IB Questionbank

Updates to Questionbank

User interface language: English | Español

Syllabus

Topic 7: Nucleic acids

Path:

Additional higher level » Topic 7: Nucleic acids

Description

Overview of the essential ideas for this topic.

7.1: The structure of DNA is ideally suited to its function.

7.2: Information stored as a code in DNA is copied onto mRNA.

7.3: Information transferred from DNA to mRNA is translated into an amino acid sequence.

Directly related questions

16N.1.SL.TZ0.15: Which is a valid comparison between prokaryotic and eukaryotic DNA?
17M.1.HL.TZ2.9: Scientists have heated a solution containing the protein albumin and measured its relative alpha...
20N.1.HL.TZ0.28:
The diagram shows the three-dimensional structure of tRNA.

[Source: Structure reproduced with the kind permission of N.R. Voss.]

What can attach to the region marked X?

A. mRNA

B. An amino acid

C. An anticodon

D. The P site of the ribosome
17N.1.HL.TZ0.26: Some regions of DNA do not code for the production of proteins. What are these regions of DNA...
21N.2.HL.TZ0.6a:
Draw labelled diagrams to show the structure of RNA nucleotides and how they are linked together to form a molecule of RNA.
22M.2.HL.TZ2.5a.iii:
There are multiple tandem repeats of nucleotide segments of DNA found in the non-coding DNA between genes. Outline how tandem repeats are used for DNA profiling.
22M.1.HL.TZ2.26:
The diagram shows the structure of a nucleosome.

[Source: Zephyris. Nucleosome 1KX5 colour coded. Available at https://en.wikipedia.org/wiki/Nucleosome#/media/File:Nucleosome_1KX5_colour_coded.png
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license (https://creativecommons.org/licenses/by-sa/3.0/deed.en).]

What is the structure labelled T?

A. 5' end of RNA

B. 5' end of uncoiled DNA

C. N-terminal tail of one DNA strand

D. N-terminal tail of one histone
18M.2.HL.TZ1.4c: Distinguish between the purpose of free and bound ribosomes.
18M.2.HL.TZ2.2b.ii: Outline how Hershey and Chase’s experiment provided evidence for DNA as the genetic material.
19M.1.HL.TZ1.27:
The diagram shows the arrangement of introns and exons in a segment of pre-mRNA. Pre-mRNA is immature mRNA containing introns and exons.

Which is a mature mRNA molecule derived from the pre-mRNA by splicing?

[Source: © International Baccalaureate Organization 2019]
19M.2.HL.TZ1.7a: Outline the roles of helicase and ligase in DNA replication.
17M.1.HL.TZ2.11: This image is taken from a visualization of a eukaryotic ribosome. The arrows show the direction...
17N.3.HL.TZ0.03a:
The Hershey and Chase experiment supported DNA as the hereditary material. Describe the experiment.
21M.1.HL.TZ1.27: Which statement applies to tRNA? A. There is at least one type of tRNA that combines with each...
21M.1.HL.TZ2.26:
The graph shows results of an experiment by Hershey and Chase in 1952 in which bacteria were infected with a mixture of virus particles labelled with either ³²P or ³⁵S. A suspension of the infected bacteria was agitated with a blender, and samples collected from the suspension were centrifuged to record the percentage of isotope remaining on the outside of the cells.

[Source: Republished with permission of ROCKEFELLER UNIVERSITY PRESS, from Independent functions of protein and nucleic acid in growth of bacteriophage. Hershey, A.D. and Chase, M., 1952. (Journal of General Physiology, 36(1), p.47). Society of General Physiologists, Rockefeller Institute for Medical Research, Rockefeller Institute; permission conveyed through Copyright Clearance Center, Inc.]

What do curves X and Y represent?
21N.1.HL.TZ1.26:
Rosalind Franklin produced X-ray diffraction images of DNA.

[Source: © King’s College, London. KCL Department of Biophysics KDBP/1/1.]

Which previously unknown aspect of DNA was deduced from these images?

A. Chromosomes are made of DNA.

B. Deoxyribose sugar is attached to a phosphate group.

C. The base A pairs with T and C with G.

D. The DNA molecule is a double helix.
21N.1.HL.TZ1.28:
What is the primary function of the free ribosomes shown in the electron micrograph?

[Source: J Gordon Betts, et al. Anatomy and Physiology. Houston Texas: OpenStax, 2013. https://openstax.org/books/
anatomy-and-physiology/pages/3-2-the-cytoplasm-and-cellular-organelles. Image file available at https://commons.
wikimedia.org/wiki/File:0313_Endoplasmic_Reticulum.jpg#/media/File:0313_Endoplasmic_Reticulum_b_labeled.
png. This file is licensed under the Creative Commons Attribution 3.0 Unported license. https://creativecommons.org/
licenses/by/3.0/deed.en.]

A. Synthesize proteins to be used within the cell

B. Synthesize proteins for use in lysosomes

C. Carry amino acids to mRNA for protein synthesis

D. Synthesize proteins for secretion
22M.1.HL.TZ1.26: The image shows a replication fork. Which row identifies X, Y and Z in the diagram?
18N.2.HL.TZ0.2a.i:
Label a peptide bond in the diagram of a polypeptide.
18M.1.HL.TZ2.11: How can environmental factors affect the expression of genes? A. By promoting the replication of...
18M.2.HL.TZ2.2c.ii:
Outline the role of tRNA activating enzymes in translation.
19M.2.HL.TZ2.2b.ii: Suggest a way methylation may affect tumour cell genes.
19M.2.HL.TZ2.2a.iii:
DNA has regions that do not code for proteins. State two functions of these regions.

1.

2.
16N.1.HL.TZ0.27: What does post-transcriptional modification of eukaryotic mRNA include? I. Introns are removed...
17M.1.HL.TZ1.28: Which types of interactions are found in a part of a protein with secondary but not tertiary...
17M.2.HL.TZ2.8c: Explain the control of gene expression in eukaryotes.
17M.2.HL.TZ2.6b: Outline the roles of the different binding sites for tRNA on ribosomes during translation.
17N.2.HL.TZ0.07b:
Nitrogen is part of many important substances in living organisms.

Distinguish between transcription and translation.
17N.1.HL.TZ0.27:
Which letter (A–D) indicates where a new nucleotide would attach?
17N.1.HL.TZ0.28: Which cell component synthesizes actin and myosin? A. Free ribosomes B. Rough endoplasmic...
21M.1.HL.TZ1.26: Which regions of DNA code for the production of specific proteins? A. Telomeres B. Genes for...
22M.2.HL.TZ2.5a.i: Describe the structure of nucleosomes.
22M.1.HL.TZ1.28:
This DNA sequence was used to synthesize a polypeptide.

DNA (sense strand): 3′ T A C T G A 5′

DNA (template strand): 5′ A T G A C T 3′

Which are the bases of the tRNA (anticodons)?

A. T A C T G A

B. U A C U G A

C. A U G A C U

D. A T G A C T
18N.1.HL.TZ0.26: Current understanding of DNA is an example of the accumulated discoveries of many scientists....
18M.2.HL.TZ2.2b.iii: State one function for a region of DNA that does not code for proteins.
18M.2.HL.TZ2.2c.i: Outline the role of the A-site of ribosomes in translation.
16N.2.HL.TZ0.7c:
Growth in living organisms includes replication of DNA. Explain DNA replication.
17M.1.SL.TZ1.1: Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C....
17M.1.HL.TZ1.27: The diagram shows how pre-mRNA is processed into mature mRNA. Which structures are indicated by...
17M.2.HL.TZ1.2a.i: Nucleosomes help to regulate transcription in eukaryotes. State the components of a nucleosome.
21M.1.HL.TZ2.28: The mRNA codon UAC codes for the amino acid tyrosine. Which tRNA carries tyrosine?
19M.1.HL.TZ1.28:
The image shows a polysome in a bacterial cell.

[Source: © International Baccalaureate Organization 2019]

How many genes have been transcribed?

A. 1

B. 2

C. 3

D. 4
19M.1.HL.TZ1.26: What contribution did the X-ray diffraction conducted by Rosalind Franklin make to our...
19M.1.HL.TZ2.13: A nucleotide containing dideoxyribose is shown. What is the reason for the use of...
16N.1.HL.TZ0.26: Where does a tRNA-activating enzyme attach the appropriate amino acid to the tRNA molecule?
17M.1.HL.TZ2.12:
In which process(es) do nucleosomes play a role in eukaryotes?

I. tRNA activation

II. Transcription regulation

III. DNA supercoiling

A. I only

B. II only

C. II and III only

D. I, II and III
18N.2.HL.TZ0.3a: State one similarity and one difference between the structure of genes and short tandem repeats.
18N.2.HL.TZ0.2a.ii: Outline the primary structure of proteins.
18M.1.HL.TZ2.12:
In which image are polysomes visible? (The images do not have the same magnification)
18M.2.HL.TZ2.2b.i: State one role of nucleosomes in eukaryotic cells.
19M.1.HL.TZ2.11:
Hershey and Chase used a bacteriophage (a virus that infects bacteria) to investigate the chemical nature of genes. The diagram shows a bacteriophage.

[Source: Graham Knott and Christel Genoud, ‘Commentary: is EM dead?’, Journal of Cell Science (2013),
126: 4545–4552, reproduced with permission. http://jcs.biologists.org/content/126/20/4545.figures-only
doi: 10.1242/jcs.124123 http://www.biologists.com/journal-of-cell-science]

The sulphur in the protein and the phosphorus in the DNA of the bacteriophage were radioactively labelled. The data obtained after bacterial infection and centrifugation are shown in the table.

What did Hershey and Chase conclude from their experiment?

A. DNA was mainly outside the bacterial cells.

B. Viruses infect bacterial cells with proteins.

C. Viral DNA was found within the bacterial cells.

D. Neither protein nor DNA were chemicals making up genes in viruses.
20N.2.HL.TZ0.6c:
Explain how polypeptides are produced by the process of translation.
20N.1.HL.TZ0.26: The number of protein-coding genes in the human genome is estimated to be about 20 000, which is...
21M.1.HL.TZ2.27:
What is a feature of transcription in the single-celled organism shown in the electron micrograph?

[Source: George E. Palade Electron Microscopy Slide Collection Harvey Cushing/John Hay Whitney Medical Library Yale University Library.]

A. mRNA splicing

B. Removal of introns

C. Codon-anticodon binding

D. Synthesis of RNA in a 5′ to 3′ direction
22M.1.HL.TZ1.27: During modification in eukaryotes, mRNA is spliced. What is splicing of mRNA? A. Separation of...
18N.2.HL.TZ0.3b: Outline the role of short tandem repeats in DNA profiling.
18M.1.HL.TZ1.28: What are polysomes? A. Strings of amino acids B. Packages of eight histones with DNA C. Many...
19N.1.HL.TZ0.27:
In the diagram of a ribosome, which letter indicates the P site?

[Source: iStock.com/ttsz]
16N.1.HL.TZ0.28: Variations in the types of antibodies are produced by mRNA splicing. What is an advantage of this...
17M.2.HL.TZ1.2a.ii: Nucleosomes help to regulate transcription in eukaryotes. State a chemical modification of a...
20N.1.HL.TZ0.27: Which are two proteins that assist in the unwinding and separation of DNA strands during...
21N.2.HL.TZ0.6b:
Explain transcription.
22M.1.HL.TZ2.28:
The diagram shows the structure of E. coli ribonuclease HI, a bacterial protein consisting of one polypeptide chain.

[Source: RCSB PDB. 1JL1 D10A E. coli ribonuclease HI. PDB DOI: 10.2210/pdb1JL1/pdb Mol* (Goedken, E.R., Marqusee, S. Native-state energetics of a thermostabilized variant of ribonuclease HI. (2001) J Mol Biol 314:
863–871 DOI:10.1006/jmbi.2001.5184) [image online] Available at: https://www.rcsb.org/structure/1jl1
[Accessed 25 November 2019]. This file is licensed under the Creative Commons CC0 1.0 Universal (https://creativecommons.org/publicdomain/zero/1.0/).]

Which level(s) of protein structure is/are shown?

A. Alpha helix only

B. Quaternary only

C. Primary and secondary

D. Secondary and tertiary
22M.1.HL.TZ2.27: Promoters are non-coding regions in DNA. What is the role of a promoter? A. It starts...
18M.1.HL.TZ1.27: What does eukaryotic DNA have that is missing from prokaryotic DNA? A. Uracil B. Promoter...
18M.1.HL.TZ2.10: Gene expression in cells is regulated at various stages. During which stage does splicing of RNA...
18M.2.HL.TZ2.4a: The diagram shows alpha amylase. Explain the secondary structure of this protein molecule.
19M.1.HL.TZ2.12: What are the functions of DNA primase and DNA polymerase I in DNA replication?
19M.1.HL.TZ2.14: What applies to DNA base sequences? I. Some genes do not code for proteins. II. Promoters are...
19M.2.HL.TZ2.2b.i: Outline the difference in methylation pattern between tumorous and normal tissue samples.
19N.2.HL.TZ0.6c: Explain how a polypeptide chain is synthesized in a eukaryotic cell.
19N.1.HL.TZ0.28: How do R group interactions contribute to protein structure? I. Determining the sequence of...
21N.1.HL.TZ1.27:
What is the difference between the DNA of adult identical (monozygotic) twins?

A. Order of genes

B. Sequence of nucleotides

C. Methylation pattern

D. Ratio of complementary base pairs
21N.2.HL.TZ0.4b:
Describe the secondary structure of proteins.
19N.1.HL.TZ0.26: What is a function of DNA polymerase I? A. Adds nucleotides in a 5’ to 3’ direction to elongate...

Sub sections and their related questions

7.1 DNA structure and replication

16N.1.SL.TZ0.15: Which is a valid comparison between prokaryotic and eukaryotic DNA?
16N.2.HL.TZ0.7c:
Growth in living organisms includes replication of DNA. Explain DNA replication.
17M.1.SL.TZ1.1: Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C....
17M.1.HL.TZ1.27: The diagram shows how pre-mRNA is processed into mature mRNA. Which structures are indicated by...
17M.2.HL.TZ1.2a.i: Nucleosomes help to regulate transcription in eukaryotes. State the components of a nucleosome.
17N.3.HL.TZ0.03a:
The Hershey and Chase experiment supported DNA as the hereditary material. Describe the experiment.
17N.1.HL.TZ0.27:
Which letter (A–D) indicates where a new nucleotide would attach?
18M.1.HL.TZ1.27: What does eukaryotic DNA have that is missing from prokaryotic DNA? A. Uracil B. Promoter...
18M.2.HL.TZ2.2b.i: State one role of nucleosomes in eukaryotic cells.
18M.2.HL.TZ2.2b.ii: Outline how Hershey and Chase’s experiment provided evidence for DNA as the genetic material.
18M.2.HL.TZ2.2b.iii: State one function for a region of DNA that does not code for proteins.
18N.1.HL.TZ0.26: Current understanding of DNA is an example of the accumulated discoveries of many scientists....
18N.2.HL.TZ0.3a: State one similarity and one difference between the structure of genes and short tandem repeats.
18N.2.HL.TZ0.3b: Outline the role of short tandem repeats in DNA profiling.
19M.1.HL.TZ1.26: What contribution did the X-ray diffraction conducted by Rosalind Franklin make to our...
19M.1.HL.TZ1.27:
The diagram shows the arrangement of introns and exons in a segment of pre-mRNA. Pre-mRNA is immature mRNA containing introns and exons.

Which is a mature mRNA molecule derived from the pre-mRNA by splicing?

[Source: © International Baccalaureate Organization 2019]
19M.1.HL.TZ2.11:
Hershey and Chase used a bacteriophage (a virus that infects bacteria) to investigate the chemical nature of genes. The diagram shows a bacteriophage.

[Source: Graham Knott and Christel Genoud, ‘Commentary: is EM dead?’, Journal of Cell Science (2013),
126: 4545–4552, reproduced with permission. http://jcs.biologists.org/content/126/20/4545.figures-only
doi: 10.1242/jcs.124123 http://www.biologists.com/journal-of-cell-science]

The sulphur in the protein and the phosphorus in the DNA of the bacteriophage were radioactively labelled. The data obtained after bacterial infection and centrifugation are shown in the table.

What did Hershey and Chase conclude from their experiment?

A. DNA was mainly outside the bacterial cells.

B. Viruses infect bacterial cells with proteins.

C. Viral DNA was found within the bacterial cells.

D. Neither protein nor DNA were chemicals making up genes in viruses.
19M.1.HL.TZ2.12: What are the functions of DNA primase and DNA polymerase I in DNA replication?
19M.1.HL.TZ2.13: A nucleotide containing dideoxyribose is shown. What is the reason for the use of...
19M.1.HL.TZ2.14: What applies to DNA base sequences? I. Some genes do not code for proteins. II. Promoters are...
19M.2.HL.TZ1.7a: Outline the roles of helicase and ligase in DNA replication.
19M.2.HL.TZ2.2a.iii:
DNA has regions that do not code for proteins. State two functions of these regions.

1.

2.
19N.1.HL.TZ0.26: What is a function of DNA polymerase I? A. Adds nucleotides in a 5’ to 3’ direction to elongate...
20N.1.HL.TZ0.27: Which are two proteins that assist in the unwinding and separation of DNA strands during...
21M.1.HL.TZ1.26: Which regions of DNA code for the production of specific proteins? A. Telomeres B. Genes for...
21M.1.HL.TZ1.27: Which statement applies to tRNA? A. There is at least one type of tRNA that combines with each...
21M.1.HL.TZ2.26:
The graph shows results of an experiment by Hershey and Chase in 1952 in which bacteria were infected with a mixture of virus particles labelled with either ³²P or ³⁵S. A suspension of the infected bacteria was agitated with a blender, and samples collected from the suspension were centrifuged to record the percentage of isotope remaining on the outside of the cells.

[Source: Republished with permission of ROCKEFELLER UNIVERSITY PRESS, from Independent functions of protein and nucleic acid in growth of bacteriophage. Hershey, A.D. and Chase, M., 1952. (Journal of General Physiology, 36(1), p.47). Society of General Physiologists, Rockefeller Institute for Medical Research, Rockefeller Institute; permission conveyed through Copyright Clearance Center, Inc.]

What do curves X and Y represent?
21N.1.HL.TZ1.26:
Rosalind Franklin produced X-ray diffraction images of DNA.

[Source: © King’s College, London. KCL Department of Biophysics KDBP/1/1.]

Which previously unknown aspect of DNA was deduced from these images?

A. Chromosomes are made of DNA.

B. Deoxyribose sugar is attached to a phosphate group.

C. The base A pairs with T and C with G.

D. The DNA molecule is a double helix.
21N.1.HL.TZ1.27:
What is the difference between the DNA of adult identical (monozygotic) twins?

A. Order of genes

B. Sequence of nucleotides

C. Methylation pattern

D. Ratio of complementary base pairs
22M.1.HL.TZ1.26: The image shows a replication fork. Which row identifies X, Y and Z in the diagram?
22M.1.HL.TZ2.26:
The diagram shows the structure of a nucleosome.

[Source: Zephyris. Nucleosome 1KX5 colour coded. Available at https://en.wikipedia.org/wiki/Nucleosome#/media/File:Nucleosome_1KX5_colour_coded.png
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license (https://creativecommons.org/licenses/by-sa/3.0/deed.en).]

What is the structure labelled T?

A. 5' end of RNA

B. 5' end of uncoiled DNA

C. N-terminal tail of one DNA strand

D. N-terminal tail of one histone
22M.2.HL.TZ2.5a.i: Describe the structure of nucleosomes.
22M.2.HL.TZ2.5a.iii:
There are multiple tandem repeats of nucleotide segments of DNA found in the non-coding DNA between genes. Outline how tandem repeats are used for DNA profiling.

7.2 Transcription and gene expression

7.3 Translation

16N.1.HL.TZ0.26: Where does a tRNA-activating enzyme attach the appropriate amino acid to the tRNA molecule?
16N.1.HL.TZ0.27: What does post-transcriptional modification of eukaryotic mRNA include? I. Introns are removed...
16N.1.HL.TZ0.28: Variations in the types of antibodies are produced by mRNA splicing. What is an advantage of this...
17M.1.SL.TZ1.1: Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C....
17M.1.HL.TZ1.28: Which types of interactions are found in a part of a protein with secondary but not tertiary...
17M.1.HL.TZ2.9: Scientists have heated a solution containing the protein albumin and measured its relative alpha...
17M.1.HL.TZ2.11: This image is taken from a visualization of a eukaryotic ribosome. The arrows show the direction...
17M.2.HL.TZ2.6b: Outline the roles of the different binding sites for tRNA on ribosomes during translation.
17N.2.HL.TZ0.07b:
Nitrogen is part of many important substances in living organisms.

Distinguish between transcription and translation.
17N.1.HL.TZ0.28: Which cell component synthesizes actin and myosin? A. Free ribosomes B. Rough endoplasmic...
18M.1.HL.TZ1.28: What are polysomes? A. Strings of amino acids B. Packages of eight histones with DNA C. Many...
18M.2.HL.TZ1.4c: Distinguish between the purpose of free and bound ribosomes.
18M.2.HL.TZ2.2c.i: Outline the role of the A-site of ribosomes in translation.
18M.2.HL.TZ2.2c.ii:
Outline the role of tRNA activating enzymes in translation.
18M.2.HL.TZ2.4a: The diagram shows alpha amylase. Explain the secondary structure of this protein molecule.
18M.1.HL.TZ2.12:
In which image are polysomes visible? (The images do not have the same magnification)
18N.2.HL.TZ0.2a.i:
Label a peptide bond in the diagram of a polypeptide.
18N.2.HL.TZ0.2a.ii: Outline the primary structure of proteins.
19M.1.HL.TZ1.28:
The image shows a polysome in a bacterial cell.

[Source: © International Baccalaureate Organization 2019]

How many genes have been transcribed?

A. 1

B. 2

C. 3

D. 4
19N.2.HL.TZ0.6c: Explain how a polypeptide chain is synthesized in a eukaryotic cell.
19N.1.HL.TZ0.27:
In the diagram of a ribosome, which letter indicates the P site?

[Source: iStock.com/ttsz]
19N.1.HL.TZ0.28: How do R group interactions contribute to protein structure? I. Determining the sequence of...
20N.2.HL.TZ0.6c:
Explain how polypeptides are produced by the process of translation.
20N.1.HL.TZ0.28:
The diagram shows the three-dimensional structure of tRNA.

[Source: Structure reproduced with the kind permission of N.R. Voss.]

What can attach to the region marked X?

A. mRNA

B. An amino acid

C. An anticodon

D. The P site of the ribosome
21M.1.HL.TZ2.28: The mRNA codon UAC codes for the amino acid tyrosine. Which tRNA carries tyrosine?
21N.1.HL.TZ1.28:
What is the primary function of the free ribosomes shown in the electron micrograph?

[Source: J Gordon Betts, et al. Anatomy and Physiology. Houston Texas: OpenStax, 2013. https://openstax.org/books/
anatomy-and-physiology/pages/3-2-the-cytoplasm-and-cellular-organelles. Image file available at https://commons.
wikimedia.org/wiki/File:0313_Endoplasmic_Reticulum.jpg#/media/File:0313_Endoplasmic_Reticulum_b_labeled.
png. This file is licensed under the Creative Commons Attribution 3.0 Unported license. https://creativecommons.org/
licenses/by/3.0/deed.en.]

A. Synthesize proteins to be used within the cell

B. Synthesize proteins for use in lysosomes

C. Carry amino acids to mRNA for protein synthesis

D. Synthesize proteins for secretion
21N.2.HL.TZ0.4b:
Describe the secondary structure of proteins.
22M.1.HL.TZ1.28:
This DNA sequence was used to synthesize a polypeptide.

DNA (sense strand): 3′ T A C T G A 5′

DNA (template strand): 5′ A T G A C T 3′

Which are the bases of the tRNA (anticodons)?

A. T A C T G A

B. U A C U G A

C. A U G A C U

D. A T G A C T
22M.1.HL.TZ2.28:
The diagram shows the structure of E. coli ribonuclease HI, a bacterial protein consisting of one polypeptide chain.

[Source: RCSB PDB. 1JL1 D10A E. coli ribonuclease HI. PDB DOI: 10.2210/pdb1JL1/pdb Mol* (Goedken, E.R., Marqusee, S. Native-state energetics of a thermostabilized variant of ribonuclease HI. (2001) J Mol Biol 314:
863–871 DOI:10.1006/jmbi.2001.5184) [image online] Available at: https://www.rcsb.org/structure/1jl1
[Accessed 25 November 2019]. This file is licensed under the Creative Commons CC0 1.0 Universal (https://creativecommons.org/publicdomain/zero/1.0/).]

Which level(s) of protein structure is/are shown?

A. Alpha helix only

B. Quaternary only

C. Primary and secondary

D. Secondary and tertiary