2024_AQA: A-level BIOLOGY Paper 1 (Merged Question paper and marking scheme) Wednesday 5 June 2024

2024_AQA: A-level BIOLOGY Paper 1 (Merged Question paper and marking scheme) Wednesday 5 June 2024 Please write clearly in block capitals. Centre number Surname Forename(s) Candidate signat ure A-level BIOLOGY Paper 1 I declare this is my own work. Candidate number Wednesday 5 June 2024 Materials For this paper you must have:  a ruler with millimetre measurements  a scientific calculator. Instructions  Use black ink or black ball-point pen.  Fill in the boxes at the top of this page.  Answer all questions. Afternoon  You must answer the questions in the spaces provided. Do not write outside the box around each page or on blank pages. Time allowed: 2 hours For Examiner’s Use Question Mark 1 2 3 4 5 6  If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s).  Show all your working.  Do all rough work in this book. Cross through any work you do not want to be marked. Information  The marks for the questions are shown in brackets.  The maximum mark for this paper is 91. 7 8 9 10 TOTAL A-level Biology Paper 1: Key Areas to Revise This paper tests your knowledge of key biological concepts, focusing on topics from the first year of A-level. The main areas to revise are: 1. Cell Recognition and the Immune System: Study the components and function of the immune system, including the role of lymphocytes, antibodies, and antigens. Understand how phagocytosis and the immune response work, and be familiar with vaccinations, monoclonal antibodies, and the concept of immunity. 2. Cell Recognition and the Immune System: Review cell structures, especially the plasma membrane, and the processes that enable cells to recognize each other. Focus on the mechanisms of the immune system, including antigen-antibody interactions, T-cells, and B-cells. 3. The Endocrine System: Revise the glands and hormones involved in homeostasis and regulation, including the hypothalamus, pituitary gland, thyroid, and adrenal glands. Be familiar with feedback mechanisms, such as negative feedback in regulating blood glucose and other hormones. 4. Excretion and Osmoregulation: Study the structure and function of the kidney in excretion and osmoregulation, including filtration, selective reabsorption, and urine formation. Know how ADH regulates water balance and how the kidneys maintain homeostasis. 5. Genetic Information, Variation, and Relationships Between Organisms: Understand the structure of DNA, gene expression, and the role of RNA in protein synthesis. Be able to explain mutation, gene sequencing, and the process of natural selection. Revise genetic variation, species classification, and evolutionary relationships, including phylogeny. 6. Photosynthesis and Respiration: Review the processes of photosynthesis (light-dependent and light independent reactions) and cellular respiration (aerobic and anaerobic), focusing on the production of ATP, energy transfer, and how these processes relate to energy use in organisms. 7. Practical Skills: Expect questions that assess your understanding of experimental techniques, data analysis, and the interpretation of biological data. Review methods used in biology, such as microscopy, enzyme assays, and other laboratory-based investigations. By focusing on these topics, you’ll be well-prepared to tackle both theoretical and applied questions in A-level Biology Paper 1. IB/M/Jun24/G4006/E11 7402/1 2 Do not write outside the box Answer all questions in the spaces provided. IB/M/Jun24/7402/1 0 1 . 1 Figure 1 shows the structure of a fatty acid molecule and the structure of a glycerol molecule. Figure 1 On Figure 1, draw a circle around the part of the fatty acid molecule and the part of the glycerol molecule that is removed to form a bond in a triglyceride molecule. Name the bond formed between a fatty acid and glycerol in a triglyceride molecule. Name the reaction involved in forming a bond between a fatty acid and glycerol in a triglyceride molecule. [3 marks] Bond Reaction 3 Do not write outside the box IB/M/Jun24/7402/1 Table 1 shows information about three fatty acids. Table 1 0 1 . 2 Name the fatty acid shown in Table 1 that is a saturated fatty acid. [1 mark] 0 1 . 3 The melting point is the temperature at which a solid changes state to be a liquid. Use Table 1 to describe the relationship between fatty acid structure and fatty acid melting point. [1 mark] Question 1 continues on the next page Turn over ► 4 Do not write outside the box IB/M/Jun24/7402/1 0 1 . 4 The ratio of saturated to unsaturated fatty acids in a cell-surface membrane determines the extent of the membrane’s fluidity. Scientists provided a cell culture of mouse phagocytes with liquid broth rich in unsaturated fatty acids. The scientists observed:  an increase in the proportion of phospholipids in the phagocytes containing unsaturated fatty acids  more phagocytosis. Suggest and explain why there was more phagocytosis. [3 marks] 8 5 Do not write outside the box IB/M/Jun24/7402/1 0 2 . 1 Describe the processes of facilitated diffusion and active transport. [3 marks] Facilitated diffusion Active transport 0 2 . 2 What are microvilli? [1 mark] Question 2 continues on the next page Turn over ► 6 Do not write outside the box IB/M/Jun24/7402/1 7 0 2 . 3 Vitamin A is a fat-soluble substance. Micelles are involved in the process of vitamin A absorption. Describe the process of vitamin A absorption into cells lining the ileum. [3 marks] 7 Do not write outside the box Turn over for the next question IB/M/Jun24/7402/1 DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED Turn over ► 8 Do not write outside the box IB/M/Jun24/7402/1 0 3 . 1 Describe how we breathe in. [3 marks] 0 3 . 2 A scientist prepared alveolar tissue to view using an optical microscope. The scientist cut very thin slices of the alveolar tissue. Explain why the scientist used very thin slices of alveolar tissue with the optical microscope. [2 marks] 9 Do not write outside the box IB/M/Jun24/7402/1 0 3 . 3 Figure 2 is an image of the lung tissue observed using an optical microscope. Figure 2 Identify the tube labelled A. [1 mark] A The scientist used a ruler to measure the diameter of some of the alveoli. Table 2 shows the scientist’s results. Table 2 Alveolus diameter / mm Alveolus diameter / mm 4 2 5 1 2 3 5 2 0 3 . 4 The magnification of the image in Figure 2 is × 40 Use this information and Table 2 to calculate the mean diameter, in μm, of the alveoli. Show your working. [2 marks] Answer μm Turn over ► 10 Do not write outside the box IB/M/Jun24/7402/1 0 3 . 5 Give the uncertainty associated with taking a measurement using a ruler with 1 mm graduations. Calculate the percentage error for a measurement using the ruler of 4 mm [2 marks] Uncertainty ± mm Percentage error 10 11 Do not write outside the box IB/M/Jun24/7402/1 0 4 . 1 Molasses is a solution obtained from sugar beet plants. The sugars present in molasses are sucrose, glucose and fructose. Give the number of different types of monosaccharides present in molasses. [1 mark] 0 4 . 2 A student used the biochemical test for reducing sugars on a clear sample of molasses. Describe the biochemical test for a reducing sugar. Explain the result expected from the test on the sample of molasses. [3 marks] Description of biochemical test Explanation of expected result 0 4 . 3 ‘Free sugar’ is the sugar in food and drinks released when food is crushed or when sugar is added to food at home or by manufacturers. Scientists recommend that no more than 5% of the energy consumed per day should come from ‘free sugar’. The mean daily energy requirement for a 10-year-old child is 8100 kJ The ‘free sugar’ in one tablespoon of molasses contains 250 kJ of energy. Calculate the number of tablespoons of molasses required for a 10-year-old child to reach the recommendation for energy consumed in ‘free sugar’ per day. [1 mark] Number of tablespoons per day Turn over ► 12 Do not write outside the box IB/M/Jun24/7402/1 0 4 . 4 A scientist used the apparatus in Figure 3 to investigate osmosis. Figure 3 Use your understanding of osmosis to explain why the air pressure in the tube increased. [3 marks] 13 Do not write outside the box IB/M/Jun24/7402/1 0 4 . 5 The scientist repeated the investigation, but made one change to the molasses. The scientist did not change the volume of molasses at the start of the investigation. The scientist observed that the air pressure inside the tube increased by 160 kPa compared with 800 kPa in the first investigation. Suggest the change the scientist made to the molasses to cause this smaller increase in air pressure. Use the air pressure figures in a calculation to support your answer. [2 marks] Suggested change Turn over for the next question Turn over ► 10 14 Do not write outside the box IB/M/Jun24/7402/1 0 5 . 1 Describe the appearance and behaviour of chromosomes during prophase and during anaphase of mitosis. [4 marks] Prophase Anaphase 0 5 . 2 A scientist used an optical microscope to determine the mitotic index in cells at different distances from the tip of onion roots. Figure 4 shows the results. Figure 4 Complete the word equation used to determine each mitotic index in Figure 4. [1 mark] Mitotic Index = 15 Do not write outside the box IB/M/Jun24/7402/1 0 5 . 3 The scientist used data from Figure 4 to calculate a correlation coefficient (r). The scientist then used a statistical test to determine the probability (P) associated with the value of r. r = –0.98 (P < 0.05) What can you conclude from this result? [2 marks] 0 5 . 4 What can you conclude about the effect that distance from the root tip has on the proportion of cells in different stages of the cell cycle? Use information in Figure 4. [3 marks] Turn over for the next question Turn over ► 10 16 Do not write outside the IB/M/Jun24/7402/1 1 2 . Give three structural differences between an mRNA molecule and a tRNA molecule. [3 marks] mRNA tRNA . Table 3 shows mRNA codons and the amino acid coded by each codon. Table 3 Figure 5 shows the mRNA base sequence produced when part of a gene coding for an enzyme is transcribed. Figure 5 UUU CGG GCG Use Table 3 to give the amino acids coded by the mRNA base sequence in Figure 5. [1 mark] box 6 0 0 6 17 Do not write outside the box IB/M/Jun24/7402/1 0 6 . 3 A mutation occurred in the part of the gene transcribed in Question 06.2. Figure 6 shows the mRNA base sequence produced when the identical part in the mutated gene is transcribed. Figure 6 UUU AGG GCG The amino acids coded by this mRNA base sequence form part of the enzyme’s active site. Use all the information in this question to:  name the type of mutation that occurred to produce the mutated gene  give the change in DNA caused by this mutation  explain the effect this mutation will have on the function of the enzyme. [4 marks] Type of mutation Change in DNA Explanation of effect on function of enzyme Turn over for the next question Turn over ► 8 18 Do not write outside the box IB/M/Jun24/7402/1 0 7 . 1 A student investigated the activity of the enzyme polyphenol oxidase (PPO) in apple tissue. When apple tissue is exposed to air, PPO catalyses a reaction between colourless phenol compounds in apple tissue and oxygen. Figure 7 shows the reaction. Figure 7 PPO phenol compounds + oxygen → brown pigment The student measured the time taken for the brown pigment to appear in two apple varieties (D and E). Method 1. Cut a 1 cm cube of apple tissue from variety D. 2. Put the cube on a plate and leave the plate at 30 °C 3. Measure the time for the brown pigment to appear. 4. Repeat steps 1 to 3 two more times. 5. Repeat steps 1 to 4 with apple tissue from variety E. The student obtained the results shown below, but did not record the data in a results table. Variety D = 15 min 50 s, 18 min, 14 min 30 s Variety E = 6 min 30 s, 8 min, 7 min In the box labelled Figure 8, design a suitable results table.  Enter the student’s results into the table.  Calculate the mean results and include these in the table.  Use 1 decimal place for both mean results. [3 marks] 19 Do not write outside the box Figure 8 IB/M/Jun24/7402/1 0 7 . 2 Suggest and explain why the results for variety D are different from the results for variety E. [2 marks] Question 7 continues on the next page Turn over ► 20 Do not write outside the box IB/M/Jun24/7402/1 0 7 . 3 The student repeated the investigation but made one change to the method used to prepare the apple tissue. The student then observed shorter times for the brown pigment to appear in both apple varieties. Suggest the change the student made to the method of preparing the apple tissue. Explain why the brown pigment appeared in a shorter time. Do not suggest using a different volume or mass of apple. [3 marks] Change to method Explanation . The student wants to change the procedure to obtain a measure of PPO activity either in terms of how much substrate is used or how much product is produced. Which change in procedure will provide a successful measure of PPO activity for the student? Tick () one box. [1 mark] Measure the increase in oxygen concentration in the air around the cube of apple tissue on a plate. Measure the intensity of brown colour by comparing apple tissue with a colour chart showing a range of apple tissues of known pigment concentration. Measure the intensity of colour produced from brown apple tissue in a biuret test. Measure the percentage of light transmitted through a cube of brown apple tissue using a colorimeter. 4 9 7 0 21 Do not write outside the box IB/M/Jun24/7402/1 0 8 . 1 Give two structural features of an aorta wall and explain how they are related to the function of an aorta. [2 marks] 1 2 Question 8 continues on the next page Turn over ► 22 Do not write outside the IB/M/Jun24/7402/1 2 . Small tears may occur in the layers of tissue in an aorta wall. These tears weaken the wall without bursting the aorta. Scientists:  measured the aorta diameter (d) in a large population of people over 60 years of age  calculated the risk of an aorta wall developing a tear. Table 4 shows their results. Table 4 Aorta diameter d / cm Number of people in the population Risk of an aorta wall developing a tear d ≤ 3.5 2765 0.06 3.5 < d ≤ 4.0 630 0.33 4.0 < d ≤ 4.5 98 4.64 d > 4.5 7 380.00 Blood may push through the tears in the aorta wall. This produces a balloon-like swelling called an aneurysm and increases the aorta diameter. Aneurysms can cause the aorta to burst. Using all the information, what can you conclude about aorta diameter and the risk of developing an aneurysm? box [3 marks] 8 0 23 Do not write outside the IB/M/Jun24/7402/1 3 . A scientist investigated changes in a diseased heart and changes in a healthy heart during cardiac cycles. For each heart, the scientist obtained a value for:  the mean blood volume in a full ventricle just before the ventricle contracts (BVB)  the mean ejection fraction (EF). The EF is the proportion of blood pumped out of a full ventricle in one heartbeat. The EF is calculated using this formula: Blood volume pumped out of a full ventricle in one heartbeat (stroke volume) box EF = Table 5 shows the scientist’s results. BVB Table 5 Diseased heart Healthy heart Mean BVB / cm3 100 120 Mean EF 0.45 0.58 Using Table 5, a student calculated that the percentage change in the stroke volume of the diseased heart compared with the stroke volume of a healthy heart is –30%. The student’s answer is wrong because the final step of the calculation was performed incorrectly. Using the equation and Table 5, calculate the correct percentage change in the stroke volume of the diseased heart compared with the stroke volume of the healthy heart. Identify the mathematical error in the final step of the student’s calculation. [3 marks] Correct answer % Mathematical error Turn over ► 8 8 0 24 Do not write outside the IB/M/Jun24/7402/1 Courtship behaviour in the frog species, Xenopus laevis, involves male frogs calling to:  attract sexually active females – these are advertisement calls  start and continue mating – these are mating calls  signal when a male is not sexually active – these are rasping calls. Scientists investigated frog courtship behaviour by feeding a population of sexually active male frogs a diet containing the hormone EE2. The scientists also fed a separate control population of sexually active male frogs a diet without EE2. They determined the percentage of males making advertisement calls or rasping calls in each population. Table 6 shows their results. Table 6 box Population Percentage of males making: Advertisement calls Rasping calls Males fed EE2 94.0 4.0 Males not fed EE2 (control) 97.0 0.5 0 9 . 1 There were 800 males in the control population. Each male made one type of call. Use this information and Table 6 to calculate the number of males making mating calls in the control population. [1 mark] Answer males 0 9 25 Do not write outside the box IB/M/Jun24/7402/1 0 9 . 2 Suggest one change the scientists could make to both frog populations to increase the number of mating calls. [1 mark] . The scientists also investigated the effect on female frog courtship behaviour of feeding EE2 to male frogs. Table 7 shows their results. Table 7 Population Median time females spent in courtship / s Males fed EE2 8 Males not fed EE2 (control) 16 EE2 is contained in human contraceptive pills. Some EE2 is released in human urine and collects in sewage. Untreated sewage pollutes the water in frog habitats. Suggest and explain the effect EE2 pollution in frog habitats will have on frog breeding. Use information from Table 6 and Table 7 in your answer. [4 marks] Effect on frog breeding Explanation Turn over ► 3 6 9 0 26 Do not write outside the box IB/M/Jun24/7402/1 1 0 . 1 Describe and explain how you would use cell fractionation and ultracentrifugation to obtain a sample of nuclei from muscle tissue. [6 marks] 27 Do not write outside the box IB/M/Jun24/7402/1 1 0 . 2 Describe the role of organelles in the production and release of enzymes by animal cells. Do not include details of transcription in your answer. [5 marks] Question 10 continues on the next page Turn over ► 28 Do not write outside the box IB/M/Jun24/7402/1 1 0 . 3 Describe the structure of ATP. Outline how named enzymes break down and resynthesise ATP. [4 marks] END OF QUESTIONS 15 29 IB/M/Jun24/7402/1 There are no questions printed on this page DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED Do not write outside the box 30 Additional page, if required. Write the question numbers in the left-hand margin. Question number IB/M/Jun24/7402/1 Do not write outside the box 31 Question number Additional page, if required. Write the question numbers in the left-hand margin. IB/M/Jun24/7402/1 Do not write outside the box 32 Do not write outside the box Question number Additional page, if required. Write the question numbers in the left-hand margin. Copyright information For confidentiality purposes, all acknowledgements of third-party copyright material are published in a separate booklet. This booklet is published after each live examination series and is available for free download from Permission to reproduce all copyright material has been applied for. In some cases, efforts to contact copyright-holders may have been unsuccessful and AQA will be happy to rectify any omissions of acknowledgements. If you have any queries please contact the Copyright Team. Copyright © 2024 AQA and its licensors. All rights reserved. IB/M/Jun24/7402/1 A-level BIOLOGY 7402/1 Paper 1 Mark scheme June 2024 Version: 1.0 Final MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2024 Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation events which all associates participate in and is the scheme which was used by them in this examination. The standardisation process ensures that the mark scheme covers the students’ responses to questions and that every associate understands and applies it in the same correct way. As preparation for standardisation each associate analyses a number of students’ scripts. Alternative answers not already covered by the mark scheme are discussed and legislated for. If, after the standardisation process, associates encounter unusual answers which have not been raised they are required to refer these to the Lead Examiner. It must be stressed that a mark scheme is a working document, in many cases further developed and expanded on the basis of students’ reactions to a particular paper. Assumptions about future mark schemes on the basis of one year’s document should be avoided; whilst the guiding principles of assessment remain constant, details will change, depending on the content of a particular examination paper. No student should be disadvantaged on the basis of their gender identity and/or how they refer to the gender identity of others in their exam responses. A consistent use of ‘they/them’ as a singular and pronouns beyond ‘she/her’ or ‘he/him’ will be credited in exam responses in line with existing mark scheme criteria. Further copies of this mark scheme are available from Copyright information AQA retains the copyright on all its publications. However, registered schools/colleges for AQA are permitted to copy material from this booklet for their own internal use, with the following important exception: AQA cannot give permission to schools/colleges to photocopy any material that is acknowledged to a third party even for internal use within the centre. Copyright © 2024 AQA and its licensors. All rights reserved. 2 MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2024 Mark scheme instructions to examiners 1. General The mark scheme for each question shows: • the marks available for each part of the question • the total marks available for the question • the typical answer or answers which are expected • extra information to help the examiner make his or her judgement and help to delineate what is acceptable or not worthy of credit or, in discursive answers, to give an overview of the area in which a mark or marks may be awarded. The extra information in the ‘Comments’ column is aligned to the appropriate answer in the left- hand part of the mark scheme and should only be applied to that item in the mark scheme. At the beginning of a part of a question a reminder may be given, for example: where consequential marking needs to be considered in a calculation; or the answer may be on the diagram or at a different place on the script. In general the right-hand side of the mark scheme is there to provide those extra details which confuse the main part of the mark scheme yet may be helpful in ensuring that marking is straightforward and consistent. 2. Emboldening 2.1 2.2 2.3 In a list of acceptable answers where more than one mark is available ‘any two from’ is used, with the number of marks emboldened. Each of the following bullet points is a potential mark. A bold and is used to indicate that both parts of the answer are required to award the mark. Alternative answers acceptable for the same mark are indicated by the use of OR. Different terms in the mark scheme are shown by a / ; eg allow smooth / free movement. 3. Marking points 3.1 Marking of lists This applies to questions requiring a set number of responses, but for which students have provided extra responses. The general principle to be followed in such a situation is that ‘right + wrong = wrong’. Each error / contradiction negates each correct response. So, if the number of errors / contradictions equals or exceeds the number of marks available for the question, no marks can be awarded. However, responses considered to be neutral (often prefaced by ‘Ignore’ in the ‘Comments’ column of the mark scheme) are not penalised. 3 MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2024 3.2 3.3 3.4 3.5 3.6 3.7 Marking procedure for calculations Full marks can be given for a correct numerical answer, without any working shown. However, if the answer is incorrect, mark(s) can usually be gained by correct substitution / working and this is shown in the ‘Comments’ column or by each stage of a longer calculation. Interpretation of ‘it’ Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the correct subject. Errors carried forward, consequential marking and arithmetic errors Allowances for errors carried forward are most likely to be restricted to calculation questions and should be shown by the abbreviation ECF or consequential in the mark scheme. An arithmetic error should be penalised for one mark only unless otherwise amplified in the mark scheme. Arithmetic errors may arise from a slip in a calculation or from an incorrect transfer of a numerical value from data given in a question. Phonetic spelling The phonetic spelling of correct scientific terminology should be credited unless there is a possible confusion with another technical term. Brackets (…..) are used to indicate information which is not essential for the mark to be awarded but is included to help the examiner identify the sense of the answer required. Ignore / Insufficient / Do not allow Ignore or insufficient is used when the information given is irrelevant to the question or not enough to gain the marking point. Any further correct amplification could gain the marking point. Do not allow means that this is a wrong answer which, even if the correct answer is given, will still mean that the mark is not awarded. 4 MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2024 Question Marking Guidance Mark Comments 01.1 1. Circle(s)/shape(s) drawn around H in one of the HO groups of the glycerol and the OH group of the fatty acid; 2. Ester (bond); 3. Condensation (reaction); 3 (3 x AO1) 1. Accept circle(s)/shape(s) drawn around the OH group of one molecule and the H of an OH group of the other molecule Question Marking Guidance Mark Comments 01.2 Stearic (acid); 1 (1 x AO1) Question Marking Guidance Mark Comments 01.3 As (number of C) double bonds increases, melting point decreases OR As unsaturation increases, melting point decreases OR As saturation increases, melting point increases; 1 (1 x AO2) Accept converse Accept C=C for double bonds Accept as (number of) hydrogen/H (atoms) increases, melting point increases Question Marking Guidance Mark Comments 01.4 1. More unsaturated fatty acids increases fluidity (in (cell-surface membrane); 2. (Making cell-surface) membrane more fluid/ flexible; 3. Easy to engulf; 3 (3 x AO2)