Spm Biology 2006 K2

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 (a) (i) On Diagram 1, label the structures p,

e, R and S.

[4 ntarksl

(ii) State the function of structure:

P:

Q:

12marl-(b) Explain the role of R to maintain cell turgidity.

\./

[2marks]

r37

(c) Every somatic cell which contains structure e has a potential to form a complete new organism. (i) Name the techniqueusedto prodi.rce new plants in large quantities.

IImarkl (ii) By using onesuitable part of the plant, explain the techniquein (cxi).

[4marksl 2

(a) Diagram 2.1 showshumandigestive system.

Duodenum

Diagrarn 2.1 structure Q in Diagram2.Lis involved in the digestionoffat. (i) Name structure Q.

[lmarkl

139

(ii) Name the enzlrmewhich digestsfat in e. ILmarhl (iii) Diagra m2.2showsa mechanismof an enzyme reaction. Dray the diagram in the spacesIII and fV provided in Diagram 2.2 to complete the mechanismof the enzJrmereaction.

n

B I

+

fl III

rv

V

Diagram2.2

12marks) (b) (i) Explain how starch is digestedin the duodenum.

[2marksf (ii) Astudent eats too many oranges. Explain the effect of eatfng too many oranges on the digestion of starch in thY duodenum

12m,arksl

t4l

(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 meat with strips ofunripe papaya

Diagram 2.9 Explain why the housewifecaries out Step 1 and Step 2.

14marksl I

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

I I I

I .l

x ---!

(a) (i) NamestructureX.

lLmarkl (ii) State the function ofX.

ILm.arkl

r43

(b) (i) Why is Y swollenat the dorsal root?

ILmarkT (ii) Complete Diagram 3.1 with the neurones involved in a reflex action. Mark the direction ofthe impulse movementon the neurones. [2 marksj (c) compare two structures of a sensoryneuroneand a motor neurone. 1.

2.

12marh^l (d) If the spinal nenreis cut offat Z,whatis the effecton the organwhich is connectedto it? -Explainyonr answer. .

12m.arksl (e) Ali's finger accidentlytouchesa flame. Explain brieflyhow his reflex action functions to avoid the injury.

13marksl

t45

4

Diagam 4 showsa longitudinal sectionof the reproductiveparts of a flower during fertilization.

Diagrarn 4 (a) On Diagram 4, name the structures p, R and S. e, (b) (t

V*ornf,

In the spacebelow,draw a seition through the ovule, showingall the cells in S. Label the cells involved in fertilization.

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

IZ marks] (c) In Diagram 4, thestructure Y has to be kept dormant for future researphpurposes.

(t

Explain howY can be preventedfrom germinating.

12marksl 147

(ii) If Yis tobe germinated,suggestone methodto stimulate the germination

of y. ILmark]

Diagram 5'1 showsa sequenceof stagesin the synthesis of an extracellular eRzJrme in a human pancreatic cell' The stages are labelled as Staie r, Stage rr and Stage rrl. Stage I shows a change in the specific part of a DNA stran*d. trre,n-Ng strand in=volvedcontains three nitrogenousbases,CTC.

-stase;"",)

7GX (:"r,",ffilTft'"[#

\

,\

ucreus cteusg, g] .

\

FiT \

,r\

,//

into the cytopla"

u1

ProteinKw"pt* ;"";; Kv-',,t;a,

Y

beingsynthesised

I

\ **\f ^io"r",J*,"

Diagram

,/

*o*"y/ 5.1

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

12rnarksl (b) Basedon Diagram 5.1: (i) state two differencesbetweenthe structure ofthe protein polypeptide morecureand the rvrr'.vv DNAmolecule. 1.

2.

[2rnarks] 149

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

[lrnark] (c) Explain how the protein formed at the ribosome is transformed into the extracellular enzyme so that it can be secreted from the cell.

tSrnarkq_, (d) Diagram 5.2 shows a gene mutation that occurs in the DNA strand containing the base sequenceCTC. Before mutation

DNAstrand

rtl

Aftermutation

trr l

C TC

AC

,l

+ o I

o

Glu tamic acid

Valine

Synthesized protein

Diagram 8.2 Explain how the mutation affects the specific characteristicor trait controlled.

13marksl 151

Section B 120marksl Answer any one question. Diagram 6 showsthree organisms,p, e and R.

-<<4-

il

u

F -";t$o*"P

R Diagram 6

(a) (i) Describethe type of nutrition in pand e.

14marksl

(ii1 Explain one similarity and four differencesbetween the alimentary canal of e and R. ILOmarks) (b) constipation, night blindness and anaemia are three health problems. State the causeand suggestthe ways to overcomethese health problems from nutritional asPects. [6 marks) (a) Plasma membrane encircles the protoplasm of a cell. As a whole plasma membrane exhibits 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 experimentis carried out using substanceR outside a cell. The aim of the experiment is to study the effect of different concentrations of substance R on the rate of its movementacrossthe plasma membraneinto the cell.

153

Graph 7.1 showsthe result of the experiment. Rate of movement of substance R / mg s-1

Concentration of substance R/ unit

Graph 7.1 Based on Graph 7.1, state an example of substanceR and explain how substuo"" *movesacrossthe plasma membrane. 16m,arksl

155

(ii) The experiment is repeatedby replacing substance R with substances. Graph 7.2showsthe result obtained. Rate of movement of substanceS / mg s-r

Concentration of substance S / unit

Graf 7.2 Based on Graph 7.1 and Gr apn 7 .2,compare and explain the movement of substancil R and 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 chemical process of photosynthesis can be summarised as in the schematic diagram in Diagram 8. Hidroxyl ion Water + Oxygen

Lightt"r.rr""I Water molecule

Chlorophyll rrrolecule ------+

Electron

Hydrogen

Dark reaction

stored

Glucose +Water

(CHrO)n

Carbon dioxide

[-

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 plad produces 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 reentered 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 the blood circulatory system. ILOmarksl 159

Multicellular organisms like humans, need specific transport systems as compared to unicellular organisms likeAm oeba sp.,which do not ""J;1;;;"";;;;;-*. Give an evaluation of the above statement based on the physical features of the organisrns with the following physiological processes:

Respiration Nutrition Excretion [L0 marks]

t6l

Conclusion: Isotonic solution will maintain the mass and the length of plant tissues and this is yo/oof sucrosesolution.

3

(a) (, Spinal cord (ir) Control reflex actions and connect the brain to the peripheral nervous system. Congregation of cell bodies of afferent neurones to form a ganglion.

o) ( ' SPM D(AMINATION

Paper I lC 2C 7B 8A 13A 14 D 19D 20 C 25 D 26 B 31D 32 A 37 B 38C 43D 44 D 49 C 508 Paper 2 Section A (a) (r) 1

PAPER 2006

(ir) tl

3C 4A 9C 10D 15c16At7A18B 2r B 22 B 27 C 28 A 33B 34 A 39A 40 B 45 D 46 D

5A 1lA

68 12 C

23 C 29 A 35D 4r D 47 A

24 B 30A 868 42D 48 C Sensory neurone

(c)

a

s

(d)

a

o) (c)

2

1. Cellbcdylocated outside the spinal cord.

1. Cellbodylocated inside the spinal cord.

2. Has a long dendron and a short axon.

2. Has a short dendron and a long axon.

P

chloroplast nucleus R vacuole Golgi apparatus (ir) P Contains chlorophyll whieh absorbs sunlight for photosynthesis. Contains genetic material in the form of chromosomes which control the activities ofthe cells. The vacuole pushes the cytoplasm and pressesthe plasma membrane against the cell wall. (l) fissueculture/cloning (ii) - Tissuesectionsareobtainedfromtheroot. - Tissues are cultured in suitable nutrient mediums 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.

(e)

4

Motorneurone

Nerve impulses cannot be transmitted from the spinal cord to the effectors and the organ will not respond. Pain receptors in the skin ofthe fingers detect stimulus - Nerve impulses are transmitted from receptors to spinal cord via sensory neurone which transmits impulses to the efferent/motor nenrone via interneurone and then to muscles in the organ which contracts and pulls hand awayfromflame.

(a) P:

pollen tube

R: ovary (b) (r)

(a) (D Small intestine/ileum (ii) Lipase (iir)

Q : male gametes S : embryo sacs

Polar nucleus

Eggcell/ovum

m (b) (t

ry

Pancreassecretespancreaticjuiceintothe duodenum. juice - Pancieatic contains amylase which hydrolyses undigested starch into maltose. (il) - Oranges contain ascorbic acid and will lower the pH in the duodenum from an optimum of pH 3. - fhis will slow down the digestion of stareh which requires an optimum pH of 7.t -8.2. (c) - Step 1 is to provide enzyme protease to digest the meat in order to tenderize the meat. - Step 2 is to provide the optimum temperature for enzyme action and to allow enough time for enzyme reaction.

(ri) -

-

(c)

(r) (ii)

(a)

*

One male gamete fuses with the egg cell. Another male gamete fuses with the two polarnucleus. - Double fertfisation occurs. Place in dry/cool plabe which is air tight Place in sugar solution

The double helix of the DNAstrand unzips. The DNA code is copied/transcribed into a strandof mRNA. (b) (t 1. DNA is double stranded whereas polypeptide is single stranddd 2. DNA is made up of repeating units of phosphate, sugar and nitrogenous bases (nucleotides) whereas polypeptide is

ffff

"r

of 20 differenttype of amino Section C 8

(a) Sunlight is absorbed by chlorophyll to break up water to provide H atom and form AIP which are used to reduce CO, to form starch. @) During light reaction, chlorophyll captures light energ'y which excites the electrons of chlorophyll molecules to higher energ'y level. In the excited state, the electrons can leave the chlorophyll ' molecules. Light energy is used to split HrO molecules into hydrogen ions (H*) and hydroxyl ions (OH-). The OH- from photolysis of water combine to form water and orygen gas. During the dark reaction, the hydrogen atoms are used to fix CO, in a series of reactions catalysed by enzymes. The overall reaction results in the reduction of CO, into glucose. The glucose monomers undergo condensation to form starch. (c) Incomplete combustion of fossil fuels produces tiny carbon particles which form smoke, haze and smog. Smoke and haze r"educe light intensity. Smoke particles can also deposit on leaves and prevent gaseous exchange. Both can lower the rate ofphotosynthesis.

9

(a)

(ii) DNA molecules consists of 2 polynucleotide strands whereas RNAconsists of a single stranded nucleotide. (c) Proteins synthesized at the ribosome enters the cistern/spaee in the endoplasmic reticulum which is transported to the Golgi apparatus in transport vesicles. The Golgi apparatus process,modify and package the enzymes into vesicles and are secreted fromthe cell. (d) This is a substitute mutation where the amino acid valine replaces glutamic acid. The amino acid sequence in the polypeptide is altered. This changes the structure ofthe protein which loses its original function. Section B (a) (t 6

P: Autotrophic Q: Heterotrophic (ii) Similarity and Both contain anaerobic bacteria protnzna in their alimentary' canal for digestion of cellulose. Dififerenees Q has a very large caecumcompared to R. - Q has one stomach and R has four stomaches; rumen, reticulum, omasum and abomasums. - R has a diastema to store cut cellulose before chewing by the molar. R has a hard upper palate to help in the cutting ofcellulose. (b) Constipa.tion - Insufficient fibre in the diet - Eat more vegetables and fruits Anaemia - Insufficientiron/ferum - Eat more red meat, liver, spinach and efgs Nightblindness - Insu{ficientvitaminA Eat more liver and egg yolks

) Z

(a) Plasma membrane consists of a bilayer of phospholipid with globular proteins interspersed in it. The phospholipid layer and able to move therefore it exhibits fluidity. (b) (t Substance R is water molecules. Water. molecules can difftrse through a plasma membrane because the size of the water moleculesare small. (ii) Substance S is sofium ions/calcium ions. The transport of sodium ions is active transport where there is movement of molecules or ions from a region of lower concentration to a higher concentration across the plasma membrane with the use of cellular energ:y. However the movement of substance R does not require enerry and it is called osmosis. The process of osmosis ddes not require energ:y as water molecules move across a semi-permeable membrane according to its concentration gradient.

lO% of interstitial fluid enters ly.mphatic capillaries to form lymph, and flows into bigger vessels called lymphatic vessels which conaect the right lymphatic duct and the thoracic duct. Both push their contents into the right and left subclavian vein and return the fluids into the blood circulatory system via the lymphatic systems. Fatty acids and glycerol diffirse into the lacteal in the small intestine. It is transported to the thoracic duct, left subclavian vein andjoins the blood 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 gasesinto, around and out oftheir bodies. - Oxygen diffuses into the cell and carbon dioxide diffirses out of the cell due to concentration gradients. j Nutrition - Amoeba engulfs microorganisms such as . bacteria by carrying out phagocytosis. - Protrusions of the cyrtoplasmforms pseudopodia which surround thd inuscles which is brought by food vacuole. Enzlrmes are secreted into it and digestion occurs. 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 concentration of albumen suspension, the more time