Molecular Basis of Inheritance
Test 2

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Helicase
Primase
DNA ligase
Topoisomerase
3

DNA ligase joins Okazaki fragments by forming phosphodiester bonds between them.

Which of the following is a component of a nucleotide?

Amino acid
Phosphate group
Fatty acid
Carbohydrate chain
2

A nucleotide consists of a phosphate group, a pentose sugar, and a nitrogenous base.

Which base is found in RNA but not in DNA?

Thymine
Cytosine
Uracil
Adenine
3

Uracil is found in RNA, whereas DNA contains thymine instead of uracil.

Which scientist's work led to the discovery of the base pairing rule in DNA?

Rosalind Franklin
Erwin Chargaff
Watson and Crick
Avery, MacLeod, and McCarty
2

Erwin Chargaff discovered that in DNA, the amount of adenine equals thymine and the amount of guanine equals cytosine.

Which of the following statements about tRNA is correct?

tRNA contains an anticodon that pairs with mRNA codons.
tRNA carries nucleotides to ribosomes for translation.
tRNA is not involved in translation.
tRNA binds directly to DNA to assist in replication.
1

tRNA contains an anticodon that pairs with mRNA codons and delivers the corresponding amino acid during translation.

Which of the following statements about mutations is incorrect?

Mutations can be caused by radiation and chemicals.
Mutations always result in harmful effects.
Mutations can be spontaneous or induced.
Some mutations are silent and do not affect the protein sequence.
2

Not all mutations are harmful; some are neutral, beneficial, or silent, meaning they do not change the protein sequence.

Which of the following statements about operons is correct?

Operons are found only in eukaryotic cells.
An operon consists of multiple genes controlled by a single promoter.
The lac operon is always active, regardless of lactose availability.
Operons regulate DNA replication.
2

Operons are clusters of genes under the control of a single promoter, found mainly in prokaryotic cells.

Which of the following statements about translation is incorrect?

Translation occurs in the cytoplasm.
Translation requires mRNA, tRNA, and ribosomes.
Translation occurs in the nucleus.
Translation converts mRNA into a polypeptide chain.
3

Translation occurs in the cytoplasm, where ribosomes decode mRNA into a protein.

Which of the following is NOT a function of RNA?

Genetic material in some viruses
Structural component of ribosomes
Catalyst in certain biochemical reactions
Main genetic material in all living organisms
4

RNA serves as genetic material in some viruses, functions structurally in ribosomes, and acts as a catalyst in some reactions. However, in most organisms, DNA, not RNA, is the main genetic material.

Which of the following enzymes catalyzes the synthesis of RNA from a DNA template?

DNA polymerase
RNA polymerase
Helicase
Ligase
2

RNA polymerase catalyzes the transcription of RNA from a DNA template.

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