Biology 9700/14 October/November 2025: question paper and mark scheme

Question

Which structures are visible in an appropriately stained plant cell using a high power (×400) light microscope? centrioles mitochondria starch grains A key B = visible C = not visible D

Question

The images show an eyepiece graticule and a stage micrometer scale viewed through a microscope. The smallest divisions of the stage micrometer scale are 0.01 mm. The images also show a photomicrograph of a transverse section through a plant root using the same eyepiece graticule and the same magnification. 0 10 20 30 40 50 eyepiece graticule stage micrometer scale 0.0 0.1 0.2 0.3 0 10 20 30 40 50 X Y What is the actual width of the vascular tissue in the plant root between X and Y? A 17 μm B 25 μm C 170 μm D 250 μm

Question

It is thought that some organelles in eukaryotic cells evolved from free-living prokaryotes. Which organelles have features that suggest they evolved from free-living prokaryotic ancestors? A chloroplasts and mitochondria B chloroplasts and Golgi bodies C mitochondria and smooth endoplasmic reticulum D Golgi bodies and smooth endoplasmic reticulum

Question

A student completed a table showing the structures that are found in four different types of cells. cell structure cell Q cell R cell S cell T cell surface membrane cellulose cell wall key chloroplast = present mitochondrion = not present nucleus How many of these types of cells can be found in plants? A 1 B 2 C 3 D 4

Question

Some features of cells are listed. 1 cytoplasm 2 cell surface membrane 3 ribosomes Which features are found in animal cells and also in prokaryotic cells? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

Trehalose is a non-reducing disaccharide. Separate samples of a mixture of fructose and trehalose were tested with Benedict’s solution before and after acid hydrolysis. What will be the results of these Benedict’s tests? before acid after acid hydrolysis hydrolysis A key B = positive result with Benedict’s test C = negative result with Benedict’s test D

Question

Which molecules have a structural formula that contains C=O bonds? 1 glucose 2 glycerol 3 protein A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

Which statement about monosaccharides and disaccharides is correct? A Sucrose is a non-reducing disaccharide produced from two identical monosaccharides joined together by a condensation reaction. B The hydrolysis of the reducing disaccharide maltose produces a reducing monosaccharide, and a non-reducing monosaccharide. C Maltose is a non-reducing disaccharide that contains two identical reducing monosaccharides connected by a glycosidic bond. D The addition of a water molecule to the glycosidic bond in a sucrose disaccharide produces two different reducing monosaccharides.

Question

Which row is correct for glycogen? glycogen is a glycogen is glycogen is compact molecule hydrolysed rapidly insoluble so the because it contains due to its branched water potential of many β-glucose structure cells is unaffected molecules A B C D key = correct for glycogen = incorrect for glycogen

Question

The diagram shows a section of a polysaccharide. H OH CH2OH H OH CH2OH O O C C C C C C O H H O H H O OH H H OH H H C C C C C C C C H OH H H OH H H O O H O O H H C C C C C C CH2OH H OH CH2OH H OH Which statement about this polysaccharide is correct? A It coils into a tight helix that provides a compact shape for energy storage in cells. B It has high tensile strength when arranged into fibrils in plant cell walls. C It folds into a globular shape that is soluble in water and easily transported. D It combines with protein molecules to act as cell markers on the cell surface membrane.

Question

Thermostable enzymes can maintain their tertiary structure at high temperatures. Scientists studying the primary structure of a thermostable enzyme found that the enzyme contained: ● more charged amino acids ● fewer polar amino acids that are not charged ● more hydrophobic amino acids than enzymes that are not thermostable. Which row shows a correct comparison between this thermostable enzyme and an enzyme that is not thermostable? number of amino acids number of ionic bonds forming interactions at in a thermostable the centre of a enzyme compared to thermostable enzyme the number in an compared to an enzyme that is not enzyme that is not thermostable thermostable A less than more than B less than less than C more than less than D more than more than

Question

Collagen is a strong, elastic molecule that is often found in the connective tissues of animals. Glycine is an amino acid found at regular positions in the primary structure of a collagen polypeptide. Which row shows features of collagen that contribute to its strength and elasticity? glycine is found on disulfide bonds form the outside of the between glycine helical polypeptides amino acids to join to allow them to lie the polypeptides closer together together A B C D key = contributes to the strength and elasticity of collagen = does not contribute to the strength and elasticity of collagen

Question

Which statements describe the action of an extracellular enzyme? 1 synthesis of a polynucleotide in the nucleus during DNA replication 2 digestion of macromolecules in the lumen of the small intestine 3 synthesis of ATP molecules in the mitochondria A 1 and 2 B 1 and 3 C 2 and 3 D 2 only

Question

Which statement about the induced-fit hypothesis of enzyme action is correct? A An enzyme that uses the induced-fit mechanism will increase the activation energy of a reaction. B The binding of a substrate causes conformational changes in an enzyme. C The active site of an enzyme changes to become the same shape as the substrate. D An enzyme that uses an induced-fit mechanism has decreased specificity to the substrate.

Question

Graph J shows the effect of pH on the rate of an enzyme reaction. Graph K shows the effect of substrate concentration on the rate of an enzyme reaction. graph J graph K R rate of rate of reaction reaction 0 0 0 0 pH P Q substrate concentration A student wrote four statements about the graphs. 1 In graph J, the enzyme is denatured at point Q. 2 In graph J, the enzyme is inactive at point P. 3 In graph K, the rate of reaction is directly proportional to the substrate concentration. 4 In graph K, Vmax is reached at point R. Which statements are correct? A 1, 2 and 3 B 1, 2 and 4 C 1, 3 and 4 D 2, 3 and 4

Question

The diagram shows a section through a cell surface membrane. Q R P S What is a correct role for a labelled molecule? A P is involved in controlling membrane stability. B Q is involved in active transport. C R is involved in cell signalling. D S is involved in diffusion of ions.

Question

When red blood cells are put into distilled water they burst (haemolysis). Which statements explain this haemolysis? 1 The water potential of the surrounding liquid is lower than the water potential of the contents of the red blood cell. 2 The cell surface membranes of red blood cells are not supported by cell walls. 3 More water moves into the red blood cells by osmosis than leaves the cells. 4 Water enters the red blood cells by osmosis but does not leave the cells. A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

Question

The diagrams show the shape and size of two types of cell. palisade mesophyll cell columnar epithelial cell surface area = 2200 μm2 volume = 2250 μm3 50 μm 45 μm not to scale 10 μm 5 μm 10 μm 10 μm Which statement about the palisade cell and epithelial cell shown in the diagrams is correct? A An increase in surface area reduces the distance for gases to reach the centre of the cell. B The surface area of the palisade mesophyll cell is 500 μm2 greater than the columnar epithelial cell. C The surface area to volume ratio is greater in the columnar epithelial cell than the palisade mesophyll cell. D The volume of the palisade mesophyll cell is 2500 μm3 greater than that of the columnar epithelial cell.

Question

The DNA content of a cell changes as the mitotic cell cycle proceeds through a series of stages. 3 DNA content 1 2 4 1 per cell time Which row correctly identifies when DNA replicates and when the nuclear envelope breaks down? nuclear envelope DNA replicates breaks down A 1 3 B 1 4 C 2 3 D 2 4

Question

The diagram shows three cycles of cell division from an original cell of cell type P in bone marrow. Some of the cells that form are cell type Q. key cell type P cell type Q not to scale Which row correctly identifies cell type P and cell type Q? cell type P cell type Q A cancer cell differentiated cell B cancer cell stem cell C differentiated cell stem cell D stem cell differentiated cell

Question

A student made a drawing of two chromosomes at stage K of a mitotic cell cycle. stage K stage J stage L no chromosomes were visible stage M Which row shows the possible events that occur in stages J, L and M? J L M A spindle attachment cytokinesis DNA replication B chromosome condensation spindle attachment cytokinesis C DNA replication chromosome condensation spindle attachment D cytokinesis DNA replication chromosome condensation

Question

During DNA replication, the two original strands of a DNA molecule separate. Which diagram shows the direction in which DNA polymerase moves along each of the original strands during DNA replication? A B 5′ 5′ 3′ 3′ O O O O O O O O O O O O O O O O 3′ 3′ 5′ 5′ C D 5′ 5′ 3′ 3′ O O O O O O O O O O O O O O O O 3′ 3′ 5′ 5′

Question

Which statements about anticodons are correct? 1 The base sequence of an anticodon will always be the same as that of the corresponding triplet on the transcribed DNA strand. 2 There are 20 naturally occurring amino acids, so therefore there are only 20 anticodons as each anticodon is specific for only one amino acid. 3 The formation of hydrogen bonds between the bases of the anticodon with those of the complementary mRNA codon must occur before the new peptide bond can form. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 3 only

Question

Part of a DNA molecule is transcribed to form an RNA molecule that is then modified. Which row describes the RNA molecule before and after modification? before modification after modification A contains exons and introns contains exons only B contains exons and introns contains introns only C contains exons only contains introns only D contains introns only contains exons only

Question

When a gene mutation occurs, which of the following may be altered, resulting in the production of a non-functional protein? 1 amino acid sequence 2 DNA nucleotide sequence 3 mRNA nucleotide sequence A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 2 only

Question

The diagrams show the arrangements of phloem and xylem tissues in some plant organs. epidermis epidermis phloem xylem phloem xylem Q R epidermis epidermis xylem phloem phloem xylem S T Where will arrangements Q, R, S and T be found in plants? Q R S T A leaf root stem root B root stem root leaf C stem stem leaf root D stem root leaf stem

Question

Which feature of xylem vessel elements allows them to have reduced resistance to water movement? A Lignin forms an incomplete secondary wall. B New vessels transport extra water as a plant grows. C There are no cross walls between vessel elements. D Vessel elements join to form narrow tubes.

Question

Which statement describes movement through a plant in the apoplast pathway? A Water moves through the cell walls. B Water moves through the cytoplasm. C Water moves through the plasmodesmata. D Water moves through the vacuoles.

Question

What is the correct name for the attraction due to the hydrogen bonding between water molecules during mass flow in plants? A transpiration B cohesion C tension D adhesion

Question

Which row shows the cause of mass flow in the phloem and the direction of movement of phloem sap by mass flow? cause of mass flow direction of movement in the phloem of phloem sap by mass flow A hydrostatic pressure gradient sink to source B hydrostatic pressure gradient source to sink C water potential gradient sink to source D water potential gradient source to sink

Question

The graph shows the thickness of the walls of the main blood vessels to and from a mammalian heart. Which blood vessel is the pulmonary artery? 1.2 1.0 0.8 thickness of blood vessel wall / mm 0.6 0.4 0.2 0 A B C D blood vessel

Question

The photomicrographs show blood smears from two different people. Person J does not have a disorder that affects their blood. Person K does have a disorder that affects their blood. person J person K The table shows some disorders that increase or decrease the number of neutrophils, red blood cells or lymphocytes. disorders related to blood count changes increase decrease neutrophil chronic inflammation autoimmune neutropenia red blood cell heart failure anaemia lymphocyte chronic leukaemia sepsis Which disorder does person K have? A autoimmune neutropenia B heart failure C sepsis D chronic leukaemia

Question

Which statement correctly describes the Bohr shift? A the decrease in affinity of haemoglobin for oxygen that occurs when pH is lowered B the increase in affinity of haemoglobin for oxygen that occurs when oxygen concentration rises C the increase in affinity of haemoglobin for oxygen that occurs when pH is at an optimum D the release of oxygen from oxyhaemoglobin in the absence of carbonic acid

Question

Which row correctly describes the features for two of the heart chambers? left atrium left ventricle A large force of contraction to allow large force of contraction to allow blood to travel a long distance blood to travel a long distance B small force of contraction as blood large force of contraction to allow only needs to travel a short distance blood to travel a long distance C small force of contraction as blood small force of contraction as blood only needs to travel a short distance only needs to travel a short distance D large force of contraction to allow small force of contraction as blood blood to travel a long distance only needs to travel a short distance

Question

The photomicrograph shows a transverse section of part of the human gas exchange system. Which row shows the correct name and function of one of the labelled structures in the photomicrograph? A B C D name function A ciliated epithelial cell traps particles B goblet cell secretes mucus C cartilage prevents collapse of trachea D smooth muscle contracts to expand airways

Question

Infectious diseases may be caused by bacteria, protoctists and viruses. Different pathogens may be transmitted by airborne droplets, from faeces to mouth (faecal-oral), by sexual intercourse and by vectors. Four examples of infectious diseases are listed. 1 cholera 2 HIV/AIDS 3 malaria 4 tuberculosis Which table classifies the four diseases correctly to show the type of pathogen that causes the disease and the mode of transmission? A B bacterium protoctist virus bacterium protoctist virus droplet 2 droplet 2 faecal-oral 1 faecal-oral 1 sexual 3 sexual 3 vector 4 vector 4 C D bacterium protoctist virus bacterium protoctist virus droplet 4 droplet 3 faecal-oral 1 faecal-oral 2 sexual 2 sexual 1 vector 3 vector 4

Question

Scientists investigated the sensitivity and resistance of a bacterium called Clostridium difficile to four antibiotics. Colonies of bacteria were grown on agar plates for 24 hours, after which a different antibiotic was added to each plate. The number of bacterial colonies that died, stopped growing and continued growing were then counted. A bacterial colony is a group of bacterial cells that have multiplied from one bacterium. Which antibiotic would be the best to treat a person infected with Clostridium difficile? number of number of number of colonies antibiotic colonies that colonies that that continued died stopped growing growing A ampicillin 2 5 13 B clindamycin 4 8 6 C metronidazole 13 6 1 D cefoxitin 9 5 4

Question

A vaccine is used to create artificial active immunity. After a person has been given a vaccine, it takes a period of time before they develop long-term immunity to the disease. Which statement about this period of time explains the delay in developing long-term immunity? A No memory cells have been produced from B-lymphocytes. B No plasma cells have been produced from B-lymphocytes. C The primary immune response has not produced enough antibodies. D The secondary immune response has not produced enough antibodies.

Question

An antiserum to a snake toxin can be obtained by injecting the toxin into a horse. The antiserum is made from blood plasma taken from the horse a few weeks later. The antiserum is injected into a person who has been bitten by the same species of snake. Which type of immunity occurs as a result of using this antiserum? A artificial active B artificial passive C natural active D natural passive

Question

Which statement describes the feature of monoclonal antibodies that allows them to accurately treat a specific disease? A They bind to human hormones to produce a colour change. B A fluorescent dye can be attached to them. C They have active sites that are complementary to antigens. D They can carry toxic chemicals.