CAPE Biology Past Papers 2008

7/22/2019 CAPE Biology Past Papers 2008

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SECTION A

Answer ALL questions in this section. You must write your answers n the spacesprovided in this

ansrverbooklet.

1. Figure I showsthe transverse ectionof the root of adicotyledon. Study Figure 1 andanswer

Questions a) to (c).

Figure 1.. Transverse sectionof a dicotyledon root

Bracegirdle B. S.Miles P, An Atlas of Plant StructureVolume .

HeinemannEdacationalBooks,1971,p'67.

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E

F

c

D

o)

(a)

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Identi$ thestructuresabelledA toH.

A

B

(c)

[ 4 marks]

In the spaceprovided, draw a plan diagram to show the distribution of the differenttypesof tissuesn Box A in Figure l. Makeyour drawing the actualsizeof Box A.(No labels equired).

[ 4 marks]

If the photographn Figure I hasbeen nagnified100 imes,what s theactualwidth ofthe specimenromX, toXr?

I lmark]

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(d)

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Figure 2 showsphotographs f the sarne lantcells seen a) with a ight microscope nd(b)withanelectronnricroscope.

othareshownatthesarnemagnificationofboutxl500.

(a) (b)

Figure 2" trXanteelXs s seenhy a light and an electron rnicroscope

niobsical Science Z TaynorD. .f et al., Carnbridge, age tr32.

(i) Account or the diff'erencen clarity befween he two photographs.

[ 2 manhs]

(ii) Corrunenton the advantages nd trirnitationsof using a Xight nicroscopeascomparedo anelectron nicroscopeo exarnineceils or tissues.

[ 4 marks]

Total 15marks

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(b)

(a)

(b)

(c)

(d)

Answer ALLprovided.

4. (a)

1, '

SECTIONB

questions in this section. You rnust write your answers in the ansryer booklet

By meansof a diagram,show he molecularstructureof sucrose. Show thepositionof the oxygen and all other groups,EXCEF for the H.OH groupson the No. 2, 3

and4 carbonsof,glucose,and he 1, 3 and4 carbonsof fructose.

Relate he structureof the water moleculeto its

(i) solventproperties

(ii) high surface ension.

[ 3 marks]

[ 4 marks]

(c) (i) Explain the modeof enzymeactionaccordingo the 'lock andkey hypothesis'.

(ii) Comrnenton differencesn the way in which competitiveandnon-competitiveinhibitorsaffectenzymeactivity" [ 8 rnarks]

Totatr15 rnarks

StateT'WOways n which variationcan occur n sexuallyproducedorganisnns nd byrneans f a graphand anexarnple, xplainwhat s rneantby EACH of the following:

(i) 'Directional selection'

(i0 'Stabilisingselection' [ 7 marks]

Outline the FOUR key stepsnvolved n producinga recombinant ieceof gene.

[ 4 rnarks]

(c) In general erms, discussFOUR major issuesassociated ith applications f geneticengineering. [ 4 rnarks]

Total 15 rnarks

6. (a) With reference to the human menstrual cycle, discuss the biological basis for thefollowing two rnethods of contraception.

(i) The rtrythm method

(iD The contraceptive ilX [ 5 marks]

O) Briefly commenton therole of thepnacentas a guardian 'or he developing oetus.

[ 2 marks]

[ 4 rnarks]escribe he structureof ayoungplantovule.

Discuss he relativemerits of cross-fertilisation ndself-fertilisation n plants.[ 4 marks]

Total 15 marksEND OF TEST

TheCouncilhasmadeeveryefforttotracecopyrightholders.Howeverrifanyhavebeenina.dvertentlyoverlooked,or any naterial hasbeen ncarrectly acknowledgcd,CXC will bepleased o correct this althe earliest apportunity.

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Flower colour in certain plants is controlledbytwo genes. One genecodesfor c.olour

pigments n the petals,*d it. allelesareR (red)andr (white). The allelesareco-dominant'

The other gene codes for an enzyme system n the petals that enables he pigments to be

made,and its alleles are C for active enzymesand c for inhibited enzymes. Plantswith

homozygousrecessive,ccareunabletosynthesizeanypigment,andthereforeproducewhiteflowers.

(a) A plant with genotypeRRcc is crossedwith the doublehornozygousecessive lant'

State he genotypeandphenotypeof the Ft plant'

o)

(i) GenotyPe

(ii) PhenotYPeI lmark]

state the FouR different combinationsof the alleles carried in the gametesof this Ft

dihybridplant (plant producedn (a) above)'

(c)

(i)

(ii)

(iii)

(iv)

(i)

[ Lmark]

use the Punnett square shown in Table 1 to show the genotypesof the F

generation f this dihybridcross'

TABLE tr.:FI.INNETTSQUARE

GametesJ

[ 2 marks]

Red : Pink : White

[ 3 marks]

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(d) A group of students determined the Chi-squared value from the figures shown inTable 2, which representa monohybrid crossbetween CC (colour enzymes)and cc (no

enzyme or colour).

TABLE 2: MONOHYBRID CROSSBETWEEN CC AIrID cc

Colour, C No Colour, c

Observed esults O) 95 35

Expected ratio 3 I

Expected results(E") 97.5 32.5

o*E

to - El'

IO-E]2+n

chi-squareds he um" ry

=

[ 4 marks]

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(e)

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ThestudentsusedtheTablefChi-squaredvalues howninTable3todeterminewhetherthe value youobtained n (d)bnpage6 ndicates hat he differencebetween he observedand expected esultsare acceptableor not acceptableas being due to chancealone.

(i) How did the studentsdetermine he degreesof freedom?

I lmark]

The students hecked he 5Voprobability in order o determinewhether heresultwas significantor insignificant. What was heir decision,and why?

[ 2 marks]

If the Chi-squaredvalue had been 7.0, what information could have beengainedconcerning he resultsof the monohybrid cross experiment?

I lmark]

Total 15 marks

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(ii)

(iii)

TABLE3: TABLE OF/3 VALUES

DegreesofFreedom

Numberof Classes Chi-squared Values

I

2

J

4

.,

3

45

0.46 1.64 2.71 3.84 6.64 10.83

1.39 3.22 4.61 5.99 9.27 13.82

2.37 4.64 6.25 7.82 11.34 16.273.36 5.99 7.78 9.49 13.28 18.47

Probability that chancealone could produce

this deviation0.50 0.20 0.10 0.05 0.01 0.001

(5oo/o) (20%) (10%) (s%) (r%) (0.r%)

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Figure 3 showsthe structureof a mammalian ovum and sperm'Questionsa) and(b).

r' Study Figure 3 and answer

Head

Neck

Midillepiece

Tail

'2.5pm'

Flgure 3. Structure of a mamnalian ovum and sperm

http://www.humanillnesses.comloriginat/images/hdc-00il0003-0-img0209ipg

(a) (i) state FouR structuraldifferencesobservedbetweenthe ovurn andthe spenn.

[ 4 marks]

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(ii) Basedon featuresobserved, omment, sing wo points, on how theovum andthe spermare suited o their respectiveunc"tions.'

(b)

[ 4 marks]

Explain why somescientists egard he ovum at the stageshown n Figure3, to be asecondary ocyte.

[ 2 marks]

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(D

(ii)

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(c) Table 4 shows the results of an experiment investigug"-g the influence of sperm

velocity on fertilisation in the freshly diluted spelm of the seaurchin, Lytechinus

variegatus.

TABLE 4: SPERM VELOCITY AGAINST FERTILISATION IN SEA URCHIN

Sperm velocitymm/sec

No. of sperm/cd needed o

fertilise 507oof female eggs

(FJ expressedas a log value

0.15 3.6

0.16 3.3

0.17 4.1

0.19 3.5

0.20 4.0

0.21 3.2

0.22 3.1

0.25 2.5

0,26 2.6

0.28 2.0

on the graph grid on page 11, plot a graph to show the relationship between

spennvltocity andfertilisation. [ 4 marksl

Suggesta likely conclusionfrom the findings of this experiment'

I lmark]

Total 15 marks

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CAPE Biology Past Papers 2008