of meiosis?
A) Separation of homologous chromosomes to opposite poles
B) Separation of sister chromatids to opposite poles
C) Crossing over between non-sister chromatids
D) Alignment of tetrads at the metaphase plate
Answer: B
Rationale: In mitotic anaphase, sister chromatids separate, whereas in anaphase I of
meiosis, homologous chromosomes separate while sister chromatids remain
attached. Crossing over and tetrad alignment occur in prophase I and metaphase I,
respectively, not anaphase. Thus, only sister chromatid separation distinguishes
mitotic anaphase.
2 A DNA template strand reads 3'-TAC GGA TTC-5'. What mRNA sequence is
transcribed?
A) 5'-AUG CCU AAG-3'
B) 5'-UAC GGA UUC-3'
C) 5'-ATG CCT AAG-3'
D) 5'-AUG GGA UUC-3'
Answer: A
,Rationale: RNA polymerase reads the template strand 3' to 5' and synthesizes mRNA
5' to 3' using complementary base pairing (A-U, T-A, C-G, G-C). The template
3'-TAC GGA TTC-5' yields 5'-AUG CCU AAG-3'. Option B is the template
sequence with U for T; C uses DNA bases; D mispairs the second codon.
3 In a dihybrid cross AaBb × AaBb, what fraction of offspring show both dominant
phenotypes?
A) 9/16
B) 3/16
C) 1/16
D) 1/4
Answer: A
Rationale: For independently assorting genes, the probability of at least one
dominant allele at each locus is 3/4 × 3/4 = 9/16. The 3/16, 1/16, and 1/4 values
correspond to other phenotypic classes or incorrect assumptions of linkage. Thus,
9/16 is the correct fraction.
4 Which statement best explains why DNA replication is described as
semiconservative?
A) Each new double helix contains one parental and one newly synthesized strand.
B) Both strands of a new double helix are synthesized from scratch.
C) Parental DNA is completely degraded before new strands are made.
D) Only one strand of the original DNA is used as a template per cycle.
Answer: A
Rationale: The Meselson-Stahl experiment demonstrated that each daughter DNA
molecule consists of one original (parental) strand and one newly synthesized strand,
which is the definition of semiconservative replication. Options B and C describe
conservative or dispersive models, and D misstates template usage.
5 A frameshift mutation is most likely caused by which type of DNA change?
A) Insertion of three nucleotides
B) Deletion of one nucleotide
C) Substitution of one purine for another
D) Inversion of a chromosome segment
Answer: B
Rationale: Insertions or deletions of nucleotides not in multiples of three shift the
reading frame, altering all downstream codons. A three-nucleotide insertion adds
one amino acid without shifting frame; a purine substitution is a transition; an
, inversion affects chromosome structure but not reading frame at the gene level.
6 Which process directly generates genetic variation by reassorting maternal and
paternal chromosomes?
A) Independent assortment during metaphase I
B) DNA replication during S phase
C) Cytokinesis in telophase II
D) Sister chromatid cohesion in anaphase
Answer: A
Rationale: Independent assortment of homologous chromosome pairs during
metaphase I produces random combinations of maternal and paternal chromosomes
in gametes. DNA replication, cytokinesis, and sister chromatid cohesion do not
reassort whole chromosomes. Thus, independent assortment is the direct source of
variation.
7 A woman with blood type AB has a child with blood type O. What is the father's
possible genotype?
A) IAIA only
B) IBIB only
C) ii only
D) IAi or IBi
Answer: C
Rationale: For a child to have type O (ii), both parents must contribute an i allele.
The mother with AB (IAIB) cannot contribute i, so the father must be ii to provide
the i allele. Options A, B, and D would not allow an O child with this mother.
8 Which checkpoint ensures that DNA replication is complete before mitosis
begins?
A) G1/S checkpoint
B) G2/M checkpoint
C) Spindle assembly checkpoint
D) Restriction point
Answer: B
Rationale: The G2/M checkpoint verifies that DNA replication is complete and DNA
is undamaged before entering mitosis. The G1/S checkpoint assesses cell size and
DNA damage before replication; the spindle assembly checkpoint monitors
chromosome attachment; the restriction point is in G1.
Essential Biology Module 5 Problem Set Questions and Correct
Answers/ BIOD 101 Module 5/ Biology 101/ Essential Biology
This module exam assesses mastery of cell division (mitosis and meiosis), the cell cycle, DNA structure and
replication, gene expression and protein synthesis, Mendelian and chromosomal inheritance, and mutations.
Questions require multi-step reasoning, data interpretation, and synthesis across molecular and organismal
levels. It contains 59 multiple-choice questions, each with four distractors and a fully worked rationale that
explains why the keyed answer is correct. Questions are organized into clearly labelled sections that mirror the
major content areas of the course. Targeted learning outcomes include: Differentiate the phases and regulatory
checkpoints of the cell cycle and predict consequences of their dysregulation.; Analyze the molecular mechanisms
of DNA replication, transcription, and translation, and infer outcomes of specific errors.; Apply Mendelian and
chromosomal inheritance principles to solve complex genetic crosses and interpret pedigrees.; Evaluate how
mutations and chromosomal alterations generate genetic variation and phenotypic change.. Every item has been
reviewed for clinical accuracy, current guidelines, and clarity so that students can study with confidence and
self-correct as they work through the bank. Use it as a high-yield review immediately before the exam, or as a
structured practice tool during the unit - the rationales double as concise teaching notes. The recommended
writing time is 3 hours, with a passing score of 70%. Aligned with Aligned with US university introductory biology
standards (AAAS Vision and Change core concepts) and Portage Learning BIOD 101 Module 5 learning
Section 1: General (Questions 1-59)
1 Which event uniquely defines anaphase of mitosis versus anaphase I of meiosis?
A) Separation of homologous chromosomes to opposite poles
B) Separation of sister chromatids to opposite poles
C) Crossing over between non-sister chromatids
D) Alignment of tetrads at the metaphase plate
Answer: B
Rationale: In mitotic anaphase, sister chromatids separate, whereas in anaphase I of
meiosis, homologous chromosomes separate while sister chromatids remain
attached. Crossing over and tetrad alignment occur in prophase I and metaphase I,
respectively, not anaphase. Thus, only sister chromatid separation distinguishes
mitotic anaphase.
2 A DNA template strand reads 3'-TAC GGA TTC-5'. What mRNA sequence is
transcribed?
A) 5'-AUG CCU AAG-3'
B) 5'-UAC GGA UUC-3'
C) 5'-ATG CCT AAG-3'
D) 5'-AUG GGA UUC-3'
Answer: A
,Rationale: RNA polymerase reads the template strand 3' to 5' and synthesizes mRNA
5' to 3' using complementary base pairing (A-U, T-A, C-G, G-C). The template
3'-TAC GGA TTC-5' yields 5'-AUG CCU AAG-3'. Option B is the template
sequence with U for T; C uses DNA bases; D mispairs the second codon.
3 In a dihybrid cross AaBb × AaBb, what fraction of offspring show both dominant
phenotypes?
A) 9/16
B) 3/16
C) 1/16
D) 1/4
Answer: A
Rationale: For independently assorting genes, the probability of at least one
dominant allele at each locus is 3/4 × 3/4 = 9/16. The 3/16, 1/16, and 1/4 values
correspond to other phenotypic classes or incorrect assumptions of linkage. Thus,
9/16 is the correct fraction.
4 Which statement best explains why DNA replication is described as
semiconservative?
A) Each new double helix contains one parental and one newly synthesized strand.
B) Both strands of a new double helix are synthesized from scratch.
C) Parental DNA is completely degraded before new strands are made.
D) Only one strand of the original DNA is used as a template per cycle.
Answer: A
Rationale: The Meselson-Stahl experiment demonstrated that each daughter DNA
molecule consists of one original (parental) strand and one newly synthesized strand,
which is the definition of semiconservative replication. Options B and C describe
conservative or dispersive models, and D misstates template usage.
5 A frameshift mutation is most likely caused by which type of DNA change?
A) Insertion of three nucleotides
B) Deletion of one nucleotide
C) Substitution of one purine for another
D) Inversion of a chromosome segment
Answer: B
Rationale: Insertions or deletions of nucleotides not in multiples of three shift the
reading frame, altering all downstream codons. A three-nucleotide insertion adds
one amino acid without shifting frame; a purine substitution is a transition; an
, inversion affects chromosome structure but not reading frame at the gene level.
6 Which process directly generates genetic variation by reassorting maternal and
paternal chromosomes?
A) Independent assortment during metaphase I
B) DNA replication during S phase
C) Cytokinesis in telophase II
D) Sister chromatid cohesion in anaphase
Answer: A
Rationale: Independent assortment of homologous chromosome pairs during
metaphase I produces random combinations of maternal and paternal chromosomes
in gametes. DNA replication, cytokinesis, and sister chromatid cohesion do not
reassort whole chromosomes. Thus, independent assortment is the direct source of
variation.
7 A woman with blood type AB has a child with blood type O. What is the father's
possible genotype?
A) IAIA only
B) IBIB only
C) ii only
D) IAi or IBi
Answer: C
Rationale: For a child to have type O (ii), both parents must contribute an i allele.
The mother with AB (IAIB) cannot contribute i, so the father must be ii to provide
the i allele. Options A, B, and D would not allow an O child with this mother.
8 Which checkpoint ensures that DNA replication is complete before mitosis
begins?
A) G1/S checkpoint
B) G2/M checkpoint
C) Spindle assembly checkpoint
D) Restriction point
Answer: B
Rationale: The G2/M checkpoint verifies that DNA replication is complete and DNA
is undamaged before entering mitosis. The G1/S checkpoint assesses cell size and
DNA damage before replication; the spindle assembly checkpoint monitors
chromosome attachment; the restriction point is in G1.
