Download 1. (a) - The West Bridgford School

1.
(a)
Glycerol / glyceride;
1
(b)
(i)
Phospholipid has (one) phosphate / Phosphoric acid;
replacing fatty acid;
2
(ii)
Saturated – all valencies of C filled / saturated with hydrogen / all (C–C)
single bonds / no double bonds;
fatty acid 1 is saturated/fatty acids 2 and 3 are unsaturated;
2
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2.
(a)
Several/more than one polypeptide chain in molecule;
1
Evidence must only relate to 4º structure
(b)
(c)
(d)
(e)
Chemical bonds formed between sulphur-containing groups/
R-groups/form disulphide bonds; Stronger bonds; Bind chain(s)
to each other;
max 2
Different number of amino acids; Different sequence of amino
acids; Bonds in different places; Gives different shape;
max 2
Outer layer of skin cells are dead; Do not respire/Do not contain
mitochondria; Do not produce ATP/release energy; Cells do not
have required proteins/carriers;
max 3
1 TEM uses (beam of) electrons;
2 These have short wavelength;
3 Allow high resolution/greater resolution/Allow more detail to
be seen/greater useful magnification;
4 Electrons scattered (by molecules in air);
5 Vacuum established;
6 Cannot examine living cells;
7 Lots of preparation/procedures used in preparing specimens
/ fixing/staining/sectioning;
8 May alter appearance/result in artefacts;
max 6
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3.
(a)
(i)
(ii)
Initial mass of cylinders not identiical;
To be able to directly compare the results;
2
From 0.3 mol dm–3 to 0.1 mol dm–3 water moves into potato cells;
By osmosis;
So mass increases;
More water has entered potato cells 0.1 mol dm–3 / converse;
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West Bridgford School
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(iii)
(b)
0.35;
No mass change/no net osmosis/
volume of water in = volume of water out;
Range from –511 to –549 kPa;
Reason e.g. Water moves from A to B, so must be lower than –510 and
Water moves from B to C, so must be higher than –550;
2
2
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4.
(a)
(b)
A ribosome (RER neutral);
1
B vacuole;
1
C smooth ER / SER;
1
(i)
(ii)
(c)
support / strength / shape / prevents osmotic lysis;
(protection, permeability neutral)
1
photosynthesis / light energy → chemical energy;
(makes food/sugar neutral)
1
0.2 – 0.24 gains 2 marks;
ELSE evidence of observed measurement
(5 – 6 mm / 0.5 – 0.6 cm) ÷ 25 000
gains one mark;
2
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5.
(i)
cold - no / reduced enzyme action / e.g. stops autolysis;
(reject “cell activity reduced”)
isotonic - stops osmotic effects / description of effect on
cells or organelles;
buffer - prevents damage to enzymes / proteins;
3
(ii)
break open the cells / release the cell contents;
1
(iii)
supernatant / liquid above the pellet;
spun at a high(er) speed;
2
(mark as independent points)
[6]
West Bridgford School
2
6.
(a)
(b)
Condensation;
removal of water molecule;
from amino and carboxyl groups;
forming peptide bonds;
same amino acids in same sequence;
bonds form between R-groups/side chains;
e.g. sulphur-containing amino acids / ionic bonds / hydrogen bonds;
bonds form in same place;
max. 6
Allows passage of charged particles / ions;
allows passage of water soluble / large molecules;
channel proteins / proteins with pores;
specificity related to diameter / charge;
carrier proteins;
specificity lined to shape of receptor sites;
functions by changing shape / conformation;
(c)
facilitated diffusion with concentration gradient;
active transport against concentration gradient;
active transport requiring energy / ATP;
max. 7
Glucagon has specific shape / structure;
receptor molecules with specific receptor sites;
concept of fitting;
glucagon receptors only on liver cells;
max. 4
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7.
(a)
(i)
(ii)
(b)
potato more negative water potential/hypertonic;
(accept more concentrated)
water enters by osmosis;
cells extend/are turgid;
2 max
little/no water remaining in potato/fully plasmolysed/all water
has moved out;
cell wall prevents further shrinkage/sucrose solution moves in;
or, water potentials are equal/equilibrium/isotonic;
no net movement of water/no further osmosis;
2
(i)
faster rate (of decrease) in 0.8 mol dm–3;
1
(ii)
bigger water potential gradient/greater difference in water
potentials (between potato and surrounding solution);
1
West Bridgford School
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(c)
(i)
(ii)
water moved into the solution from the potato;
solution diluted/becomes less concentrated;
2
no net movement of water (in or out);
drops move up/less dense;
or, no net movement of water (in or out);
drop would not move/densities the same;
2
[10]
West Bridgford School
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