Biology 9700 · AS & A Level
Protein synthesis
100 practice questions on Protein synthesis, with worked solutions and instant marking.
The electron micrograph shows a section of a eukaryotic cell. Which labelled organelle is the site where protein synthesis occurs?
Feb/March 2016
Statements A to E are about biological molecules. For each one, identify the term that best fits the description.
Feb/March 2016
Erythropoietin, or EPO, is a large glycoprotein made by specialised kidney cells. These cells detect changes in the oxygen concentration of the blood flowing through the kidney and, when oxygen concentration is low, they increase EPO synthesis. EPO acts on the surface of certain target cells, such as cells in the bone marrow. These bone marrow cells are then stimulated to make red blood cells.
Feb/March 2016
What size ribosomes are present in chloroplasts?
Feb/March 2017
Fig. 1.1 shows an electron micrograph of part of a eukaryotic cell.
Feb/March 2018
The unicellular fungus Kluyveromyces lactis is present in dairy products. It is a safe microorganism to culture for obtaining the enzyme lactase. Lactase catalyses the breakdown of lactose, a sugar present in milk. The reaction catalysed by lactase is shown in Fig. 3.1.
Feb/March 2018
Radioactively tagged amino acids are added to a cell that is actively secreting an enzyme. In which cell structure would the radioactivity first accumulate?
Feb/March 2019
Ribosomes are made up of distinct subunits that come together during protein synthesis. What do these subunits consist of?
Feb/March 2019
In mammalian red blood cells, carbonic anhydrase plays a significant part in transporting carbon dioxide. Carbonic anhydrase is an enzyme.
Feb/March 2019
Starch is the principal storage substance in many cereal grains, including barley grains.
Feb/March 2021
Enzymes consist of polymers made from amino acids. Complete Fig. 3.1 so that it shows the general structure of an amino acid.
Feb/March 2022
Fig. 6.1 presents a diagram of part of the structure of a DNA molecule.
Feb/March 2022
Plant tissues were each given a radioactively labelled substance in order to determine which tissues were actively synthesising mRNA. Which radioactively labelled substances would be suitable for this experiment?
Feb/March 2023
Cysteine is an amino acid that contains sulfur. Fig. 2.1 displays the structure of the molecule produced when two cysteine molecules are joined together. Draw a circle around an R-group in the molecule shown in Fig. 2.1.
Feb/March 2023
Collagen is the most abundant structural protein in vertebrates. It gives the skin flexibility and strength. Explain how the structure of a collagen fibre gives the skin strength.
Feb/March 2023
Table 4.1 gives a 12-nucleotide sequence in the template strand of a short DNA segment, together with the matching primary transcript and the four amino acids encoded by the sequence. The table is not complete.
Feb/March 2024
Fig. 2.1 shows an incomplete structural diagram of an $\alpha$-glucose molecule. Complete Fig. 2.1 so that it shows the structure of an $\alpha$-glucose molecule.
Feb/March 2025
Fig. 1.1 illustrates how a sucrose molecule is broken down.
May/June 2010
Fig. 4.1 depicts the primary structure of a lysozyme molecule, an enzyme present in tears, saliva and lysosomes.
May/June 2010
Fig. 1.1 displays part of an animal cell as seen with an electron microscope.
May/June 2010
Fig. 3.1 shows the amino acid sequence for the protein hormone insulin.
May/June 2010
A messenger RNA (mRNA) molecule was formed during gene transcription. The DNA template sequence was ATGC. Fig. 3.1 illustrates the section of messenger RNA that corresponds to that four-base sequence.
May/June 2011
Sucrase is an enzyme that catalyses the breaking of the glycosidic bond in sucrose. A student studied how raising the sucrose concentration affected the rate of sucrase activity.
May/June 2011
Fig. 5.1 presents five distinct biological molecules.
May/June 2011
Complete the table to show three structural differences between DNA and RNA.
May/June 2011
Penicillin is an antibiotic that prevents bacteria from synthesising cell walls. Long before penicillin became widely available in the 1940s, the enzyme penicillinase, which breaks down penicillin, had already been isolated. This enzyme is now present in many bacteria and makes them resistant to penicillin. Fig. 4.1 shows a ribbon model of the structure of the enzyme penicillinase. The arrow shows the enzyme’s active site.
May/June 2012
DNA and RNA are essential biological molecules that take part in the synthesis of polypeptides.
May/June 2012
The two DNA strands are joined by hydrogen bonds formed between complementary base pairs.
May/June 2012
Which type of molecule is always produced as the final product of transcription?
May/June 2013
What role do nucleoli play?
May/June 2013
Which organelles are needed to make the hydrolytic enzymes present in lysosomes?
May/June 2013
The diagram has been obtained from an electronmicrograph of a cell that secretes enzymes. In which part are these enzymes synthesized?
May/June 2013
The diagram illustrates a cell that makes protease enzymes. Which row is right?
May/June 2013
In certain organisms, trehalose acts as an energy store and helps protect against the harmful effects of extremely low temperatures. Trehalose is sometimes called a cryoprotectant because it enables organisms to survive in freezing conditions. Low temperatures can damage the cell surface membrane and internal membranes inside the cell.
May/June 2013
Scientists often use a procedure known as in vitro translation to make proteins in the laboratory. This procedure uses extracts from animal cells, plant cells or bacteria. These are selected because they have a very high rate of protein synthesis. The cells are processed so that the cell walls, where present, and the cell membranes are broken down, and then treated so that any DNA and mRNA belonging to the cell are destroyed. If mRNA from any source is added to these extracts, it is translated into the matching protein.
May/June 2013
A protein called mitosis-promoting factor (MPF) has been identified in cells. MPF is a globular protein composed of two polypeptide chains.
May/June 2013
An amino acid enters a cell and is then used to make an enzyme that is secreted by the cell. In what order do the cell structures take part in the synthesis of the enzyme?
May/June 2014
Vibrio cholerae is a prokaryotic organism, and Fig. 1.1 illustrates the structure of a V. cholerae cell.
May/June 2014
As haemoglobin in red blood cells passes through the lung capillaries, it binds with oxygen and forms oxyhaemoglobin. Once oxyhaemoglobin reaches respiring tissues, it dissociates and releases oxygen.
May/June 2014
What is the role of the nucleolus?
May/June 2015
What size of ribosome occurs in both chloroplasts and mitochondria?
May/June 2015
A ribosome has two subunits, and each subunit includes rRNA. When all the $70\text{S}$ ribosomes in one Escherichia coli cell were examined, the results showed $38\,000$ rRNA molecules, $2$ principal kinds of rRNA molecule, and $19\,000$ copies of each rRNA type. What number of $70\text{S}$ ribosomes were present in the E. coli cell?
May/June 2015
Ribosomes are found as distinct subunits that join up during protein synthesis. What are these subunits made up of?
May/June 2015
Fig. 4.1 illustrates two distinct ways enzymes interact with their substrates.
May/June 2015
Fig. 5.1 is a diagram showing the molecular structures of tristearin (a triglyceride) and phosphatidylcholine (a phospholipid).
May/June 2015
Red blood cells develop from cells known as reticulocytes. Stem cells in the bone marrow divide to make reticulocytes, and these then differentiate into red blood cells. As differentiation occurs, haemoglobin is synthesised. Fig. 6.1 shows the arrangement of short sections of DNA and messenger RNA (mRNA) in the nucleus of a reticulocyte during transcription.
May/June 2015
A range of microorganisms are able to break down cellulose with a set of enzymes known as cellulases. The disaccharide formed as cellulose is digested is cellobiose. The cellulase called $\beta$-glucosidase finishes cellulose digestion by hydrolysing one cellobiose molecule to make two $\beta$-glucose molecules.
May/June 2015
Statements A to E concern the structure and function of enzymes. State the term that matches each statement from A to E.
May/June 2016
Trypsin is a protease enzyme in the digestive system. Fig. 2.1 illustrates how substrate concentration influences the rate of reaction of trypsin.
May/June 2016
Electron micrographs can reveal many ribosomes arranged in chains along mRNA molecules. What advantage does this arrangement have, compared with ribosomes being present singly on the mRNA?
May/June 2017
Statements A to D each describe a structure present in eukaryotic cells.
May/June 2017
Phosphatases are enzymes that speed up the removal of phosphate groups from organic compounds. Some students studied how substrate concentration affected the rate of the reaction catalysed by an acid phosphatase (enzyme A). Their results are shown in Fig. $2.1$.
May/June 2017
Fig. 4.1 illustrates a section of a DNA molecule.
May/June 2017
Through transcription and translation, a polypeptide chain is formed. Proteins with quaternary structure consist of two or more polypeptide chains. An antibody molecule and a haemoglobin molecule each display quaternary structure.
May/June 2017
Fig. 2.1 shows a transmission electron micrograph of a leaf cell.
May/June 2017
Complete Table 4.1 by placing a tick (✓) beside every statement that applies to each molecule. Put a cross (\times) beside statements that do not apply. Some of the boxes have already been filled in for you.
May/June 2017
Fig. 1.1 shows a transmission electron micrograph of a cell taken from the root of thale cress, Arabidopsis thaliana.
May/June 2018
A sucrase enzyme was isolated from the bacterium $\textit{Bacillus subtilis}$. The enzyme was then immobilised in alginate beads. The researchers examined how temperature affected the activity of the immobilised sucrase and compared this with the activity of the same enzyme when it was free in solution. The findings are shown in Fig. 3.1.
May/June 2018
Fig. 4.1 shows a photomicrograph of some cells that are in interphase and others that are at different stages of mitosis.
May/June 2018
Which cell structures contain ribosomal RNA (rRNA)?
May/June 2019
The diagram illustrates a typical animal cell as it appears under an electron microscope. Which of the numbered structures are required for proteins to be released at the cell surface membrane?
May/June 2019
Neutrase® is an enzyme used to hydrolyse proteins in solution. When this enzyme is added to a 2% protein solution, the mixture changes from white to colourless. A student investigated the effects of copper sulfate and potassium sulfate on Neutrase® activity. Four reaction mixtures were prepared in test-tubes A to D. Test-tubes A to C each had equal volumes of protein solution and $0.1\,\text{cm}^3$ of copper sulfate or potassium sulfate solutions. Test-tube D contained the same volume of protein solution and $0.1\,\text{cm}^3$ of water. $0.5\,\text{cm}^3$ of a 1% Neutrase® solution was added to test-tube A and it was placed straight into a colorimeter. The colorimeter measured the intensity of light absorbed by the solution (absorbance) for 100 seconds. The same procedure was carried out with the other reaction mixtures, B, C and D. The outcomes are displayed in Fig. 3.1.
May/June 2019
The electron micrograph displays part of a eukaryotic cell. Which cell structure is a site where protein synthesis occurs?
May/June 2020
Fig. 1.1 illustrates five biological molecules.
May/June 2020
The enzyme glucose 6-phosphate dehydrogenase (G6PD) is made up of two polypeptide chains that are identical.
May/June 2020
Fig. 6.1 depicts the assembly of a polypeptide during translation in a eukaryotic cell.
May/June 2020
Which sequence gives the correct order of some stages involved in the production and secretion of an enzyme?
May/June 2021
A number of the events that happen during transcription are shown. Before the mRNA molecule exits the nucleus, which events happen twice during transcription?
May/June 2021
Fig. 1.1 presents a transmission electron micrograph of duckweed cells from $Spirodela oligorrhiza$.
May/June 2021
Fig. 2.1 displays three water molecules.
May/June 2021
The induced-fit hypothesis and the lock-and-key hypothesis describe the mode of action of enzymes.
May/June 2021
The Golgi body, rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER) are components of the cell’s internal membrane system. These membranes display a fluid mosaic arrangement. Fig. 1.1 shows a transmission electron micrograph of part of a liver cell, with one region containing RER and another containing SER. Mitochondria can also be seen in the image.
May/June 2021
HIV protease is an enzyme made up of two identical polypeptide chains. Each polypeptide chain contains 99 amino acids. While translation is taking place, the amino acids are linked together by peptide bonds to produce the polypeptide chain.
May/June 2021
A tyrosine kinase receptor (TKR) is a protein complex located in the cell surface membrane of mammalian cells. TKR contains two parts that take part in cell signalling: a receptor that binds the signalling molecule (ligand) and an enzyme that catalyses the transfer of a phosphate group from ATP to an intracellular protein. Fig. 3.1 illustrates the role of TKR in cell signalling.
May/June 2022
Cotransporter proteins are membrane proteins located in companion cells of phloem tissue. Messenger RNA (mRNA) is the cell molecule that carries genetic information from DNA, which codes for cotransporter proteins, to the sites of protein synthesis in the cytoplasm.
May/June 2022
Bacterial cells are prokaryotic. Plant cells are classified as eukaryotic.
May/June 2022
Which structures take part in transcription alone?
May/June 2023
Six organelles present in eukaryotic cells are shown. Which organelles take part in the synthesis and secretion of a glycoprotein?
May/June 2023
Inside which cell structures may mRNA be found?
May/June 2023
An electron micrograph displays a structure present in the cytoplasm of an animal cell. Which biological molecules occur in this structure?
May/June 2023
Fig. 1.1 shows a transmission electron micrograph of a cell taken from the stem of sago pondweed, S. pectinata.
May/June 2023
Food crops like barley and wheat contain gluten. Gluten is made up of two proteins, glutenin and gliadin.
May/June 2023
Polysaccharides, for example glycogen, consist of thousands of monomers. Oligosaccharides are carbohydrates with three to ten monomers in the chain.
May/June 2023
In eukaryotes, RNA molecules produced during transcription are altered by removing non-coding sequences. After that, the coding sequences are joined together to make mRNA. What are the coding sequences also known as?
May/June 2024
Inside the mesophyll tissue of leaves, the products of photosynthesis may be used to build organic compounds, including the polysaccharide cellulose and certain amino acids. Nitrate ions absorbed by the roots and carried to the leaves can provide a nitrogen source for amino acid synthesis.
May/June 2024
Collagen is a fibrous protein present in many animal tissues.
May/June 2024
In some cells, non-coding RNA sequences are cut out after transcription. Which row correctly gives the name of these non-coding RNA sequences and the type of cell in which they are removed?
May/June 2025
The diagram comes from an electron micrograph of a cell that secretes enzymes. In what location are the polypeptides for these enzymes synthesised?
May/June 2025
Which of the following statements about tRNA are correct?
May/June 2025
Which cell structures house ribosomal RNA?
May/June 2025
A cell takes in amino acids. It then makes and releases a digestive enzyme. Several cell structures take part in the different stages of this process. Which row shows a possible order of the cell structures through which the amino acids move?
May/June 2025
Researchers followed how two enzyme-catalysed reactions developed, using dopa oxidase and neutrase. Because each reaction altered the look of its reaction mixture, the progress could be tracked by the change in appearance. The reactions are illustrated in Fig. 3.1. For dopa oxidase: L-dopa (colourless solution) → dopachrome (orange-brown solution). For neutrase: casein + water (white solution) → peptides (short chains of amino acids) (colourless solution). Since the appearance of the mixtures changes, a colorimeter can be used to monitor the reactions. Fig. 3.2 presents the progress of the reaction catalysed by dopa oxidase as recorded from a colorimeter. Fig. 3.3 presents the progress of the reaction catalysed by neutrase as recorded from a colorimeter.
May/June 2025
Cells in the immune system have cell-surface receptors that recognise molecules produced by pathogens. One such cell-surface receptor is called TLR8. In humans, the gene TLR8 is located on the X chromosome. Fig. 4.1 shows messenger RNA (mRNA) being produced from the gene TLR8 in the nucleus of a macrophage.
May/June 2025
Bees are insects that use venom as a defence against attack. Melittin is a polypeptide found in bee venom.
May/June 2025
Telomeres are stretches of DNA composed of repeating nucleotide sequences. Telomeres occur in eukaryotic chromosomes.
May/June 2025
Protein production is controlled by a complicated chain of events and several cell structures.
Oct/Nov 2010
Enzymes are globular proteins that catalyse metabolic reactions. Describe the features shown by globular proteins.
Oct/Nov 2010
Fig. 1.1 is a diagram of a section of a cell surface membrane.
Oct/Nov 2010
Ribosomes are made up of separate subunits that join together during protein synthesis. What are these subunits made of?
Oct/Nov 2011
Which cell components hold mRNA?
Oct/Nov 2011