Which of the following is the sugar present in RNA?
A) Deoxyribose
B) Ribose
C) Glucose
D) Fructose
In DNA, adenine (A) always pairs with which nitrogenous base?
A) Cytosine
B) Thymine
C) Guanine
D) Uracil
The central dogma of molecular biology describes the flow of genetic information as:
A) Protein → RNA → DNA
B) DNA → RNA → Protein
C) RNA → DNA → Protein
D) DNA → Protein → RNA
Which enzyme is responsible for DNA replication?
A) RNA polymerase
B) DNA polymerase
C) Ligase
D) Helicase
RNA differs from DNA because it:
A) Contains uracil instead of thymine
B) Is single-stranded
C) Has ribose sugar instead of deoxyribose
D) All of the above
Which of the following nitrogenous bases is found in RNA but not in DNA?
A) Cytosine
B) Thymine
C) Uracil
D) Guanine
The process of copying DNA into RNA is called:
A) Translation
B) Replication
C) Transcription
D) Mutation
The three-letter sequence in mRNA that codes for an amino acid is called:
A) Anticodon
B) Nucleotide
C) Codon
D) Gene
What is the function of tRNA during translation?
A) Carries genetic information
B) Forms ribosomes
C) Brings amino acids to the ribosome
D) Catalyzes peptide bond formation
Which molecule carries the genetic code from the nucleus to the ribosome?
A) tRNA
B) mRNA
C) rRNA
D) DNA
Which enzyme unwinds the DNA double helix during replication?
A) Helicase
B) Ligase
C) Primase
D) RNA polymerase
What type of bond holds the two strands of DNA together?
A) Covalent bond
B) Hydrogen bond
C) Ionic bond
D) Peptide bond
Which of the following is a stop codon?
A) AUG
B) UAA
C) GGG
D) AAA
Which RNA type forms the structural component of ribosomes?
A) mRNA
B) rRNA
C) tRNA
D) snRNA
The start codon in most organisms is:
A) UGA
B) AUG
C) UAA
D) UAG
What is the complementary DNA strand for the sequence 5′-ATGCGA-3′?
A) 5′-TACGCT-3′
B) 5′-CGTATC-3′
C) 5′-GCTAGT-3′
D) 5′-TAGCGT-3′
Which process converts mRNA into a polypeptide?
A) Replication
B) Transcription
C) Translation
D) Mutation
Which of the following best describes a gene?
A) A segment of RNA that codes for a protein
B) A segment of DNA that codes for a protein
C) A protein molecule in the nucleus
D) A sequence of amino acids
Which nitrogenous base pairs with cytosine in DNA?
A) Adenine
B) Thymine
C) Guanine
D) Uracil
Which scientist(s) discovered the double-helix structure of DNA?
A) Watson and Crick
B) Franklin and Wilkins
C) Hershey and Chase
D) Griffith and Avery
What is the role of ribosomes in protein synthesis?
A) Replicating DNA
B) Synthesizing mRNA
C) Translating mRNA into proteins
D) Transporting amino acids
Which enzyme is responsible for transcribing RNA from DNA?
A) DNA polymerase
B) RNA polymerase
C) Ligase
D) Helicase
A mutation that changes one nucleotide without changing the amino acid sequence is called:
A) Missense mutation
B) Nonsense mutation
C) Silent mutation
D) Frameshift mutation
What is the function of a promoter in transcription?
A) Signals where transcription should begin
B) Binds amino acids together
C) Removes introns from mRNA
D) Attaches ribosomes to tRNA
Which of the following mutations is most likely to be harmful?
A) Silent mutation
B) Frameshift mutation
C) Missense mutation
D) Point mutation
Which molecule brings amino acids to the ribosome during translation?
A) tRNA
B) mRNA
C) rRNA
D) DNA
What is the term for non-coding regions of mRNA that are removed before translation?
A) Exons
B) Codons
C) Anticodons
D) Introns
Which process repairs mistakes in DNA replication?
A) Translation
B) DNA proofreading
C) Splicing
D) Codon recognition
Which of the following best describes the genetic code?
A) Overlapping and ambiguous
B) Universal and redundant
C) Species-specific
D) Contains only 10 codons
