Cell Structure Compared to Function

Topics: Kompakt, Genotype, Allele Pages: 9 (1236 words) Published: September 4, 2013
Mark scheme June 2002 GCE
Biology B Unit BYB4

Copyright © 2002 AQA and its licensors. All rights reserved. The Assessment and Qualifications Alliance (AQA) is a company limited by guarantee registered in England and Wales 3644723 and a registered charity number 1073334 Registered address: Addleshaw Booth & Co., Sovereign House, PO Box 8, Sovereign Street, Leeds LS1 1HQ Kathleen Tattersall: Director General

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SECTION A
Question 1
(a)

GCE: Biology B – BYB4

June 2002

X = grana/lamellae/thylakoid (membranes); Y = stroma; NADPH2/ NADPH/ reduced NADP/reduced coenzyme; ATP; carbon dioxide/CO2; stroma; NOT “Y” production/breakdown of starch (or equivalent);

2

(b)

2 1 1 1

(c) (d) (i) (ii)

Total 7 __________________________________________________________________________________

Question 2
(a) Oryctolagus, Helix, Trichonympha; (reject if specific names included) (not insisting on generic capitals) any two for 1 mark Animals, Protoctists, Prokaryotes;; (accept Latin equivalents) any two for one mark, all three for both that (they are) fertile; 1

(b)

2 1

(c)

Total 4 __________________________________________________________________________________

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Question 3
(a)

GCE: Biology B – BYB4

June 2002

Mark across whole of two parts in (a) to credit the following possible points (structure) Distant object Close object

Cornea suspensory ligament Ciliary Body - in tension - relaxed;

- converges light/refracts/bends light; - tension relaxed; - contracts;

- pulled thin; Lens

- allowed to become fatter/more spherical;

- the more convex/fatter the lens, the shorter focal length (or converse) Each itemised point in a box (-) worth one mark. Any 6 from 8 points. (b) (i) (ii) (c) (d) only blue-(sensitive) cones/cells stimulated; (mixture of) green- and red(-sensitive) cones/cells stimulated; value or range 575 to 600(nm) (accept any range within 551 to 649 nm); there are two phases/sections to the curve (or equivalent idea) OR one cell type reaches full sensitivity before other; (ignore any ‘cell’ identification if wrong) 1 1 1

1

(e)

rhodopsin was bleached/is resynthesised; to/ from pigment/retinal; and to/from protein/opsin; any 2 from 3

2

Total 12 __________________________________________________________________________________

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Question 4
(a)

GCE: Biology B – BYB4

June 2002

(acetylcholine) made in/stored in synaptic vesicles; released into (synaptic) cleft; diffuses/moves across (cleft); binds to protein/receptor molecules on (postsynaptic) membrane/neurone; causes depolarisation/action potential/new impulse (in postsynaptic neurone); any 3 from 5 3 to provide energy for the (re)synthesis of Ach OR associated active transport; receptor detects stimulus; impulse to muscle (escape response effected by muscle to withdraw head into burrow) muscle (M) longitudinal OR when it contracts it pulls animal shorter; no coordinator involved/only 3 neurones in reflex (arc); reflex is ‘automatic’ (or equivalent point); any 3 from 5 (impulses) may cross synapses in one direction only/transmitter may only travel one way; axon P myelinated; OR axon diameter of P greater (than that of other axons); (increased speed of escape response) increases the animal’s chances of survival;

(b)

1

(c)

3

(d)

1

(e) (i)

1

(ii)

1

Total 10 __________________________________________________________________________________

Question 5
(a) (b) D; Krebs cycle; electron transport/transfer chain/oxidative phosphorylation; (glycolysis negates one point of credit) (link reaction and glycogenesis etc. are ‘neutral’) some radioactivity in intermediates/other compounds (e.g. glucose); ACCEPT idea of less present because of radioactive decay; NOT because of ‘rounding off’ 1

2

(c)

1

(d)

(1200 / 8000) x 100; 15 (%); (allow (1800 / 8000) x 100 = 22.5% for 1 mark) (2 marks for the correct answer as 15% without working, 1 mark for...
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