ACE Your Biology Exam - Biology Mock Test About RNA And Protein Synthesis

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ACE Your Biology Exam - Biology Mock Test About RNA And Protein Synthesis - Quiz

Protein synthesis is the process in which cells make proteins. It occurs in two stages: transcription and translation. Transcription is the transfer of genetic instructions in DNA to mRNA in the nucleus. It includes three steps: initiation, elongation, and termination.
Ace Your Biology Exam by passing Biology Mock Test about RNA and Protein Synthesis


Questions and Answers
  • 1. 

    What are the missing nucleotides (1), (2), (3) and (4) respectively in the following figure?

    • A.

      U – A – C – G

    • B.

      A – A – C – G

    • C.

      A – U – G – C

    • D.

      A – A – G – C

    Correct Answer
    D. A – A – G – C
  • 2. 

    Bacteria produce ---------- when infected by a Bacteriophage.

    • A.

      Restriction enzymes then ligase enzymes

    • B.

      Modified enzymes then polymerase enzymes

    • C.

      Restriction enzymes then modified enzymes

    • D.

      Modified enzymes then restriction enzymes

    Correct Answer
    D. Modified enzymes then restriction enzymes
    Explanation
    When bacteria are infected by a Bacteriophage, they produce modified enzymes. These modified enzymes then activate restriction enzymes. Therefore, the correct answer is "Modified enzymes then restriction enzymes."

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  • 3. 

    What is the number of nucleotides of a DNA molecule that contains two complete turns?

    • A.

      10

    • B.

      20

    • C.

      30

    • D.

      40

    Correct Answer
    D. 40
    Explanation
    A DNA molecule contains two complete turns when it forms a double helix structure. Each complete turn of the DNA helix consists of 10 nucleotide pairs. Since each nucleotide pair consists of two nucleotides, the total number of nucleotides in two complete turns of a DNA molecule is 20 nucleotides per turn. Therefore, the total number of nucleotides in a DNA molecule that contains two complete turns is 40.

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  • 4. 

    The maximum number of different genetic codes for amino acids on mRNA is …...

    • A.

      3

    • B.

      20

    • C.

      61

    • D.

      64

    Correct Answer
    D. 64
    Explanation
    There are 64 different genetic codes for amino acids on mRNA. This is because there are 4 different nucleotides (A, U, G, C) that make up mRNA, and each amino acid is coded for by a sequence of three nucleotides called a codon. Since there are 4 possible nucleotides at each position and a codon is made up of three positions, the total number of possible codons is 4^3 = 64.

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  • 5. 

    For the formation of a protein consists of 300 amino acids, then the number of turns of the DNA molecule which is going to be transcribed is ……

    • A.

      30

    • B.

      90

    • C.

      15

    • D.

      45

    Correct Answer
    B. 90
    Explanation
    The formation of a protein consisting of 300 amino acids requires the transcription of a DNA molecule. Each amino acid is encoded by a sequence of three nucleotides in DNA, known as a codon. Since there are 300 amino acids, there would be 300 codons on the DNA molecule that need to be transcribed. Each turn of the DNA molecule transcribes approximately 3.3 codons. Therefore, to transcribe 300 codons, approximately 90 turns of the DNA molecule would be required.

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  • 6. 

    The pores in the nuclear membrane transfer -------- to the cytoplasm

    • A.

       Ribosomes

    • B.

       tRNA

    • C.

       mRNA

    • D.

       All the previous

    Correct Answer
    D.  All the previous
    Explanation
    The correct answer is "All the previous". The pores in the nuclear membrane allow the transfer of ribosomes, tRNA, and mRNA to the cytoplasm. This means that all of these components can pass through the nuclear membrane and move into the cytoplasm, where they can carry out their respective functions in protein synthesis.

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  • 7. 

    The ------- is responsible for reading the language of the amino acids and nucleotides.

    • A.

      Transfer RNA

    • B.

      RNA polymerase

    • C.

      Messenger RNA

    • D.

      Ribosome

    Correct Answer
    A. Transfer RNA
    Explanation
    Transfer RNA (tRNA) is responsible for reading the language of the amino acids and nucleotides. tRNA molecules carry specific amino acids to the ribosome during protein synthesis. Each tRNA molecule has an anticodon sequence that is complementary to a specific codon on the messenger RNA (mRNA). This allows the tRNA to recognize and bind to the corresponding codon on the mRNA, ensuring that the correct amino acid is added to the growing protein chain. Therefore, tRNA plays a crucial role in the translation process, decoding the genetic information and facilitating the synthesis of proteins.

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  • 8. 

    The codon is three successive nucleotides found on ……….

    • A.

      DNA

    • B.

      Messenger RNA

    • C.

      Transfer RNA

    • D.

      Ribosome

    Correct Answer
    A. DNA
    Explanation
    The codon is three successive nucleotides found on DNA. DNA is the genetic material that carries the instructions for the development and functioning of all living organisms. It consists of a sequence of nucleotides, which are the building blocks of DNA. The codon is a specific sequence of three nucleotides that codes for a specific amino acid or signals the start or stop of protein synthesis. Therefore, the correct answer is DNA.

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  • 9. 

    A recombinant DNA molecule is produced by .....

    • A.

      Joining of two DNA fragments of the same organism.

    • B.

      Joining of more than two DNA fragments of the same organism.

    • C.

      Joining of two DNA fragments originating from different organisms.

    • D.

      Joining two mRNA molecules.

    Correct Answer
    C. Joining of two DNA fragments originating from different organisms.
    Explanation
    A recombinant DNA molecule is produced by joining two DNA fragments originating from different organisms. This process is known as genetic recombination and is commonly used in genetic engineering to create new combinations of genes. By combining DNA from different organisms, scientists can introduce new traits or characteristics into an organism, such as producing insulin in bacteria or creating genetically modified crops. This technique has revolutionized many fields, including medicine, agriculture, and biotechnology.

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  • 10. 

    Which of the following statements are true regarding recombinant-DNA technology?

    • A.

      Is used to obtain large number of copies of specific DNA fragments

    • B.

      Is used to obtain large quantities of the protein produced by the concerned gene

    • C.

      Is used to integrate gene of interest into chromosomes where it expresses itself

    • D.

      All of them

    Correct Answer
    D. All of them
    Explanation
    Recombinant-DNA technology is a technique used in genetic engineering to manipulate DNA sequences. It involves combining DNA fragments from different sources to create a new DNA molecule. This technology can be used to obtain large numbers of copies of specific DNA fragments, which is useful for various applications such as DNA sequencing and cloning. It can also be used to obtain large quantities of the protein produced by the concerned gene, as the recombinant DNA can be inserted into host cells that will produce the desired protein. Additionally, recombinant-DNA technology can be used to integrate a gene of interest into chromosomes, where it will express itself. Therefore, all of the given statements are true regarding recombinant-DNA technology.

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  • 11. 

    Which of the following enzymes in bacteria are responsible for restricting the growth of viruses?

    • A.

      Reverse transciptase

    • B.

      Restriction endonuclease

    • C.

      Peptidyl transferase

    • D.

      Ligases

    Correct Answer
    B. Restriction endonuclease
    Explanation
    Restriction endonucleases are enzymes found in bacteria that play a crucial role in the defense against viral infections. These enzymes are responsible for cutting viral DNA at specific recognition sites, thereby restricting the growth and replication of viruses. This mechanism is part of the bacterial immune system and helps to protect the bacteria from viral invasion. Reverse transcriptase is an enzyme found in retroviruses, not bacteria. Peptidyl transferase is an enzyme involved in protein synthesis, and ligases are enzymes involved in joining DNA fragments.

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  • 12. 

    Which enzyme is used to join together two different types of DNA molecules?

    • A.

      Ligase

    • B.

      Endonuclease

    • C.

      Gyrase

    • D.

      Peptidyl transferase

    Correct Answer
    A. Ligase
    Explanation
    Ligase is the enzyme used to join together two different types of DNA molecules. Ligase catalyzes the formation of phosphodiester bonds between the sugar-phosphate backbones of DNA strands, resulting in the formation of a continuous DNA molecule. This enzyme plays a crucial role in DNA replication, repair, and recombination processes by sealing nicks or gaps in the DNA strands. It is commonly used in molecular biology techniques, such as cloning and DNA sequencing, to join DNA fragments together.

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  • 13. 

    How many DNA double strands are obtained from one DNA double strand after 4 cycles in PCR?

    • A.

      4

    • B.

      8

    • C.

      16

    • D.

      32

    Correct Answer
    C. 16
    Explanation
    In PCR, each cycle doubles the amount of DNA. Therefore, after 4 cycles, the DNA double strand would have undergone 2^4 (2 raised to the power of 4) amplifications, resulting in 16 DNA double strands.

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  • 14. 

    At what temperature do denaturation of DNA double helix takes place in the PCR?

    • A.

      60˚

    • B.

      54˚

    • C.

      74˚

    • D.

      94˚

    Correct Answer
    D. 94˚
    Explanation
    The denaturation of the DNA double helix takes place in the PCR at a temperature of 94˚. This high temperature is necessary to separate the two strands of the DNA molecule, allowing for the amplification of specific DNA sequences during the PCR process.

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  • 15. 

    At what temperature do annealing of DNA and primer takes place in PCR?

    • A.

      42˚

    • B.

      54˚

    • C.

      74˚

    • D.

      96˚

    Correct Answer
    B. 54˚
    Explanation
    In PCR, the annealing step occurs when the DNA template and primer bind together. This step requires a specific temperature at which the primer can bind to the complementary DNA sequence. The correct answer is 54˚ because it is the temperature at which the primer and DNA template can form a stable and specific bond.

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  • 16. 

    Which of the following is a mismatch?

    • A.

      Polymerase – Taq polymerase

    • B.

      Template – double stranded DNA

    • C.

      Primer – small number of nucleotides

    • D.

      Synthesis – 5’ to 3’ direction

    Correct Answer
    B. Template – double stranded DNA
    Explanation
    The mismatch in the given options is "Template - double stranded DNA". In DNA replication, the template strand is single-stranded, while the newly synthesized strand is complementary and forms a double-stranded DNA molecule. The template strand serves as a guide for the synthesis of the new DNA strand. Therefore, the correct answer is "Template - double stranded DNA".

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  • 17. 

    Which of the following is true about DNA hybridization and species relatedness?

    • A.

      The more similar the DNA, the higher the DNA melting temperature

    • B.

      The less similar the DNA, the more hydrogen bonds will be formed

    • C.

      Unrelated species are more likely to share genetic similarities

    • D.

      Only species living in the same region will have similar DNA

    Correct Answer
    A. The more similar the DNA, the higher the DNA melting temperature
    Explanation
    DNA hybridization is a process in which two single strands of DNA from different sources are allowed to form a double-stranded molecule by base pairing. The stability of this double-stranded DNA is measured by its melting temperature, which is the temperature at which the two strands separate. The more similar the DNA sequences are between two species, the more hydrogen bonds they will form, resulting in a higher melting temperature. Therefore, the statement "The more similar the DNA, the higher the DNA melting temperature" is true.

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  • 18. 

    Which of the following is a use for DNA hybridization?

    • A.

      To look for species' relatedness

    • B.

      To look for changes in gene expression

    • C.

      To understand the mechanisms of evolution in isolated populations

    • D.

      To decrease genetic mutation in a population

    Correct Answer
    A. To look for species' relatedness
    Explanation
    DNA hybridization is a technique used to determine the degree of genetic similarity between different species. By comparing the DNA sequences of different organisms, scientists can determine their evolutionary relationships and identify how closely related they are. This information can be used to study the evolutionary history of species, understand their genetic diversity, and track their evolutionary changes over time. Therefore, DNA hybridization is commonly used to look for species' relatedness.

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  • 19. 

    Conversion of messages carried by mRNA into amino acid sequences is called________.

    • A.

      Replication

    • B.

      DNA repair

    • C.

      Translation

    • D.

      Transcription

    Correct Answer
    C. Translation
    Explanation
    Translation is the process by which the information carried by messenger RNA (mRNA) is converted into a sequence of amino acids, which then form proteins. This process occurs in the ribosomes of the cell and is essential for protein synthesis. Replication is the process of copying DNA, DNA repair is the process of fixing damaged DNA, and transcription is the process of creating mRNA from DNA. None of these processes directly involve the conversion of mRNA into amino acid sequences, making translation the correct answer.

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  • 20. 

    Name the suppressor which blocks translation in eukaryotes?

    • A.

      Stop codon

    • B.

      Releasing factor

    • C.

      Terminator

    • D.

      Poly-adenine tail

    Correct Answer
    B. Releasing factor
    Explanation
    Releasing factors are proteins that bind to the stop codon on the mRNA during translation in eukaryotes. This binding triggers the release of the newly synthesized protein from the ribosome and prevents further translation. Therefore, releasing factors act as suppressors that block translation in eukaryotes.

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  • 21. 

    A section in the nucleic acid marks the end of a gene during transcription process .....

    • A.

      Promoter

    • B.

      Terminator

    • C.

      Releasing factor

    • D.

      RNA polymerase

    Correct Answer
    B. Terminator
    Explanation
    The section in the nucleic acid that marks the end of a gene during the transcription process is called the terminator. The terminator signals the RNA polymerase to stop transcribing the gene and release the newly formed RNA molecule. This is an essential step in gene expression as it ensures that the correct portion of the gene is transcribed and that the RNA molecule is properly formed. The promoter, on the other hand, marks the start of a gene and signals the RNA polymerase to begin transcription. The releasing factor is involved in the termination of protein synthesis, not transcription.

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  • 22. 

    What is the role of mRNA in protein synthesis?

    • A.

      It translates genetic code to a specific amino acid.

    • B.

      It modifies mRNA molecules prior to protein synthesis.

    • C.

      It provides a genetic map for the protein.

    • D.

      It catalyzes the process.

    Correct Answer
    C. It provides a genetic map for the protein.
    Explanation
    mRNA (messenger RNA) plays a crucial role in protein synthesis by providing a genetic map for the protein. It carries the genetic information from DNA to the ribosomes, where the actual synthesis of proteins occurs. The sequence of nucleotides in the mRNA molecule determines the sequence of amino acids in the protein, thus acting as a blueprint or genetic map for protein synthesis. This process is known as translation, where the mRNA is "read" by ribosomes to assemble the correct amino acids in the correct order to form a protein.

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  • 23. 

    What is the role of the r-RNA in protein synthesis?

    • A.

      It translates genetic code to a specific amino acid.

    • B.

      It modifies mRNA molecules prior to protein synthesis.

    • C.

      It provides a genetic map for the protein.

    • D.

      It catalyzes the process.

    Correct Answer
    D. It catalyzes the process.
    Explanation
    r-RNA plays a catalytic role in protein synthesis. It is a component of the ribosome, the cellular machinery responsible for translating mRNA into proteins. Within the ribosome, r-RNA helps to position the mRNA and t-RNA molecules, allowing for the formation of peptide bonds between amino acids. This catalytic activity of r-RNA facilitates the assembly of amino acids into a polypeptide chain, ultimately leading to protein synthesis.

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  • 24. 

    Protein synthesis refers to the ......

    • A.

      Process of formation of amino acids directly from a DNA template.

    • B.

      Process of formation of mRNA from DNA template.

    • C.

      Process of formation of amino acids from mRNA.

    • D.

      Process of duplicating DNA required for protein synthesis.

    Correct Answer
    C. Process of formation of amino acids from mRNA.
    Explanation
    Protein synthesis refers to the process of formation of amino acids from mRNA. This is because mRNA carries the genetic information from the DNA to the ribosomes, where it serves as a template for the assembly of amino acids into proteins. The ribosomes read the mRNA sequence and use it to determine the order of amino acids in the protein chain. This process is essential for the production of proteins, which play a crucial role in various biological functions.

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  • 25. 

    Peptide bond formation between amino acids of growing polypeptide chain is catalysed by .....

    • A.

      Peptidyl transfrase

    • B.

      Amino acyl-tRNA synthetase

    • C.

      Peptide polymerase

    • D.

      Peptidyl synthetase

    Correct Answer
    A. Peptidyl transfrase
    Explanation
    Peptidyl transfrase is the enzyme responsible for catalyzing peptide bond formation between amino acids of a growing polypeptide chain during protein synthesis. It is found in the ribosome and plays a crucial role in the elongation phase of translation. Peptidyl transfrase transfers the amino acid from the tRNA in the A site of the ribosome to the growing polypeptide chain in the P site, forming a peptide bond. This process allows the sequential addition of amino acids to the growing chain, ultimately leading to the synthesis of a functional protein.

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  • 26. 

    Translocation in protein synthesis begins with the .........

    • A.

      Movement of tRNA from A-site to P-site.

    • B.

      Movement of dipeptidyl tRNA from A-site to P-site.

    • C.

      Movement of tRNA from P-site to A-site.

    • D.

      Movement of tRNA from P-site to E-site.

    Correct Answer
    B. Movement of dipeptidyl tRNA from A-site to P-site.
    Explanation
    The correct answer is "Movement of dipeptidyl tRNA from A-site to P-site." During protein synthesis, the ribosome moves along the mRNA strand in a process called translocation. This movement involves shifting the tRNA molecules bound to the A-site and P-site of the ribosome. The A-site holds the incoming aminoacyl-tRNA, while the P-site holds the peptidyl-tRNA. The correct answer indicates the movement of the dipeptidyl-tRNA, which is a tRNA molecule carrying a dipeptide, from the A-site to the P-site. This movement allows the ribosome to add the incoming amino acid to the growing polypeptide chain.

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  • 27. 

    Peptidyl transfrase involved in peptide bond formation, is located in the .....

    • A.

      3’ region of tRNA.

    • B.

      Smaller subunit of ribosome.

    • C.

      Larger subunit of ribosome.

    • D.

      5' region of tRNA.

    Correct Answer
    C. Larger subunit of ribosome.
    Explanation
    The peptidyl transferase enzyme, which is responsible for forming peptide bonds, is located in the larger subunit of the ribosome. The ribosome is composed of two subunits, the smaller subunit and the larger subunit. The larger subunit contains the active site for peptidyl transferase, where the actual peptide bond formation occurs. Therefore, the correct answer is the larger subunit of the ribosome.

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  • 28. 

    Consider a protein with the sequence Lys-Ser-Gly-Ala-Ala-Glu-Tyr-Pro-Thr-Val-Phe. Which of the following statements is correct?

    • A.

      Number of codons on the mRNA responsible for the synthesis of this protein is 10

    • B.

      Number of codons on the mRNA responsible for the synthesis of this protein is more than 10

    • C.

      The first codon on the mRNA responsible for the synthesis of this protein is AUG

    • D.

      The number of nitrogenous bases on the mRNA responsible for the synthesis of this protein is 30

    Correct Answer
    B. Number of codons on the mRNA responsible for the synthesis of this protein is more than 10
    Explanation
    The given protein sequence consists of 11 amino acids. Each amino acid is encoded by a codon on the mRNA. Since there are 11 amino acids, there must be more than 10 codons on the mRNA responsible for the synthesis of this protein.

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  • 29. 

    Which of the following is not a necessary component of translation?

    • A.

      Anticodon

    • B.

      The mRNA

    • C.

      Ligase

    • D.

      Amino acid

    Correct Answer
    C. Ligase
    Explanation
    Ligase is not a necessary component of translation because it is not directly involved in the process of protein synthesis. Translation is the process by which the mRNA molecule is used as a template to assemble a sequence of amino acids in the correct order to form a protein. Anticodon is a necessary component as it is part of the tRNA molecule and helps in matching the codons on the mRNA with the appropriate amino acids. The mRNA molecule itself is essential as it carries the genetic information from DNA to the ribosomes. Amino acids are the building blocks of proteins and are necessary for protein synthesis.

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  • 30. 

    A polysome could be best described as an ……..

    • A.

      Active site of synthesizing the same polypeptide.

    • B.

      Active site of synthesizing different polypeptides.

    • C.

      Active site of DNA replication.

    • D.

      Active site of RNA replication.

    Correct Answer
    A. Active site of synthesizing the same polypeptide.
    Explanation
    A polysome refers to a complex of multiple ribosomes simultaneously translating the same mRNA molecule. This means that the ribosomes in a polysome are all synthesizing the same polypeptide chain. Therefore, the correct answer is "Active site of synthesizing the same polypeptide."

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  • 31. 

    Which of the following is the site for attachment of amino acid in tRNA molecule?

    • A.

      5' end

    • B.

      3' end

    • C.

      Anti-codon loop

    • D.

      None of the above

    Correct Answer
    A. 5' end
    Explanation
    The 5' end of tRNA molecule is the site for attachment of amino acid. This is where the amino acid is covalently attached to the tRNA molecule through an ester bond. The 3' end of tRNA molecule contains the CCA sequence which is important for amino acid attachment, but the actual attachment site is the 5' end. The anti-codon loop is responsible for base-pairing with the codon on mRNA during protein synthesis. Therefore, the correct answer is 5' end.

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  • 32. 

    The promoter is a sequence of nucleotides found on ......

    • A.

      The rRNA

    • B.

      The tRNA

    • C.

      The mRNA

    • D.

      The DNA

    Correct Answer
    D. The DNA
    Explanation
    The promoter is a sequence of nucleotides found on the DNA. It is located upstream of a gene and serves as the binding site for RNA polymerase, which initiates the transcription process. The promoter region contains specific nucleotide sequences that determine the efficiency and specificity of gene transcription.

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  • 33. 

    If the DNA template reads "ATA," then which of the following would be the corresponding sequence on the mRNA?

    • A.

      ATA

    • B.

      TUT

    • C.

      UCU

    • D.

      UAU

    Correct Answer
    D. UAU
    Explanation
    The DNA template reads "ATA," and in mRNA, the base pairs are complementary. In DNA, A pairs with T, so in mRNA, T would pair with A. Therefore, the corresponding sequence on the mRNA would be "UAU."

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  • 34. 

    The followings are some events that take place during protein synthesis. Which is the correct order of these events?

    • A.

      C-B-A-E-D

    • B.

      B-E-A-C-D

    • C.

      D-A-E-C-B

    • D.

      B-C-E-D-A

    Correct Answer
    B. B-E-A-C-D
    Explanation
    The correct order of events during protein synthesis is B-E-A-C-D. This means that first, the DNA molecule unwinds and unzips, exposing the template strand. Then, RNA polymerase binds to the promoter region and begins transcription, where a complementary RNA strand is synthesized. Next, the RNA molecule is modified and processed, including the removal of introns and addition of a 5' cap and poly-A tail. After that, the mRNA molecule moves out of the nucleus and into the cytoplasm, where it binds to a ribosome. Finally, translation occurs, where the sequence of codons on the mRNA is read by tRNA molecules, resulting in the synthesis of a protein.

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  • 35. 

    Which of the following is the mRNA sequence for the DNA sequence: 5’CAAGGT 3’?

    • A.

      GTTCCA

    • B.

      CAAGGU

    • C.

      GUUCCA

    • D.

      CAAGGT

    Correct Answer
    B. CAAGGU
    Explanation
    The mRNA sequence is complementary to the DNA sequence and replaces the T nucleotides with U nucleotides. Therefore, the correct mRNA sequence for the given DNA sequence 5'CAAGGT 3' would be CAAGGU.

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  • 36. 

    Which of the following changes would be expected if a CAUUUG sequence of bases mutated to CACUUG?

    • A.

      The identity of one amino acid would change.

    • B.

      The amino acid sequence would be shorter than expected.

    • C.

      The identity of more than one amino acid would change.

    • D.

      The amino acid sequence would remain unchanged.

    Correct Answer
    A. The identity of one amino acid would change.
    Explanation
    If a CAUUUG sequence of bases mutated to CACUUG, only one base has changed (A to C) in the sequence. This change in the DNA sequence would lead to a change in the corresponding mRNA sequence during transcription. Since the genetic code is read in groups of three bases (codons), this single base change would result in a different codon being formed. As a result, the codon would specify a different amino acid, causing a change in the identity of one amino acid in the protein sequence. Therefore, the correct answer is that the identity of one amino acid would change.

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  • 37. 

    Which of the following is not true concerning protein synthesis?

    • A.

      Each codon on mRNA codes for only one kind of amino acids.

    • B.

      Some amino acids could be coded by more than one codon on the mRNA.

    • C.

      The AUG codon on the mRNA is positioned as the start codon on the A-site of the ribosome.

    • D.

      Some amino acids could be transferred by more than one tRNA.

    Correct Answer
    C. The AUG codon on the mRNA is positioned as the start codon on the A-site of the ribosome.
    Explanation
    The AUG codon on the mRNA is not positioned as the start codon on the A-site of the ribosome.

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  • 38. 

    Which of the following mRNAs can be transcribed from the DNA sequence shown below?

    • A.

      3' AGGUACU 5'

    • B.

      5' AGGUACU 3'

    • C.

      3' UCCAUGA 5'

    • D.

      5' UCCAUGA 3'

    Correct Answer
    B. 5' AGGUACU 3'
    Explanation
    The correct answer is 5' AGGUACU 3'. This is because the DNA sequence is transcribed into mRNA by replacing T with U. Therefore, the mRNA sequence would be 5' AGGUACU 3'.

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  • 39. 

    In a protein molecule, amino acids bonded with each other by ……..

    • A.

      Nitrogenous bases

    • B.

      Peptide bonds

    • C.

      Phosphate groups

    • D.

      Hydrogen bonds

    Correct Answer
    B. Peptide bonds
    Explanation
    Peptide bonds are the type of chemical bonds that connect amino acids together in a protein molecule. These bonds form through a condensation reaction between the carboxyl group of one amino acid and the amino group of another amino acid. This reaction results in the formation of a peptide bond and the release of a water molecule. Peptide bonds are essential for the structure and function of proteins as they create the linear chain of amino acids that fold and interact to form the three-dimensional structure of the protein.

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  • 40. 

    Which of the following DNA sequences can be restricted by endonucleases?

    • A.

      A

    • B.

      B

    • C.

      C

    • D.

      D

    Correct Answer
    B. B
    Explanation
    Endonucleases are enzymes that can recognize specific DNA sequences and cleave the DNA at those sites. Therefore, the correct answer is B because it implies that the DNA sequence in option B can be recognized and cleaved by endonucleases.

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  • 41. 

    Coded messages are transferred from the nucleus to the cytoplasm by means of the ……….. molecule.

    • A.

      Transfer RNA

    • B.

      Ribosomal RNA

    • C.

      Messenger RNA

    • D.

      DNA

    Correct Answer
    C. Messenger RNA
    Explanation
    Messenger RNA (mRNA) is responsible for transferring coded messages from the nucleus to the cytoplasm. It carries the genetic information from DNA in the nucleus to the ribosomes in the cytoplasm, where proteins are synthesized. mRNA acts as a template for protein synthesis, carrying the instructions for the sequence of amino acids that make up the protein. This process is known as transcription, and mRNA plays a crucial role in the transfer of genetic information and protein synthesis.

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  • 42. 

    The following figure illustrates certain reactions that can take place in vitro. What are numbers (1), (2), (3) and (4) respectively?

    • A.

      Messenger RNA / RNA polymerase / DNA polymerase / DNA single strand

    • B.

      DNA single strand / DNA polymerase / DNA ligase / DNA double strands

    • C.

      Messenger RNA / reverse transcriptase / DNA polymerase / DNA double strands

    • D.

      Transfer RNA / RNA polymerase / DNA polymerase / DNA double strands

    Correct Answer
    C. Messenger RNA / reverse transcriptase / DNA polymerase / DNA double strands
  • 43. 

    The number of polymerase enzymes in the nucleus of your body cells is …….

    • A.

      1

    • B.

      2

    • C.

      3

    • D.

      4

    Correct Answer
    D. 4
    Explanation
    The number of polymerase enzymes in the nucleus of your body cells is 4.

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  • 44. 

    Which of the following does the figure shown below represent?

    • A.

      Protein synthesis in cells of a Bean plant

    • B.

      DNA replication in cells of a dog

    • C.

      Transcription and translation in an E. coli cell

    • D.

      Transcription of DNA to RNA in Streptococcus Bacteria

    Correct Answer
    C. Transcription and translation in an E. coli cell
    Explanation
    The figure shown below represents transcription and translation in an E. coli cell. Transcription is the process of synthesizing RNA from a DNA template, and translation is the process of synthesizing proteins using the information encoded in the RNA. In an E. coli cell, both transcription and translation occur in the cytoplasm, allowing for the rapid production of proteins. This is in contrast to eukaryotic cells, where transcription occurs in the nucleus and translation occurs in the cytoplasm. Therefore, the correct answer is transcription and translation in an E. coli cell.

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  • 45. 

    The number of polymerase enzymes in the Escherichia coli is …….

    • A.

      1

    • B.

      2

    • C.

      3

    • D.

      4

    Correct Answer
    B. 2
    Explanation
    Escherichia coli is a bacterium that typically contains two polymerase enzymes, DNA polymerase I and DNA polymerase III. These enzymes are responsible for DNA replication, repair, and recombination. DNA polymerase I has a role in removing RNA primers during replication, while DNA polymerase III is the main enzyme responsible for DNA synthesis. Therefore, the correct answer is 2, indicating that there are two polymerase enzymes in Escherichia coli.

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  • 46. 

    All tRNA molecules have the same ………

    • A.

      General shape

    • B.

      Chemical structure

    • C.

      Amino acids that are carried by them

    • D.

      Anticodons

    Correct Answer
    A. General shape
    Explanation
    All tRNA molecules have the same general shape. This shape consists of a cloverleaf structure with several loops and stems. The loops and stems are formed by base pairing between complementary nucleotides within the tRNA molecule. This general shape allows tRNA molecules to interact with other molecules involved in protein synthesis, such as ribosomes and amino acids. While tRNA molecules may vary in their specific nucleotide sequences and anticodons, they all share this common general shape.

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  • 47. 

    What is the mRNA that can be transcribed from the following sequence of DNA: 5’- C-C-G-T-A-T-G-C-T-G-C-C-3’

    • A.

      5’-C-C-G-U-A-U-G-C-U-G-C-C-3’

    • B.

      5’-C-C-G-T-A-T-G-C-T-G-C-C-3’

    • C.

      3’-G-G-C-A-U-A-C-G-A-C-G-G-5’

    • D.

      3’-C-C-G-T-A-T-G-C-T-G-C-C-5’

    Correct Answer
    A. 5’-C-C-G-U-A-U-G-C-U-G-C-C-3’
    Explanation
    The correct answer is 5’-C-C-G-U-A-U-G-C-U-G-C-C-3’ because in mRNA, the base thymine (T) is replaced by uracil (U). Therefore, the mRNA transcribed from the given DNA sequence would have the same sequence except for the replacement of T with U.

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  • 48. 

    The sequence that is found at the 3’ end of the tRNA molecule is …...

    • A.

      AUG

    • B.

      UGA

    • C.

      CCA

    • D.

      CGA

    Correct Answer
    C. CCA
    Explanation
    The sequence CCA is found at the 3' end of the tRNA molecule. This sequence is important for the binding of specific amino acids to the tRNA during protein synthesis. The 3' end of the tRNA molecule contains a CCA sequence that serves as a binding site for the amino acid. This allows the tRNA to carry the correct amino acid to the ribosome during translation.

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  • 49. 

    The least number of tRNA molecules needed to form a polypeptide chain that consists of 50 amino acids of 15 type is …….. molecules.

    • A.

      15

    • B.

      20

    • C.

      35

    • D.

      50

    Correct Answer
    A. 15
    Explanation
    The least number of tRNA molecules needed to form a polypeptide chain that consists of 50 amino acids of 15 types is 15 molecules. Each tRNA molecule can only carry one specific amino acid, so for a polypeptide chain with 50 amino acids of 15 types, there needs to be at least one tRNA molecule for each type of amino acid. Therefore, 15 tRNA molecules are needed.

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  • 50. 

    To form a protein of 150 amino acids, the number of nucleotides found on the mRNA is at least …….. nucleotides.

    • A.

      50

    • B.

      150

    • C.

      300

    • D.

      450

    Correct Answer
    D. 450
    Explanation
    To form a protein of 150 amino acids, each amino acid is coded by a sequence of three nucleotides on the mRNA. Therefore, the number of nucleotides needed is 150 x 3 = 450 nucleotides.

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