General Certificate of Education BIOL2 The variety of ...

Version 1.0: 05/2010

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General Certificate of Education June 2010

Biology

BIOL2

The variety of living organisms

Final

Mark Scheme

Mark schemes are prepared by the Principal Examiner and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation meeting attended by all examiners and is the scheme which was used by them in this examination. The standardisation meeting ensures that the mark scheme covers the candidates' responses to questions and that every examiner understands and applies it in the same correct way. As preparation for the standardisation meeting each examiner analyses a number of candidates' scripts: alternative answers not already covered by the mark scheme are discussed at the meeting and legislated for. If, after this meeting, examiners encounter unusual answers which have not been discussed at the meeting they are required to refer these to the Principal Examiner. It must be stressed that a mark scheme is a working document, in many cases further developed and expanded on the basis of candidates' reactions to a particular paper. Assumptions about future mark schemes on the basis of one year's document should be avoided; whilst the guiding principles of assessment remain constant, details will change, depending on the content of a particular examination paper.

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Biology - AQA GCE Mark Scheme 2010 June series

Question Part Sub Part

1

(a)

Marking Guidance Helical /spiral/coiled; Compact / description e.g. `tightly packed';

Insoluble; Prevents osmosis/uptake of water / does not affect water potential / (starch) does not leave cell;

Large molecule / long chain; Does not leave cell;

1

(b) (i)

1

(b) (ii)

1

(c)

/beta Glucose; Glycosidic; Long/straight/unbranched chains (of glucose); (Joined by) hydrogen bonds; Form (micro)fibrils/(macro)fibrils; Provide rigidity/strength/support;

Mark

1 1

Comments

2 max Feature = one mark Explanation = one mark

1 These must be related for both 1 marks but can be in reverse

order. 1 1 Allow idea of

compact/helical/spiral/coiled due to bonding for two marks.

1 Q Reject alpha glucose

1

1 3 max

1 Q Ignore reference to alpha glucose

1

1 Allow suitable descriptions for last point e.g. `prevents bursting';

3

Question Part Sub Part

2

(a)

Marking Guidance Endothelium/epithelium;

2

(b)

2

(c) (i)

Measurement divided by 8;

Allow answer in range of 3-3.3 for two marks; Stretches/'expands' under high pressure/when ventricle contracts / systole;

Recoils/'springs back' under low pressure/when ventricle relaxes / diastole;

Smooths blood flow / maintains blood pressure / reduces pressure surges;

2

(c) (ii)

(Muscle) contracts;

(Arteriole) constricts / narrows/alters size of lumen / reduces/regulates blood flow (to capillaries);

Biology - AQA GCE Mark Scheme 2010 June series

Mark Comments 1 Allow endothelial/epithelial

Reject - epidermis/endodermis 1 Correct answer gains 2 marks.

1 2 max

1

Q References to aorta 1 contracting or relaxing negates

marks for stretch and recoil.

1 Stretch and recoil without reference to blood pressure etc. = one mark.

Stretch and recoil to smooth blood flow etc. = two marks

Ignore references to aorta withstanding blood pressure or not being damaged. 1 `It' in answer = muscle

Allow converse (muscle) 1 relaxes and (arteriole) dilates

etc / increase blood flow etc.

Ignore references to pressure

4

2

(d) (i)

2

(d) (ii)

Large/increase in (total) cross sectional area / friction / resistance;

(More) time for exchange of substances;

Biology - AQA GCE Mark Scheme 2010 June series

1 1

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