CAPE Biology Past Papers 2006

7/27/2019 CAPE Biology Past Papers 2006

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SECTION A

Answer ALL questions n this section.You must write your answers n the spaces rovided on the

questionpaper.

1. (a) Carbohydratemoleculesmay be oined by either cror B linkages.

Figure I shows2 glucosemoleculesoined by an a-t-4 glycosidic inkage.

CH" OH cH2oll

H C-OH HC-O OH\-/i v v; \.//'\9" T/--.,rVt tll-\

HO C_C_

C-C H

t! 6" it o"

Figure 1. Two glucose molecules

(i) Using an o-1-6linkage, attacha third glucose molecule in Figure 1.

[ 2 marks]

(ii) Name ONE example of a carbohydrate that is made up of components with

BOTH an a-l-4 glycosidic linkage and an a,-1-6linkage.

I lmark]

(iii) Distinguishbetweenan cr glycosidic inkage' anda 'B linkage'.

I lmark]

Comment on the difference in function between a carbohvdratewith ct inkaees

and a carbohydrate with B linkages.

[ 2 marks]

GO ON TO THE NEXT PAGE

(iv)

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=Ii

(i )b)

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Keratin, a protein found in hair, is made up of ct helices. Describe the ct helix

bond in keratin.

[ 2 marks]

In contrast to keratin, fibroin, a protein found in silk, is made up of B pleated

sheets. Comment on TWO differences in physical properties of theseproteins.

Write your answer in the table below.

cr helixes p pleated

I

2

[ 2 marks]

Figure 2 showsanother wo structuralbonds ound n proteins'

(ii)

H-C-H TI-C-Hr l

SidechaindH S

otcyslelne+ F__

\qr s\t l -B

H-C-H H-C_H

Figure 2. Structural bonds n proteins

Identify the TWO bonds abelledA and B asshown n Figure2.

A

[ 2 marks]

NEXT PAGE

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GO ON TO THE



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(c) Outlineanexperimento determine xperimentallyhepresencefcatalasenchickpeas.

[ 3 marks]

Total 15 marks

(a) Briefly outline he role of DNA in genetic nheritance.

[ 2 marks]

Distinguishbetween he terms"chromatin'and chromosome'.

Chromatin

Chromosome

[ 4 marks]

GO ON

I

(ii)

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(b) StateTHREEreasonswhy mitosis s importantinthe lifecycleof aeukaryotic organism.

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[ 3 marks]

(c) Figure 3 shows two phasesof the early stagesofMeiosis I. In the abelled boxesprovided

in Figure 3, DRAW threeconsecutive phases o illustrate the MAIN changes hat occur

between the two phasesshown.

Figure 3. Diagrams showingtwo phasesn Meiosis I

[ 6 marks]

Total 15 marks

2.

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IV

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(a ).

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Figure 4 representsan incomplete longitudinal section (LS) through a carpel just prior

to fertilization.

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Figure 4. Incomplete LS through a carpel

(i) Draw on the diagram in Figure 4

a) the ovule

b) the path taken by the germinating pollen grain.

(ii) On Figure 4, label TWO features of the embryo sac.

(iii) Identify ONE role for EACH of the features in (ii) above.

[ 2 marks]

I lmark]

[ 2 marks]

l

ii

[ 2 marks]

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(b)

1

The pawpaw has male and female flowers which are borne on different plants.

(i) State the term used to describe this reproductive feature.

I lmark]

(ii) StateONE disadvantageto the plant in having this feature.

I lmark]

Plants can also be propagated non-sexually. Suggest TWO mechanisms thatoccur NATURALLY in plants to aid NON-SEXUAL propagation.

[ 2 marks]

(ii) StateONE advantage f the mechanisms ou identified n (c) (i).

I lmark]

Methods exist for the artificial propagation of plants utilizing small amounts of plantmaterials. Discuss THREE advantagesof these methods over the natural methods ofnon-sexual propagation.

[ 3 marks]

Total 15 marks

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( i)c)

(d)

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Answer ALLprovided.

(ii)

(iiD

(a)

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SECTION B

questionsn this section.You'must write your answersn the answerbooklet

According to the endosymbiont theory, mitochondria and chloroplasts are organelles

which are thought to have evolved from prokaryotes, and which established symbiotic

relationships with eukaryotic cells.

(D DescribeTWO featuresof mitochondria and chloroplasts that support the theory

that they have evolved from prokaryotic cells.

Define the term 'symbiosis'.

[ 2 marks]

[ 2 marks]

(b) (i )

(ii)

Comment on evidence that supports the theory that a symbiotic relationship

existed between eukaryotic cells and chloroplasts and mitochondria. Include

in your answer the benefits that BOTH the eukaryotic cells and the symbiont

received. [ 4 marks]

Define the terms 'tissue' and'organ'. [ 2 marks]

Use the dicotyledonous root to distinguish between the levels of organization

found in tissuesand organs. [ 5 marksl

Total 15 marks

According to the biological species concept, a speciesrepresents he lowest taxonomic

group which is capableof being defined with any degreeof precision. While there are

severalways in which the term maybe defined, most biologists define species n relation

to their breeding behaviour.

(i) State ONE definition of a species n terms of breeding behaviour'

[ 2 marks]

(ii) Discuss he limitations of defining a'species' in termsof breeding.

[ 6 marks]

(i) With reference o animal populations, outline the processby which a new speciesmay arise rom a previouslyexistingone. [ 4 marks]

(ii) According to Darwin and Wallace the mechanism for speciation is natural

selection. Comment on the basis of this mechanism. [ 3 marks]

Total 15 marks

(a)

(b)

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(a)

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(i) State the functions of EACH of the following in oogenesis in humans:

a) gonadotrophin releasing hormone

b) luteinising hotrmone

c) follicle stimulation hormone. [ 4 marks]

(ii) Explain how thesehormones function in males as compared to females.

[ 3 marks]

(b) The inhibition of the production of luteinising hormone and follicle stimulatrnghormone by oestrogen and progesterone is the basis of one contraceptive method infemales. Comment on why the same principles CANNOT be applied to develop amale hormonal contraceptive. [ 4 marks]

(c) In addition to similarities, differences exist between oogenesis and spermatogenesis.

Discuss TWO significant differences with respect to the timing of oogenesis andspeflnatogenesrs. [ 4 marks]

Total 15 marks

END OF TEST

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CAPE Biology Past Papers 2006

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