Page 1 of 56
BIOD 210 – GENETICS – MODULE 3 2026
EXAM COMPLETE (160) CURRENT TESTING
QUESTIONS AND CORRECT ANSWERS WITH
DETAILED RATIONALES|GRADED A+.
BIOD
Prepare for the BIOD 210 Genetics Module 3 Exam with practice
questions covering DNA structure, gene expression, basic
inheritance patterns, chromosomal organization, mutations, and
foundational molecular genetics concepts. This study guide helps
reinforce essential genetics knowledge and supports effective
biology exam preparation. Designed to improve understanding of
genetic principles and boost confidence in analyzing hereditary
processes. Suitable for biology, pre-med, nursing, and allied health
students.
MULTIPLE CHOICE.
Section 1: Chromosomal Basis of Inheritance & Sex
Determination (Questions 1–30)
1. The chromosomal theory of inheritance states that:
A) Genes are located on chromosomes
B) Chromosomes are made of DNA
C) Traits are inherited through cytoplasmic organelles
D) Only dominant traits are linked to chromosomes
, Page 2 of 56
Answer: A. Genes are located on chromosomes
Explanation: Sutton and Boveri proposed that genes are carried on
chromosomes, explaining Mendelian segregation.
2. In humans, the sex chromosomes of a normal male are:
A) XX
B) XY
C) XO
D) XXY
Answer: B. XY
Explanation: Human males are heterogametic (XY); females are
homogametic (XX).
3. Which of the following organisms has a ZW sex-determination
system where females are heterogametic?
A) Humans
B) Fruit flies
C) Birds
D) Grasshoppers
Answer: C. Birds
Explanation: In birds, females are ZW and males are ZZ.
4. In grasshoppers, males have XO sex chromosomes. This means:
A) Males have one X and no Y
B) Males have two X chromosomes
C) Females have one X
D) Females have XY
Answer: A. Males have one X and no Y
Explanation: XO males produce X-bearing and O (nullo) sperm.
, Page 3 of 56
5. A human female with Turner syndrome has which chromosomal
composition?
A) 45,X
B) 47,XXY
C) 47,XXX
D) 46,XX
Answer: A. 45,X
Explanation: Turner syndrome is monosomy X (45,X).
6. The SRY gene, located on the Y chromosome, is responsible for:
A) Male sex determination
B) Female sex determination
C) Color vision
D) Blood clotting
Answer: A. Male sex determination
Explanation: SRY (sex-determining region Y) triggers testis
development.
7. In fruit flies (Drosophila melanogaster), sex is determined by the
ratio of:
A) X chromosomes to autosomes
B) Y chromosomes to autosomes
C) X chromosomes to Y chromosomes
D) Autosomes to X chromosomes
Answer: A. X chromosomes to autosomes
Explanation: Drosophila sex is based on X:A ratio (1.0 = female, 0.5
= male, >1.0 = metafemale, <0.5 = metamale).
, Page 4 of 56
8. A human male with Klinefelter syndrome has which karyotype?
A) 47,XXY
B) 45,X
C) 47,XYY
D) 46,XY
Answer: A. 47,XXY
Explanation: Klinefelter syndrome (XXY) results in male phenotype
with infertility and tall stature.
9. A human female with triple X syndrome has karyotype:
A) 45,X
B) 46,XX
C) 47,XXX
D) 47,XXY
Answer: C. 47,XXX
Explanation: Triple X syndrome (XXX) is often phenotypically
normal.
10. A human male with XYY syndrome has which karyotype?
A) 47,XYY
B) 47,XXY
C) 46,XY
D) 45,X
Answer: A. 47,XYY
Explanation: XYY males are usually tall and fertile, often with
normal intelligence.
11. In humans, which parent determines the sex of the offspring?
A) Father (sperm carries X or Y)
BIOD 210 – GENETICS – MODULE 3 2026
EXAM COMPLETE (160) CURRENT TESTING
QUESTIONS AND CORRECT ANSWERS WITH
DETAILED RATIONALES|GRADED A+.
BIOD
Prepare for the BIOD 210 Genetics Module 3 Exam with practice
questions covering DNA structure, gene expression, basic
inheritance patterns, chromosomal organization, mutations, and
foundational molecular genetics concepts. This study guide helps
reinforce essential genetics knowledge and supports effective
biology exam preparation. Designed to improve understanding of
genetic principles and boost confidence in analyzing hereditary
processes. Suitable for biology, pre-med, nursing, and allied health
students.
MULTIPLE CHOICE.
Section 1: Chromosomal Basis of Inheritance & Sex
Determination (Questions 1–30)
1. The chromosomal theory of inheritance states that:
A) Genes are located on chromosomes
B) Chromosomes are made of DNA
C) Traits are inherited through cytoplasmic organelles
D) Only dominant traits are linked to chromosomes
, Page 2 of 56
Answer: A. Genes are located on chromosomes
Explanation: Sutton and Boveri proposed that genes are carried on
chromosomes, explaining Mendelian segregation.
2. In humans, the sex chromosomes of a normal male are:
A) XX
B) XY
C) XO
D) XXY
Answer: B. XY
Explanation: Human males are heterogametic (XY); females are
homogametic (XX).
3. Which of the following organisms has a ZW sex-determination
system where females are heterogametic?
A) Humans
B) Fruit flies
C) Birds
D) Grasshoppers
Answer: C. Birds
Explanation: In birds, females are ZW and males are ZZ.
4. In grasshoppers, males have XO sex chromosomes. This means:
A) Males have one X and no Y
B) Males have two X chromosomes
C) Females have one X
D) Females have XY
Answer: A. Males have one X and no Y
Explanation: XO males produce X-bearing and O (nullo) sperm.
, Page 3 of 56
5. A human female with Turner syndrome has which chromosomal
composition?
A) 45,X
B) 47,XXY
C) 47,XXX
D) 46,XX
Answer: A. 45,X
Explanation: Turner syndrome is monosomy X (45,X).
6. The SRY gene, located on the Y chromosome, is responsible for:
A) Male sex determination
B) Female sex determination
C) Color vision
D) Blood clotting
Answer: A. Male sex determination
Explanation: SRY (sex-determining region Y) triggers testis
development.
7. In fruit flies (Drosophila melanogaster), sex is determined by the
ratio of:
A) X chromosomes to autosomes
B) Y chromosomes to autosomes
C) X chromosomes to Y chromosomes
D) Autosomes to X chromosomes
Answer: A. X chromosomes to autosomes
Explanation: Drosophila sex is based on X:A ratio (1.0 = female, 0.5
= male, >1.0 = metafemale, <0.5 = metamale).
, Page 4 of 56
8. A human male with Klinefelter syndrome has which karyotype?
A) 47,XXY
B) 45,X
C) 47,XYY
D) 46,XY
Answer: A. 47,XXY
Explanation: Klinefelter syndrome (XXY) results in male phenotype
with infertility and tall stature.
9. A human female with triple X syndrome has karyotype:
A) 45,X
B) 46,XX
C) 47,XXX
D) 47,XXY
Answer: C. 47,XXX
Explanation: Triple X syndrome (XXX) is often phenotypically
normal.
10. A human male with XYY syndrome has which karyotype?
A) 47,XYY
B) 47,XXY
C) 46,XY
D) 45,X
Answer: A. 47,XYY
Explanation: XYY males are usually tall and fertile, often with
normal intelligence.
11. In humans, which parent determines the sex of the offspring?
A) Father (sperm carries X or Y)
