BIOD 210 Genetics Module 3 Exam – (2026) Actual Questions & Answers –
Portage Learning
Section 1: Chromosomal Basis of Inheritance (Questions 1-30)
1. During which phase of the cell cycle are chromosomes in their most condensed
and visible form?
A) Interphase
B) G1 phase
C) S phase
D) Mitotic phase
Answer: D
Rationale: Chromosomes are loosely organized as chromatin during most of
interphase (G1, S, G2) to allow for DNA replication and transcription. They only
condense into visible, compact structures during the mitotic phase (mitosis and
meiosis) to facilitate proper segregation .
2. A student observes a cell under a microscope and notes that sister chromatids
are being pulled apart to opposite poles of the cell. In which phase of mitosis is
this cell?
A) Prophase
B) Metaphase
,C) Anaphase
D) Telophase
Answer: C
Rationale: Anaphase is characterized by the separation of sister chromatids (now
called chromosomes) at their centromeres. This process, known as disjunction, is
driven by spindle fibers that shorten and pull the chromatids toward opposite
poles of the cell .
3. The protein complex that holds sister chromatids together after DNA
replication is called:
A) Shugoshin
B) Cohesin
C) Kinetochore
D) Cyclin
Answer: B
Rationale: Cohesin is a multi-subunit protein complex that is loaded onto
chromosomes during S phase. It functions like a molecular glue to hold the two
identical sister chromatids together until they are ready to be separated during
anaphase .
,4. What is the function of the kinetochore?
A) To hold sister chromatids together
B) To serve as the site for DNA replication
C) To provide an attachment point for spindle fibers
D) To condense chromosomes
Answer: C
Rationale: The kinetochore is a complex protein structure that assembles on the
centromere region of each sister chromatid. Its primary role is to attach the
chromosome to the microtubules of the mitotic or meiotic spindle, enabling
chromosome movement .
5. True or False: Chromosomes are in a condensed form throughout most of the
cell cycle.
A) True
B) False
Answer: B
, Rationale: This statement is false. Chromosomes are primarily in a decondensed,
thread-like form called chromatin during interphase, which allows for
transcription and DNA replication. They only condense for cell division .
6. A fertilized egg resulting from the fusion of a sperm and an oocyte is called a:
A) Gamete
B) Zygote
C) Embryo
D) Homunculus
Answer: B
Rationale: A zygote is the single diploid cell formed immediately upon the fusion
of two haploid gametes (sperm and egg). This cell is totipotent and contains the
complete genetic blueprint for the new organism .
7. Which of the following statements about human sex chromosomes is TRUE?
A) The X and Y chromosomes share no homology.
B) The Y chromosome is the primary determinant for male sex.
C) The X chromosome determines sex.
D) Incorrect segregation of X and Y is always embryonic lethal.
Portage Learning
Section 1: Chromosomal Basis of Inheritance (Questions 1-30)
1. During which phase of the cell cycle are chromosomes in their most condensed
and visible form?
A) Interphase
B) G1 phase
C) S phase
D) Mitotic phase
Answer: D
Rationale: Chromosomes are loosely organized as chromatin during most of
interphase (G1, S, G2) to allow for DNA replication and transcription. They only
condense into visible, compact structures during the mitotic phase (mitosis and
meiosis) to facilitate proper segregation .
2. A student observes a cell under a microscope and notes that sister chromatids
are being pulled apart to opposite poles of the cell. In which phase of mitosis is
this cell?
A) Prophase
B) Metaphase
,C) Anaphase
D) Telophase
Answer: C
Rationale: Anaphase is characterized by the separation of sister chromatids (now
called chromosomes) at their centromeres. This process, known as disjunction, is
driven by spindle fibers that shorten and pull the chromatids toward opposite
poles of the cell .
3. The protein complex that holds sister chromatids together after DNA
replication is called:
A) Shugoshin
B) Cohesin
C) Kinetochore
D) Cyclin
Answer: B
Rationale: Cohesin is a multi-subunit protein complex that is loaded onto
chromosomes during S phase. It functions like a molecular glue to hold the two
identical sister chromatids together until they are ready to be separated during
anaphase .
,4. What is the function of the kinetochore?
A) To hold sister chromatids together
B) To serve as the site for DNA replication
C) To provide an attachment point for spindle fibers
D) To condense chromosomes
Answer: C
Rationale: The kinetochore is a complex protein structure that assembles on the
centromere region of each sister chromatid. Its primary role is to attach the
chromosome to the microtubules of the mitotic or meiotic spindle, enabling
chromosome movement .
5. True or False: Chromosomes are in a condensed form throughout most of the
cell cycle.
A) True
B) False
Answer: B
, Rationale: This statement is false. Chromosomes are primarily in a decondensed,
thread-like form called chromatin during interphase, which allows for
transcription and DNA replication. They only condense for cell division .
6. A fertilized egg resulting from the fusion of a sperm and an oocyte is called a:
A) Gamete
B) Zygote
C) Embryo
D) Homunculus
Answer: B
Rationale: A zygote is the single diploid cell formed immediately upon the fusion
of two haploid gametes (sperm and egg). This cell is totipotent and contains the
complete genetic blueprint for the new organism .
7. Which of the following statements about human sex chromosomes is TRUE?
A) The X and Y chromosomes share no homology.
B) The Y chromosome is the primary determinant for male sex.
C) The X chromosome determines sex.
D) Incorrect segregation of X and Y is always embryonic lethal.
