Biology 9700/12 May/June 2024: question paper and mark scheme

Question

A prokaryotic cell which is 1 μm in diameter is magnified 50 000 times in an electron micrograph. What is the diameter of the cell in the electron micrograph? A 5 × 10–1 mm B 5 × 100 mm C 5 × 101 mm D 5 × 102 mm

Question

The diagram shows a plant cell with some labelled structures. Q P R S Which labelled structures are bound by a double membrane? A P and Q B P and S C R and Q D R and S

Question

Which size of ribosome is found in mitochondria and typical prokaryotic cells? A 50S B 60S C 70S D 80S

Question

Which row about typical prokaryotic cells and typical animal cells is correct? lysosomes present ATP is produced for the break down by the cell of old organelles A B C D key = correct for typical prokaryotic cells and typical animal cells = not correct for both cells but correct for either typical prokaryotic cells or typical animal cells

Question

Which row is correct for the structures present in typical plant cells and typical animal cells? cell structure plant cell animal cell A plasmodesmata present present B Golgi body present not present C centriole not present present D tonoplast not present not present

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Which row is correct for cellulose? rotation of alternate hydrogen bonds shape of molecule monomers by 180° between molecules A branched key B branched = present C unbranched = not present D unbranched

Question

Which statements about peptide bond formation are correct? 1 The bond formation occurs between a carbon of one amino acid and a nitrogen of the next amino acid after the amino acids detach from tRNA. 2 The bond formation occurs at the ribosome while the amino acids are still attached to tRNA, and is a hydrolysis reaction. 3 The bond formation is important for growth of an organism and when the bond forms, a water molecule is removed. A 1 and 3 B 2 and 3 C 2 only D 3 only

Question

The diagram shows naturally occurring D-glucose and a form of glucose that can be synthesised in the laboratory, known as L-glucose. CH2OH H C O C O H H HO OH H CH2OH C C C C OH H H HO HO OH H H C C C C H HO OH H D-glucose L-glucose The enzyme glucose oxidase catalyses the oxidation of D-glucose. The enzyme cannot catalyse the oxidation of L-glucose. Which statement about L-glucose explains this? A L-glucose does not fit into the active site of glucose oxidase. B L-glucose has a different structural formula to D-glucose. C L-glucose is a synthetic sugar. D L-glucose is the mirror image of D-glucose.

Question

Tests for biological molecules were carried out on three solutions. Each solution contained only one type of biological molecule. The observations were as follows. solution test observation 1 Benedict’s test blue to orange 2 Benedict’s test after acid hydrolysis blue to red 3 biuret test blue to purple Which solutions would contain either sucrose or amylase? A 1, 2 and 3 B 1 and 3 only C 2 and 3 only D 2 only

Question

Which row describes the expected effect on Vmax and Km when a competitive reversible inhibitor is added to an enzyme-catalysed reaction? substrate effect on Vmax concentration at Km A no change increases B no change no change C decreases increases D decreases no change

Question

The graph shows the effect of substrate concentration on the rates of reaction of three enzymes, X, Y, and Z. 2500 enzyme Y 2000 rate of 1500 enzyme X reaction / product per second 1000 500 enzyme Z 0 0 200 400 600 800 1000 1200 substrate concentration / μmol dm–3 What is the correct order of affinity of these enzymes for their substrates, starting with the enzyme with the highest affinity? A X→Y→Z B X→Z→Y C Y→X→Z D Z→X→Y

Question

Which row correctly identifies the weak and strong bonds in the tertiary and quaternary structure of a typical protein? type of bond disulfide hydrogen hydrophobic ionic A strong strong weak weak B strong weak weak weak C weak weak strong strong D weak weak weak strong

Question

Which row correctly describes haemoglobin? A four polypeptide iron ions can in each chain, at 50% saturation, chains, each associate with hydrophobic R-groups two oxygen containing a oxygen, forming of amino acids point molecules are haem group oxyhaemoglobin towards the centre of transported by the the molecule molecule B polypeptide chains each chain consists of two each chain can interact to produce a contains a haem identical alpha chains transport an globular chain group of amino and two identical oxygen molecule acids surrounding beta chains an iron ion C polypeptide chains an iron ion is quaternary structure each molecule can interact to produce present within each has two alpha chains transport a total of an almost spherical haem group and two beta chains four oxygen atoms molecule D polypeptide chains iron ions in the in each chain, each molecule can produce a loose molecule can bind hydrophobic R-groups transport a total of helical shape, which reversibly with of amino acids eight oxygen atoms folds to form a oxygen surround the iron ion spherical molecule

Question

Which process always takes place without the involvement of energy from ATP? A active transport B endocytosis C exocytosis D facilitated diffusion

Question

The diagram shows the entry of molecule X into a cell. molecule X Which row shows a property of molecule X and the effect of the concentration of ATP in the cytoplasm on the rate of entry of molecule X? property of molecule X concentration of ATP in the cytoplasm A non-polar affects rate of entry of molecule X B non-polar has no effect on rate of entry of molecule X C polar affects rate of entry of molecule X D polar has no effect on rate of entry of molecule X

Question

The electron micrograph shows some human blood cells. X Which row correctly shows the net movement of water by osmosis and the water potential of the cytoplasm of cell X compared with the solution surrounding the cells? water potential of net movement of cytoplasm of cell X water by osmosis compared with the solution A into the cell higher B into the cell lower C out of the cell higher D out of the cell lower

Question

A red indicator solution was mixed with agar and the resulting solid was cut into small cylindrical blocks. The blocks were placed in an acid which turns the indicator yellow and all other variables were kept constant. The dimensions of the blocks are shown. block 1 height 3 mm diameter 6 mm block 2 height 6 mm diameter 12 mm block 3 height 8 mm diameter 16 mm The formula for calculating the surface area of a cylinder is 2πrh + 2πr 2. The formula for calculating the volume of a cylinder is πr 2h. Which row shows the correct surface area (SA) to volume (V) ratio for each block and the time taken for the block to turn yellow? block 1 block 2 block 3 SA to V time to turn SA to V time to turn SA to V time to turn ratio yellow / mins ratio yellow / mins ratio yellow / mins A 0.75 : 1.0 4 1.5 : 1.0 5 2.0 : 1.0 11 B 0.75 : 1.0 11 1.5 : 1.0 5 2.0 : 1.0 4 C 1.33 : 1.0 4 0.67 : 1.0 5 0.5 : 1.0 11 D 1.33 : 1.0 11 0.67 : 1.0 5 0.5 : 1.0 4

Question

Which metabolic processes will be very active in a cell that has just completed cytokinesis? 1 ATP formation 2 DNA replication 3 protein synthesis A 1, 2 and 3 B 1 and 3 only C 2 only D 3 only

Question

The diagram shows a typical mitotic cell cycle and the point in the cell cycle that has been reached by each of four cells, V, W, X and Y. mitosis cytokinesis Y X W G2 phase G1 phase S phase V Which row correctly identifies the cells that match the two descriptions? preparation for DNA replication is microtubule formation complete but the cell is nearly complete but has not yet reached chromosomes have its maximum size not yet condensed A V X B W Y C V Y D W X

Question

The graph shows the mean length of the spindle fibres during mitosis. Which region of the graph shows when all the centromeres have detached from the spindle fibres? B C mean length of spindle fibres A D time

Question

The mRNA codons ACU, ACC, ACA and ACG all code for the same amino acid, threonine. Which anticodons could specify an amino acid other than threonine? 1 UCA 2 ACC 3 UGU 4 UGC A 1, 3 and 4 B 1 and 2 C 2 and 3 D 3 and 4 only

Question

Which bond formation does DNA polymerase catalyse? A hydrogen bonds between bases B hydrogen bonds between nucleotides C phosphodiester bonds between bases D phosphodiester bonds between nucleotides

Question

In eukaryotes, the RNA molecules formed during transcription are modified by the removal of non-coding sequences. This is followed by the joining together of coding sequences to form mRNA. What are the coding sequences also called? A codons B exons C introns D primary transcripts

Question

Which row correctly identifies sinks for sucrose transported by mass flow in plants? root storage growing growing organ leaf bud shoot tip A key B = sink C = not a sink D

Question

The diagram shows a transverse section through a transport tissue in a plant. 1 2 Which row correctly identifies cell 1 and cell 2? cell 1 cell 2 A companion cell phloem sieve tube element B companion cell xylem vessel element C phloem sieve tube element phloem sieve tube element D phloem sieve tube element xylem vessel element

Question

Which statement correctly describes the movement of solutes in the symplast pathway? A Cell surface membranes regulate the selective absorption of solutes into the symplast pathway. B Plasmodesmata control the movement of solutes from the symplast pathway to the apoplast pathway. C The symplast pathway transports dissolved mineral ions from the soil that cannot be transported by the apoplast pathway. D The movement of solutes through plasmodesmata in the symplast pathway is prevented in the endodermis by suberin.

Question

Which statement helps to explain why water molecules are forced to move through xylem vessel elements as a consequence of transpiration? A Water molecules form hydrogen bonds with cellulose in the walls of xylem vessel elements in a process known as adhesion. B Water molecules form hydrogen bonds with neighbouring water molecules in a process known as cohesion. C Water molecules form ionic bonds with dissolved mineral ions, which helps to keep the water molecules together in a continuous column. D Water has a high latent heat of vaporisation and this prevents the evaporation of water in the xylem vessel elements.

Question

The diagram shows the internal structure of the mammalian heart. Which letter identifies the location of the atrioventricular node? A C B D

Question

The diagram shows pressure changes in the left side of the heart during the cardiac cycle. pressure key / kPa left ventricle aorta left atrium X 0 0 0.2 0.4 0.6 0.8 time / s What happens in the heart at X? A The atrioventricular valves close. B The atrioventricular valves open. C The semilunar valves close. D The semilunar valves open.

Question

Which components of blood are present in tissue fluid? phagocytes some proteins sodium ions A key B = present C = not present D

Question

In the lungs, movement of dissolved carbon dioxide out of the capillaries occurs in one of two ways: ● by diffusion through the endothelial cells of the capillaries ● by leakage through pores in the endothelial cells of the capillaries. What is the minimum number of times that a carbon dioxide molecule that has been transported to the lungs in a red blood cell must cross a cell surface membrane to reach an air space in an alveolus? A 2 B 3 C 4 D 5

Question

What maintains the steep concentration gradients needed for successful gas exchange in the lungs? 1 Air flow in the alveoli is in the opposite direction to blood flow in the capillaries. 2 Blood arrives in the lungs with a lower oxygen concentration and a higher carbon dioxide concentration than the air in the alveoli. 3 Blood is constantly flowing through and out of the lungs, bringing a fresh supply of red blood cells. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

Where is cartilage tissue always found in the human gas exchange system? A in the trachea only B in the bronchi only C in the bronchioles and trachea D in the bronchi and trachea

Question

Scientists compared the density of goblet cells in the lungs and the density of mucus in the lungs of three groups of people: ● people who do not smoke and do not have lung disease ● people who smoke tobacco but do not have lung disease ● people who smoke tobacco and have lung disease. The results are shown in the table. goblet cell density mucus density group / cells per mm2 / arbitrary units non-smokers 19 6 smokers who do not have lung disease 54 26 smokers with lung disease 37 15 What is indicated by these data? 1 There is a positive correlation (relationship) between density of goblet cells and density of mucus. 2 Lung disease results in an increase in goblet cell density. 3 There is an association between tobacco smoking and an increase in mucus density. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

Which disease does Mycobacterium bovis cause? A cholera B HIV / AIDS C malaria D tuberculosis

Question

An antibiotic inhibits the formation of cross-links between the molecules that form cell walls in bacteria. Which statements explain why bacteria are killed by the antibiotic? 1 The bacterial cell is destroyed by osmotic lysis. 2 Cellulose molecules cannot form hydrogen bonds. 3 The cell wall is no longer partially permeable. A 1 and 2 only B 2 and 3 only C 1 only D 2 only

Question

Scientists investigated the effect of increasing concentrations of an antibiotic on the development of antibiotic resistance in bacteria. The scientists grew four groups of bacteria and added a different concentration of antibiotic to each group. The number of resistant bacteria and the total population of bacteria were measured at intervals for 24 hours for each group. The graphs show the results. antibiotic concentration = 0 mg dm–3 antibiotic concentration = 90 mg dm–3 10 10 9 9 8 8 7 7 population 6 population 6 of bacteria 5 of bacteria 5 × 106 4 × 106 4 3 3 2 2 1 1 0 0 0 3 6 9 12 15 18 21 24 0 3 6 9 12 15 18 21 24 time / hours time / hours antibiotic concentration = 215 mg dm–3 antibiotic concentration = 600 mg dm–3 10 10 9 9 8 8 7 7 population 6 population 6 of bacteria 5 of bacteria 5 × 106 4 × 106 4 3 3 2 2 1 1 0 0 0 3 6 9 12 15 18 21 24 0 3 6 9 12 15 18 21 24 time / hours time / hours key total population resistant population Which statements are correct conclusions that can be made from the results of this investigation? 1 Increasing the concentration of antibiotic decreases the population of non-resistant bacteria at the end of 24 hours. 2 The proportion of antibiotic-resistant bacteria increases with increasing concentrations of antibiotics. 3 Increasing the concentration of antibiotic always increases the number of resistant bacteria. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

What is the correct sequence of events in a primary immune response? A T-lymphocyte activation → B-lymphocyte selection → plasma cell release B antigen presentation by macrophages → cytokines released by T-helper cells → B-lymphocyte differentiation C antigen presentation by neutrophils → T-memory cell activation → B-lymphocyte selection D T-memory cell activation → B-memory cell activation → antibody production

Question

Which statement about the properties of the antigen-binding sites in different antibody molecules is correct? A They are located on the light chains only. B They have a hinge region to give flexibility for different antigens. C They have binding sites for receptors on phagocytes. D They have variable amino acid sequences for different antigens.

Question

The diagram shows a stage in monoclonal antibody production. X + cancer cells hybridoma cells What is represented by X? A T-lymphocytes B B-lymphocytes C antigens D antibodies