BIOL 2053 Exam #2 (Grade 1) for Principles of Genetics (COMPLETE WALK-THROUGH PRACTICE QUESTIONS AND ANSWERS) Louisiana State University

BIOL 2053 Exam #2 (Grade 1) for Principles of Genetics
(COMPLETE WALK-THROUGH PRACTICE QUESTIONS
AND ANSWERS) Louisiana State University
Exam #2 (Grade 1) for Principles of Genetics, Fall Term2025, Section 5-10. Bubble in
your name and student identification number on SIDE TWO of the scantron. Also, you
need to mark in the grade section whether your exam is Grade 1 or 2. The correct
answer for each question will be awarded 3 points (3 x 33 = 99) and one extra point will
be added to make 100 point. Keep this exam booklet and bring it to your next
discussion session, when the exam will be reviewed.


(Q1-4) In domesticated cats, one locus in X chromosome is responsible for coat color
variations: B allele for orange color and b allele for black color. We have a set of 6 cats
with the following genotypes:

Cat 1 (XBY) Cat 2 (XbY) Cat 3 (XBXbY)
Cat 4 (XBXB) Cat 5 (XbXb) Cat 6 (XBXb)

1. Which cats have a mosaic pattern of coat color with orange and black?
a. Cat 2 and 3
b. Cat 3 and 4
c. Cat 4 and 5
d. Cat 5 and 6
e. Cat 3 and 6

2. Which cat does go through X chromosomal inactivation?
a. Cat 1 and 4
b. Cat 2 and 4
c. Cat 3 and 4
d. Cat 2 and 5
e. Cat 2 and 6

3. Among the following pairs, which pair will produce the most number of male
kittens with black color?
a. Cat 1 and 4
b. Cat 1 and 6
c. Cat 2 and 4
d. Cat 2 and 5
e. Cat 2 and 6

4. If we do breeding experiments with these cats, which pair will produce the most
numbers of kittens with the mosaic pattern of coat color?
1

,a. Cat 1 and 4
b. Cat 1 and 5
c. Cat 1 and 6
d. Cat 2 and 5
e. Cat 2 and 6




2

,(Q5-9) In early 20th century, the inheritance pattern of two fly mutants (eye color, w + or w;
body color, y+ or y) was used for discovering genetic linkage and crossing- over. Answer
the following questions.
P w+,y/w+,y x w,y+/Y

F1 w+,y/w,y+ x w+y/Y

,y+/Y (Category 1)
w,y/Y (Category 2)
,y/Y (Category
3)
+/Y (Category
4)

5. Who did this experiment?
a. Gregor Mendel
b. James Watson
c. Francis Crick
d. Thomas Morgan
e. none of the above

6. Which is INCORRECT about F1 male and female?
a. All the females should be normal with red eye and brown body.
b. All the males should be normal with red eyes and brown body.
c. All the females should be heterozygotes for two genes.
d. All the males should be hemizygous for two genes.

7. Which categories are the products of crossing-over during the meiosis of F1
females?
a. Category 1 and 2
b. Category 2 and 3
c. Category 3 and 4
d. Category 1 and 4
e. Category 2 and 4

8. The number of each category is as follow:
Category 1, 12
Category 2,
Category 3,
Category 4,
No

What is the mapping distance between w and y?
a. 4%
b. 6%
c. 10%
d. 20%
3

, e. none of the above




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