Edexcel as level biology question paper 1 ju ne 2023 + mark scheme

Mark Scheme (Results) Summer 2023 Pearson Edexcel GCE In Biology B (8BI0) Paper 01: Core Cellular Biology and MicrobiologyEdexcel and BTEC Qualifications Edexcel and BTEC qualifications are awarded by Pearson, the UK’s largest awarding body. We provide a wide range of qualifications including academic, vocational, occupational and specific programmes for employers. For further information visit our qualifications websites at or . Alternatively, you can get in touch with us using the details on our contact us page at Pearson: helping people progress, everywhere Pearson aspires to be the world’s leading learning company. Our aim is to help everyone progress in their lives through education. We believe in every kind of learning, for all kinds of people, wherever they are in the world. We’ve been involved in education for over 150 years, and by working across 70 countries, in 100 languages, we have built an international reputation for our commitment to high standards and raising achievement through innovation in education. Find out more about how we can help you and your students at: Summer 2023 Question Paper Log Number P71924A Publications Code 8BI0_01_2306_MS All the material in this publication is copyright © Pearson Education Ltd 2023General Marking Guidance • All candidates must receive the same treatment. Examiners must mark the first candidate in exactly the same way as they mark the last. • Mark schemes should be applied positively. Candidates must be rewarded for what they have shown they can do rather than penalised for omissions. • Examiners should mark according to the mark scheme not according to their perception of where the grade boundaries may lie. • There is no ceiling on achievement. All marks on the mark scheme should be used appropriately. • All the marks on the mark scheme are designed to be awarded. Examiners should always award full marks if deserved, i.e. if the answer matches the mark scheme. Examiners should also be prepared to award zero marks if the candidate’s response is not worthy of credit according to the mark scheme. • Where some judgement is required, mark schemes will provide the principles by which marks will be awarded and exemplification may be limited. • When examiners are in doubt regarding the application of the mark scheme to a candidate’s response, the team leader must be consulted. • Crossed out work should be marked UNLESS the candidate has replaced it with an alternative response.Question Number Answer Additional Guidance Mark 1(a) The only correct answer is B A is incorrect because Down’s syndrome is an example of polysomy not monosomy C is incorrect because Down’s syndrome is caused by a chromosome mutation not a gene mutation D is incorrect because Down’s syndrome is caused by a chromosome mutation not a gene mutation (1) Question Number Answer Additional Guidance Mark 1(b) An answer that makes reference to the following: • birth order has no effect on the incidence (1) • the incidence increases with the age (of the mother) (1) • credit use of manipulated figures to support answer (1) ACCEPT no pattern e.g. approx. 80 times greater chance if over 40 than under 20 approx. 4 times greater chance if over 40 than between 35 and 39 approx. 500 per 100 000 more if over 40 than between 35 and 39 (3)Question Number Answer Additional Guidance Mark 2(a) A description that makes reference to the following: • to {digest / breakdown} the {egg cell / ovum / secondary oocyte} membrane (1) • so that the sperm {nucleus / genetic material} can enter the {egg cell / ovum / secondary oocyte} (1) ACCEPT zona pellucida (2) Question Number Answer Additional Guidance Mark 2(b) A description that makes reference to three of the following: • transcription of the genes coding for the (acrosome) enzymes (1) • translation (of the mRNA) (to synthesise the enzymes) (1) • transported in the RER (to the Golgi) (1) • {modification / processing / packaging} (of the enzymes) in the Golgi (1) • packaging (by the Golgi of the enzymes) into {the membrane / vesicles} (of the acrosome) (1) ACCEPT description of transcription e.g. mRNA copy of gene coding for enzyme made ACCEPT description of translation e.g. amino acids joined by peptide bonds DO NOT ACCEPT for exocytosis (3)Question Number Answer Additional Guidance Mark 3(a) A description that makes reference to the following: • glucose and galactose (1) • joined by a (1-4) glycosidic bond (1) (2) Question Number Answer Additional Guidance Mark 3(b) • tangent drawn as a straight line touching at 2 hours, on the outside of the curve (1) • rate calculated (1) ACCEPT value between 0.034 and 0.052 to 2 or 3 dps Correct answer gains 2 marks 0.08 / 0.075 gains 1 mark (2)Question Number Answer Additional Guidance Mark 3(c) A description that makes reference to the following: • (2.5 % and 7.5 %) lactose stimulates growth of pollen tubes (1) • the effect is dose-dependent / growth depends on the concentration (1) • high concentrations inhibit pollen tube growth (1) ACCEPT pollen tubes can grow in lactose increases pollen tube growth ACCEPT pollen tube did not grow in high concentrations 10% was too concentrated for growth (3