| Date | November 2021 | Marks available | 2 | Reference code | 21N.2.HL.TZ0.4 |
| Level | Higher level | Paper | Paper 2 | Time zone | TZ0 / no time zone |
| Command term | Describe | Question number | 4 | Adapted from | N/A |
Question
The figure shows a tripeptide.
Label one peptide bond in this molecule.
Describe the secondary structure of proteins.
Outline the action taken by the diaphragm during inhalation.
Markscheme
circle/bracket around peptide bond / arrow pointing to peptide bond / peptide bond labelled;
Allow either peptide bond
Allow if adjacent C=O and NH groups are included in the circle/bracket, but do not allow if other parts of the molecule are included.
a. polypeptide wound into a helical structure / alpha/α helix
OR
polypeptide folded back on itself forming a pleated sheet / beta/β pleated sheet;
b. stabilized/held in shape by/due to hydrogen bonds (between C=O and N-H groups);
c. secondary structures are regular/unvarying (within polypeptides/proteins);
Allow annotated diagrams
contracts/flattens/becomes less domed/increases volume of thorax;
Examiners report
80 % of candidates indicated one of the two peptide bonds in the diagram correctly.
There were some good answers here describing secondary structures and the role of hydrogen bonding.
80 % of candidates knew that the diaphragm contracts than relaxes during inhalation, or stated that it flattens rather than moves upwards.
Syllabus sections
- 17M.1.HL.TZ2.11: This image is taken from a visualization of a eukaryotic ribosome. The arrows show the...
-
18M.1.HL.TZ2.12:
In which image are polysomes visible? (The images do not have the same magnification)
- 17M.1.HL.TZ2.9: Scientists have heated a solution containing the protein albumin and measured its relative...
- 16N.1.HL.TZ0.26: Where does a tRNA-activating enzyme attach the appropriate amino acid to the tRNA molecule?
- 18M.2.HL.TZ2.4a: The diagram shows alpha amylase. Explain the secondary structure of this protein molecule.
-
18M.2.HL.TZ2.2c.ii:
Outline the role of tRNA activating enzymes in translation.
- 18M.2.HL.TZ2.2c.i: Outline the role of the A-site of ribosomes in translation.
-
18N.2.HL.TZ0.2a.i:
Label a peptide bond in the diagram of a polypeptide.
- 17M.1.SL.TZ1.1: Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C....
- 16N.1.HL.TZ0.27: What does post-transcriptional modification of eukaryotic mRNA include? I. Introns are...
- 18M.1.HL.TZ1.28: What are polysomes? A. Strings of amino acids B. Packages of eight histones with DNA C....
- 21M.1.HL.TZ2.28: The mRNA codon UAC codes for the amino acid tyrosine. Which tRNA carries tyrosine?
-
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
- 17N.1.HL.TZ0.28: Which cell component synthesizes actin and myosin? A. Free ribosomes B. Rough endoplasmic...
-
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
-
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
- 17M.1.HL.TZ1.28: Which types of interactions are found in a part of a protein with secondary but not tertiary...
- 18M.2.HL.TZ1.4c: Distinguish between the purpose of free and bound ribosomes.
- 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.1.HL.TZ0.28: How do R group interactions contribute to protein structure? I. Determining the sequence of...
- 17M.2.HL.TZ2.6b: Outline the roles of the different binding sites for tRNA on ribosomes during translation.
- 16N.1.HL.TZ0.28: Variations in the types of antibodies are produced by mRNA splicing. What is an advantage of...
- 19N.2.HL.TZ0.6c: Explain how a polypeptide chain is synthesized in a eukaryotic cell.
-
17N.2.HL.TZ0.07b:
Nitrogen is part of many important substances in living organisms.
Distinguish between transcription and translation.
-
20N.2.HL.TZ0.6c:
Explain how polypeptides are produced by the process of translation.
-
19N.1.HL.TZ0.27:
In the diagram of a ribosome, which letter indicates the P site?
[Source: iStock.com/ttsz]
-
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
