march p2 (q & a) sem paper bio

7/25/2019 March P2 (Q & A) Sem Paper Bio

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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]

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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]

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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.%.

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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]

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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]

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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.

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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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10/13

.

[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

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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

march p2 (q & a) sem paper bio

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