Syllabus Edition

First teaching 2014

Last exams 2024

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Translation (DP IB Biology: HL)

Exam Questions

3 hours35 questions
1a
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1 mark

The diagram below shows the structure of a tRNA molecule.

structure-of-trna-sq

Identify the type of molecule that would bind to site A.

1b
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2 marks
(i)

Identify the type of bond present at B.

[1]

(ii)

State the purpose of these bonds in a tRNA molecule.

[1]

1c
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2 marks

Describe the role of C in the process of translation.

1d
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1 mark

Before tRNA molecules can partake in translation, they bind to tRNA-activating enzymes.

State the purpose of tRNA-activating enzymes.

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2a
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1 mark

The following diagram shows polysomes.

prokaryotic-polysomes-sq

Define the term 'polysome'.

2b
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2 marks

Polysomes are present in both prokaryotic and eukaryotic cells.

(i)

Identify whether the polysomes in the diagram at part a) are prokaryotic or eukaryotic.

[1]

(ii)

State a reason for your answer at part b) i).

[1]

2c
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1 mark

Describe one advantage of polysomes.

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3a
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2 marks

The diagram below shows the secondary structure of a protein.

kWNOSr2H_hl-ib-7-3-e-q3a

Identify structures S and U.

3b
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2 marks

The structure of a protein is held together by different types of chemical bonds.

Label the bonds R and T in the diagram.

3c
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2 marks

Describe how the bond at T forms and the way it contributes to the secondary structure of a protein.

3d
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1 mark

Explain how a mutation would affect the primary structure of a protein.

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4a
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1 mark

The diagram below shows a ribosome producing proteins that are to be secreted from the cell. In order for this to occur, the ribosome must bind to organelle X.

VMU7SmIw_hl-ib-7-3-e-q4a

State the name of organelle X.

4b
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2 marks

Binding to Y will result in the ribosome moving towards organelle X and binding to Z.

Identify Y and Z in the diagram.

4c
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1 mark

State the effect that binding to Y would have on the process of translation.

4d
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2 marks

Describe the path of the protein after it is produced, until it is secreted out of the cell.

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5a
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4 marks

One mark is available for clarity of communication throughout this question.

Ribosomes play an important role during the process of translation.

Describe the structure of ribosomes.

5b
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3 marks

Outline the steps involved in the initiation of translation.

5c
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6 marks

Proteins are large, complex molecules that have several levels comprising their structure.

Describe the tertiary structure of proteins.

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1a2 marks

Messenger RNA (mRNA) and transfer RNA (tRNA) are important molecules required for the transcription and translation of proteins. 

Contrast the structures of mRNA and tRNA.

1b3 marks

Describe the role of tRNA in the process of translation.

1c1 mark

Tobacco plants have been genetically modified to produce human haemoglobin. The first three triplets of the antisense strand of the human haemoglobin gene are:

                                   ATG GTG CAT 

Identify the anticodons of the corresponding tRNA molecule.

1d1 mark

The base sequence below is found in a section of the mRNA strand used to synthesise an enzyme found in tobacco plants.

G   U   U   A   A   A   G   U   U   U   C   A   A   C   G   A   A   A   A   A   C

Using the diagram, deduce how many different types of tRNA molecules would attach to the section of mRNA shown in the diagram?

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2a3 marks

The table below shows some of the events which take place in protein synthesis.

A

mRNA nucleotides join with exposed DNA bases and form a molecule of mRNA

B

Peptide bonds form between the amino acids

C

tRNA molecules bring specific amino acids to the mRNA molecule

D

The introns are spliced from the pre-mRNA to produce mRNA

E

A ribosome attaches to the mRNA molecule

F

The two strands of a DNA molecule separate

G

The mRNA molecule leaves the nucleus

Identify the correct order of letters to show the sequence of events during protein synthesis, starting with the earliest.

2b1 mark

Haemoglobin is a protein made of alpha and beta polypeptides. Each alpha polypeptide has 141 amino acids and each beta polypeptide has 146 amino acids.

Deduce the total number of peptide bonds present in one alpha polypeptide and one beta polypeptide.

2c2 marks

Haemoglobin is a quaternary protein.

Describe the structures of haemoglobin that make it a quaternary protein.

2d3 marks

State the types of bonding present in the different levels of protein structure.

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3a4 marks

Describe the function of ribosomes in protein synthesis.

3b2 marks

Within a cell ribosomes can be found free or bound to structures.

Contrast free ribosomes with bound ribosomes.

3c1 mark

The image below shows the structure of a ribosome. Ribosomes contain an A site, an E site, and a P site.

q3c_7-3_translation_medium_ib_hl_biology_sq

Label the A site, the E site, and the P site on the image above.

3d2 marks

Ribosomes are made of ribosomal RNA (rRNA). Messenger RNA (mRNA), transfer RNA (tRNA) and DNA are all involved in the synthesis of proteins.

Complete the table to show the differences between DNA, mRNA and tRNA.

Type of nucleic acid

Number of polynucleotide strands in the molecule

The nitrogenous base uracil present (✓) or not present (X)

DNA

   

mRNA

   

tRNA

   

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4a4 marks

Enzymes play an important role during transcription and translation.

Discuss the importance of enzyme-substrate specificity in the activation of tRNA molecules.

4b3 marks

The tRNA-activating enzyme relies on phosphorylation.

Outline the role of phosphorylation during translation.

4c2 marks

Enzymes, such as the tRNA-activating enzyme, are proteins.

State, with named examples, two functions of proteins.

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5a6 marks

One mark is available for clarity of communication throughout this question. 

Describe how the process of translation leads to the production of a polypeptide.

5b5 marks

Explain why cellular enzymes are made predominantly from protein.

5c4 marks

Contrast protein synthesis in eukaryotes with protein synthesis in prokaryotes. 

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1a
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1 mark

The following diagram shows a section of mRNA containing five codons. 

6-2-fig-5-1

The triplets of bases in a DNA molecule that codes for some of the amino acids are listed in the table below.

Amino acid Abbreviation DNA triplets on the coding polynucleotide
Aspartic acid Asp CTA, CTG
Glycine Gly CCA, CCG, CCT, CCC
Leucine Leu AAC, AAT, GAA, GAC, GAG, GAT
Proline Pro GGA, GGC, GGG, GGT
Threonine Thr TGA, TGC, TGG, TGT
STOP STOP ATT, ATC, ACT

Identify the amino acid sequence on this section of the mRNA molecule, using the information in the diagram and table.

1b
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4 marks

The five codons in the diagram at part a) are near the start of the sequence coding for a polypeptide. A mutation led to the deletion of one of the bases from codon 3.

Explain the possible consequences of this mutation.

1c
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2 marks

Guanine (G) in codon 4 changed to adenine (A) due to a mutation.

(i)

Describe the effect this mutation would have on the amino acid sequence in the diagram of part a).

[1]

(ii)

Explain your answer.

[1]

1d
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2 marks

The following diagram shows a section of a polypeptide, indicating the polarity of the amino acid R-groups.

polypeptide-tertiary-structure-sq

Describe the possible interactions that could contribute to the tertiary structure of this polypeptide, by using the information in the diagram.

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2a
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3 marks

Duchenne muscular dystrophy (DMD) is a genetic disorder that leads to the degeneration of muscle tissue over time due to changes in a protein called dystrophin.

Dystrophin is a rod-shaped protein that acts as a link connecting actin filaments in muscle fibres to the extracellular matrix by attaching to a protein complex (DAPC) located in the sarcolemma.

Dystrophin is coded for by the DMD gene, and the complete protein consists of four domains (N-terminal, Rod, Cys-domain and C-terminal), as shown in the diagram below.

dystrophin-protein-in-muscle-fibre-sq

 

The following diagram shows the regions of the DMD gene that codes for the different domains of dystrophin.

gene-coding-for-dystrophin-protein-sq

One of the causes of Duchenne muscular dystrophy is a substitution mutation that leads to the formation of a stop codon in the rod domain of the DMD gene.

Explain the impact this mutation would have on the resulting dystrophin protein by using the information in the diagrams.

2b
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2 marks

After transcription of the DMD gene, the pre-mRNA measures about 2.1 megabases (Mb) while the mature mRNA consists of about 14 kilobases (kb). Note that 1 Mb = 103 kb.

Calculate the percentage decrease in size of the mRNA molecule after modification. Show your working and give your answer to three significant figures.

2c
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2 marks

Dystrophin contains many hydrophobic regions that plays an important role in maintaining its structure. Some of the mutations leading to DMD replaces amino acids within the hydrophobic regions with ones containing polar or charged R-groups.

Suggest the effect that this would have on the structure of dystrophin.

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3a
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3 marks

Hereditary transthyretin (hATTR) amyloidosis is an inherited condition that is caused by a mutation of a gene that codes for the blood protein transthyretin.

This mutation results in the protein forming clumps in different areas of the body, such as the cardiovascular system, digestive system and around nerve fibres.

Certain drugs that are designed to bind to mRNA molecules are used as treatment for this condition.

Suggest why these drugs could be used as a treatment for hATTR.

3b
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2 marks
The gene that codes for transthyretin is known as the TTR gene. The following diagram shows a section of this gene in a normal individual and someone suffering from hATTR.

hl-ib-7-3-h-q3b

The table below shows the genetic code and the amino acids that it codes for.

mrna-codons-and-amino-acids-table

Use the information in the diagram and table to describe the effect the mutation would have on transthyretin.

3c
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3 marks

Mitochondrial diseases (MD) are a group of genetic disorders where body cells cannot aerobically respire properly.

One example of an MD is caused by the mutation of a mitochondrial gene that codes for a tRNA molecule. The mutation leads to the replacement of a guanine base with adenine in the anticodon of the tRNA molecule. This results in the formation of a non-functional protein in the mitochondrion.

Suggest how the change in the anticodon of a tRNA molecule leads to an MD.

3d
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1 mark

Explain the role of ATP in translation.

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4a
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2 marks

Ricin is a protein produced by castor beans. In animal cells, ricin acts as an enzyme which removes the adenine base from one of the nucleotides in the RNA of ribosomes. As a result, the ribosome changes shape. Ricin causes the death of cells and is very poisonous to certain animals.

Suggest how the action of ricin on ribosomes could cause the death of cells.

4b
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2 marks

The image below shows the structure of ricin.

hl-ib-7-3-q4b

Image courtesy of Aza Toth. Licensed under Creative Commons Attribution 3.0 Unported license. Reused and distributed under conditions found at: https://creativecommons.org/licenses/by/3.0/deed.en

Discuss the level(s) of protein structure visible in the diagram.

4c
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3 marks

The Flavr Savr tomato plant was genetically engineered to ripen and soften more slowly than a normal tomato. The inserted gene prevents the enzyme Beta polygalacturonase from breaking down pectin which softens the tomatoes.

The diagram below shows the matching parts of the base sequences for the mRNA produced from the transcription of the softening gene in a normal tomato and that of the inserted gene.

picture2

Suggest how the inserted gene reduces the production of the softening enzyme.

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5a
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4 marks

One mark is available for clarity of communication throughout this question.

Discuss the importance of hydrogen bonds in the process of translation.

5b
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7 marks

Outline the uses of bioinformatics in scientific research.

5c
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4 marks

Draw labelled diagrams contrasting the structure of an mRNA and tRNA molecule.

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