Section A

[60 marks]

Answer all questions in this section.

1 Diagram 1 shows a plant cell as seen under an electron microscope.

Diagram I

On Diagram 1, label the structures p, e, R and S.

State the function of structure:

(a) (i)

(ii)

[4 ntarksl

P:

Q:

12marl--\./

(b) Explain the role of R to maintain cell turgidity.

r37

[2marks]

(c) Every somatic cell which contains structure e has a potential to formorganism.

(i) Name the technique used to prodi.rce new plants in large quantities.

a complete new

IImarkl(ii) By using one suitable part of the plant, explain the technique in (cxi).

[4marksl2 (a) Diagram 2.1 showshumandigestive system.

Duodenum

Diagrarn 2.1

structure Q in Diagram2.Lis involved in the digestion offat.

(i) Name structure Q.

139

[lmarkl

(ii) Name the enzlrme which digests fat in e.

ILmarhl(iii) Diagra m2.2shows a mechanism of an enzyme reaction.

Dray the diagram in the spaces III and fV provided in Diagram 2.2 to complete themechanism of the enzJrme reaction.

I III

Diagram2.2

(b) (i) Explain how starch is digested in the duodenum.

12marks)

B n+

flVrv

(ii) Astudent eats too many oranges.Explain the effect of eatfng too many oranges onduodenum

[2marksf

the digestion of starch in thY

t4l

12m,arksl

(c) In a food preparation process, a houservife carries out the following steps:step 1 : Marinate pieces of meat with strips of unripe papaya in a uarln.Step 2 : Immerse the basin in a'eontainei frlled with watei at 40 "C for B0 minutes as in

Diagram 2.3.

Water at 40 "C

Mixture of pieces of meatwith strips ofunripe papaya

Diagram 2.9

Explain why the housewife caries out Step 1 and Step 2.

14marksl

I Diagram 3.1 shows a cross section of part ofthe nervous sistem.

III

x ---!

I. l

(a) (i) NamestructureX.

lLmarkl

(ii) State the function ofX.

ILm.arkl

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(b) (i) Why is Y swollen at the dorsal root?

(ii) Complete Diagram 3.1 with the neurones involved in a reflex action.direction ofthe impulse movement on the neurones.

(c) compare two structures of a sensory neurone and a motor neurone.

1.

ILmarkT

Mark the

[2 marksj

2.

12marh^l

(d) If the spinal nenre is cut offat Z,whatis the effect on the organ which is connected to it?-Explainyonr answer. .

12 m.arksl

(e) Ali's finger accidentlytouches a flame.Explain brieflyhow his reflex action functions to avoid the injury.

13 marksl

t45

4 Diagam 4 shows a longitudinal section of the reproductive parts of a flower during fertilization.

(a)

(b)

Diagrarn 4

On Diagram 4, name the structures p, e, R and S.

(t In the space below, draw a seition through the ovule, showing all the cells in S.Label the cells involved in fertilization.

(ii) What is tbe significance of having two Q structures in the fertilization?

V*ornf,

[3 marks]

(c)

IZ marks]

In Diagram 4, thestructure Y has to be kept dormant for future researph purposes.

(t Explain howY can be prevented from germinating.

147

12 marksl

(ii) If Yis tobe germinated, suggest one method to stimulate the germination of y.

ILmark]Diagram 5'1 shows a sequence of stages in the synthesis of an extracellular eRzJrme in a humanpancreatic cell' The stages are labelled as Staie r, Stage rr and Stage rrl. Stage I shows achange in the specific part of a DNA stran*d. trre,n-Ng strand in=volved contains threenitrogenous bases, CTC.

Diagram 5.1(a) Explain the changes that occured in the double helix of the DNAstrand during stage I.

12rnarksl(b) Based on Diagram 5.1:

(i) state two differences between the structure ofthe protein polypeptide morecure and theDNAmolecule. rvrr'.vv

1.

7GX -stase;"",)

(:"r,",ffilTft'"[#\ FiT, \ \ ,r\ into the cytopla" ,/cteus g] ,/ Y Protein Kv-',,t;a,

ucreus g, / u1 ;"";; Kw"pt*. I \ beingsynthesised

\ ^io"r",J*,"

**\f *o*"y/

2.

149

[2rnarks]

(c)

(ii) Ditrerentiate betrareen the structure of DNA and RNA.

[lrnark]

Explain how the protein formed at the ribosome is transformed into the extracellularenzyme so that it can be secreted from the cell.

(d) Diagram 5.2 shows a gene mutation that occurs in the DNA strandsequence CTC.

Before mutation

DNAstrand

Synthesizedprotein

t r r lTC

,lotamic acid

Diagram 8.2

Explain how the mutation affects the specific characteristicor trait controlled.

tS rnarkq_,

containing the base

r t lC AC

I+o

ValineGlu

Aftermutation

151

13 marksl

Section B

120 marksl

Answer any one question.

Diagram 6 shows three organisms, p, e and R.

ilF

-";t$o*"-P R

Diagram 6

Describe the type of nutrition in pand e. 14marksl(a) (i)

(ii1Explain one similarity and four differences between the alimentary canal of e and R.ILO marks)

(b) constipation, night blindness and anaemia are three health problems.

State the cause and suggest the ways to overcome these health problems from nutritionalasPects.

[6 marks)

(a) Plasma membrane encircles the protoplasm of a cell. As a whole plasma membraneexhibits fiuidity as if it is a layer of oil in a beaker of water.

what is meant byplasma membrane exhibits fluidity? [4marksl

(b) (i) An experiment is carried out using substance R outside a cell.

The aim of the experiment is to study the effect of different concentrations of substanceR on the rate of its movement across the plasma membrane into the cell.

-<<4-

u

153

Graph 7.1 shows the result of the experiment.Rate of movementof substance R / mg s-1

Concentration ofsubstance R/ unit

Graph 7.1

Based on Graph 7.1, state an example of substance R and explain how substuo"" *-moves across the plasma membrane. 16 m,arksl

155

(ii) The experiment is repeated by replacing substance R with substance s.

Graph 7.2 shows the result obtained.

Rate of movementof substance S / mg s-r

Concentration ofsubstance S / unit

Graf 7.2

Based on Graph 7.1 and Gr apn 7 .2,compare and explain the movement of substancil Rand substance S across the plasma membrane. [L0 marksl

t57

Section C

[20 marks]

Answer'any one question.

Green plants sJmthesize their food through the process of photosynthesis. The chemicalprocess of photosynthesis can be summarised as in the schematic diagram in Diagram 8.

Hidroxyl ion

Lightt"r.rr""I

Water + Oxygen

Water molecule

Chlorophyll rrrolecule ------+ Electron

Hydrogen

Dark reaction

stored Glucose+- (CHrO)n Carbon

dioxideWater

Diagram 8

(a) State the meaningof photos5mthesis based on the schematic diagram in Diagram 8.

. t2 marksT

(b) Starting with water and cbrbon dioxide as the raw materials, describe how a green pladproduces starch molecules tg ma;i,,-_

(c) It is found that the process of photosynthesis contributes to the balance of nature.

Explain how air pollution may have an effect on photos5mthesis and the balance of nature.t10 marks]

I (a) The following statements are on lymphatic system and blood circulaiory system.

' llhe substances that come out from the blood capillaries into the body tissue will be re-entered into the blood circulatory system.

o Lymphatic system also functions in transporting products of digestion.

Explain the above statements to justifr that lymphatic system is a complementary to theblood circulatory system. ILO marksl

[-

159

Multicellular organisms like humans, need specific transport systems as comparedto unicellular organisms likeAm oeba sp.,which do not ""J;1;;;"";;;;;-*.

Give an evaluation of the above statement based on the physical features of the organisrnswith the following physiological processes:

RespirationNutritionExcretion

[L0 marks]

t6l

Conclusion: Isotonic solution will maintain themass and the length of plant tissues and this is yo/o ofsucrose solution.

SPM D(AMINATION PAPER 2006Paper IlC 2C7B 8A

13A 14 D19D 20 C25 D 26 B31D 32 A37 B 38C43D 44 D49 C 508

Paper 2Section A1 (a) (r) chloroplast

nucleusvacuoleGolgi apparatusContains chlorophyll whieh absorbssunlight for photosynthesis.Contains genetic material in the form ofchromosomes which control the activitiesofthe cells.

The vacuole pushes the cytoplasm and presses theplasma membrane against the cell wall.(l) fissueculture/cloning(ii) - Tissuesectionsareobtainedfromtheroot.

- Tissues are cultured in suitable nutrientmediums with growth hormones.

- Callus tissues are formed through mitosis.- Callus tissues are transfetred to agar

medium.- New plantlets/clones formed are then

transfened and grown in the soil.

Small intestine/ileumLipase

(b) (t - Pancreassecretespancreaticjuiceintotheduodenum.

- Pancieatic juice contains amylasewhich hydrolyses undigested starch intomaltose.

(il) - Oranges contain ascorbic acid and willlower the pH in the duodenum from anoptimum of pH 3.

- fhis will slow down the digestion of starehwhich requires an optimum pH of 7.t-8.2.

(c) - Step 1 is to provide enzyme protease to digestthe meat in order to tenderize the meat.

- Step 2 is to provide the optimum temperaturefor enzyme action and to allow enough timefor enzyme reaction.

Spinal cordControl reflex actions and connect the brainto the peripheral nervous system.Congregation of cell bodies of afferentneurones to form a ganglion.

3 (a) (,(ir)

o)( '(ir)

3C 4A 5A 689C 10D 1lA 12 C

15c16At7A18B2r B 22 B 23 C 24 B27 C 28 A 29 A 30A33B 34 A 35D 86839A 40 B 4r D 42D45 D 46 D 47 A 48 C

(c) Sensory neurone Motorneurone

1. Cellbcdylocatedoutside the spinalcord.

1. Cellbodylocatedinside the spinalcord.

2. Has a longdendron and ashort axon.

2. Has a shortdendron and along axon.

Nerve impulses cannot be transmitted from thespinal cord to the effectors and the organ will notrespond.

- Pain receptors in the skin ofthe fingers detectstimulus

- Nerve impulses are transmitted from receptorsto spinal cord via sensory neurone whichtransmits impulses to the efferent/motornenrone via interneurone and then to musclesin the organ which contracts and pulls handawayfromflame.

PaRsP

a

(ir)

(d)

(e)o)(c)

2 (a) (D(ii)(iir)

4 (a)

(b)

pollen tubeovary

P:R:(r)

Q : male gametesS : embryo sacs

rym

Polar nucleus

Eggcell/ovum

(ri) - One male gamete fuses with the egg cell.- Another male gamete fuses with the two

polarnucleus.- Double fertfisation occurs.

(r) Place in dry/cool plabe which is air tight(ii) Place in sugar solution

- The double helix of the DNAstrand unzips.* The DNA code is copied/transcribed into a

strandof mRNA.(t 1. DNA is double stranded whereas

polypeptide is single stranddd2. DNA is made up of repeating units of

phosphate, sugar and nitrogenous bases(nucleotides) whereas polypeptide is

(c)

(a)

t l

(b)

ffff "r of 20 different type of amino

(ii) DNA molecules consists of 2 polynucleotidestrands whereas RNAconsists of a singlestranded nucleotide.

(c) Proteins synthesized at the ribosome enters thecistern/spaee in the endoplasmic reticulum whichis transported to the Golgi apparatus in transportvesicles. The Golgi apparatus process, modify andpackage the enzymes into vesicles and are secretedfromthe cell.

(d) This is a substitute mutation where the aminoacid valine replaces glutamic acid. The aminoacid sequence in the polypeptide is altered. Thischanges the structure ofthe protein which loses itsoriginal function.

Section B6 (a) (t P: Autotrophic

Q: Heterotrophic(ii) Similarity

Both contain anaerobic bacteria andprotnzna in their alimentary' canal fordigestion of cellulose.Dififerenees

Q has a very large caecum compared to R.- Q has one stomach and R has four

stomaches; rumen, reticulum, omasumand abomasums.

- R has a diastema to store cut cellulosebefore chewing by the molar.R has a hard upper palate to help in thecutting ofcellulose.

(b) Constipa.tion- Insufficient fibre in the diet- Eat more vegetables and fruitsAnaemia- Insufficientiron/ferum- Eat more red meat, liver, spinach and efgsNightblindness- Insu{ficientvitaminA

Eat more liver and egg yolks

) Z (a) Plasma membrane consists of a bilayer ofphospholipid with globular proteins interspersedin it. The phospholipid layer and able to movetherefore it exhibits fluidity.

(b) (t Substance R is water molecules. Water.molecules can difftrse through a plasmamembrane because the size of the watermolecules are small.

(ii) Substance S is sofium ions/calcium ions. Thetransport of sodium ions is active transportwhere there is movement of molecules orions from a region of lower concentration toa higher concentration across the plasmamembrane with the use of cellular energ:y.However the movement of substance R doesnot require enerry and it is called osmosis.The process of osmosis ddes not requireenerg:y as water molecules move across asemi-permeable membrane according to itsconcentration gradient.

Section C8 (a) Sunlight is absorbed by chlorophyll to break up

water to provide H atom and form AIP which areused to reduce CO, to form starch.

@) During light reaction, chlorophyll captures lightenerg'y which excites the electrons of chlorophyllmolecules to higher energ'y level. In the excitedstate, the electrons can leave the chlorophyll

' molecules. Light energy is used to split HrOmolecules into hydrogen ions (H*) and hydroxylions (OH-). The OH- from photolysis of watercombine to form water and orygen gas. Duringthe dark reaction, the hydrogen atoms are usedto fix CO, in a series of reactions catalysed byenzymes. The overall reaction results in thereduction of CO, into glucose. The glucosemonomers undergo condensation to form starch.

(c) Incomplete combustion of fossil fuels producestiny carbon particles which form smoke, hazeand smog. Smoke and haze r"educe lightintensity. Smoke particles can also deposit onleaves and prevent gaseous exchange. Both canlower the rate ofphotosynthesis.

9 (a) lO% of interstitial fluid enters ly.mphaticcapillaries to form lymph, and flows into biggervessels called lymphatic vessels which conaectthe right lymphatic duct and the thoracic duct.Both push their contents into the right and leftsubclavian vein and return the fluids into the bloodcirculatory system via the lymphatic systems.

Fatty acids and glycerol diffirse into thelacteal in the small intestine. It is transported tothe thoracic duct, left subclavian vein andjoins theblood circulatory system.

(b) Respiration- Gaseous exchange takes plaee by diffr.rsion

across the thin plasma membrane.- Has a relatively large surface area compared to

the volume.- Simple diffirsion is sufficient to transport the

gases into, around and out oftheir bodies.- Oxygen diffuses into the cell and carbon dioxide

diffirses out of the cell due to concentrationgradients.

Nutrition j

- Amoeba engulfs microorganisms such as. bacteria by carrying out phagocytosis.

- Protrusions of the cyrtoplasm forms pseudopodiawhich surround thd inuscles which is broughtby food vacuole.Enzlrmes are secreted into it and digestionoccurs.

Excretion- Undigested food or waste products are excreted

by exocytosis.- The vacuole fuses with the plasma membrane.- Its contents are then excreted when the

membrane burst open to the exterior.

Paper 3

1 (a) (t 1. The higher the percentage concentrationof albumen suspension, the more time