MMSC491 Exam 1, 2 & 3 Complete Study Guide | 200 Practice
Questions & Detailed Answers | 2026/2027 Update | A+
Graded
1. What term describes heritable changes in phenotype that are not due to changes in the DNA
sequence?
A. Mutation
B. Epigenetic
C. Genotype
D. Polymorphism
Answer: B. Epigenetic
Explanation: Epigenetic changes are heritable modifications in phenotype that occur without alterations
to the DNA sequence itself. These changes typically involve DNA methylation or histone modifications
that affect gene expression.
2. Which of the following is the collective term for all different DNA molecules within a cell or organism?
A. Chromosome
B. Genome
C. Proteome
D. Transcriptome
Answer: B. Genome
Explanation: The genome is the complete set of genetic material (all DNA molecules) present in a cell or
organism.
,3. A DNAprotein complex is known as a:
A. Chromosome
B. Gene
C. Nucleotide
D. Allele
Answer: A. Chromosome
Explanation: Chromosomes are structures composed of DNA wrapped around histone proteins, formin g
a DNAprotein complex that organizes and compacts genetic material.
4. How many DNA molecules does a typical male human have?
A. 23
B. 24
C. 46
D. 48
Answer: B. 24
Explanation: A male human has 24 DNA molecules: 22 autosomes + X chromosome + Y chromosome. A
female has 23 (22 autosomes + two X chromosomes considered as 23 distinct molecules).
5. Which of the following bases are pyrimidines?
,A. Adenine and Guanine
B. Cytosine and Thymine
C. Adenine and Thymine
D. Guanine and Cytosine
Answer: B. Cytosine and Thymine
Explanation: Pyrimidines are singlering structures containing carbon and nitrogen atoms. Cytosine (C)
and Thymine (T) are pyrimidines.
6. Which of the following bases are purines?
A. Cytosine and Thymine
B. Adenine and Guanine
C. Adenine and Thymine
D. Guanine and Cytosine
Answer: B. Adenine and Guanine
Explanation: Purines are doublering structures. Adenine (A) and Guanine (G) are the purine bases found
in DNA.
7. How many hydrogen bonds hold guanine and cytosine together?
A. 1
B. 2
C. 3
, D. 4
Answer: C. 3
Explanation: Guanine (G) and Cytosine (C) form three hydrogen bonds, making GC pairs more stable
than AT pairs.
8. How many hydrogen bonds hold adenine and thymine together?
A. 1
B. 2
C. 3
D. 4
Answer: B. 2
Explanation: Adenine (A) and Thymine (T) form two hydrogen bonds in DNA.
9. During DNA replication, each strand unwinds with the help of which enzyme?
A. DNA polymerase
B. Helicase
C. Ligase
D. Primase
Answer: B. Helicase
Questions & Detailed Answers | 2026/2027 Update | A+
Graded
1. What term describes heritable changes in phenotype that are not due to changes in the DNA
sequence?
A. Mutation
B. Epigenetic
C. Genotype
D. Polymorphism
Answer: B. Epigenetic
Explanation: Epigenetic changes are heritable modifications in phenotype that occur without alterations
to the DNA sequence itself. These changes typically involve DNA methylation or histone modifications
that affect gene expression.
2. Which of the following is the collective term for all different DNA molecules within a cell or organism?
A. Chromosome
B. Genome
C. Proteome
D. Transcriptome
Answer: B. Genome
Explanation: The genome is the complete set of genetic material (all DNA molecules) present in a cell or
organism.
,3. A DNAprotein complex is known as a:
A. Chromosome
B. Gene
C. Nucleotide
D. Allele
Answer: A. Chromosome
Explanation: Chromosomes are structures composed of DNA wrapped around histone proteins, formin g
a DNAprotein complex that organizes and compacts genetic material.
4. How many DNA molecules does a typical male human have?
A. 23
B. 24
C. 46
D. 48
Answer: B. 24
Explanation: A male human has 24 DNA molecules: 22 autosomes + X chromosome + Y chromosome. A
female has 23 (22 autosomes + two X chromosomes considered as 23 distinct molecules).
5. Which of the following bases are pyrimidines?
,A. Adenine and Guanine
B. Cytosine and Thymine
C. Adenine and Thymine
D. Guanine and Cytosine
Answer: B. Cytosine and Thymine
Explanation: Pyrimidines are singlering structures containing carbon and nitrogen atoms. Cytosine (C)
and Thymine (T) are pyrimidines.
6. Which of the following bases are purines?
A. Cytosine and Thymine
B. Adenine and Guanine
C. Adenine and Thymine
D. Guanine and Cytosine
Answer: B. Adenine and Guanine
Explanation: Purines are doublering structures. Adenine (A) and Guanine (G) are the purine bases found
in DNA.
7. How many hydrogen bonds hold guanine and cytosine together?
A. 1
B. 2
C. 3
, D. 4
Answer: C. 3
Explanation: Guanine (G) and Cytosine (C) form three hydrogen bonds, making GC pairs more stable
than AT pairs.
8. How many hydrogen bonds hold adenine and thymine together?
A. 1
B. 2
C. 3
D. 4
Answer: B. 2
Explanation: Adenine (A) and Thymine (T) form two hydrogen bonds in DNA.
9. During DNA replication, each strand unwinds with the help of which enzyme?
A. DNA polymerase
B. Helicase
C. Ligase
D. Primase
Answer: B. Helicase
