Biology

Molecular Biology and Genetics

717 Questions

Molecular biology and genetics explore the structure and function of DNA, RNA, genetic mutations, and heredity. Understanding these building blocks of life is essential for most biology examinations. Review these practice questions to test your molecular genetics knowledge.

DNA structure and basesGenetic mutationsNucleic acids compositionDNA sequencing and replication

Molecular Biology and Genetics Questions

Multiple choice

What is the basic structural unit of DNA?

  1. Nucleotide

  2. Amino acid

  3. Monosaccharide

  4. Fatty acid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The basic structural unit of DNA is the nucleotide, which consists of a nitrogenous base, a deoxyribose sugar, and a phosphate group.

Multiple choice

What are the four nitrogenous bases found in DNA?

  1. Adenine, cytosine, guanine, and thymine

  2. Adenine, cytosine, guanine, and uracil

  3. Thymine, cytosine, guanine, and uracil

  4. Adenine, thymine, guanine, and uracil
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The four nitrogenous bases found in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T).

Multiple choice

What is the complementary base pairing rule in DNA?

  1. A pairs with C, and G pairs with T

  2. A pairs with T, and G pairs with C

  3. A pairs with G, and C pairs with T

  4. A pairs with U, and G pairs with C
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In DNA, adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C).

Multiple choice

What is the structure of DNA?

  1. Double helix

  2. Single helix

  3. Triple helix

  4. Quadruple helix
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DNA typically exists as a double helix, where two strands of nucleotides are twisted around each other to form a spiral structure.

Multiple choice

What is the genetic code?

  1. A set of rules that determines how genetic information is translated into proteins

  2. A sequence of nucleotides in DNA or RNA

  3. A type of genetic mutation

  4. A method for sequencing DNA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The genetic code is a set of rules that determines how the sequence of nucleotides in DNA or RNA is translated into the sequence of amino acids in a protein.

Multiple choice

How many codons are there in the genetic code?

  1. 64

  2. 16

  3. 32

  4. 128
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

There are 64 codons in the genetic code, each consisting of a sequence of three nucleotides.

Multiple choice

What is a mutation in DNA or RNA?

  1. A permanent change in the nucleotide sequence

  2. A temporary change in the nucleotide sequence

  3. A change in the structure of the DNA or RNA molecule

  4. A change in the function of the DNA or RNA molecule
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A mutation is a permanent change in the nucleotide sequence of DNA or RNA.

Multiple choice

What is the unit of distance used in genetic mapping?

  1. Centimorgan (cM)

  2. Base pairs (bp)

  3. Micrometers (μm)

  4. Nanometers (nm)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The unit of distance used in genetic mapping is the centimorgan (cM). One centimorgan is defined as the distance between two genetic markers that are 1% recombinant.

Multiple choice

What is the approximate number of genes encoded by mitochondrial DNA?

  1. 13

  2. 37

  3. 100

  4. 1000
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Human mitochondrial DNA encodes approximately 37 genes, including those involved in oxidative phosphorylation and protein synthesis.

Multiple choice

What is the immediate precursor of inosine monophosphate (IMP) in de novo purine biosynthesis?

  1. 5-Phosphoribosyl-1-amine (PRA)

  2. Glycinamide ribonucleotide (GAR)

  3. Succinyl-aminoimidazole carboxamide ribonucleotide (SAICAR)

  4. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

AICAR is the immediate precursor of IMP in de novo purine biosynthesis. It is formed by the cyclization of SAICAR.

Multiple choice

Which of the following is the correct sequence of nucleotides in a DNA molecule?

  1. Adenine, Thymine, Guanine, Cytosine

  2. Adenine, Uracil, Guanine, Cytosine

  3. Thymine, Adenine, Guanine, Cytosine

  4. Uracil, Adenine, Guanine, Cytosine
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In DNA, the sequence of nucleotides is Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).

Multiple choice

Which of the following is not a type of DNA replication?

  1. Conservative replication

  2. Semiconservative replication

  3. Dispersive replication

  4. Rolling circle replication
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Conservative replication, semiconservative replication, and rolling circle replication are all types of DNA replication. Dispersive replication is not a type of DNA replication.

Multiple choice

Which of the following is NOT a component of a nucleotide?

  1. A nitrogenous base

  2. A phosphate group

  3. A deoxyribose sugar

  4. A ribose sugar
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A deoxyribose sugar is not a component of a nucleotide, but rather a component of DNA. Nucleotides are composed of a nitrogenous base, a phosphate group, and a ribose sugar.

Multiple choice

Which of the following is NOT a type of mutation?

  1. Substitution

  2. Deletion

  3. Insertion

  4. Transversion
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Transversion is not a type of mutation, but rather a type of substitution mutation in which a purine base is replaced by a pyrimidine base, or vice versa.

Multiple choice

What is the structure of DNA?

  1. Double helix

  2. Single helix

  3. Triple helix

  4. Quadruple helix
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DNA is a double helix, meaning that it consists of two strands of nucleotides that are twisted around each other. The nucleotides in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).