Specimen MS Paper 1 AQA Biology A Level_a_marking_scheme_2020.

Specimen MS Paper 1 AQA Biology A Level_a_marking_scheme_2020. 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. Downloaded by: kavijanananth | Distribution of this document is illegal S - The Marketplace for Revision Notes & Study Guides MARK SCHEME – AS BIOLOGY – 7401/1 – JUNE 2020 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. Downloaded by: kavijanananth | Distribution of this document is illegal S - The Marketplace for Revision Notes & Study Guides MARK SCHEME – AS BIOLOGY – 7401/1 – JUNE 2020 5 Question Marking Guidance Mark Comments 01.1 Letter Statement B; is a monomer in an enzyme’s active site D; is a monomer in cellulose C; is produced during photosynthesis and respiration B; forms a polymer that gives a positive result with a biuret test 4 Must be in correct order 01.2 C = 18, H = 32, O = 16; 1 Accept only these answers 01.3 1. Heat with acid and neutralise; 2. Heat with Benedict's (solution); 3. Red precipitate/colour; 3 Accept boil/water bath for heat Accept named alkali for neutralise 1. Accept named examples, eg HCl, NaHCO3 3. Accept other colours eg orange/ brown/green TOTAL 8 Downloaded by: kavijanananth | Distribution of this document is illegal S - The Marketplace for Revision Notes & Study Guides MARK SCHEME – AS BIOLOGY – 7401/1 – JUNE 2020 6 Question Marking Guidance Mark Comments 02.1 1. Bilayer OR Water is present inside and outside a cell; 2. Hydrophobic (fatty acid) tails point away/are repelled from water OR Hydrophilic (phosphate) heads point to/are in/are attracted to water; 2 1. Accept annotated diagram for ‘bilayer’ Accept cytoplasm/tissue fluid for water Accept for two marks, annotated diagram of bilayer with water labelled on each side Ignore hydrophilic/phosphate heads protect hydrophobic/fatty acid tails 02.2 1. Condensation (reaction) OR Loss of water; 2. Between of glycerol and fatty acid; 2 Accept labelled diagram 02.3 1. High (specific) heat capacity; 2. Buffers changes in temperature; 2 2. Accept ideas such as a lot of energy needed/gained to change temperature TOTAL 6 Downloaded by: kavijanananth | Distribution of this document is illegal S - The Marketplace for Revision Notes & Study Guides MARK SCHEME – AS BIOLOGY – 7401/1 – JUNE 2020 7 Question Marking Guidance Mark Comments 03.1 1. Engulfs; 2. Forming vesicle/phagosome and fuses with lysosome; 3. Enzymes digest/hydrolyse; 3 1. Accept endocytosis OR Description 1. Ignore ‘taken in’ 3. Accept lysozymes for ‘enzymes’ 03.2 1. (Cells from) other organisms/transplants; 2. Abnormal/cancer/tumour (cells); 3. (Cells) infected by virus; 2 max Accept ‘own cells’ if autoimmune response suggested Accept APCs Accept non-self 03.3 ‘X’ written at either or both ends of Y shape; 1 03.4 Joins two (different) polypeptides; 1 Accept holds/attaches Accept ‘prevents polypeptide chains separating’ TOTAL 7 Downloaded by: kavijanananth | Distribution of this document is illegal S - The Marketplace for Revision Notes & Study Guides MARK SCHEME – AS BIOLOGY – 7401/1 – JUNE 2020 8 Question Marking Guidance Mark Comments 04.1 1. DNA in nucleus is code (for protein); 2. Ribosomes/rough endoplasmic reticulum produce (protein); 3. Mitochondria produce ATP (for protein synthesis); 4 Golgi apparatus package/modify; OR Carbohydrate added/glycoprotein produced by Golgi apparatus; 5 Vesicles transport OR Rough endoplasmic reticulum transports; 6. (Vesicles) fuse with cell(-surface) membrane; 4 max 2. and 5. Accept rER for ‘rough endoplasmic reticulum’ 4. Accept body for ‘apparatus’ 6. Accept exocytosis at cell membrane 04.2 A section/slice (so nucleus in another part of cell) OR (Nucleus) not stained; 1 04.3 S = Vacuole T = Chloroplast; 1 Reject thylakoid/granum Reject incorrect spelling 04.4 Higher resolution OR View internal structures; 1 Downloaded by: kavijanananth | Distribution of this document is illegal S - The Marketplace for Revision Notes & Study Guides MARK SCHEME – AS BIOLOGY – 7401/1 – JUNE 2020 9 04.5 Correct answer of 4.71 x 107 for 2 marks;; Accept for 1 mark Any answer showing conversion factor of / 108 OR Correct answer for any number divided by 150 eg 70.65 ÷ 150 / 0.471 OR Any answer including digits 471 in this order, irrespective of position of decimal place 2 TOTAL 9