Page 1 of 146
HOLECHEK BIO 340 EXAM 3 ACTUAL 2026
QUESTIONS AND 100% CORRECT ANSWERS
Q1. In pea plants, tall (T) is dominant to dwarf (t). If a
heterozygous tall plant is crossed with a dwarf plant, what
proportion of the offspring will be tall?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%
Answer: C) 50%
Rationale: Tt × tt → half Tt (tall) and half tt (dwarf). Therefore,
50% tall.
,Page 2 of 146
Q2. Two heterozygous tall pea plants (Tt) are crossed. What is
the probability of obtaining a dwarf offspring?
A) 1/2
B) 1/4
C) 3/4
D) 1/3
E) 0
A) 1/2
B) 1/4
C) 3/4
D) 1/3
E) 0A) A and B only
B) A, B, AB, O
C) AB only
,Page 3 of 146
D) A only
E) B only
Answer: A) A and B only
Rationale: AB (I^A I^B) × O (ii) → 50% I^A i (type A),
50% I^B i (type B). No AB or O.
Q5. Scenario: A woman with type A blood has a child with
type O blood. Which of the following blood types could
the father NOT have?
A) Type A
B) Type B
C) Type AB
D) Type O
Answer: C) Type AB
Rationale: Child type O (ii) must receive i from both
, Page 4 of 146
parents. Type AB father (I^A I^B) cannot contribute i. Thus
impossible.
Q6. In a dihybrid cross (AaBb × AaBb), what fraction of
offspring are expected to show both dominant phenotypes?
(Assume independent assortment)
A) 9/16
B) 3/16
C) 1/16
D) 1/2
E) 3/4
Answer: A) 9/16
Rationale: Both dominant = A_ B_ → probability
(3/4)(3/4)=9/16.
HOLECHEK BIO 340 EXAM 3 ACTUAL 2026
QUESTIONS AND 100% CORRECT ANSWERS
Q1. In pea plants, tall (T) is dominant to dwarf (t). If a
heterozygous tall plant is crossed with a dwarf plant, what
proportion of the offspring will be tall?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%
Answer: C) 50%
Rationale: Tt × tt → half Tt (tall) and half tt (dwarf). Therefore,
50% tall.
,Page 2 of 146
Q2. Two heterozygous tall pea plants (Tt) are crossed. What is
the probability of obtaining a dwarf offspring?
A) 1/2
B) 1/4
C) 3/4
D) 1/3
E) 0
A) 1/2
B) 1/4
C) 3/4
D) 1/3
E) 0A) A and B only
B) A, B, AB, O
C) AB only
,Page 3 of 146
D) A only
E) B only
Answer: A) A and B only
Rationale: AB (I^A I^B) × O (ii) → 50% I^A i (type A),
50% I^B i (type B). No AB or O.
Q5. Scenario: A woman with type A blood has a child with
type O blood. Which of the following blood types could
the father NOT have?
A) Type A
B) Type B
C) Type AB
D) Type O
Answer: C) Type AB
Rationale: Child type O (ii) must receive i from both
, Page 4 of 146
parents. Type AB father (I^A I^B) cannot contribute i. Thus
impossible.
Q6. In a dihybrid cross (AaBb × AaBb), what fraction of
offspring are expected to show both dominant phenotypes?
(Assume independent assortment)
A) 9/16
B) 3/16
C) 1/16
D) 1/2
E) 3/4
Answer: A) 9/16
Rationale: Both dominant = A_ B_ → probability
(3/4)(3/4)=9/16.
