9700 Biology November 2025 Question Paper 14

Which structures are visible in an appropriately stained plant cell using a high power (400) light microscope? centrioles mitochondria starch grains

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. 0.0 0.1 0.2 0.3 eyepiece graticule stage micrometer scale X Y What is the actual width of the vascular tissue in the plant root between X and Y?

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 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?

Some features of cells are listed. cytoplasm cell surface membrane ribosomes Which features are found in animal cells and also in prokaryotic cells?

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 hydrolysis after acid hydrolysis

Which molecules have a structural formula that contains C=O bonds? glucose glycerol protein

Which statement about monosaccharides and disaccharides is correct?

Which row is correct for glycogen? glycogen is hydrolysed rapidly due to its branched structure glycogen is insoluble so the water potential of cells is unaffected glycogen is a compact molecule because it contains many -glucose molecules

The diagram shows a section of a polysaccharide. O O H H H H CH2OH OH H OH O

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 forming interactions at the centre of a thermostable enzyme compared to an enzyme that is not thermostable number of ionic bonds in a thermostable enzyme compared to the number in an enzyme that is not thermostable

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 the outside of the helical polypeptides to allow them to lie closer together disulfide bonds form between glycine amino acids to join the polypeptides together

Which statements describe the action of an extracellular enzyme? synthesis of a polynucleotide in the nucleus during DNA replication digestion of macromolecules in the lumen of the small intestine synthesis of ATP molecules in the mitochondria

Which statement about the induced-fit hypothesis of enzyme action is correct?

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. rate of reaction rate of reaction pH substrate concentration graph J graph K P Q R A student wrote four statements about the graphs. In graph J, the enzyme is denatured at point Q. In graph J, the enzyme is inactive at point P. In graph K, the rate of reaction is directly proportional to the substrate concentration. In graph K, Vmax is reached at point R. Which statements are correct?

The diagram shows a section through a cell surface membrane. P Q R S What is a correct role for a labelled molecule?

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

The diagrams show the shape and size of two types of cell. 10 μm 10 μm 50 μm 10 μm 5 μm 45 μm palisade mesophyll cell surface area = 2200 μm2 columnar epithelial cell volume = 2250 μm3 not to scale Which statement about the palisade cell and epithelial cell shown in the diagrams is correct?

The DNA content of a cell changes as the mitotic cell cycle proceeds through a series of stages. time DNA content per cell Which row correctly identifies when DNA replicates and when the nuclear envelope breaks down? DNA replicates nuclear envelope breaks down

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. not to scale key cell type P cell type Q Which row correctly identifies cell type P and cell type Q? cell type P cell type Q

A student made a drawing of two chromosomes at stage K of a mitotic cell cycle. no chromosomes were visible stage J stage K stage M stage L Which row shows the possible events that occur in stages J, L and M? J L M

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?

Which statements about anticodons are correct? The base sequence of an anticodon will always be the same as that of the corresponding triplet on the transcribed DNA strand. There are 20 naturally occurring amino acids, so therefore there are only 20 anticodons as each anticodon is specific for only one amino acid. 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.

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

When a gene mutation occurs, which of the following may be altered, resulting in the production of a non-functional protein? amino acid sequence DNA nucleotide sequence mRNA nucleotide sequence

The diagrams show the arrangements of phloem and xylem tissues in some plant organs. R Q epidermis phloem xylem epidermis phloem xylem T S epidermis phloem xylem epidermis phloem xylem Where will arrangements Q, R, S and T be found in plants? Q R S T

Which feature of xylem vessel elements allows them to have reduced resistance to water movement?

Which statement describes movement through a plant in the apoplast pathway?

What is the correct name for the attraction due to the hydrogen bonding between water molecules during mass flow in plants?

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 in the phloem direction of movement of phloem sap by mass flow

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 0.6 0.4 0.2

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?

Which statement correctly describes the Bohr shift?

Which row correctly describes the features for two of the heart chambers? left atrium left ventricle

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?

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. cholera HIV/AIDS malaria tuberculosis Which table classifies the four diseases correctly to show the type of pathogen that causes the disease and the mode of transmission? droplet faecal-oral sexual vector bacterium protoctist virus

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? antibiotic number of colonies that died number of colonies that stopped growing number of colonies that continued growing

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?

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?

Which statement describes the feature of monoclonal antibodies that allows them to accurately treat a specific disease?