Biology 9700/11 May/June 2025: question paper and mark scheme

Question

Which statements about light microscopes are correct? 1 To calculate the magnification of a light microscope, the eyepiece lens and objective lens magnifications are added together. 2 The resolution of a light microscope is limited by the wavelength of light. 3 The divisions on the scale on a stage micrometer are closer together than the divisions on the scale on an eyepiece graticule. A 1, 2 and 3 B 1 and 2 only C 2 only D 3 only

Question

A student measured the width of a mitochondrion in an electron micrograph of an animal cell with a magnification of ×9600. The width was 6 mm. What was the actual width of the mitochondrion? A 6 μm B 0.6 μm C 0.06 μm D 0.006 μm

Question

The photomicrograph shows a section of the stem of a plant. Q Which statements could describe Q? 1 The cell wall contains pits. 2 The cell wall contains cellulose and also lignin. 3 It is connected to adjacent cells via plasmodesmata. A 1 and 2 B 1 and 3 C 1 only D 2 and 3

Question

The diagram is taken from an electron micrograph of a cell that secretes enzymes. Where are the polypeptides for these enzymes made? A B C D

Question

Which comparisons between a typical bacterial cell and a typical plant cell are correct? bacterial cell plant cell 1 cytoplasmic DNA nuclear DNA 2 no smooth ER present smooth ER present 3 peptidoglycan cell walls found cellulose cell walls found 4 80S ribosomes 70S ribosomes 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 virus. X W Y Z Which row correctly identifies the labelled biological molecules? W X Y Z A RNA proteins phospholipids carbohydrates B DNA phospholipids proteins proteins C DNA proteins proteins carbohydrates D RNA phospholipids phospholipids proteins

Question

The iodine test and the Benedict’s test were carried out on samples of a starch solution. Amylase was added to another sample of the starch solution and incubated for 10 minutes. The Benedict’s test was then carried out on this sample. What were the results of the tests? iodine test Benedict’s test Benedict’s test before adding before adding after adding amylase amylase amylase A key B = positive result C = negative result D

Question

Which row about α-glucose and β-glucose molecules is correct? carbon atom on cellulose contains which the OH both molecules position is different A 1 no B 1 yes C 4 no D 4 yes

Question

Which molecules are monosaccharides? 1 ribose 2 glucose 3 deoxyribose 4 sucrose A 1, 2 and 3 B 1, 2 and 4 C 1, 3 and 4 D 2, 3 and 4

Question

Many animals use triglycerides for long-term energy storage. Which statements are correct additional functions of triglycerides? 1 They provide buoyancy in some marine animals. 2 They are the main components of cell membranes. 3 They are used as thermal insulation. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

The diagrams show three different bonds. 1 2 3 O NH O C N CH2 S S CH2 H Which bonds are found in proteins? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

What describes the quaternary structure of a collagen molecule? A polypeptides that form an α-helix, which are held together by covalent bonds B polypeptides that form a double helix, which are held together by hydrogen bonds C four polypeptides that are held together by covalent bonds, which form a helix D three polypeptides that form helix structures, which are held together by hydrogen and covalent bonds

Question

The diagram shows the structure of the enzyme amylase. Which level of protein structure results in the folding of amylase into its globular shape? A primary B secondary C tertiary D quaternary

Question

Which statement explains why large volumes of water maintain a constant temperature when the air temperature increases? A The latent heat of vaporisation of water is high. B The specific heat capacity of water is high. C Each water molecule can form a hydrogen bond with a maximum of three water molecules. D Water is able to evaporate rapidly from a surface with little loss of heat.

Question

Which statements about the mode of action of an enzyme are correct? 1 Some enzymes have a region on their surface to which the substrate has a complementary shape. 2 Some enzymes and their substrates can change shape slightly as the substrate enters the active site. 3 Enzymes permanently change shape when they react with their substrates to form an enzyme–substrate complex. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

The graph shows the effect of increasing substrate concentration on the rate of reaction of two enzymes that catalyse reactions with the same substrate. enzyme P rate of reaction enzyme Q substrate concentration Which statement is correct? A Enzyme Q has a higher Km and a higher affinity for the substrate than enzyme P. B Enzyme Q has a higher Km and a lower affinity for the substrate than enzyme P. C Enzyme Q has a lower Km and a higher affinity for the substrate than enzyme P. D Enzyme Q has a lower Km and a lower affinity for the substrate than enzyme P.

Question

The cell surface membrane structure is described as a ‘fluid mosaic’. What correctly describes the ‘mosaic’ part of the cell surface membrane? A the different patterns that are obtained by the moving phospholipid molecules B the random distribution of cholesterol molecules within the phospholipid bilayer C the regular pattern produced by the phospholipid heads and membrane proteins D the scattering of the different proteins within the phospholipid bilayer

Question

A student immersed a plant tissue in solution S. For the next 30 minutes, the student used a microscope to observe the cells in the plant tissue. During this time, the cytoplasm of the cells shrunk and no longer pushed up against the cell wall. In many cells, a space appeared between the cytoplasm and the cell wall. Which statements are correct conclusions from these observations? 1 The water potential in solution S was more negative than the water potential in the cytoplasm of the cells at the start of the experiment. 2 Without a cell wall to provide support, it is likely that many of the cells would have burst. 3 The clear space between the cell wall and the cytoplasm of many of the cells was filled with air. A 1 and 3 B 1 only C 2 and 3 D 2 only

Question

A sample of 500 cells dividing by mitosis was examined to identify the stage of mitosis for each cell. The table shows the results. percentage stage of mitosis of cells in the stage late prophase 23 end of metaphase 45 between the start of anaphase 24 and the end of telophase Which row is correct? number of cells number of cells with chromosomes with separated at the equator of chromatids the cell A 225 120 B 225 345 C 380 120 D 380 345

Question

The diagram shows a chromosome. P Q What are structures P and Q? P Q A centriole chromatid B centromere telomere C centromere centriole D centriole telomere

Question

Which processes are used by stem cells during tissue repair? 1 cytokinesis 2 DNA replication 3 transcription A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

The enzyme telomerase prevents loss of telomeres after many mitotic cell cycles. Which cells transcribe a high concentration of telomerase? 1 neutrophils 2 mature red blood cells 3 activated memory T-lymphocytes A 1 and 2 B 1 and 3 C 1 only D 3 only

Question

Which statements are correct? 1 All polypeptides are coded for by genes. 2 All genes are made up of a sequence of nucleotides. 3 All gene mutations result in a change to the nucleotide sequence. 4 All gene mutations will result in an altered polypeptide. A 1, 2, 3 and 4 B 1, 2 and 3 only C 1 and 4 only D 2 and 3 only

Question

A double-stranded DNA molecule was analysed and 29% of its nucleotide bases were found to be adenine. Which percentage of its nucleotide bases will be cytosine? A 21% B 29% C 42% D 58%

Question

In some cells, non-coding sequences of RNA are removed after transcription. Which row correctly states the name of these non-coding sequences of RNA and the type of cell in which the non-coding sequences are removed? type of cell in which name of non-coding non-coding sequences sequences are removed A exons eukaryotic B exons prokaryotic C introns eukaryotic D introns prokaryotic

Question

Water potentials were measured inside a leaf cell, in the air spaces of the leaf and in the atmosphere. Which values of water potential () would allow water to move from the leaf to the atmosphere? inside the of air of leaf cell / MPa spaces / MPa atmosphere / MPa A –1 –7 –100 B –100 –7 –1 C 1 7 100 D 100 7 1

Question

Three samples of liquid were taken from different locations in a plant and tested to measure the concentration of four solutes. The results are shown. concentration of solute / mol m–3 sample sucrose nitrate ions amino acids magnesium ions 1 652 0.14 41 3.4 2 0.12 7.1 7.2 1.1 3 433 0.6 68 3.7 Which samples have been taken from phloem sieve tube elements? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

A heated band was wrapped around the stem of a plant at a height of 1 m above the ground and left for 10 minutes. How will heating a small section of the stem to 60 °C affect the transport of phloem sap and xylem sap between the roots and leaves? transport of transport of phloem sap xylem sap A key B = transport continues C = transport stops D

Question

The diagram shows the structure of an amphibian heart and the movement of blood through it. to lung from lung from body to body Which statements about differences between the amphibian heart and a human heart are correct? 1 The hearts have a different number of ventricles. 2 The hearts have a different number of atrioventricular valves. 3 A septum is absent in the amphibian heart and a septum is present in the human heart. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

A mutation in one of the genes that codes for haemoglobin changes the affinity of haemoglobin for oxygen. This mutation lowers the partial pressure of oxygen at which haemoglobin is 50% saturated with oxygen. Which row shows the effect of the mutation on the affinity of haemoglobin for oxygen and the change in the position of the oxygen dissociation curve for haemoglobin? the effect of the mutation change in the position of on the affinity of the oxygen dissociation haemoglobin for oxygen curve for haemoglobin A higher shift to the left B higher shift to the right C lower shift to the left D lower shift to the right

Question

Which processes are responsible for the Bohr shift? 1 Carbon dioxide reacts with haemoglobin to form carbaminohaemoglobin. 2 Carbon dioxide reacts with water to form carbonic acid. 3 Haemoglobinic acid is formed from the dissociation of carbonic acid. A 1, 2 and 3 B 1 only C 2 and 3 only D 3 only

Question

A student viewed a drop of human blood with a microscope and described a cell as having a very large diameter and a U-shaped nucleus that occupies half the volume of the cell. Which type of cell was the student viewing? A monocyte B neutrophil C red blood cell D lymphocyte

Question

How many times must an oxygen molecule pass through a cell surface membrane to get from the air in the alveolus to the haemoglobin in a red blood cell? (Assume there are no pores between the cells the oxygen molecule must pass through.) A 2 B 3 C 4 D 5

Question

Asthma can affect children and adults. The air passages become narrower, severely restricting the flow of air into the lungs. Salbutamol is a drug that widens the air passages to relieve the symptoms of asthma. How does salbutamol relieve the symptoms of asthma? A It decreases mucus secretions in the terminal bronchioles. B It decreases the surface area of the alveoli. C It causes recoil of elastic tissue in the bronchioles. D It relaxes smooth muscle in the bronchi and bronchioles.

Question

The photomicrograph shows the transverse section of part of the trachea. Which letter represents a tissue that can contract and relax to adjust the diameter of the airways? B A C D

Question

Which statements about an infectious disease may be correct? 1 It can be caused by a protoctist. 2 It can be transmitted by an insect vector. 3 It can be transmitted from mother to child. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Question

Which statements explain why cholera has not been eradicated by vaccination? 1 There is limited availability of an affordable vaccine. 2 Protection takes several weeks to develop after vaccination. 3 The under-reporting of cholera in the community. 4 Immunity to cholera decreases after two years. A 1, 2, 3 and 4 B 1 and 2 only C 2 and 4 only D 3 and 4 only

Question

Antibiotic resistance is a serious threat to global health. Which statement describes a step that can be taken to reduce the impact of antibiotic resistance? A Antibiotics prescribed by a doctor should be shared with family members to protect them. B Antibiotics should only be used to treat infectious diseases caused by viruses. C Farmers should give antibiotics to healthy animals to prevent infections occurring. D Vaccination programmes should be used to reduce the spread of bacterial diseases.

Question

Tetanus is an infectious disease caused by a type of bacterium. This bacterium produces a protein that is a toxin which causes illness. Scientists have produced a vaccine for tetanus which contains a harmless form of the toxin called a toxoid. The toxoid is produced by mixing the toxin with the chemical formaldehyde. This chemical binds to the toxin making it harmless. Which statement about the tetanus vaccine is correct? A After vaccination, the toxoid in the vaccine will be ingested by neutrophils and displayed in their cell surface membranes. B The tetanus vaccine containing the toxoid does not contain antigens because it does not contain any cells of the pathogen. C The toxoid protein in the vaccine stimulates the production of antibodies which remain in the blood to provide long-term immunity. D When formaldehyde binds to the toxin, it causes the toxin to completely change shape.

Question

What is an effect on the immune system of a reduced number of T-helper cells? A a decrease in the destruction of infected body cells by T-helper cells B a decrease in the activation of B-lymphocytes C an increase in the activation of T-killer cells D an increase in the production of plasma cells