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GCSE

Additional Science B
General Certificate of Secondary Education B624/02
Unit 2: Modules B4, C4, P4




Mark Scheme for June 2010




Oxford Cambridge and RSA Examinations

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OCR (Oxford Cambridge and RSA) is a leading UK awarding body, providing a wide range of
qualifications to meet the needs of pupils of all ages and abilities. OCR qualifications include
AS/A Levels, Diplomas, GCSEs, OCR Nationals, Functional Skills, Key Skills, Entry
Level qualifications, NVQs and vocational qualifications in areas…

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B624/02 Mark Scheme June 2010


Question Expected Answers Marks Additional Guidance
1 (a) upper epidermis (1) 1 allow labelled on diagram by part X



(b) more or many chloroplasts or chlorophyll (to 2 allow densely packed
absorb light) (1) ignore large surface area

at or near top of leaf (to…

Page 4

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B624/02 Mark Scheme June 2010


Question Expected Answers Marks Additional Guidance
2 (a) 2 second mark is dependent on first marking point
blue tits (area 30 squares)
allow scale drawing non-pyramid
caterpillars (area 50 squares) e.g.

cabbages (area 450 squares)


correct labelled pyramid i.e. caterpillars in middle
and blue tits…

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B624/02 Mark Scheme June 2010


Question Expected Answers Marks Additional Guidance
(c) 2 ignore (mechanism of transfer) run-off / leaching / spray drift from land
into river
ignore references to eutrophication

idea that herons' food is killed or reduced / e.g. pesticide kills the stickleback
pesticide kills or reduces things…

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B624/02 Mark Scheme June 2010


Question Expected Answers Marks Additional Guidance
3 (a) high temperature kills microorganisms 1 more than one tick scores zero


the solution prevents microorganisms
getting oxygen
the solution causes microorganisms to
lose water

the solution is too acidic for
microorganisms
(b) (i) osmosis (1) 1 allow…

Page 7

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B624/02 Mark Scheme June 2010


Question Expected Answers Marks Additional Guidance
4 (a) 101 (1) 1



(b) (i) nitric (acid) (1) 1 allow correct formula i.e. HNO3



(ii) neutralisation (1) 1 if answer line blank allow correct answer circled, underlined or ticked in
list


(c) 3 Use ticks in this…

Page 8

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B624/02 Mark Scheme June 2010


Question Expected Answers Marks Additional Guidance
5 (a) N2 + 3H2 2NH3 2 balancing mark is conditional on correct formulae
formulae (1) allow any correct multiple e.g. 2N2 + 6H2 4NH3
balancing (1) allow = or for arrow
not `and' or & for +
allow…

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B624/02 Mark Scheme June 2010


Question Expected Answers Marks Additional Guidance
6 (a) filtration - to remove solid particles (1) 2 allow remove (large) objects or bits
allow to remove insoluble particles
ignore to remove (large) particles

sedimentation (1)


(b) from lead pipes (1) 1 allow from lead compounds in…

Page 10

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B624/02 Mark Scheme June 2010


Question Expected Answers Marks Additional Guidance
7 (a) allotrope (1) 1 if answer line is blank then allow correct answer circled, underlined or
ticked in list


(b) layers weakly held together / layers can slide over 1 ignore references to intermolecular forces or bonds
each…

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