Introduction to Genetic Analysis Exam Prep 2026: 200 Practice
Questions & Detailed Answers | Based on Griffiths 12th Edition
Chapter 1: The Genetics Revolution in the Life Sciences (Questions 1–20)
1. The early 1900s was an important period for genetics due to which major event(s)?
A) The rediscovery of Gregor Mendel’s scientific findings
B) Watson and Crick solving the structure of DNA
C) Walter Sutton and Theodore Boveri hypothesizing that chromosomes are the hereditary elements
D) All of the above
E) Both A and C
Answer: E (Both A and C)
Explanation: While Watson and Crick’s discovery of DNA’s structure occurred in 1953, the early 1900s
were defined by the rediscovery of Mendel’s work and the chromosome theory of inheritance proposed
by Sutton and Boveri.
2. A sample of normal double‑stranded DNA was found to have a guanine content of 18%. What is the
expected proportion of adenine?
A) 9%
B) 32%
C) 36%
D) 68%
E) 82%
Answer: B (32%)
Explanation: According to Chargaff’s rules, G = C and A = T. If G = 18%, then C = 18%, so G + C = 36%.
Thus A + T = 64%, so A = 32%.
,3. In one strand of DNA, the nucleotide sequence is 5′‑ATGC‑3′. The complementary sequence in the
other strand must be:
A) 3′‑ATGC‑5′
B) 3′‑TACG‑5′
C) 5′‑ATCG‑3′
D) 5′‑CGTA‑3′
E) 5′‑TACG‑3′
Answer: B (3′‑TACG‑5′)
Explanation: In DNA, A pairs with T and G pairs with C. The complementary strand runs antiparallel, so a
5′‑ATGC‑3′ sequence pairs with 3′‑TACG‑5′.
4. How many different DNA molecules that are eight‑nucleotide‑pairs long are theoretically possible?
A) 24
B) 32
C) 64
D) 256
E) 65,536
Answer: E (65,536)
Explanation: For each nucleotide pair there are 4 possibilities (A‑T, T‑A, C‑G, G‑C). For 8 pairs, the total is
4⁸ = 65,536.
5. Which of the following is/are TRUE about genes?
A) Genes are located on chromosomes.
B) Genes come in variants known as alleles.
C) Genes usually encode protein products.
D) All of the above are true.
E) None of the above is true.
,Answer: D (All of the above)
Explanation: A gene is a hereditary unit located on a chromosome that exists in different forms (alleles)
and typically encodes a protein (though some encode functional RNAs).
6. Wild cats (Felis silvestris) and common mice (Mus musculus) are diploid. In wild cats, 2n = 38; in mice,
2n = 40. Based on this, we can conclude that wild‑cat cells have:
A) less DNA than mouse cells
B) smaller genomes than mouse cells
C) fewer DNA molecules than mouse cells
D) fewer genes than mouse cells
E) fewer sets of chromosomes than mouse cells
Answer: C (fewer DNA molecules than mouse cells)
Explanation: Both are diploid, so they have the same number of sets of chromosomes (two sets).
However, the total number of DNA molecules (chromosomes) is given by the 2n number, which is lower
in cats (38) than in mice (40). Chromosome number does not directly correlate with genome size or gene
number.
7. Which of the following is a component of DNA?
A) Alanine
B) Arginine
C) Cysteine
D) Guanine
E) Tyrosine
Answer: D (Guanine)
Explanation: Guanine (G) is a purine nitrogenous base found in DNA. The other options are amino acids,
not DNA components.
8. Which of the following is/are TRUE of the DNA structure solved by Watson and Crick?
A) It is a double‑helical structure.
, B) The sugar‑phosphate backbone is always on the outside.
C) There are two hydrogen bonds between A‑T and three between C‑G.
D) There are four types of nitrogenous bases.
E) All of the above are true.
Answer: E (All of the above)
Explanation: Watson and Crick described DNA as a double helix with the sugar‑phosphate backbone on
the exterior, complementary base pairing (A=T [2 H‑bonds], C≡G [3 H‑bonds]), and four bases (A, T, G,
C).
9. Which of the following is a CORRECT representation of the central dogma?
A) RNA → DNA → protein
B) Protein → DNA → RNA
C) DNA → RNA → protein
D) DNA → protein → DNA
E) None is correct
Answer: C (DNA → RNA → protein)
Explanation: The central dogma describes the flow of genetic information: DNA is transcribed into RNA,
which is translated into protein.
10. You have come across a dog (named Cindy) that does not have a tail. Interestingly, all the puppies
produced by this dog also lack tails. If the lack of tail is inherited, what can you conclude?
A) The trait is dominant.
B) The trait is recessive.
C) The trait is sex‑linked.
D) The trait is influenced by environment.
E) Not enough information.
Answer: A (The trait is dominant)
Questions & Detailed Answers | Based on Griffiths 12th Edition
Chapter 1: The Genetics Revolution in the Life Sciences (Questions 1–20)
1. The early 1900s was an important period for genetics due to which major event(s)?
A) The rediscovery of Gregor Mendel’s scientific findings
B) Watson and Crick solving the structure of DNA
C) Walter Sutton and Theodore Boveri hypothesizing that chromosomes are the hereditary elements
D) All of the above
E) Both A and C
Answer: E (Both A and C)
Explanation: While Watson and Crick’s discovery of DNA’s structure occurred in 1953, the early 1900s
were defined by the rediscovery of Mendel’s work and the chromosome theory of inheritance proposed
by Sutton and Boveri.
2. A sample of normal double‑stranded DNA was found to have a guanine content of 18%. What is the
expected proportion of adenine?
A) 9%
B) 32%
C) 36%
D) 68%
E) 82%
Answer: B (32%)
Explanation: According to Chargaff’s rules, G = C and A = T. If G = 18%, then C = 18%, so G + C = 36%.
Thus A + T = 64%, so A = 32%.
,3. In one strand of DNA, the nucleotide sequence is 5′‑ATGC‑3′. The complementary sequence in the
other strand must be:
A) 3′‑ATGC‑5′
B) 3′‑TACG‑5′
C) 5′‑ATCG‑3′
D) 5′‑CGTA‑3′
E) 5′‑TACG‑3′
Answer: B (3′‑TACG‑5′)
Explanation: In DNA, A pairs with T and G pairs with C. The complementary strand runs antiparallel, so a
5′‑ATGC‑3′ sequence pairs with 3′‑TACG‑5′.
4. How many different DNA molecules that are eight‑nucleotide‑pairs long are theoretically possible?
A) 24
B) 32
C) 64
D) 256
E) 65,536
Answer: E (65,536)
Explanation: For each nucleotide pair there are 4 possibilities (A‑T, T‑A, C‑G, G‑C). For 8 pairs, the total is
4⁸ = 65,536.
5. Which of the following is/are TRUE about genes?
A) Genes are located on chromosomes.
B) Genes come in variants known as alleles.
C) Genes usually encode protein products.
D) All of the above are true.
E) None of the above is true.
,Answer: D (All of the above)
Explanation: A gene is a hereditary unit located on a chromosome that exists in different forms (alleles)
and typically encodes a protein (though some encode functional RNAs).
6. Wild cats (Felis silvestris) and common mice (Mus musculus) are diploid. In wild cats, 2n = 38; in mice,
2n = 40. Based on this, we can conclude that wild‑cat cells have:
A) less DNA than mouse cells
B) smaller genomes than mouse cells
C) fewer DNA molecules than mouse cells
D) fewer genes than mouse cells
E) fewer sets of chromosomes than mouse cells
Answer: C (fewer DNA molecules than mouse cells)
Explanation: Both are diploid, so they have the same number of sets of chromosomes (two sets).
However, the total number of DNA molecules (chromosomes) is given by the 2n number, which is lower
in cats (38) than in mice (40). Chromosome number does not directly correlate with genome size or gene
number.
7. Which of the following is a component of DNA?
A) Alanine
B) Arginine
C) Cysteine
D) Guanine
E) Tyrosine
Answer: D (Guanine)
Explanation: Guanine (G) is a purine nitrogenous base found in DNA. The other options are amino acids,
not DNA components.
8. Which of the following is/are TRUE of the DNA structure solved by Watson and Crick?
A) It is a double‑helical structure.
, B) The sugar‑phosphate backbone is always on the outside.
C) There are two hydrogen bonds between A‑T and three between C‑G.
D) There are four types of nitrogenous bases.
E) All of the above are true.
Answer: E (All of the above)
Explanation: Watson and Crick described DNA as a double helix with the sugar‑phosphate backbone on
the exterior, complementary base pairing (A=T [2 H‑bonds], C≡G [3 H‑bonds]), and four bases (A, T, G,
C).
9. Which of the following is a CORRECT representation of the central dogma?
A) RNA → DNA → protein
B) Protein → DNA → RNA
C) DNA → RNA → protein
D) DNA → protein → DNA
E) None is correct
Answer: C (DNA → RNA → protein)
Explanation: The central dogma describes the flow of genetic information: DNA is transcribed into RNA,
which is translated into protein.
10. You have come across a dog (named Cindy) that does not have a tail. Interestingly, all the puppies
produced by this dog also lack tails. If the lack of tail is inherited, what can you conclude?
A) The trait is dominant.
B) The trait is recessive.
C) The trait is sex‑linked.
D) The trait is influenced by environment.
E) Not enough information.
Answer: A (The trait is dominant)
