A-level BIOLOGY 7402/1 Paper 1 Mark scheme June 2022 Version: 1.0 Final

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A-level BIOLOGY 7402/1 Paper 1 Mark scheme June 2022 Version: 1.0 Final *226A7402/1/MS* MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2022 2 Mark schemes are prepared by the Lead Asse... ssment 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. Further copies of this mark scheme are available from aqa.org.uk 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 © 2022 AQA and its licensors. All rights reserved. MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2022 3 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 lefthand 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 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. 2.2 A bold and is used to indicate that both parts of the answer are required to award the mark. 2.3 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. MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2022 4 3.2 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. 3.3 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. 3.4 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. 3.5 Phonetic spelling The phonetic spelling of correct scientific terminology should be credited unless there is a possible confusion with another technical term. 3.6 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. 3.7 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. MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2022 5 Question Marking Guidance Mark Comments 01.1 Structure 1. Nuclear envelope and pores OR Double membrane and pores; 2. Chromosomes/chromatin OR DNA with histones; 3. Nucleolus/nucleoli; Function 4. (Holds/stores) genetic information/material for polypeptides (production) OR (Is) code for polypeptides; 5. DNA replication (occurs); 6. Production of mRNA/tRNA OR Transcription (occurs); 7. Production of rRNA/ribosomes; 4 max (4 x AO1) Max 2 for structure or function 1. Ignore porous for pores 2 Ignore genetic material/information 2. Accept nucleoplasm 2. Ignore promoter regions OR genes OR alleles Accept regulation of gene expression 4. Accept protein OR amino acid sequences OR primary structure for polypeptides 6 Ignore mRNA leaves nucleus Question Marking Guidance Mark Comments 01.2 Cellulose (plants) and Chitin (fungi); 1 (AO1) For fungi, accept Nacetylglucosamine Question Marking Guidance Mark Comments 01.3 Individual organisms could not be identified/separated OR Too small/numerous to count individuals OR Too time consuming; 1 (AO2) Ignore too difficult to identify/distinguish different species Ignore too difficult to count unless qualified Accept reference to fungi for plants MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2022 6 Question Marking Guidance Mark Comments 01.4 Correct answer for 2 marks, 0.7– 0.71;; Accept for 1 mark, 0.29 – 0.3 (correct calculation not subtracted from 1) OR 120 (correct total shoot biomass) 2 (2 x AO2) A common correct answer is 0.707 Accept numbers rounding down to 0.71 Question Marking Guidance Mark Comments 01.5 1. Plant (bio)diversity is lower on (previously used) crop land OR Plant (bio)diversity is higher on land not used (previously to grow crops); 2. Farming reduces (bio)diversity of fungi OR Farming reduces fungal species richness; 2 (2 x AO3) Assume index of diversity refers to plants If no context is given assume answer refers to land previously used to grow crops 1. Accept farming reduces plant (bio)diversity 2. Accept farming reduces number of fungal species MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2022 7 Question Marking Guidance Mark Comments 02.1 1. (Some bacteria have) alleles for resistance; 2. (Exposure to) antibiotics is the selection pressure OR Non-resistant bacteria die OR Resistant bacteria survive/reproduce; 3. More antibiotics used in hospital (compared with elsewhere) OR Patients have weakened immune systems OR (So) high frequency of resistance allele (in bacterial population); 3 (3 x AO1) 1 and 2 Reject reference to immunity only once 1. and 3. Accept gene for allele 1. Reject if antibiotics cause production of resistance gene/allele 2. Accept strain for bacteria 3. Ignore antibiotics prescribed when not needed OR antibiotic course is not finished 3. Ignore defence system, for immune system 3. Accept proportion/percentage for frequency Question Marking Guidance Mark Comments 02.2 Maltose; 1 (AO1) Reject maltase Accept phonetic spelling eg moltose/maltosse/maltoze/moltoes/maltoez MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2022 8 Question Marking Guidance Mark Comments 02.3 1. Wash hands with soap OR Disinfect surfaces; 2. Use sterile pipette/syringe (to transfer bacteria); 3. (Remove bottle lid and) flame neck of bottle; 4. Lift lid of (agar) plate at an angle; 5. Work close to upward air movement; 6. Use sterile spreader; 7. Place pipette/spreader into disinfectant (immediately after use); 3 max (3 x AO1) 1. Ignore sterilise hands OR surfaces 1. Accept sanitise for disinfect 1. Accept antiseptic /antimicrobial/alcohol (wipes) 1. and 7 Accept a named type of disinfectant 2. Reject loop 2. Accept use unopened pipette/syringe for sterile 4. Accept lift lid slightly OR keep lid over plate 4. Ignore work quickly with lid off 5 Reject air movements sterilise air 5 Accept convection current for air movement 6. Accept loop for spreader 6. Examples of sterilising technique eg, flame OR dip in alcohol and flame OR dip in disinfectant and rinse (in sterile water) MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2022 9 Question Marking Guidance Mark Comments 02.4 For 1. Resistant bacteria grow faster with trehalose; 2. (So) resistant bacteria (likely to) increase in frequency in the population/people; 3. Resistant bacteria (likely to) outcompete non-resistant bacteria; Against 4. In laboratory not in people; 5. Other disaccharides (in the diet) might affect bacteria; 6. Other bacterial species (in the body) might affect bacteria; 7. No stats test to see if difference/increase is significant; 8. No data for both resistant and non-resistant bacteria growing together; 9. No data for different concentrations of trehalose; 3 max (3 x AO3) Max 2 if only ‘For’ or only ‘Against’ marks 1, 2, 3 ,4 and 5 Accept C. difficile/strain for bacteria 2. Accept ‘percentage/ proportion’ for ‘frequency’ 5. Accept carbohydrate OR polysaccharide OR sugar, for disaccharide 7. Accept ‘is not due to chance’ for ‘is significant’ 7. Ignore standard deviation/SD (as not a stats test) 7 Reject ‘to see if results are significant’ MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2022 10 Question Marking Guidance Mark Comments 03.1 For 1 mark, accept any two from Prokaryotes have No membrane-bound organelles/correct example OR (Single,) circular/loop DNA (in cytoplasm) OR DNA free in cytoplasm OR DNA not associated with proteins/histones OR Murein/peptidoglycan (in) cell wall; 1 (AO1) Apply list rule Accept (prokaryotes) only have smaller ribosomes /60S/70S Accept mesosome Accept no introns Accept nucleoid for single, circular DNA Reject nucleosome Reject plasmid Reject (bacterial) chromosome Reject capsule/slime layer Reject flagellum Question Marking Guidance Mark Comments 03.2 Hydrogen  1 (AO1) Question Marking Guidance Mark Comments 03.3 1. Hydrophobic side next to/in/face fatty acids/tails OR Hydrophobic side next to/in/face hydrophobic (part of) phospholipid/bilayer; 2. Hydrophilic sides allow ion movement through membrane OR Hydrophilic sides form a channel; 2 (2 x AO2) 1 and 2 Accept ‘part/region/bit/half’ for side 2. Accept water OR charged/polar molecules/substances OR water-soluble substances for ions MARK SCHEME – A-LEVEL BIOLOGY – 7402/1 – JUNE 2022 11 Question Marking Guidance Mark Comments 03.4 Correct answer for 2 marks, 2.5;; Accept for 1 mark, 2.5434 (Correct answer but 2 or more decimal places) OR 10.2 (correct area calculation using diameter, to 1 decimal place) OR 6.6 (correct calculation using radius (4 – 1.1) ÷ 2, to 1 decimal place) OR 26.4 (correct calculation using diameter, 4 – 1.1, to 1 decimal place [Show More]

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