Unit 3b: DNA And The Central Dogma
Questions and Answers
- 1.
Which of the following is a pair of complementary bases?
- A.
Cytosine and cytosine
- B.
Thymine and adenine
- C.
Adenine and guanine
- D.
Thymine and ctyosine
Correct Answer
B. Thymine and adenineExplanation
Thymine and adenine are a pair of complementary bases in DNA. They form hydrogen bonds with each other, creating a stable base pairing. This base pairing is essential for the double helix structure of DNA and plays a crucial role in DNA replication and protein synthesis. Cytosine and cytosine cannot form a complementary base pair, as they both have the same structure and cannot create the necessary hydrogen bonds. Adenine and guanine also cannot form a complementary base pair, as they have different structures and cannot bond together effectively. Therefore, the correct answer is thymine and adenine.Rate this question:
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- 2.
In a DNA molecule, which molecules make up the sides of the double helix?
- A.
Single nucleotides
- B.
Pairs of nucleotides
- C.
Joined sugars and phosphates
- D.
Joined nitrogenous bases and phosphates
Correct Answer
C. Joined sugars and phosphatesExplanation
The sides of the DNA double helix are made up of joined sugars and phosphates. The sugar in DNA is deoxyribose, which is joined to a phosphate group to form a sugar-phosphate backbone. This backbone runs along the outside of the helix, providing stability and structure to the DNA molecule. The nitrogenous bases, on the other hand, are found in the interior of the helix and form the rungs of the DNA ladder, connecting the two sides of the helix. Therefore, the correct answer is joined sugars and phosphates.Rate this question:
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- 3.
If one strand of a DNA molecule reads TATCGAT, what does the complementary strand read?
- A.
GCGATCG
- B.
ATAGCTA
- C.
CGCATCG
- D.
ATAGCAT
Correct Answer
B. ATAGCTAExplanation
The complementary strand of DNA is formed by pairing nucleotides with their complementary bases. In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). Therefore, the complementary strand of TATCGAT would be ATAGCTA, as each base is paired with its complement.Rate this question:
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- 4.
Which of the following statements is true?
- A.
The sugar molecules in each nucleotide contain genetic information.
- B.
Chromosomes are contained within genes, which are contained within DNA.
- C.
When DNA replicates, each strand is used to create three new strands for division.
- D.
Each organism of the same species has the same number of chromosomes in each cell.
Correct Answer
D. Each organism of the same species has the same number of chromosomes in each cell.Explanation
Each organism of the same species has the same number of chromosomes in each cell. This statement is true because chromosomes carry the genetic information of an organism, and the number of chromosomes is specific to each species. In sexually reproducing organisms, chromosomes are passed down from parent to offspring, ensuring that individuals of the same species have the same number of chromosomes in each cell. This consistency in chromosome number is crucial for maintaining the genetic integrity and stability of a species.Rate this question:
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- 5.
Which of the following statements about DNA and RNA is true?
- A.
RNA is arranged in a double helix.
- B.
The kinds of sugar in the nucleotides of DNA and RNA differ.
- C.
DNA contains nitrogenous bases and phosphates, while RNA does not.
- D.
DNA contains uracil, while RNA contains thymine.
Correct Answer
B. The kinds of sugar in the nucleotides of DNA and RNA differ.Explanation
The correct answer is "The kinds of sugar in the nucleotides of DNA and RNA differ." This statement is true because the sugar in DNA is deoxyribose, while the sugar in RNA is ribose. This difference in sugar composition is one of the key distinctions between DNA and RNA molecules. DNA contains deoxyribose, which lacks an oxygen atom in its structure, while RNA contains ribose, which has an additional oxygen atom. This variation in sugar structure contributes to the functional differences between DNA and RNA in terms of their roles in genetic information storage and protein synthesis.Rate this question:
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- 6.
Which DNA sequence produced an mRNA strand with the sequence AGUACA?
- A.
UCAUGU
- B.
TCATGT
- C.
GUACAG
- D.
CAGTAC
Correct Answer
B. TCATGTExplanation
The correct answer is TCATGT because when transcribing DNA into mRNA, adenine (A) pairs with uracil (U), guanine (G) pairs with cytosine (C), and thymine (T) pairs with adenine (A). Therefore, the DNA sequence TCATGT would produce an mRNA strand with the sequence AGUACA.Rate this question:
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- 7.
Transcription creates an mRNA molecule using DNA as a template. Where does this occur?
- A.
Outside the cell
- B.
In the cytoplasm
- C.
In the nucleus
- D.
In the ribosomes
Correct Answer
C. In the nucleusExplanation
Transcription, the process of creating an mRNA molecule using DNA as a template, occurs in the nucleus. This is where the DNA is located and where the transcription machinery, including RNA polymerase, is present. After transcription, the mRNA molecule is transported out of the nucleus and into the cytoplasm, where it will be used as a template for protein synthesis on the ribosomes.Rate this question:
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- 8.
The sequence of a strand of mRNA is GCATUGUAA. If the sequence includes a stop codon, how many amino acids does this code for?
- A.
2
- B.
3
- C.
6
- D.
9
Correct Answer
A. 2Explanation
The given mRNA sequence is GCATUGUAA. A stop codon is a sequence of three nucleotides that signals the end of protein synthesis. The stop codons are UAA, UAG, and UGA. In this case, the sequence includes the stop codon UAA. Since the stop codon does not code for any amino acid, the mRNA sequence only codes for the amino acids before the stop codon. Therefore, the code only specifies 2 amino acids.Rate this question:
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- 9.
What process is illustrated in the diagram?
- A.
Replication
- B.
Transcription
- C.
Translation
- D.
Mutation
Correct Answer
A. ReplicationExplanation
The process illustrated in the diagram is replication. Replication is the process by which DNA makes an identical copy of itself. It occurs during the S phase of the cell cycle and is essential for cell division and the transmission of genetic information from one generation to the next. In replication, the DNA double helix is unwound, and each strand serves as a template for the synthesis of a new complementary strand. This results in two identical DNA molecules, each consisting of one original strand and one newly synthesized strand.Rate this question:
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- 10.
What type of mutation has occured in this piece of DNA? Original sequence: TACGCG Mutated sequence: TCGCGT
- A.
Deletion
- B.
Insertion
- C.
Substitution
- D.
Translocation
Correct Answer
A. DeletionExplanation
The original sequence "TACGCG" has changed to "TCGCGT" in the mutated sequence. In this case, a deletion mutation has occurred because one nucleotide (A) has been deleted from the original sequence, resulting in a shorter sequence in the mutated DNA.Rate this question:
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- 11.
What does the circle represent in this diagram of a nucleotide?
- A.
Phosphate group
- B.
Nitrogenous base
- C.
Pentose sugar
- D.
Adenine base
Correct Answer
A. Phosphate groupExplanation
The circle in the diagram of a nucleotide represents the phosphate group. A nucleotide is composed of three components: a phosphate group, a nitrogenous base, and a pentose sugar. The phosphate group is represented by a circle in the diagram and is responsible for providing the negative charge to the nucleotide. It plays a crucial role in the structure and function of DNA and RNA molecules.Rate this question:
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- 12.
Ribosomes are made of ___.
- A.
RRNA and two protein subunits
- B.
TRNA and mRNA
- C.
RRNA and mRNA
- D.
Protein and tRNA
Correct Answer
A. RRNA and two protein subunitsExplanation
Ribosomes are cellular structures responsible for protein synthesis. They are composed of ribosomal RNA (rRNA) and two protein subunits. The rRNA provides the structural framework for the ribosome, while the protein subunits contribute to its function. Together, rRNA and the protein subunits form a complex that reads the genetic information carried by mRNA and assembles amino acids into a protein chain. Therefore, the correct answer is rRNA and two protein subunits.Rate this question:
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- 13.
Watson and Crick, with the help of Rosalind Franklin, were the first to suggest that DNA is ___.
- A.
A short molecule
- B.
A protein molecule
- C.
The shape of a double helix
- D.
The genetic material
Correct Answer
C. The shape of a double helixExplanation
Watson and Crick, along with the assistance of Rosalind Franklin, proposed that DNA has the structure of a double helix. This means that DNA is shaped like a twisted ladder, with two strands that are connected by pairs of nucleotides. This groundbreaking discovery revolutionized our understanding of genetics and the transmission of genetic information. It provided a structural explanation for how DNA carries and replicates genetic material.Rate this question:
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- 14.
The chromosome abnormality that occurs when part of one chromosome breaks off and is added to a different chromosome is ___.
- A.
Deletion
- B.
Nondisjunction
- C.
Translocation
- D.
Inversion
Correct Answer
C. TranslocationExplanation
Translocation is the correct answer because it refers to the chromosome abnormality where a part of one chromosome breaks off and attaches to a different chromosome. This can result in genetic disorders or diseases, as the rearrangement of genetic material can disrupt normal gene function.Rate this question:
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- 15.
Which of the following is least likely to happen as a result of a mutation in a person's skin cells?
- A.
Skin cancer
- B.
Reduced functioning of the skin cell
- C.
No change in functioning of the skin cell
- D.
The person's offspring have mutated skin cells
Correct Answer
D. The person's offspring have mutated skin cellsExplanation
A mutation in a person's skin cells is least likely to result in the person's offspring having mutated skin cells. Mutations in an individual's somatic cells, such as skin cells, are not passed on to their offspring as they are not present in the germ cells (sperm or egg). Offspring inherit genetic material from both parents, but mutations occurring in somatic cells do not affect the genetic makeup of the germ cells. Therefore, the likelihood of the person's offspring having mutated skin cells is very low.Rate this question:
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- 16.
Messenger RNA is formed in the process of ___.
- A.
Transcription
- B.
Translation
- C.
Replication
- D.
Mutation
Correct Answer
A. TranscriptionExplanation
Messenger RNA is formed in the process of transcription. Transcription is the process in which the DNA sequence of a gene is copied into a complementary RNA sequence. During transcription, the enzyme RNA polymerase binds to the DNA and synthesizes a complementary RNA molecule using the DNA template. The resulting messenger RNA (mRNA) molecule carries the genetic information from the DNA to the ribosomes, where it is translated into a protein during the process of translation. Replication is the process of copying the entire DNA molecule, while mutation refers to changes in the DNA sequence.Rate this question:
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- 17.
The process by which a DNA molecule is copied is ___.
- A.
Transcription
- B.
Translation
- C.
Replication
- D.
Mutation
Correct Answer
C. ReplicationExplanation
The process by which a DNA molecule is copied is called replication. During replication, the DNA molecule unwinds and separates into two strands, and each strand serves as a template for the synthesis of a new complementary strand. This results in two identical DNA molecules, each containing one original strand and one newly synthesized strand. Replication is essential for cell division and the transmission of genetic information from one generation to the next. Transcription is the process of synthesizing RNA from a DNA template, translation is the process of synthesizing proteins from RNA, and mutation refers to a change in the DNA sequence.Rate this question:
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- 18.
Each set of three nucleotides on mRNA coding for an amino acid is referred to as a(n) ___.
- A.
Codon
- B.
Anticodon
- C.
Ribosome
- D.
Base pair
Correct Answer
A. CodonExplanation
A codon is a set of three nucleotides on mRNA that codes for a specific amino acid. It acts as a genetic code that determines the sequence of amino acids in a protein. The other options, anticodon, ribosome, and base pair, are not correct because they do not specifically refer to a set of three nucleotides on mRNA coding for an amino acid.Rate this question:
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- 19.
The nucleotide triplet on tRNA that complements a codon is called a(n) ___.
- A.
Codon
- B.
Anticodon
- C.
Ribosome
- D.
Base pair
Correct Answer
B. AnticodonExplanation
The nucleotide triplet on tRNA that complements a codon is called an anticodon. This is because during protein synthesis, the anticodon on tRNA pairs with the codon on mRNA through complementary base pairing. This ensures that the correct amino acid is added to the growing polypeptide chain according to the genetic code. The anticodon and codon pairing is essential for accurate translation of the genetic information from mRNA into protein.Rate this question:
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- 20.
Adenine is to thymine as guanine is to ___.
- A.
Uracil
- B.
Cytosine
- C.
Adenine
- D.
Thymine
Correct Answer
B. CytosineExplanation
Adenine pairs with thymine in DNA, while guanine pairs with cytosine. This is known as complementary base pairing, where adenine and thymine form two hydrogen bonds, and guanine and cytosine form three hydrogen bonds. Therefore, the correct answer is cytosine.Rate this question:
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- 21.
DNA is to RNA as double strand is to ___.
- A.
Single strand
- B.
Ribose
- C.
Triple strand
- D.
Double helix
Correct Answer
A. Single strandExplanation
DNA and RNA are both nucleic acids that play a crucial role in genetic information transfer. DNA is a double-stranded molecule, consisting of two complementary strands that are held together by hydrogen bonds. Similarly, RNA is a single-stranded molecule, meaning it is composed of only one nucleotide chain. Therefore, the analogy suggests that the relationship between DNA and RNA is similar to the relationship between a double strand and a single strand.Rate this question:
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- 22.
Transcription is to mRNA as translation is to ___.
- A.
Protein
- B.
Codon
- C.
TRNA
- D.
DNA
Correct Answer
A. ProteinExplanation
Transcription is the process of synthesizing mRNA from DNA, while translation is the process of synthesizing protein from mRNA. Therefore, the correct answer is protein, as it represents the end product of translation.Rate this question:
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- 23.
A(n) ___ involves the insertion or deletion of a single base in a DNA molecule.
- A.
Frameshift mutation
- B.
Point mutation
- C.
Translocation
- D.
Mutagen
Correct Answer
A. Frameshift mutationExplanation
A frameshift mutation involves the insertion or deletion of a single base in a DNA molecule. This type of mutation shifts the reading frame of the DNA sequence, causing a change in the codons and ultimately leading to a different amino acid sequence in the resulting protein. Frameshift mutations can have significant effects on the structure and function of proteins, often resulting in non-functional or partially functional proteins.Rate this question:
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- 24.
A(n) ___ involves thesubstitution of a single base in a DNA molecule.
- A.
Frameshift mutation
- B.
Point mutation
- C.
Translocation
- D.
Mutagen
Correct Answer
B. Point mutationExplanation
A point mutation is a type of mutation that involves the substitution of a single base in a DNA molecule. This means that one base in the DNA sequence is replaced with another base. Point mutations can occur randomly or be caused by mutagens, which are agents that can induce mutations. Unlike frameshift mutations, which involve the insertion or deletion of bases, point mutations only affect a single base and can result in changes to the genetic code. Translocation, on the other hand, involves the movement of a segment of DNA to another location, and is not related to the substitution of a single base.Rate this question:
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- 25.
The term for a substance or energy form that can cause a mutation in DNA is ___.
- A.
Frameshift mutation
- B.
Point mutation
- C.
Translocation
- D.
Mutagen
Correct Answer
D. MutagenExplanation
A mutagen is a substance or energy form that can cause a mutation in DNA. Mutations are changes in the DNA sequence, and mutagens are agents that can induce these changes. They can include chemicals, radiation, or certain viruses. Mutagens can cause different types of mutations, such as point mutations, which involve changes in a single nucleotide, or frameshift mutations, which involve the insertion or deletion of nucleotides. Translocations, on the other hand, refer to the rearrangement of genetic material between different chromosomes. Therefore, the correct answer for a substance or energy form that can cause a mutation in DNA is mutagen.Rate this question:
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