Practice Paper – Set 2. A Level Biology B (Advancing Biology) H422/02 Scientific lit, Exams of Biology

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Practice Paper – Set 2.

A Level Biology B (Advancing Biology)

H422/02 Scientific literacy in biology

MARK SCHEME

MAXIMUM MARK 100 Duration : 2 hour 15 minutes

Version: FINAL

This document consists of 18 pages

MARKING INSTRUCTIONS

PREPARATION FOR MARKING

SCORIS

1. Make sure that you have accessed and completed the relevant training packages for on-screen marking: scoris assessor Online Training ; OCR Essential Guide to Marking.
2. Make sure that you have read and understood the mark scheme and the question paper for this unit. These are posted on the RM Cambridge

Assessment Support Portal http://www.rm.com/support/ca

3. Log-in to scoris and mark the required number of practice responses (“scripts”) and the number of required standardisation responses. YOU MUST MARK 10 PRACTICE AND 10 STANDARDISATION RESPONSES BEFORE YOU CAN BE APPROVED TO MARK LIVE SCRIPTS. MARKING
4. Mark strictly to the mark scheme.
5. Marks awarded must relate directly to the marking criteria.
6. The schedule of dates is very important. It is essential that you meet the scoris 50% and 100% (traditional 40% Batch 1 and 100% Batch 2) deadlines. If you experience problems, you must contact your Team Leader (Supervisor) without delay.
7. If you are in any doubt about applying the mark scheme, consult your Team Leader by telephone or the scoris messaging system, or by email.
8. Work crossed out: Crossed Out Responses Where a candidate has crossed out a response and provided a clear alternative then the crossed out response is not marked. Where no alternative response has been provided, examiners may give candidates the benefit of the doubt and mark the crossed out response where legible. Rubric Error Responses – Optional Questions Where candidates have a choice of questions across a whole paper or a whole section and have provided more answers than required, then all responses are marked and the highest mark allowable within the rubric is given. Enter a mark for each question answered into RM assessor, which will select the highest mark from those awarded. (The underlying assumption is that the candidate has penalised themselves by attempting more questions than necessary in the time allowed.)

Multiple Choice Question Responses When a multiple choice question has only a single, correct response and a candidate provides two responses (even if one of these responses is correct), then no mark should be awarded (as it is not possible to determine which was the first response selected by the candidate). When a question requires candidates to select more than one option/multiple options, then local marking arrangements need to ensure consistency of approach. Contradictory Responses When a candidate provides contradictory responses, then no mark should be awarded, even if one of the answers is correct. Short Answer Questions (requiring only a list by way of a response, usually worth only one mark per response ) Where candidates are required to provide a set number of short answer responses then only the set number of responses should be marked. The response space should be marked from left to right on each line and then line by line until the required number of responses have been considered. The remaining responses should not then be marked. Examiners will have to apply judgement as to whether a ‘second response’ on a line is a development of the ‘first response’, rather than a separate, discrete response. (The underlying assumption is that the candidate is attempting to hedge their bets and therefore getting undue benefit rather than engaging with the question and giving the most relevant/correct responses.) Short Answer Questions (requiring a more developed response, worth two or more marks ) If the candidates are required to provide a description of, say, three items or factors and four items or factors are provided, then mark on a similar basis – that is downwards (as it is unlikely in this situation that a candidate will provide more than one response in each section of the response space.) Longer Answer Questions (requiring a developed response) Where candidates have provided two (or more) responses to a medium or high tariff question which only required a single (developed) response and not crossed out the first response, then only the first response should be marked. Examiners will need to apply professional judgement as to whether the second (or a subsequent) response is a ‘new start’ or simply a poorly expressed continuation of the first response.

6. Always check the pages (and additional objects if present) at the end of the response in case any answers have been continued there. If the candidate has continued an answer there then add a tick to confirm that the work has been seen.
7. There is a NR (No Response) option. Award NR (No Response)
   • if there is nothing written at all in the answer space
   • OR if there is a comment which does not in any way relate to the question (e.g. ‘can’t do’, ‘don’t know’)
   • OR if there is a mark (e.g. a dash, a question mark) which isn’t an attempt at the question Note: Award 0 marks – for an attempt that earns no credit (including copying out the question)

8. The scoris comments box is used by your team leader to explain the marking of the practice responses. Please refer to these comments when checking your practice responses. Do not use the comments box for any other reason. If you have any questions or comments for your team leader, use the phone, the scoris messaging system, or e-mail.
9. Assistant Examiners will send a brief report on the performance of candidates to their Team Leader (Supervisor) via email by the end of the marking period. The report should contain notes on particular strengths displayed as well as common errors or weaknesses. Constructive criticism of the

question paper/mark scheme is also appreciated.

10. For answers marked by levels of response: Read through the whole answer from start to finish, concentrating on features that make it a stronger or weaker answer using the indicative scientific content as guidance. The indicative scientific content indicates the expected parameters for candidates’ answers, but 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 set of level descriptors, Level 1, Level 2 or Level 3, best describes the overall quality of the answer using the guidelines described in the level descriptors in the mark scheme. Once the level is located, award the higher or lower mark. The higher mark should be awarded where the level descriptor has been evidenced and all aspects of the communication statement (in italics) have been met. The lower mark should be awarded where the level descriptor has been evidenced but aspects of the communication statement (in italics) are missing. In summary: - The science content determines the level. - The communication statement determines the mark within a level. Level of response questions on this paper are 2(c) and 4(a)(ii).

11. 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 argument

12. Subject Specific Marking Instructions INTRODUCTION Your first task as an Examiner is to become thoroughly familiar with the material on which the examination depends. This material includes: - the specification, especially the assessment objectives • the question paper - the mark scheme.

You should ensure that you have copies of these materials. You should ensure also that you are familiar with the administrative procedures related to the marking process. These are set out in the OCR booklet Instructions for Examiners. If you are examining for the first time, please read carefully Appendix 5 Introduction to Script Marking: Notes for New Examiners. Please ask for help or guidance whenever you need it. Your first point of contact is your Team Leader. Question Answer Mark Guidance 1 (a) (i) tissue (mature) xylem (no mark) justification idea that xylem vessels , are hollow / have no cytoplasm / have no organelles  1 DO NOT ALLOW xylem without further explanation IGNORE reference to xylem being dead (ii) lysosomal enzymes produced on , RER / rough endoplasmic reticulum  idea that lysosomal enzymes are enclosed in vesicles  lysosomes bud off Golgi (body)  max 2 (b) (i) evidence - only one gene (locus) (paragraph 8)  idea that one gene codes for one polypeptide 

(ii) protein - haemoglobin  similarity - idea of same prosthetic group / haem attached to each sub-unit  difference - idea that there are two different sub-units in haemoglobin / 2 alpha and 2 beta sub-units 

IGNORE reference to same number of sub-units ALLOW 'haemoglobin is not a homotetramer' or 'haemoglobin is a heterodimer' IGNORE 'haemoglobin is a heterotetramer'

(c) 1 NADH produced from glycolysis and Krebs  2 FADH produced from Krebs cycle  3 idea that NADH / FADH are co-enzymes for dehydrogenase enzymes  4 hydrogen (atom) passed to acceptor  5 hydrogen (atom) split into, proton / H+^ and electron / e-  6 electrons passed from carrier to carrier in inner (mitochondrial) membrane and then to oxygen  7 idea that carriers accepting electrons become reduced / max 4 mp1 Reference to both glycolysis and Krebs needed mp 1 and 2 ALLOW 'reduced NAD' or 'reduced FAD' mp 4 and 5 DO NOT ALLOW hydrogen molecule / H 2 carriers donating electrons become oxidised  (d) (i) citrate  1 (ii) 2  1 (iii) malate / fumarate / succinate  1 (iv) carbon dioxide  1 ALLOW CO 2 (e) (i) ATP / ADP / AMP / NAD / NADH / FAD / FADH  2 (ii) idea that free radicals cause mutations within proto-oncogenes and/or tumour suppressor genes  1 ALLOW DNA damage rather than mutation but the link to relevant genes must be present (f) (i) 0.991  2 If answer incorrect look for = q = 1 mark (for frequency of mutant / low catalase allele) = p ALLOW ECF if q calculated incorrectly (ii) idea that founding population had a high frequency of alleles for low catalase / high proportion of individuals heterozygous or homozygous for low catalase allele  1 IGNORE reference to selective advantage of recessive allele ALLOW ref to 'founder effect'

(g) (track) D  explanation - up to 2 marks detergent destroys (secondary, tertiary and) quarternary

structure 

(4) subunits smaller so migrate lower down gel  all subunits are , same / a similar size / 492 amino acids  max 3 If incorrect track identified then award up to two marks Question Answer Mark Guidance 2 (a) (i) idea that cells are more distinct in Fig.2.1a / less distinct in 2.1b idea that bundles are similar sizes in 2.1a / vary in size in 2.1b  2 ALLOW clearer / less clear (ii) idea that veins parallel in monocot leaves and branch in dicot leaves  idea that a cross section will cut dicot veins at different angles / cut monocot veins at same angle 2 ALLOW 'vascular bundles' instead of veins (b) 3 (kPa ) 2 If answer is incorrect award 1 mark for 0.003 ( 0.15 ÷ 50) (r not converted to m) OR 3000 (not converted to kPa)

(c)* Please refer to the marking instructions on page X 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)

A comprehensive description of most of the processes involved

in the movement of water in xylem, which relates these to the

observations.

There is a well-developed line of reasoning which is clear and

logically structured and uses scientific terminology at an

appropriate level. All the information presented is relevant

6 Indicative scientific points may include:

• hydrogen bonding to explain cohesion between water molecules
• adhesion of water molecules to the hydrophilic wall of the xylem vessel
• loss of water by transpiration from the aerial parts of the plant
• water evaporating from cell walls and diffusing

and forms a continuous narrative.

Level 2 (3–4 marks)

A description of some of the processes involved in the

movement of water in xylem, which attempts to relate them to

some of the observations.

There is a line of reasoning presented with some structure and

use of appropriate scientific language. The information

presented is mostly relevant.

Level 1 (1–2 marks)

An outline of some of the processes involved in the movement

of water in xylem is provided, which may not be linked to any

observations.

The information is communicated with only a little structure.

Communication is hampered by the inappropriate use of

technical terms.

0 marks

No response or no response worthy of credit.

• • • • • • •

into the atmosphere water moving out of the leaf down a gradient of water potential negative pressure creating a tension in the xylem vessel (observation) water above puncture pulled up due to tension (observation) puncture breaks tension so column falls back below puncture (observation) water only falls back so far and is held by adhesion root pressure described as active transport of ions into the xylem tissue lowering water potential water moves into the xylem down a water potential gradient creating a positive pressure Question Answer Mark Guidance 3 (a) (i) H  1

(ii) K  1 (ii) G 1 (b) prostate (gland)  1 (c) (i) volumes idea of using the appropriate measuring instrument (e.g. 1 cm^3 syringe for urease / 5 cm^3 for urine / microsyringe instead of 'drops' for indicator)  times idea of a stop watch / timer and a comparison to determine final colour 

ALLOW alternative relevant answers ALLOW suggestion that reaction is monitored in a colorimeter and the same absorbance value used each time for the end point (ii) use same concentration of urease (throughout)  place tubes in a water bath  2 ALLOW alternative relevant answers DO NOT ALLOW 'add a buffer' or 'control pH as a change in pH is the dependent variable (d) (i) mean = 58.6  standard deviation = 5.8  3 ALLOW ECF for incorrect calculation of mean 2 max if either answer is given to more than 3 significant figures (ii) Sample B (no mark) justification idea of more substrate molecules available  more enzyme-substrate complexes form in a given time  rate of the reaction increases  max 2 ALLOW ammonia produced at a faster rate (e) (i) Line on graph line steeper than current line 

ALLOW a straight line IGNORE starting position and end position of the line (line may start and finish above or below the line on the diagram)

Justification idea that water would leave the collecting duct at a faster rate (were ADH concentration to rise)  DO NOT ALLOW a line that drops downwards at any point (ii) (ADH) binds to receptors on cell surface membrane  (leading to) increase in concentration of cAMP  idea that (cAMP) causes vesicles containing aquaporins to move  idea that aquaporins / AW, increase in cell surface membrane lining the lumen  (more) water is reabsorbed and concentration (of urine) increases  detail of action of cAMP  max 4 ALLOW a description of an aquaporin for this mark point e.g. activates protein kinase(s), increased transcription of aquaporin genes

Question Answer Mark Guidance 4 (a) (i) cerebral cortex  1 ALLOW cerebrum / hippocampus

(ii)* Please refer to the marking instructions on page X 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)

A comprehensive description of the action of

acetylcholine and other neurotransmitters, including

inhibitory neurotransmitters.

There is a well-developed line of reasoning which is

clear and logically structured and uses scientific

terminology at an appropriate level. All the information

presented is relevant and forms a continuous narrative.

Level 2 (3–4 marks)

A description of the action of acetylcholine and

reference to the idea of inhibitory neurotransmitters.

There is a line of reasoning presented with some

structure and use of appropriate scientific language.

The information presented is mostly relevant.

Level 1 (1–2 marks)

6 Indicative scientific points may include:

• named excitatory neurotransmitter e.g. acetylcholine, glutamate
• named inhibitory neurotransmitter e.g. GABA
• neurones interact at synapses
• formation of new synapses linked to memory
• neurotransmitter released from pre-synaptic membrane by exocytosis
• neurotransmitter released following arrival of action potential in pre-synaptic neurone
• entry of calcium ions causes vesicles containing neurotransmitter to fuse with presynaptic membrane
• neurotransmitter diffuses across the synaptic cleft
• neurotransmitter binds to complementary receptor on post synaptic membrane
• (excitatory) results in opening of (ligand or chemical gated) sodium ion channels

• sodium ions enter post synaptic neurone

A description of the action of either an excitatory or an

inhibitory neurotransmitter.

The information is communicated with only a little

structure. Communication is hampered by the

inappropriate use of technical terms.

0 marks

No response or no response worthy of credit.

• post-synaptic membrane is depolarised
• (inhibitory) causes potassium ions to leave post-synaptic neurone
• (inhibitory) causes chloride ions to enter post synaptic neurone
• (inhibitory) hyper-polarises the post-synaptic membrane (becomes more negative (b) (i) 600  2 For incorrect reading(s) from the graph but a correct calculation allow 1 max (ii) idea that^ (over trial period), cognitive function improved / was higher than baseline for all three drugs tested OR idea that no significant difference between the three drugs OR idea that improvement not sustained / dropping back to baseline  figures given in support 

(iii) (the curve would) plateau / AW , below the curve in Fig. 4.2 

(c ) idea that higher drug concentration will be needed to achieve same effect  idea of tolerance linked to physical drug dependency 

Question Answer Mark Guidance 5 (a) (i) B lymphocyte / plasma cell  Mast cell  T-helper lymphocytes  max 2 (ii) idea that an antigen / allergen triggers the production of an antibody / IgE (antibody)

(b) (i) idea that histones are deacetylated / acetyl groups are removed

(ii) inflammatory cell histamine / IgE / cytokine  structural cell mucin / cytokine  2 ALLOW cytokine once only for either type of cell ALLOW a named cytokine (iii) tissue smooth muscle  location wall of , bronchi / bronchioles 

(c) idea that white asbestos less carcinogenic / blue and brown asbestos more carcinogenic  j ustification fibre length is shorter in white asbestos / fibre length is longer in blue and brown asbestos / fibres are wider in white asbestos / fibres are narrower in blue and brown asbestos AND idea that longer / narrower , fibres are more carcinogenic  idea that white asbestos linked more to asbestosis / blue and brown asbestos less likely to cause asbestosis  OR max 2 One mark for conclusion and one for justification Justification must be linked to the conclusion ALLOW white asbestos less likely to cause mesothelioma / lung cancer shorter / thicker , fibres that cause asbestosis more likely in white asbestos AND data in support 

Question Answer Mark Guidance 6 (a) (i) idea of (reversibly) bound to haemoglobin  1 ALLOW 'as oxyhaemoglobin' (ii) statement in support mean values higher for males than females AND data quotation  alternative statement idea that conclusion not valid AND a reason 

e.g. too small a sample, different sporting disciplines compared, training would vary (between individuals or disciplines), only endurance sports looked at and not other athletic disciplines (b) (women have) less haemoglobin so able to transport less oxygen  idea that (women have) smaller heart / lower stroke volume , so less oxygen pumped  idea that (women have) less muscle and more body fat / adipose tissue which is less metabolically active  3 ALLOW reverse argument for men throughout ALLOW idea that muscle cells have more mitochondria than adiopocytes (c) biosensor  immobilised  coenzyme  reduced 

ALLOW a term which describes immobilisation e.g. covalently bonded (d) (i) frequency of exercise OR time / duration of exercise 

(ii) X axis to be labelled with variable in part (i) AND appropriate units  Y axis to be labelled lactate concentration (following run) AND appropriate units  Slope downwards from left to right / negative correlation  max 2

Question Answer Mark Guidance 7 (a) (i) 2  1 (ii) (class) mammal(ia)  (order) primates 

(b) (i) idea of more copies per cell OR smaller so less likely to fragment 

(ii) cytochrome c oxidase  1 (c) (i) diagram to show Denisovan branch from common ancestor before H. sapiens and H. neanderthalensis branched  1 ALLOW sapiens and neanderthalensis in either order DO NOT ALLOW 3 species drawn parallel to each other on the bottom line (ii) idea that mitochondrial DNA only from female parent OR idea that recombination possible in nuclear DNA / no recombination in mitochondrial DNA OR AVP  1 ALLOW valid alternative suggestions e.g. different mutation rate