GCE Biology B H422/01: Fundamentals of biology Advanced GCE Mark Scheme for Autumn 2021

Document Content and Description Below

GCE Biology B H422/01: Fundamentals of biology Advanced GCE Mark Scheme for Autumn 2021 Oxford Cambridge and RSA Examinations GCE Biology B H422/01: Fundamentals of biology Advanced GCE Mark Sch... eme for Autumn 2021Oxford Cambridge and RSA Examinations OCR (Oxford Cambridge and RSA) is a leading UK awarding body, providing a wide range of qualifications to meet the needs of candidates of all ages and abilities. OCR qualifications include AS/A Levels, Diplomas, GCSEs, Cambridge Nationals, Cambridge Technicals, Functional Skills, Key Skills, Entry Level qualifications, NVQs and vocational qualifications in areas such as IT, business, languages, teaching/training, administration and secretarial skills. It is also responsible for developing new specifications to meet national requirements and the needs of students and teachers. OCR is a not-for-profit organisation; any surplus made is invested back into the establishment to help towards the development of qualifications and support, which keep pace with the changing needs of today’s society. This mark scheme is published as an aid to teachers and students, to indicate the requirements of the examination. It shows the basis on which marks were awarded by examiners. It does not indicate the details of the discussions which took place at an examiners’ meeting before marking commenced. All examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. Mark schemes should be read in conjunction with the published question papers and the report on the examination. © OCR 2021H422/01 Mark Scheme October 2021 Annotations Annotation Meaning DO NOT ALLOW Answers which are not worthy of credit IGNORE Statements which are irrelevant ALLOW Answers that can be accepted ( ) Words which are not essential to gain credit __ Underlined words must be present in answer to score a mark ECF Error carried forward AW Alternative wording ORA Or reverse argumentH422/01 Mark Scheme October 2021H422/01 Mark Scheme October 2021 Question Answer Marks AO element Guidance 1 D 1 AO1.2 2 A 1 AO1.1 3 C 1 AO2.3 4 C 1 AO1.1 5 D 1 AO2.1 6 A 1 AO1.2 7 C 1 AO2.2 8 C 1 AO1.1 9 D 1 AO1.1 10 B 1 AO1.1 11 B 1 AO2.8 12 D 1 AO1.1 13 B 1 AO1.2 14 D 1 AO2.7 15 A 1 AO1.1 16 C 1 AO2.1 17 C 1 AO1.1 18 B 1 AO2.2 19 C 1 AO2.6 20 D 1 AO2.5 21 C 1 AO2.6 ((150x60)x20))/9000 22 A 1 AO1.1 23 B 1 AO1.2 24 A 1 AO1.1 25 D 1 AO1.2 26 A 1 AO1.2H422/01 Mark Scheme October 2021 27 D 1 AO1.1 28 B 1 AO2.8 29 C 1 AO1.1 30 C 1 AO2.7 Total 30H422/01 Mark Scheme October 2021 Question Answer Mark AO element Guidance 31 (a) head (contains) haploid nucleus AND to ensure diploid number of chromosomes is maintained on fertilisation  (has) acrosome AND contains hydrolytic enzymes to digest zona pellucida  max 1 midpiece (contains) mitochondria AND (provide) energy for movement / tail (of spermatozoa)  tail (contains) contractile fibres / microtubules / flagellum AND creates whip-like movements / enable swimming action  3 max AO1.1 Structure AND function required for 1 mark in each section ALLOW for fertilisation of haploid secondary oocyte / to donate DNA (to zygote formed) at fertilisation DO NOT ALLOW to create / make energy 31 (b) (i) DNA has phosphate (groups) in the backbone  phosphate (group) is charged  idea that forces of attraction occurs between opposite charges on phosphate and arginine  2 max AO2.1 ALLOW has sugar-phosphate backbone 31 (b) (ii) enables sperm nucleus to be small  greater protection of DNA molecules  1 max AO2.1 ALLOW enables the head of the sperm to be small 31 (c) (i) similar age men used in all study groups  no significant difference in (mean) age of men in study  2 AO3.2 31 (c) (ii) control (group) 1 AO3.3H422/01 Mark Scheme October 2021 Question Answer Mark AO element Guidance 31 (c) (iii) 1 2 3 4 5 6 7 group 1 / men with normal sperm count and motility had lowest percentage of sperm with protamine deficiency  group 4 / men with low sperm count and motility had highest percentage of sperm with protamine deficiency (group 3 and 4 shows) protamine deficiency affects sperm motility more than sperm count / AW  percentage of sperm with protamine deficiency is higher in men with , low fertility / infertility  difference between , groups 1 and 2 / groups 2 and 3 / groups 3 and 4 , is not statistically significant  difference between , groups 1 and 3 / groups 2 and 4 / groups 1 and 4 is statistically significant  AVP  4 max AO3.1 e.g. overlap of error bars group 2 and 3 e.g. no overlap of error barsH422/01 Mark Scheme October 2021 Question Answer Mark AO element Guidance 31 (d)* Please refer to the marking instructions on page 4 of this mark scheme for guidance on how to mark this question. In summary: Read through the whole answer. (Be prepared to recognise and credit unexpected approaches where they show relevance.) Using a ‘best-fit’ approach based on the science content of the answer, first decide which of the level descriptors, Level 1, Level 2 or Level 3, best describes the overall quality of the answer. Then, award the higher or lower mark within the level, according to the Communication Statement (shown in italics): o award the higher mark where the Communication Statement has been met. o award the lower mark where aspects of the Communication Statement have been missed. • The science content determines the level. • The Communication Statement determines the mark within a level. Level 3 (5–6 marks) There are statements showing similarities and differences between spermatogenesis and oogenesis. Role of hormones included in similarities and differences. There is a well-developed line of reasoning which is clear and logically structured. The information presented is relevant and substantiated. Level 2 (3–4 marks) There are statements showing similarities and differences between spermatogenesis and oogenesis. Role of hormones is unclear or not linked to similarities / differences. There is a line of reasoning presented with some structure. The information presented is relevant and supported by some evidence. Level 1 (1–2 marks) There are statements showing either similarities or differences between spermatogenesis and oogenesis. Role of hormones is unclear or not linked to similarities / differences. There is an attempt at a logical structure with a line of reasoning. The information is in the most part relevant. 6 AO2.5 Indicative scientific points may include Similarities • meiotic division • mitotic divisions • primordial germ cells • haploid gametes produced • multiplication phase • growth phase • maturation phase • initiated by gonadotrophin releasing hormone / GnRH • both affected by luteinising hormone / LH and follicle stimulating hormone / FSH Differences spermatogenesis • second meiotic division is completed immediately after the first • spermatozoa are smaller than ova • primary spermatocytes form secondary spermatocytes of even size • no polar bodies formed • FSH causes cells in testes to be more receptive to testosteroneH422/01 Mark Scheme October 2021 0 marks No response or no response worthy of credit. • LH causes cells in testes to release testosterone • continuous process oogenesis • second meiotic division only occurs after fertilisation • primary oocyte has uneven division • primary oocyte forms secondary oocyte and polar body • one large ovum and smaller polar bodies formed • FSH / LH cause maturation of follicles in ovary • FSH / LH cause release of oestrogen • surge of LH causes release of secondary oocyte • staggered processH422/01 Mark Scheme October 2021 Question Answer Mark AO element Guidance 32 (a) differential (staining technique)  different tissues / cell structures , stained different colours  allows identification of cell nuclei  2 max AO2.7 ALLOW gives an indication of tissue location within an organ 32 (b) (i) contains collagen fibres  protection / maintains shape , of the eye  enables muscle / ligament attachment  2 max AO1.1 AO2.1 32 (b) (ii) choroid  prevents internal reflection  2 AO1.1 32 (c) (i) 640 µm  2 AO2.8 ALLOW for 1 mark 64 (mm) ÷ 100 OR 0.64 (mm) 32 (c) (ii) (+/-) 1.25  2 AO3.2 ALLOW for 1 mark (66-61) ÷ 2√4 32 (d) (i) cilia connect inner and outer segments of (cone) cell  (mutated BBS genes cause) production of non-functional proteins in , cilia / microtubules  less / no , transport of proteins between segments  2 max AO2.1 32 (d) (ii) different (cone) cells have different type of iodopsin  (so iodopsin) absorbs either red or green or blue light  (so) cone cells differ in sensitivity to different wavelengths of light  trichromatic vision  3 max AO1.1 ALLOW description 32 (d) (iii) widespread effects in the body  affects , several organs / systems, in the body  1 max AO2.5 32 (d) (iv) apoptosis  1 AO1.1 ALLOW descriptionH422/01 Mark Scheme October 2021 Question Answer Mark AO element Guidance 33 (a) Any two from: sit person down in upright position with knees bent  help them take their medicine for , heart problem / angina  give an aspirin tablet / get them to chew aspirin tablet  monitor breathing and pulse rates  2 max AO1.1 ALLOW sit in ‘W’ position 33 (b) (i) idea that in note 1 Daphnia would already have been in water so already acclimatised  idea that in note 5 time is required for alcohol to be taken in by Daphnia  1 max AO3.4 33 (b) (ii) Daphnia died so invalid results  AVP  1 max AO3.4 e.g. ethical reason 33 (c) (i) (t = ) 108.1  3 AO3.1 ALLOW 107.96 to 109.32 ALLOW 1 mark for Sd = √11.85 = 3.44 ALLOW 1 mark for t = (107.3 √ 12) ÷ (ANS) 33 (c) (ii) students are correct that alcohol lowers heart rate but incorrect because it is significantly lower  (because) critical value for 11 degrees of freedom / 2.20 , is much lower than value for t  2 AO3.2 ALLOW ECF ALLOW ORA e.g. t is much higher than 2.20H422/01 Mark Scheme October 2021 Question Answer Mark AO element Guidance 34 (a)* Please refer to the marking instructions on page 4 of this mark scheme for guidance on how to mark this question. In summary: Read through the whole answer. (Be prepared to recognise and credit unexpected approaches where they show relevance.) Using a ‘best-fit’ approach based on the science content of the answer, first decide which of the level descriptors, Level 1, Level 2 or Level 3, best describes the overall quality of the answer. Then, award the higher or lower mark within the level, according to the Communication Statement (shown in italics): o award the higher mark where the Communication Statement has been met. o award the lower mark where aspects of the Communication Statement have been missed. • The science content determines the level. • The Communication Statement determines the mark within a level. Level 3 (5–6 marks) Evaluation with both positive and negative impact statements using examples. There is a well-developed line of reasoning which is clear and logically structured. The information presented is relevant and substantiated. Level 2 (3–4 marks) Evaluation with either positive or negative impact statements using examples. There is a line of reasoning presented with some structure. The information presented is in the most-part relevant and supported by some evidence. Level 1 (1–2 marks) Little evaluation with basic descriptive statement that may not include reference. There is an attempt at a logical structure with a line of reasoning. The information is in the most part relevant. 6 AO3.2 Indicative scientific points may include Must be about impact on biodiversity / ecosystem Positive impacts: • bioreserve area will maintain biodiversity and habitats • protected areas and fish sanctuary could limit decline in fish stocks • city could provide ecotourism to encourage maintaining biodiversity • traditional ways of living in floating villages more sustainable • human waste from floating villages could provide nutrients for fish increase in certain species (could also be negative impact) Negative impacts: • clearance of flooded forests could lead to loss of tree-dwelling species • clearance of flooded forests could lead to change extent of flood plain area leading to change in biodiversityH422/01 Mark Scheme October 2021 0 marks No response or no response worthy of credit. • possible conflicts between fishermen and rice growers / over-fishing or over - planting could cause decline or loss of certain species • agricultural expansion leading to loss of habitats • illegal fishing causes decline of some speciesH422/01 Mark Scheme October 2021 Question Answer Mark AO element Guidance 34 (b) (i) least species in rice growing areas due to , disturbance / clearance of habitats , for , planting / harvesting  most species in shrubland and forest due to more different types of habitat available  abandoned rice fields more than existing rice fields due to repopulation of areas  2 max AO2.1 ALLOW idea of lack of different habitats / monoculture ALLOW idea that secondary succession is occurring 34 (b) (ii) Simpson’s Diversity Index  number of individuals in each species  2 AO1.1 ALLOW species abundance 34 (c) (i) chance event occurs  (causing) significant reduction in , population / number of individuals , in Tonle Sap Lake area  surviving crocodile population have fewer alleles than original population  decrease in genetic diversity  3 max AO2.1 34 (c) (ii) habitat destruction  over-hunting / over-poaching  disease  toxic chemicals in the lake  loss of prey species  named natural disaster  1 max ALLOW description Must be relevant to the lake e.g. drought IGNORE flooding 34 (d) (i) (farm 1) 20%  (farm 2) 35%  2 AO2.6 (28/35) x 100 = 80% monomorphic (26/40) x 100 = 65% monomorphic 34 (d) (ii) Farm 2 would be most suitable  Farm 2 has greater genetic diversity  Farm 1 has more individuals in the population so more options for breeding pairs  2 max AO2.5 ALLOW ECF from Q34diH422/01 Mark Scheme October 2021 Question Answer Mark AO element Guidance 35 (a) (i) carries , genetic information / code , from nucleus to ribosomes  1 AO1.1 ALLOW a correct description of mRNA in a mitochondria or prokaryotic cell 35 (a) (ii) carries specific amino acid / forms complex with amino acid AND anticodon binds to codon on mRNA  1 AO1.1 ALLOW descriptions of anticodon and codon 35 (b) (ii) genes  three  degenerate  overlap  4 AO1.1 35 (c) genetic modification  avidin gene is identified and isolated from bird genome  gene inserted into vector  vector incorporated into plant cell  gene inserted into genome / DNA , of wheat plant  AVP  3 max AO1.2 AO2.1 ALLOW named vector e.g. plasmid e.g. gene ‘gun’ used to introduce gene e.g. tissue culturing 35 (d) (i) binds to biotin preventing absorption  inhibits channels / carriers / enzymes in the membrane  breaks down biotin before it can be used  1 max AO2.1 35 (d) (ii) cofactor / biotin , required for enzyme activity  lack of biotin stops specific (metabolic) reaction  example of reaction e.g. could prevent weevils synthesising proteins  weevils can’t synthesise biotin  2 max AO2.1H422/01 Mark Scheme October 2021 Question Answer Mark AO element Guidance 36 (a) Statement True (T) or False (F) ATP is used to pump Na+ into and K+ out of the axon F The inside of the axon membrane has a positive charge relative to the outside. F The axon membrane is more permeable to K+ than Na+ T  2 AO1.1 All three rows correct 2 marks Two rows correct 1 mark One or no rows correct 0 marks 36 (b) positive feedback  Na+ enter due to opening of voltage-gated Na+ channels  (causes) generator potential  entry of Na+ causes more channels to open which leads to more Na+ entering  3 max AO1.1OCR (Oxford Cambridge and RSA Examinations) The Triangle Building Shaftesbury Road Cambridge CB2 8EA OCR Customer Contact Centre Education and Learning Telephone: 01223 553998 Facsimile: 01223 552627 Email: general.qualifications@ocr.org.uk [Show More]

Last updated: 2 years ago

Preview 1 out of 18 pages