University of Michigan
3 MAXE · 171 OIB
★ ★
M College of Literature, Science & the Arts — Department of Biology
EST. 1817
ARTES · SCIENTIA · VERITAS
Bio 171 Exam 3
M E I O S I S · M E N D E L I A N G E N E T I CS · C H R O M O S O M A L I N H E R I TA N C E · C E L L CYC L E
INSTITUTION University of Michigan PROGRAM Bachelor of Science — Biology
COURSE CODE BIO 171 COURSE TITLE Introduction to Molecular &
Cellular Biology
ACADEMIC YEAR EXAM TITLE Bio 171 Exam 3
TOTAL QUESTIONS 44 Questions FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question unless otherwise instructed.
▸ This examination covers meiosis, Mendelian genetics, chromosomal inheritance, the cell cycle, and
patterns of inheritance.
▸ Questions address synapsis, independent assortment, nondisjunction, epistasis, pleiotropy, and related
genetic concepts.
▸ Correct answers and explanatory rationales appear below each question for review purposes.
▸ All content reflects standard introductory biology curriculum for BIO 171 at the University of Michigan.
, SECTION I — MEIOSIS, GENETICS & CHROMOSOMAL
Questions 1 – 44
INHERITANCE
1. Independent assortment of chromosomes is a result of which of the following?
A. The random way each pair of homologous chromosomes lines up at the metaphase plate
during meiosis I
B. The random combinations of eggs and sperm during fertilization
C. The random distribution of sister chromatids in the two daughter cells during anaphase II
D. The diverse combination of alleles that may be found within any given chromosome
CORRECT ANSWER A — The random way each pair of homologous chromosomes lines up at
the metaphase plate during meiosis I
RATIONALE Independent assortment occurs during metaphase I of meiosis. Each homologous
pair of chromosomes aligns independently at the metaphase plate — the
orientation of one pair does not influence the orientation of any other pair. This
random alignment means maternal and paternal chromosomes are distributed
independently into gametes. For an organism with n chromosome pairs, this
produces 2^n possible gamete combinations from independent assortment
alone. This is a fundamental source of genetic variation in sexually reproducing
organisms.
, 2. What is the difference between a gene and an allele?
A. A gene is part of the DNA; alleles refer to different versions of the same gene
B. A gene codes for proteins; alleles code for carbohydrates
C. Genes are on autosomes; alleles are on sex chromosomes
D. There is no difference — the terms are interchangeable
CORRECT ANSWER A — A gene is part of the DNA; alleles refer to different versions of the same
gene
RATIONALE A gene is a specific sequence of DNA that occupies a particular locus on a
chromosome and codes for a functional product (typically a protein). Alleles are
alternative versions of the same gene that arise through mutation and produce
different phenotypic effects. For example, the gene for flower color in pea plants
has a purple allele and a white allele. Every diploid individual carries two alleles
for each gene — one inherited from each parent — which may be identical
(homozygous) or different (heterozygous).
3. Which of the following processes occurs in meiosis but NOT in mitosis?
A. Chromosome replication
B. Synapsis of chromosomes
C. Alignment of chromosomes at the metaphase plate
D. Condensation of chromosomes
CORRECT ANSWER B — Synapsis of chromosomes
RATIONALE Synapsis — the close pairing of homologous chromosomes — is unique to
prophase I of meiosis. During synapsis, the synaptonemal complex forms
between homologous chromosomes, holding them together as bivalents
(tetrads). This intimate pairing enables crossing over (genetic recombination)
between non-sister chromatids. Synapsis does NOT occur in mitosis, where
chromosomes align individually without pairing with homologs. The other
processes (replication, metaphase alignment, condensation) occur in both
meiosis and mitosis.
3 MAXE · 171 OIB
★ ★
M College of Literature, Science & the Arts — Department of Biology
EST. 1817
ARTES · SCIENTIA · VERITAS
Bio 171 Exam 3
M E I O S I S · M E N D E L I A N G E N E T I CS · C H R O M O S O M A L I N H E R I TA N C E · C E L L CYC L E
INSTITUTION University of Michigan PROGRAM Bachelor of Science — Biology
COURSE CODE BIO 171 COURSE TITLE Introduction to Molecular &
Cellular Biology
ACADEMIC YEAR EXAM TITLE Bio 171 Exam 3
TOTAL QUESTIONS 44 Questions FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question unless otherwise instructed.
▸ This examination covers meiosis, Mendelian genetics, chromosomal inheritance, the cell cycle, and
patterns of inheritance.
▸ Questions address synapsis, independent assortment, nondisjunction, epistasis, pleiotropy, and related
genetic concepts.
▸ Correct answers and explanatory rationales appear below each question for review purposes.
▸ All content reflects standard introductory biology curriculum for BIO 171 at the University of Michigan.
, SECTION I — MEIOSIS, GENETICS & CHROMOSOMAL
Questions 1 – 44
INHERITANCE
1. Independent assortment of chromosomes is a result of which of the following?
A. The random way each pair of homologous chromosomes lines up at the metaphase plate
during meiosis I
B. The random combinations of eggs and sperm during fertilization
C. The random distribution of sister chromatids in the two daughter cells during anaphase II
D. The diverse combination of alleles that may be found within any given chromosome
CORRECT ANSWER A — The random way each pair of homologous chromosomes lines up at
the metaphase plate during meiosis I
RATIONALE Independent assortment occurs during metaphase I of meiosis. Each homologous
pair of chromosomes aligns independently at the metaphase plate — the
orientation of one pair does not influence the orientation of any other pair. This
random alignment means maternal and paternal chromosomes are distributed
independently into gametes. For an organism with n chromosome pairs, this
produces 2^n possible gamete combinations from independent assortment
alone. This is a fundamental source of genetic variation in sexually reproducing
organisms.
, 2. What is the difference between a gene and an allele?
A. A gene is part of the DNA; alleles refer to different versions of the same gene
B. A gene codes for proteins; alleles code for carbohydrates
C. Genes are on autosomes; alleles are on sex chromosomes
D. There is no difference — the terms are interchangeable
CORRECT ANSWER A — A gene is part of the DNA; alleles refer to different versions of the same
gene
RATIONALE A gene is a specific sequence of DNA that occupies a particular locus on a
chromosome and codes for a functional product (typically a protein). Alleles are
alternative versions of the same gene that arise through mutation and produce
different phenotypic effects. For example, the gene for flower color in pea plants
has a purple allele and a white allele. Every diploid individual carries two alleles
for each gene — one inherited from each parent — which may be identical
(homozygous) or different (heterozygous).
3. Which of the following processes occurs in meiosis but NOT in mitosis?
A. Chromosome replication
B. Synapsis of chromosomes
C. Alignment of chromosomes at the metaphase plate
D. Condensation of chromosomes
CORRECT ANSWER B — Synapsis of chromosomes
RATIONALE Synapsis — the close pairing of homologous chromosomes — is unique to
prophase I of meiosis. During synapsis, the synaptonemal complex forms
between homologous chromosomes, holding them together as bivalents
(tetrads). This intimate pairing enables crossing over (genetic recombination)
between non-sister chromatids. Synapsis does NOT occur in mitosis, where
chromosomes align individually without pairing with homologs. The other
processes (replication, metaphase alignment, condensation) occur in both
meiosis and mitosis.
