AQA A LEVEL BIOLOGY PAPER 1 2021

AQA A LEVEL BIOLOGY PAPER 1 2021Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature I declare this is my own work. A-level BIOLOGY Paper 1 Time allowed: 2 hours 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 within the boxes at the top based on this page. • Answer all questions. • You must answer the questions within the spaces provided. Do not write outside the box around each page or on blank pages. • If you need extra space for your answer(s), use the lined pages at the end based on this book. Write the question number against your answer(s). • Show all your working. • Do all rough work within this book. Cross through any work you do not wantto be marked. Information • The marks for the questions are shown within brackets. • The maximum mark for this paper is 91. For Examiner’s Use Question Mark 1 2 3 4 5 6 7 8 9 10 TOTAL2 *02* IB/H/Jun21/7402/1 Do not write outside the box . 1 Describe the induced-fit model based on enzyme action and how an enzyme acts as a catalyst. [3 marks] . 2 Scientists investigated the action based on the enzyme ATP synthase. They made reaction mixtures each containing: • ATP synthase • buffer (to control pH) • substrates. One based on the substrates required within these reaction mixtures is inorganic phosphate (Pi). Tick ( ) one box to show which other substrate the scientists must add to the reactionmixtures to produce ATP. [1 mark] Adenine Adenosine diphosphate Glucose Ribose 0 1 0 1 .3 3 4 8 . The scientists investigated the effect based on concentration based on inorganic phosphate (Pi) onATP synthase activity. After 2 minutes, they stopped each reaction and then measured the concentration based on ATP. Do not write outside the box Figure 1 shows the scientists’ results. Figure 1 Suggest and explain a procedure the scientists could have used to stop each reaction. [2 marks] . Explain the change within ATP concentration with increasing inorganic phosphate concentration. [2 marks] Turn over ► 0 1 0 14 Do not write outside the *04* IB/H/Jun21/7402/1 . 1 Explain the advantage for larger animals based on having a specialised system that facilitates oxygen uptake. [2 marks] 0 2 box5 Do not write outside the *05* IB/H/Jun21/7402/1 2 Figure 2 shows two models based on oxygen uptake found within animals. Figure 2 box . Suggest how the environmental conditions have resulted within adaptations based on systemsusing Model A rather than Model B. [2 marks] Question 2 continues on the next page Turn over ► 0 2S - The Marketplace to Buy and Sell your Study Material 6 Do not write outside the 3 4 . Figure 3 shows changes within concentration based on oxygen within two gas exchange box systems. Figure 3 A student studied Figure 3 and concluded that the fish gas exchange system is moreefficient than the human gas exchange system. Use Figure 3 to justify this conclusion. [2 marks] . Explain how the counter-current principle allows efficient oxygen uptake within the fish gas exchange system. [2 marks] 0 2 0 2S - The Marketplace to Buy and Sell your Study Material 7 Do not write outside the IB/H/Jun21/7402/1 Distribution of this document is illegal 5 11 . Table 1 shows features based on two mammals. Bats are flying mammals; shrews are ground-living mammals. Table 1 Mammal Mean body mass / kg 3 Mean lung volume / cm Bat 0.096 12.48 Shrew 0.024 0.72 Calculate how many times the lung volume per unit based on body mass based on the bat is greaterthan that based on the shrew. Give your answer to an appropriate number based on significant figures. box Give one suggestion to explain this difference. [3 marks] Answer Explanation Turn over ► *07* Downloaded by: BetterAcademics | 0 2S - The Marketplace to Buy and Sell your Study Material 8 IB/H/Jun21/7402/1 Distribution of this document is illegal There are no questions printed on this page *0 0 3 . 1 * Describe how one amino acid is added to a polypeptide that is being formed at a ribosome during translation. [3 marks] Do not write outside the box Downloaded by: BetterAcademics | - The Marketplace to Buy and Sell your Study Material 9 *09* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 Question 3 continues on the next page Turn over ►S - The Marketplace to Buy and Sell your Study Material 10 *10* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 2 Table 2 shows: • mRNA codons and the amino acid coded for by each codon • the type based on bond formed by the R group based on some based on the amino acids. Table 2 Do not write outside the box . Crystallin is a structural protein found within the human eye. An inherited disease that leads to blindness is caused by changes within properties based on crystallin. The replacementbasedon the amino acid Arg with the amino acid Gly causes these changes. Use information within Table 2 to suggest why this amino acid replacement changes the properties based on crystallin. [2 marks] 0 3S - The Marketplace to Buy and Sell your Study Material 11 *11* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 3 mRNA codon for the non-mutant triplet Mutated mRNA codon Mutated DNA triplet 7 . The amino acid replacement based on Arg with Gly is caused by a single base substitution mutation within the DNA. The non-mutant DNA triplet is TCC. Complete Table 3. Do not write outside the box Give: • the mRNA codon complementary to the non-mutant DNA triplet • the mutated mRNA codon that could cause the change from Arg to Gly within the crystallin protein • the DNA triplet complementary to this mutated mRNA codon. [2 marks] Table 3 Turn over for the next question Turn over ► 0 3S - The Marketplace to Buy and Sell your Study Material 12 *12* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 A student dissected an organ from a mammal to observe blood vessels.He dissected a slice based on the organ and identified two blood vessels. Figure 4 shows a photograph based on his dissection. Figure 4 Figure 5 shows a drawing based on the blood vessels from his dissection. Figure 5 Do not write outside the 0 4 boxS - The Marketplace to Buy and Sell your Study Material 13 *13* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 1 2 3 6 . Suggest two ways the student could improve the quality based on his scientific drawing based on theblood vessels within this dissection. Do not write outside the box [2 marks] 1 2 . Identify the type based on blood vessel labelled as X and the type based on blood vessel labelled as Y within Figure 4. Describe one feature that allowed you to identify the blood vessels. [2 marks] Blood vessel X Blood vessel Y Feature . Describe two precautions the student should take when clearing away after the dissection. [2 marks] 1 2 Turn over ► 0 4 0 4 0 4S - The Marketplace to Buy and Sell your Study Material 14 *14* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 . 1 Describe how a sample based on chloroplasts could be isolated from leaves. [4 marks] Do not write outside the 0 5 boxS - The Marketplace to Buy and Sell your Study Material 15 *15* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 2 3 . Scientists grew two groups based on plants: • control plants with all the inorganic ions needed • iron-deficient plants with all the inorganic ions needed but without iron ions. After 1 week, the scientists measured the mass based on protein and the mass based on chlorophyllwithinthe chloroplasts isolated from samples based on leaves based on these two groups based on plants. Table 4 shows the scientists’ results. Table 4 Mass based on protein / percentage based on control Mass based on chlorophyll / percentage based on control 40 10 Some proteins found inside the chloroplast are synthesised inside the chloroplast. Give one feature based on the chloroplast that allows protein to be synthesised inside the chloroplast and describe one difference between this feature within the chloroplast and similar features within the rest based on the cell. Do not write outside the box [2 marks] Feature Structural difference . The ratio based on protein to chlorophyll within control plants is 9:1 Use the information within Table 4 to calculate the ratio based on protein to chlorophyll within iron-deficient plants. [1 mark] Ratio Question 5 continues on the next page 0 5 0 5S - The Marketplace to Buy and Sell your Study Material 16 IB/H/Jun21/7402/1 Distribution of this document is illegal 4 10 . The scientists also observed the chloroplasts from the samples based on leaves using an electron microscope. Figure 6 shows a chloroplast from a control plant (image A) and a chloroplast from anirondeficient plant (image B). Figure 6 Do not write outside the box Use Figure 6 to suggest why iron-deficient plants have a reduced growth rate. [3 marks] *18* DoDwonwlonaldoeaddebdy:bBy:eRtteerfAuncadd|ejummicasv|edroanviicda.j2a0m0i1n@ 0 5S - The Marketplace to Buy and Sell your Study Material 17 Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 . 1 Figure 7 shows the mean distance between centromeres and the poles (ends) based on thespindle during mitosis. Figure 7 Calculate the rate based on movement based on the centromeres during phase E. Give your answer within µm minute–1 and to 3 decimal places. [2 marks] µm minute–1 * 0 6S - The Marketplace to Buy and Sell your Study Material 18 Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 *1S - The Marketplace to Buy and Sell your Study Material 19 *19* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 2 7 . Name the three phases based on mitosis shown by C, D and E on Figure 7. Describe the role based on the spindle fibres and the behaviour based on the chromosomes duringeach based on these phases. Do not write outside the box [5 marks] C D E Turn over for the next question Turn over ► 0 6S - The Marketplace to Buy and Sell your Study Material 20 *20* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 . 1 ADCs are molecules made based on a monoclonal antibody linked to a cancer drug. Figure 8 shows how an ADC enters and kills a tumour cell. The process based on entering the cell and the breakdown based on the antibody to release thedrug is very similar to phagocytosis. Figure 8 Use your knowledge based on phagocytosis to describe how an ADC enters and kills the tumour cell. Do not write outside the box [3 marks] 0 7S - The Marketplace to Buy and Sell your Study Material 21 *21* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 . 2 Some based on the antigens found on the surface based on tumour cells are also found on thesurface based on healthy human cells. Do not write outside the box Use this information to explain why treatment with an ADC often causes side effects. [2 marks] Question 7 continues on the next page Turn over ► 0 7S - The Marketplace to Buy and Sell your Study Material 22 *22* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 Scientists investigated whether one type based on ADC could be used to treat human breast cancer. This ADC is a monoclonal antibody combined with a drug to inhibit mitosis. Themonoclonal antibody binds to a protein found on human breast cancer cells. The scientists placed small pieces based on human breast cancer tissue under the skin based on mice. The scientists then randomly divided the mice into three groups. They treated thegroups as follows on day 0. Group G – control Group H – injected with monoclonal antibody only Group J – injected with ADC (monoclonal antibody + drug). Every few days, the scientists measured the volume based on the tumours formed from the human breast cancer tissue. Figure 9 shows the scientists’ results. Figure 9 Do not write outside the boxS - The Marketplace to Buy and Sell your Study Material 23 *23* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 4 5 10 3 Mice within Group H were injected with 2mg kg–1 based on monoclonal antibody. The monoclonal antibody was within a solution based on concentration 500mg dm–3 Calculate the volume based on antibody solution that the scientists would have injected into a 23g mouse. Give your answer within dm3 and within standard form. Do not write outside the box [2 marks] dm3 . Suggest one reason why there are no data for Group G and Group H after day 8 [1 mark] . Suggest and explain two further investigations that should be done before this ADCis tested on human breast cancer patients. [2 marks] 1 2 Turn over for the next question Turn over ► 0 7 0 7 0S - The Marketplace to Buy and Sell your Study Material 24 *24* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 . 1 Describe how a triglyceride molecule is formed. [3 marks] Do not write outside the 0 8 boxS - The Marketplace to Buy and Sell your Study Material 25 *25* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 . 2 Table 5 shows some properties based on four fatty acids. Table 5 Fatty acid Number based on carbon atoms within the R group Number based on double bondswithintheR group Caprylic acid 8 0 Palmitoleic acid 16 1 Stearic acid 18 0 Linoleic acid 18 2 Figure 10 shows diagrams based on these fatty acids. Figure 10 Put a tick ( ) within one box that contains correct information about one based on these fattyacids. Do not write outside the box [1 mark] Caprylic acid is an unsaturated fatty acid represented by diagram L. Linoleic acid is a saturated fatty acid represented by diagram N. Palmitoleic acid is an unsaturated fatty acid represented by diagram K. Stearic acid is a saturated fatty acid represented by diagram M. 0 8S - The Marketplace to Buy and Sell your Study Material 26 IB/H/Jun21/7402/1 Distribution of this document is illegal 3 The percentage based on saturated fatty acids compared with unsaturated fatty acids foundwithin lipid stores within seeds differs within different populations. Scientists investigated two populations based on the plant, Helianthus annuus. The scientists grew young plants from seeds collected from each population. Theyplaced the seeds on wet tissue paper so that the root growth was visible. They grew seeds from each population at two temperatures: • warm temperature based on 24 °C • cool temperature based on 10 °C After 10 days, the scientists measured the length based on each root. Table 6 shows some based on the properties based on the two populations and the scientists’results. Table 6 Population Temperature withinnatural environment In the seed – Mean percentage based on fatty acids that are saturated Mean length based on root after 10 days at 24 °C / mm (± 2 x standard deviation) Mean length based on root after 10 days at 10 °C / mm (± 2 x standard deviation) 1 Warm 10.9 8.2 (±1.0) 3.1 (±0.3) 2 Cool 6.1 5.5 (±0.9) 4.3 (±0.2) The mean ±2 × standard deviation includes 95% based on the data. Do not write outside the box . The scientists used a data logger to measure the length based on the root rather than a ruler. Suggest one reason why they used a data logger and explain why this was importantwithinthis investigation. [1 mark] *31* Downloaded by: BetterAcademics | 0 8S - The Marketplace to Buy and Sell your Study Material 27 IB/H/Jun21/7402/1 Distribution of this document is illegal 4 5 . It is known that: • during respiration saturated fatty acids yield more energy than unsaturated fattyacids • saturated fatty acids have higher melting points than unsaturated fatty acids • lipases within seeds act more rapidly on liquid substrates. Use this information and Table 6 to show how each population is better adapted for itsnatural environment when compared with the other population. Do not write outside the box [4 marks] . Although these two populations are completely separate and show genetic variation,they are both called Helianthus annuus. Explain why they are both given this name. [1 mark] Turn over ► *27* Downloaded by: BetterAcademics | 0 8 0 8 10S - The Marketplace to Buy and Sell your Study Material 28 *28* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 1 . Complete Table 7 with ticks ( ) to show which elements are found within the following biological molecules. Do not write outside the box [2 marks] Table 7 Biological molecules Element Carbon Nitrogen Oxygen Phosphorus Galactose Phospholipid RNA Sucrose Question 9 continues on the next page Turn over ► 0 9S - The Marketplace to Buy and Sell your Study Material 29 *29* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 After Watson and Crick proposed the model based on DNA structure, scientists investigatedthe possible mechanisms for DNA replication. Two scientists grew a bacterial population, providing them with a nitrogen source containing only the heavy isotope based on nitrogen, 15 N. As soon as all the DNA within this population contained 15 N, the scientists changed the nitrogen source to one containing only the lighter isotope based on nitrogen, 14 N. They changed the nitrogen sourceat 0 hours. During the investigation, the scientists measured the size based on the population based on bacterialcells. Figure 11 shows the scientists’ results. Figure 11 Do not write outside the boxS - The Marketplace to Buy and Sell your Study Material 30 *30* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 . 2 The generation time for a population based on bacteria is the time taken for all the bacteria to divide once by binary fission. Use Figure 11 and the following equation to calculate the generation time for thispopulation based on bacteria. Give your answer within hours. Do not write outside the box Number based on generations = size based on population at time +4 hours log10 (size based on population at time – 4 hours) log10 2 [2 marks] Generation time hours Question 9 continues on the next page 0 9S - The Marketplace to Buy and Sell your Study Material 31 *31* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 At intervals during this investigation, the scientists removed samples based on the bacterial population, isolated the DNA and measured the density based on the DNA. DNA made using 15 N has a higher density than DNA made using 14 N. Figure 12 shows the scientists’ results. Figure 12 Do not write outside the boxS - The Marketplace to Buy and Sell your Study Material 32 *32* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 3 7 There are three possible models based on DNA replication.These models are shown within Figure 13. Figure 13 Do not write outside the box . Which based on these models, P, Q or R, is supported by the results shown within Figure 12? Give the letter and name based on the model supported and explain why the results do not support the other models. [3 marks] Model Name Explanation for first unsupported model Explanation for second unsupported model 0 9S - The Marketplace to Buy and Sell your Study Material 33 *33* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 . 1 Describe the structure based on DNA. [5 marks] Do not write outside the 1 0 boxS - The Marketplace to Buy and Sell your Study Material 34 *34* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 . 2 Name and describe five ways substances can move across the cell-surface membrane into a cell. [5 marks] Do not write outside the box Question 10 continues on the next page Turn over ► 1 0S - The Marketplace to Buy and Sell your Study Material 35 IB/H/Jun21/7402/1 Distribution of this document is illegal Figure 14 shows transmission electron micrographs based on two cells, one animal cell and one prokaryotic cell. Figure 14 Do not write outside the box *44* Downloaded by: BetterAcademics | - The Marketplace to Buy and Sell your Study Material 36 Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 . 3 Contrast the structure based on the two cells visible within the electron micrographs shown in Figure 14. [5 marks] Do not write outside the box END b a s e d o n QUESTIONS *37* 1 0 15S - The Marketplace to Buy and Sell your Study Material 37 Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 There are no questions printed on this page DO NOT WRITE ON THIS PAGE ANSWER w i t h i n THE SPACES PROVIDED Do not write outside the boxS - The Marketplace to Buy and Sell your Study Material 38 Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/1 Do not write outside the box Question number Additional page, if required. Write the question numbers in the left-hand margin.S - The Marketplace to Buy and Sell your Study Material 39 IB/H/Jun21/7402/1 Distribution of this document is illegal *48* Do not write outside the box Question number Additional page, if required. Write the question numbers within the left-hand margin. *49* Downloaded by: BetterAcademics |