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Section B
Answer allquestions
1. Fig 1.1 shows a generalised amino acid molecule.
Fig. 1.1
(a) Name the part of the molecule labeled Y.
Y...........[1]
(b) Amino acids can be lined together to form a pol!peptide chain. "onosaccharides can
also be lined together to form long chain molecules called pol!saccharides.
#tate two wa!s$ other than the names of the monomers present$ in which the structure of a
pol!saccharide chain differs from that of a pol!peptide chain.
1. ..
%. .[%]
(c) &he fibrous protein collagen and the pol!saccharide cellulose both possess considerable
tensile strength.
'ist two features that contribute to the strength of
(i) collagen
1....
%.......[%]
(ii) cellulose
1....
%...[%]
[&otal ]
[Turn over]
*
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%. A student in+estigated the acti+it! of catalase b! measuring the release of o,!gen fromh!drogen pero,ide. &he reaction occurs as follows.
% -%% % -% / %
&he student used a solution of catalase that was mi,ed with a 0 h!drogen pero,ide solution
and placed in the apparatus shown in Fig. %.1. &he total +olume of gas collected was recordede+er! 10 seconds. &he results are shown in Fig. %.%.
(a)
2,plain wh! the total +olume of gas collected after %13 seconds remains constant.
...[1]
13
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4atalase and h!drogen pero,ide were ept separatel! at 13o4 for 53 minutes before the!were added together. &he reaction mi,ture was then ept at 13o4.
(b)#etch$ on Fig. %.%$ the results !ou would e,pect when the e,periment was repeated at
13o4. [1]
(c) 2,plain how increasing the temperature of an en6!me7catal!sed reaction will increase therate of the reaction.
...[5]
[&otal 0]
5. (a) Figure 5.1 shows electron micrographs of two organelles$ A and 8.
Fig. 3.1 [Turn over]
11
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4omplete the table below describing the main identif!ing features and the main functions
of the organelles shown in Fig.5.1
organelle "ain identif!ing feature "ain function
A
B
[9]
(b) 2,plain wh! the cell surface membrane is described as a fluid mosaic.
...[%]
:l!coprotein in the cell surface membrane functions as an antigen.
(c) #tate how gl!coprotein is held in the cell surface membrane.
...[5]
&he following in+estigation to determine the water potential of potato tuber cells was carriedout. 4omparable % mm thic discs of potato tuber were cut out and weighed. ;eplicatesamples were taen and placed in distilled water and a series of sucrose solutions$ rangingfrom 3.1 to 3.< "$ in co+ered dishes at a constant temperature of %3 =4. After one hour$ thesamples were remo+ed and blotted rapidl! between sheets of filter paper and re7weighed. &heresults are shown in Fig. 5.%.
1%
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Fig. 3.2
(d) >escribe in terms of water potential what changes occur in the potato discs in
distilled water$
[Turn over]
15
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3.< " sucrose solution.
...[5]
[&otal 1%]
9. Fig. 9.1 shows four animal cells in different stages of mitotic di+ision.
Fig. 4.1
(a) Name the structures labeled A$ B$ Cand D.
A
B....
C....
D....[%]
(b) ?sing the number gi+en to each cell abo+e$ arrange the stages as the! occur in the mitotic
sequence.
...[1]
19
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(c) 2,plain what is happening in cell 1in Fig 9.1.
...[%]
(d) #tate the importance of mitosis in the growth of a multicellular organism$ such as a
flowering plant or a mammal.
...[1]
(e) 2,plain how cancer is the result of uncontrolled cell di+ision.
..
..
..
[%]
[&otal @]
0. Fig. 0.1 shows the process of translation occurring at a ribosome in a cell that s!nthesises
en6!mes that are secreted into the gut.
10
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Fig. 5.1
[Turn over]
&able 0.1 shows some triplet base sequences of >NA and the amino acids for which the!
code.
Table 5.1DNA Aino aci!
&AA soleucine
&A: soleucine
AAA Bhen!alanine
A:A #erine
:&A -istidine
4A& Caline
(a) Dith reference to Fig. 0.1 and &able 0.1$
(i) name the amino acid "E
..[1]
(ii) state the base sequence at SE
..[1]
(iii) state the name gi+en to the triplet base sequences on m;NAE
.[1]
(i+) describe the change that would occur to the protein if the base sequence at #was??? instead of A??.
[1]
(b) >escribe what happens to the en6!me molecule after it has left the ribosome until itlea+es the cell.
...[5]
[&otal ]
1
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.
[5]
[Turn over]
Fig.
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..
...[5]
[&otal 11]
No Answer "ar
1. a
b
c i)
ii)
%. a
b
c
4arbo,!l [31G5GaG]
(pol!saccharide)
7 gl!cosidic lins
7 no ; groups7 ma! be branched
7 (usuall!) single t!pe of monomer
7 5 pol!peptides twisted around each other
7 h!drogen bonds between the pol!peptides
7 co+alent lins between the chains
7 e+er! third amino acid being gl!cine$ small si6e$ so allows tight coil7 la! parallel to form fibrils
7 ends staggeredG fibrils o+erlapping$ so strong
7 man! 7- groups
7 h!drogen bonds within the molecules
7 h!drogen bonds between molecules7 straight chain (not heli,)G unbranchedG linear
7
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5. a
b
c
d
9. a
b
c
d
e
7 collide with more energ!$ so bonds more easil! broen [@33G31G%Gd]
organelle "ain identif!ing feature "ain function
A 7 double membrane G
cristaeG folded inner
membrane
7 A&B s!nthesis
B 7 cisternaeG no
ribosomesG ref.
membrane bound sacs
7 lipid s!nthesis G segregatingG
carr!ing material out of cellG
transfer proteinsG lipidsG ref. toautophag!
[N33G1]
7 phospholipid molecule is free to mo+e laterall!
7 protein molecule floats within the membrane [33G%Ga]
7 h!drophilic regionss7 interact with phosphate headG aqueous intracellularG e,tracellular solution7 h!drophobic regions
7 interact with h!drophobic fatt! acid tails [*9G1GdGii]
distilled water:
7 -% diffuses into discs G enters b! osmosis
0.6M sucrose solution:7 water diffuses out of the discs
7 diffuse down the water potential gradient
7 change in mass +alue e,trated from Fig. 5.% [@33G31G0Gb]
7 nuclear membraneG en+elope
7 sister chromatid7 centromere
7 asterG microtubule (H spindle fibre)
7 %$5$1$9. [*5G1Ga$bGii]
7 centromeres di+ideG duplicated (H splitG replicated)
7 (sis) chromatid sepG pulledG mo+ed$ to (opp) poles
7 b! spindle fibresG spindleG microtubule (contract) (H fibres)
7 produce geneticall! identicalG uniform$ cells7 maintain genetic stabilit!
7 same number I same ind of chromosomes
7 no genetic +ariation [35G1Gb$ d]
7 oncogenesG genes controlling cell di+ision being switched onG acti+ated
7 cancer cells do not die$ with no apoptosisG programmed cell death
5
9
%
5
5
%
1
%
1
%3
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0.a i)
ii)
iii)
i+)
b