Edexcel A-Level Biology 2027 Predicted Practice Paper — Paper 1

Answer ALL questions. Write your answers in the spaces provided. You must write down all the stages in your working.

Section A

Multiple choice. Answer ALL questions.

• 1

  Question SECTION-A1 (1 mark)

  Which type of chemical bond forms between the carboxyl group of one amino acid and the amino group of the next during protein synthesis?

  A. Peptide bondB. Glycosidic bondC. Ester bondD. Hydrogen bond

  (Total for Question SECTION-A1 is 1 mark)
• 2

  Question SECTION-A2 (1 mark)

  A globular protein loses its function after being heated to 70 degrees C. Which level of structure is directly disrupted first by breaking hydrogen and ionic bonds?

  A. Primary structureB. Tertiary structureC. The peptide backboneD. The sequence of amino acids

  (Total for Question SECTION-A2 is 1 mark)
• 3

  Question SECTION-A3 (1 mark)

  Which statement correctly describes facilitated diffusion across a cell surface membrane?

  A. Movement of molecules down a concentration gradient through channel or carrier proteins, without ATPB. Movement of molecules against a concentration gradient using ATPC. Movement of water through the phospholipid bilayer onlyD. Bulk movement of large particles by vesicle formation

  (Total for Question SECTION-A3 is 1 mark)
• 4

  Question SECTION-A4 (1 mark)

  In a mammalian gas exchange system, which feature most directly increases the rate of diffusion of oxygen into the blood?

  A. A large number of alveoli providing a large surface areaB. A thick layer of cartilage around the bronchiC. A high concentration of goblet cells in the tracheaD. The presence of elastic fibres in the bronchioles

  (Total for Question SECTION-A4 is 1 mark)
• 5

  Question SECTION-A5 (1 mark)

  Which molecule is the main store of energy in a plant cell?

  A. GlycogenB. StarchC. CelluloseD. Chitin

  (Total for Question SECTION-A5 is 1 mark)
• 6

  Question SECTION-A6 (1 mark)

  During the cardiac cycle, the semilunar valves of the aorta close because:

  A. Pressure in the ventricle exceeds pressure in the aortaB. Pressure in the aorta exceeds pressure in the ventricleC. The atria contractD. The sinoatrial node stops firing

  (Total for Question SECTION-A6 is 1 mark)
• 7

  Question SECTION-A7 (1 mark)

  Which of the following is an example of a risk factor for cardiovascular disease that can be reduced by a change in behaviour?

  A. Genetic predispositionB. Increasing ageC. A diet high in saturated fatD. Being male

  (Total for Question SECTION-A7 is 1 mark)
• 8

  Question SECTION-A8 (1 mark)

  The enzyme catalase catalyses the breakdown of hydrogen peroxide. According to the induced-fit model, when the substrate binds:

  A. The active site is already an exact rigid complementary shape to the substrateB. The active site changes shape slightly to fit more closely around the substrateC. The substrate permanently changes the primary structure of the enzymeD. The enzyme is used up and cannot catalyse another reaction

  (Total for Question SECTION-A8 is 1 mark)
• 9

  Question SECTION-A9 (1 mark)

  Which statement best describes the role of the tricuspid (right atrioventricular) valve?

  A. Prevents backflow from the right ventricle into the right atriumB. Prevents backflow from the aorta into the left ventricleC. Prevents backflow from the pulmonary artery into the right ventricleD. Prevents backflow from the left ventricle into the left atrium

  (Total for Question SECTION-A9 is 1 mark)
• 10

  Question SECTION-A10 (1 mark)

  A haemoglobin dissociation curve shifts to the right when carbon dioxide concentration increases. This is known as the:

  A. Bohr effectB. Cohesion-tension effectC. Chloride shiftD. Cardiac output effect

  (Total for Question SECTION-A10 is 1 mark)
• 11

  Question SECTION-A11 (1 mark)

  Which of the following correctly pairs a monomer with its polymer?

  A. Amino acid -> polypeptideB. Glucose -> triglycerideC. Nucleotide -> celluloseD. Glycerol -> glycogen

  (Total for Question SECTION-A11 is 1 mark)
• 12

  Question SECTION-A12 (1 mark)

  Which stage of the cell cycle involves the separation of sister chromatids to opposite poles of the cell?

  A. ProphaseB. MetaphaseC. AnaphaseD. Telophase

  (Total for Question SECTION-A12 is 1 mark)
• 13

  Question SECTION-A13 (1 mark)

  The lungs are described as having a large surface area to volume ratio. Which best explains why a large surface area to volume ratio is important for gas exchange?

  A. It reduces the diffusion distance for gasesB. It increases the total area available for diffusion relative to the cells being suppliedC. It increases the temperature of the exchange surfaceD. It reduces the water potential of the alveolar fluid

  (Total for Question SECTION-A13 is 1 mark)
• 14

  Question SECTION-A14 (1 mark)

  Which type of transport requires the direct hydrolysis of ATP by a carrier protein?

  A. Simple diffusionB. OsmosisC. Facilitated diffusionD. Active transport

  (Total for Question SECTION-A14 is 1 mark)
• 15

  Question SECTION-A15 (1 mark)

  Genetic biodiversity within a species is best measured by:

  A. The number of different species in a habitatB. The proportion of genes that are polymorphic (have more than one allele)C. The total mass of organisms in an ecosystemD. The number of different habitats in an area

  (Total for Question SECTION-A15 is 1 mark)
• 16

  Question SECTION-A16 (1 mark)

  Natural selection is most likely to lead to evolution of a population when:

  A. All individuals in the population are genetically identicalB. There is genetic variation and a selection pressure favouring certain allelesC. The environment is completely stable and unchangingD. Reproduction is entirely asexual with no mutation

  (Total for Question SECTION-A16 is 1 mark)
• 17

  Question SECTION-A17 (1 mark)

  Which structure in a prokaryotic cell is NOT surrounded by a membrane?

  A. The circular DNA in the cytoplasmB. The mitochondrionC. The nucleusD. The endoplasmic reticulum

  (Total for Question SECTION-A17 is 1 mark)
• 18

  Question SECTION-A18 (1 mark)

  The presence of many mitochondria in a cell that carries out active transport suggests that the cell has a high demand for:

  A. ATPB. WaterC. Carbon dioxideD. Cellulose

  (Total for Question SECTION-A18 is 1 mark)
• 19

  Question SECTION-A19 (1 mark)

  Which of the following would increase the rate of transpiration from a leaf?

  A. An increase in air humidity around the leafB. A decrease in air movement (wind)C. An increase in temperatureD. A decrease in light intensity closing the stomata

  (Total for Question SECTION-A19 is 1 mark)
• 20

  Question SECTION-A20 (1 mark)

  An antibody molecule has a quaternary structure. This means that the functional molecule:

  A. Consists of a single polypeptide chain onlyB. Consists of more than one polypeptide chainC. Contains no hydrogen bondsD. Has no specific three-dimensional shape

  (Total for Question SECTION-A20 is 1 mark)

Section B

Short-answer and structured questions. Answer ALL questions.

• 1

  Question SECTION-B1 (5 marks)

  A student investigated the effect of temperature on the rate of an enzyme-catalysed reaction between the enzyme amylase and starch. At each temperature they recorded the time taken for the starch to be fully broken down, tested using iodine solution. (a) State the independent variable and the dependent variable in this investigation. (2 marks) (b) Explain why the rate of reaction increases as temperature rises from 10 degrees C to 40 degrees C. (2 marks) (c) The rate fell sharply above 55 degrees C. Explain this observation in terms of enzyme structure. (1 mark)

  (Total for Question SECTION-B1 is 5 marks)
• 2

  Question SECTION-B2 (6 marks)

  Figure 1 (described) shows a section through the mammalian gaseous exchange system, including the alveoli and surrounding capillaries. (a) Describe how the structure of an alveolus is adapted for efficient gas exchange. (3 marks) (b) Using Fick's law, explain how TWO of these adaptations increase the rate of oxygen diffusion into the blood. (3 marks)

  (Total for Question SECTION-B2 is 6 marks)
• 3

  Question SECTION-B3 (7 marks)

  Atheroma formation can lead to cardiovascular disease. (a) Describe the sequence of events by which an atheroma forms in an artery wall following damage to the endothelium. (4 marks) (b) Explain how the formation of an atheroma can increase the risk of a myocardial infarction (heart attack). (3 marks)

  (Total for Question SECTION-B3 is 7 marks)
• 4

  Question SECTION-B4 (6 marks)

  The cell cycle consists of interphase followed by mitosis and cytokinesis. (a) Describe what happens during the S phase of interphase and explain why this phase is essential before mitosis. (3 marks) (b) Explain the importance of mitosis producing two genetically identical daughter cells. (3 marks)

  (Total for Question SECTION-B4 is 6 marks)
• 5

  Question SECTION-B5 (8 marks)

  A researcher measured the biodiversity of insects in two woodland sites, A and B. Site A had recently been managed by removing many tree species; site B was undisturbed. (a) State what is meant by an index of diversity and explain why it is a more useful measure of biodiversity than simply counting the number of species present. (3 marks) (b) Site A had a lower index of diversity than site B. Explain, using ideas about ecosystems and stability, why a lower index of diversity may make site A more vulnerable to environmental change. (3 marks) (c) Suggest ONE valid sampling technique the researcher could use to collect insects from the ground layer, and state one way to make the sampling representative. (2 marks)

  (Total for Question SECTION-B5 is 8 marks)
• 6

  Question SECTION-B6 (6 marks)

  Cell surface membranes control the movement of substances into and out of cells. (a) Describe the arrangement of phospholipids in a cell surface membrane and explain how this arrangement allows the membrane to act as a barrier to water-soluble substances. (3 marks) (b) Explain why oxygen and carbon dioxide can cross the phospholipid bilayer easily by simple diffusion, whereas glucose cannot. (3 marks)

  (Total for Question SECTION-B6 is 6 marks)
• 7

  Question SECTION-B7 (7 marks)

  Haemoglobin transports oxygen in the blood. Figure 2 (described) shows two oxygen dissociation curves: one for adult haemoglobin and one for fetal haemoglobin, with fetal haemoglobin's curve to the left of the adult's. (a) Explain what is meant by the statement that fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin, and why this is important for the fetus. (3 marks) (b) Explain how the Bohr effect helps to unload oxygen at respiring tissues in an adult. (4 marks)

  (Total for Question SECTION-B7 is 7 marks)
• 8

  Question SECTION-B8 (7 marks)

  Cardiac output is the volume of blood pumped by one ventricle per minute and is calculated as heart rate multiplied by stroke volume. (a) A person has a resting heart rate of 68 beats per minute and a stroke volume of 75 cm3. Calculate their resting cardiac output in cm3 per minute, and give your answer in dm3 per minute. (2 marks) (b) During exercise the person's cardiac output rises. Explain, in terms of the heart and its control, TWO ways in which cardiac output can be increased during exercise. (3 marks) (c) Explain the role of the sinoatrial node (SAN) in initiating and coordinating each heartbeat, and how the heart rate can be increased by the nervous system. (2 marks)

  (Total for Question SECTION-B8 is 7 marks)

Section C

Extended writing. Answer ALL questions.

• 1

  Question SECTION-C1 (6 marks)

  Water is often described as a molecule that is essential for life. Discuss the properties of water that arise from its structure and explain how these properties make water important both as a metabolic reactant and as a transport medium in living organisms. (6 marks)

  (Total for Question SECTION-C1 is 6 marks)
• 2

  Question SECTION-C2 (6 marks)

  Explain how the structure of the mammalian heart and the events of the cardiac cycle ensure that blood is pumped efficiently and in one direction through the heart. (6 marks)

  (Total for Question SECTION-C2 is 6 marks)
• 3

  Question SECTION-C3 (6 marks)

  Antibiotic resistance in bacteria is an example of evolution by natural selection. Explain how a population of bacteria can become resistant to an antibiotic over time, and discuss why the overuse of antibiotics increases the problem. (6 marks)

  (Total for Question SECTION-C3 is 6 marks)