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2 Diagram 2 shows a series of reaction. Process X is the formation of molecules

Q, while process Y is the breakdown of polypeptide.

[Rajah 2 menunjukkan satu siri tindakbalas. Proses X adalah pembentukan molekul Q, manakala

proses Y adalah penguraian polipeptida.]

Diagram 2

Rajah 2

(a) Name molecules P and Q.

[Namakan molekul P dan molekul Q.]

Molecules P :

[Molekul P]Molecules Q ; .......

[Molekul Q]

[2 marks]

(b) Explain processes X and Y.

[Terangkan proses X dan proses Y.]

(i) Process X [Proses X]

.. [2 marks]

(ii) Process Y [Proses Y]

..

[2 marks]

2(a)

2(b)(i)

Molecules PMolekul P

Molecules QMolekul Q

PolypeptidePolipeptida

Process XProses X

Process YProses Y

2(b)(ii)

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(c) The breakdown of polypeptide molecule to molecule Q through process

Y occurs in human digestive system.

[Pemecahan molekul polipeptida kepada molekul Q melalui proses Y berlaku dalamsistem pencernaan manusia.]

(i) State one organ where process Y occurs.

[Nyatakan satu organ dimana proses Y berlaku.]

(ii) Name one enzyme secreted by the organ which is needed in

process Y.

[Namakan satu enzim yang dirembes oleh orgam tersebut yang diperlukan dalamproses Y.]

.

[2 marks](d) Enzyme is used to wash away the blood stain on a shirt.

Explain how the enzyme acts on the blood stain at a maximum rate.

[Enzim digunakan untuk mencuci kesan darah yang terlekat pada baju.Terangkan bagaimana enzim bertindak keatas kesan darah pada kadar maksimum.]

..

..

[2 marks]

(e) Enzyme is made up of chains of polypeptide molecule. The Golgi

apparatus in a living cell are malfunction. Explain the effect of the

malfunction to the production of extracellular enzyme.

[Enzim terbina dari rantaian molekul polipeptida. Alat Golgi dalam sel hidup gagal

berfungsi. Terangkan kesan kegagalan itu dalam penghasilan enzim luar sel.]

[2 marks]

2(c)

2(d)

2(e)

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2 (a) Able to name molecules P and Q.Answer:

Molecules P : Amino acidsMolecules Q : Dipeptides

11 2

(b) Able to explain processes X and Y.Sample answer:

Process X : Condensation of amino acids / (molecules) P // (Two unit of)

amino acids / (molecules) P combine / link and water(molecules) are released.

Peptide bond formed (between amino acids / P).

Process Y : Hydrolysis of dipeptides / (molecules) Q // Dipeptides / Q is

broken down by water (molecules). Peptide bonds are broken down.

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1

2

2

(c) (i) Able to state the organ in which process Y occurs.

Answer: Stomach / Ileum / Small intestine/duodenum 1 1

(ii)

Able to name one enzyme needed in process Y.

Sample answer: Pepsin / Erepsin/ Peptidase/ Trypsin / ProteaseNote:The enzyme named is related to the organ stated in (c)(i).

1 1

(d) Able to explain how to ensure the process Y occurs at amaximum rate in the washing of blood stain on a shirtSample answer:

Use (warm) water with temperature of 37C. This is an optimum temperature for enzyme (activity) //

Enzymes work best at this temperature.

OR Add a little vinegar / acid (in the water) Enzymes / pepsin work best in an acidic medium.

OR

Add more soap / alkali solution (in the water) Enzymes / trypsin / protease work best in an alkaline

medium.

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(e) Able to explain the effect of the malfunction of golgi apparatus.

Sample answer: Processing/ modifying/ packaging/ sorting/ transporting of

the synthesised protein / carbohydrates/ glycoproteins/ 1

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phospholipids could not be carried out

Resulting thesynthesised protein/ carbohydrates/glycoproteins are not able to be released out of the cellthrough the plasma membrane.

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TOTAL 12

No Marking criteria Marks Totalmarks

3 (a)(i) Able to name stages X and Y .Answer: X : Prophase I

Y : Metaphase I(ii) Able to explain the differences in chromosomal behavior

At X and Y.Sample Answer:

Prophase I Metaphase I(Paired homologouschromosomes) are arrangedrandomly.

(Paired homologouschromosomes) are arrangedon the metaphase plate /equatorial plane.

Spindle fibre does not holdon the centromer of thechromosomes .

Spindle fibre holds on thecentromer of thechromosomes.

(The homologouschromosomes paired and)crossing over take place.

(The homologouschromosomes paired)crossing over does not takeplace.

Any 2

(b)(i) Able to explain the occurrence at Z.Sample answer:P1 : Four daughter cells formedP2 : Each daughter cell has two chromosomes / haploid / n

(ii) Able to state the chromosome number in the daughtercell and give reason for the answer.

Answer:Six (chromosomes)Reason:(During meiosis) the daughter cell / n receives halfThe number of chromosome from the parent cell / 2n //Daughter cell haploid / n, daughter cell diploid / 2n

(d)(i) Able to explain why the chromosomes contain 24chromosomes.

Sample answer:1. Homologous chromosomes fail to separate equally

(during anaphase I)2. due to exposure to mutagen // any example of mutagens

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1

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