[edu.joshuatly.com] pahang stpm 2012 biology [1ac4debf]

7/29/2019 [Edu.joshuatly.com] Pahang STPM 2012 Biology [1AC4DEBF]

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This question paper is CONFIDENTIAL until the examination is over. CONFIDENTIAL*

BIOLOGYPAPER 1

One hour and forty five minutes

Instructions to candidates:

DO NOT OPEN THE BOOKLET UNTIL YOU ARE TOLD TO DO SO

There are fifty questions in this paper. For each question, four suggested answers are given.

Choose one correct answer and indicate it on the multiple-choice answer sheet provided.

Read the instructions on the multiple-choice answer sheet carefully.

Answerall questions. Marks will not be deducted for wrong answers.

________________________________________________________________________This question paper consists of 22 printed pages.

PEPERIKSAAN PERCUBAAN

SIJIL TINGGI PERSEKOLAHAN MALAYSIA

NEGERI PAHANG DARUL MAKMUR

2012

Percubaan Pahang STPM 2012http://edu.joshuatly.com/http://fb.me/edu.joshuatly


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1. The diagram below shows a pentose sugar molecule which can be found in DNA.

Which of the following is true about the pentose sugar?

A The sugar is ribose.

B X represents a hydroxyl group.

C X represents a hydrogen atom.

D The sugar is fructose.

2. Which of the following are characteristics of lipid?

I Insoluble in water

II Soluble in non polar solvents

III Combine with fatty acids to form esters

A I and II only

B I and III only

C II and III only

D I, II and III

3. Which of the following is the most important function of epithelium tissue?

A Secretion

B Protection

C Absorption

D Transportation



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4. Which statements about a non competitive inhibitor are true?

I Its molecular shape is the same as that of a substrate.

II It binds to sites other than active sites.

III Its effect is not influenced by increases in substrate concentration

IV Vmax is constant

V Km varies

A II and III only

B I, IV and V only

C II, III and IV only

D II, III, IV and V only

5. Which statement best explains why enzymes are specific in their action?

A Enzymes have polypeptide chains.

B Enzymes have large fibrous protein.

C Enzymes are not changed or consumed during reaction.

D Enzymes have specific surface configuration.

6. Which of the following statements is not true the genetic code?

A Genetic code is a triplet.

B Genetic code is specific.

C Genetic code AUG is the termination codon

D Genetic code AUG is the code for amino acid methionine



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7. Which of the following about cyclic photophosphorylation and non-cyclic

phototophosphorylation is correct?

Cyclic Non-cyclic Cyclic and non cyclic

photophosphorylation photophosphorylation photophosphorylation

A Oxygen is produced ATP is produced NADPH is not formed

B NADPH is not formed Oxygen is produced ATP is produced

C ATP is produced Oxygen is produced NADPH is not formed

D NADPH is not formed ATP is produced Oxygen is produced

8. Which of these are the pathways involved in the photosynthesis of C4plants ?

I Krebs cycle

II Calvin cycle

III Glycolysis pathway

IV Hatch-Slack pathway

A I and III

B II and IV

C I, II and III

D I, III and IV



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9. The following reaction happens in all aerobic cells.

OH

C=O S-CoA

C=O C=O

CH3 CH3

Pyruvate Acetyl coenzyme A

Which of the following statements are true about the above reaction?

I The reaction happens in cell cytoplasm

II Oxygen is needed for the above reaction.

III 2 H+ are released and received by NAD.

IV ATP energy is used in the above reaction.

V Carbon dioxide is released during the reaction.

A I and III

B II and V

C III and V

D I, II and IV

10. Which of the following reaction in glycolysis is catalysed by phosphofructokinase?

A Fructose 1,6-diphosphate to fructose

B Glucose 6-phosphate to fructose 6-phosphate

C Fructose 6-phosphate to fructose 1,6-diphosphate

D Fructose 1,6-diphosphate to two triose phosphate



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11. The diagram below shows the Krebs cycle. What is process X?

A Phosphorylation

B Oxidation of GTP

C Oxidative phosphorylation

D Substrate level phosphorylation

12. Which of the following are saprophytic organisms?

I Yeast

II Mushroom

III Rhizobium bacteria inside root nodules

A I and II

B I and III

C II and III

D I, II and III

ADP

ATP

GDP

GTP

Krebs

cycleX

Acetyl coenzyme A



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13. The diagram below shows the diffusion of carbon dioxide from respiring cells into the

blood involving steps P, Q, R and S.

Which step shows the formation of haemoglobinic acid?

A P

B Q

C R

D S

14. Which process does not occur during the opening of stomata?

A Sugar is converted into starch.

B Starch is converted into malic acid.

C Water enters osmotically into the guard cells.

D Potassium ions diffuse into the guard cells from the adjacent cells.



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15. What is the volume of air that can be forced out following the deepest possible

inspiration?

A tidal volume

B vital capacity

C residue volume

D expiratory reserve volume

16. The following structures are found in the heart:

I Bundle of His

II Purkinje tissue

III Atrioventricular node

IV Sinoatrial node

Which of the following shows the correct sequence for impulse conduction in the heart?

A III, IV, I, II

B IV, III, I, II

C III, IV, II, I

D IV, III, II, I

17. In a study of the movement of substances in plants, aphids were used. The study showed

that

A translocation occurred in two ways.

B translocation occurred electro-osmotically.

C the phloem was responsible for the transportation of organic substances.

D the xylem was responsible for the transportation of water and minerals.



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18. When diabetics inject themselves with insulin, which event will occur in the liver?

A an increase in the synthesis of lipid and polysaccharide molecules

B a decrease in the permeability of the cells to glucose

C a decrease in the rate of uptake of amino acids and protein synthesis

D an increase in the breakdown of glycogen

19. The table below shows the substances that diffuse out via passive or active transportation

from the nephron and the part of the nephron where it occurs.

Nephron part Substance(s) that dif fuse out

I Proximal convoluted tubule

II Descending loop of Henle

III Ascending loop of Henle

IV Distal convoluted tubule

(a)Sodium chloride

(b)Glucose, sodium chloride, water

(c)Sodium ion, hydrogen carbonate ion, water

(d)Water

Which of the following are correctly paired?

I II III IV

A (b) (d) (a) (c)

B (b) (d) (c) (a)

C (c) (a) (d) (b)

D (c) (d) (a) (b)

20. The drug curare acts by

A blocking the action of acetylcholine

B increasing the secretion of acetylcholine

C activating the action of acetylcholinesterase

D inhibiting the action of acetylcholinesterase



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21. The table below shows some parts of the neuron and their functions.

Part of neuron Function

I Synaptic knob

II Cell body

III Schwann cells

IV Axon

V Dendrites

(a)To receive information from the receptor

(b)To transmit the information received

(c)To transmit the information to a target organ

(d)To coordinate all metabolic activities of cells

(e)To wrap the axon and dendron

Which of the following is correct for the parts of the neuron and their functions?

I II III IV V

A (c) (a) (d) (e) (b)

B (c) (d) (e) (b) (a)

C (e) (a) (d) (b) (c)

D (d) (b) (e) (c) (a)

22. Where are the receptor sites for neurotransmitters situated?

A nodes of Ranvier

B postsynaptic membrane

C presynaptic membrane

D membranes of the synaptic vesicles



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23. Which of the following distinguish between the two mechanisms of hormonal actions?

Gene activation Activation of cyclic AMP system

A The effects last longer The effects last shorter

B For non-steroid hormones For steroid hormones

C Involves a second messenger Does not involve a second messenger

D Hormones do not enter the cells Hormones enter the cells

24. The table shows four hormones and their physiological effects.

Hormone Physiological eff ect

I Aldosterone

II Insulin

III Thyroxine

IV Glucagon

(a)To control the metabolic rate

(b)To maintain the balance of Na+ and K+ ions

(c)To decrease the glucose level in the blood

(d)To increase the glucose level in the blood

Which of the following is correct for the hormones and their physiological effects?

I II III IV

A (a) (d) (c) (b)

B (b) (c) (a) (d)

C (c) (d) (b) (a)

D (d) (c) (a) (b)

25. Which of the following hormones is incorrectly paired with its action?

A progesterone stimulates follicles to develop

B GnRH control the release of FSH and LH

C oestrogen responsible for primary and secondary female sex characteristics

D human chorion gonadotrophin maintains secretions from the corpus luteum



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26. Which of the following enables HIV to act dormantly in the human body?

A The virus rests in the cytoplasm of T4 cell.

B The viral DNA integrates into the DNA of T4 cell.

C The viral RNA takes some time to replicate.

D The viral reverse transcriptase is engulfed by T4 cell.

27. Which of these statements is true about the reproduction difference between Cnidaria and

Coniferophyta?

A Cnidaria is bisexual.

B Coniferophyta needs water for bisexual reproduction.

C Coniferophyta produces spores in dry environment.

D The movement of the male gametes in Cnidaria happens as a chemotaxis.

28. Which of the following is true of an oviparous animal?

A An individual hatches from the egg outside the female parents body

B An individual hatches from the egg in the uterus of the female parent

C An individual is born before maturity and continues to develop in the sac of the

female parent

D An individual develop in the uterus of the female parent and the embryo obtains the

nutrient from the placenta.



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29. The table below shows three organs and the germinal layers that form them.

Organs Germinal layer

I Spinal cord

II Kidney

III Liver

(a) Endoderm

(b) Mesoderm

(c) Ectoderm

Which of the following is the correct match for the above three organs and germinal

layers that form them?

I II III

A (a) (c) (b)

B (b) (a) (c)

C (b) (c) (a)

D (c) (b) (a)

30. Which of the following parameters is plotted to obtain a relative growth rate curve of a

plant?

A The height against time

B Absolute rate of growth against time

C The growth rate against time

D The height against the growth rate



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31. A typical sigmoid growth curve is shown below.

Which of the following are represented by P, Q, Rand S?

P Q R S

A Lag phase Log phase Linear phase Plateau phase

B Lag phase Linear phase Log phase Plateau phase

C Plateau phase Log phase Linear phase Lag phase

D Plateau phase Linear phase Log phase Lag phase

32. In a species of flowering plant, CRCRgenotypes produces red flowers, CW CW genotype

produce white flowers and CRCW genotype produces pink flowers. What is the percentage

of the progeny that have pink flowers if a cross is made between CRCW and CRCW?

A 0 %

B 25 %

C 50 %

D 75 %



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33. White eye colour in fruit fly is inherited as sex-linked recessive. What are the results

obtained if a white-eyed female fruit fly is crossed with a red eye male fruit fly?

A All males and female have red eye.

B 50% males have white eyes, 50% male have red eyes and all female have have red

eyes.

C 50% males have white eyes, 50% male have red eyes, 50% female have have white

eyes and 50% female have have red eyes.

D All males have white eyes and all females have red eyes.

34. Which of the following mutations is human is / are trisomic?

I Down syndrome

II Turner syndrome

III Thallasemia major

IV Klinefelter syndrome

A I only

B I, II and III only

C I and IV only

D II and III only

35. Cystic fibrosis is a recessive condition that affects about 1 in 2 500 babies in the

Caucasian population in the United States. Calculate the percentage of individuals who are

carriers in the population.

A 4 %

B 98 %

C 2 %

D 40 %



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36. In a population that is in Hardy-Weinberg equilibrium , 16 % of the individual show the

recessive trait. What is the frequency of the dominant allele in the population?

A 0.84

B 0.36

C 0.6

D 0.4

37. A condition of the lac operon is shown in the diagram below.

Which statement is true of the lac operon?

A The operon is switched on

B Glucose is present

C -galactosidase is produced

D Transcription of the structural genes occurs.



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38. Which of the following are the characteristics of cloning vectors?

I They are able to accept foreign DNA.

II They can replicate freely in their host cells.

III They harm their host cells.

IV They are able to express the cloned gene.

A I and III

B II and IV

C I, II and III

D I, II and IV

39. The transgenic plant is different from the wild type of plant because

A It is tetraploid

B It is formed by interbreeding of two different plants.

C It contains a foreign gene in their genomes.

D It contains cDNA.

40. Which of the following statements is/are true of an artificial classification system?

I The system is based on phylogenetic relationship

II The system can be used to construct dichotomous keys

III Organisms are placed into groups for specific purposes

IV Organisms are placed into groups according to their different characteristicss

which are arbitrarily chosen

A I only

B I and II only

C II, III and IV only

D III and IV only



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41. Which of the following is likely to be radially symmetrical?

A An annelid

B An arthropod

C A chordate

D A platyhelminth

42. The table below shows four phyla and their examples.

Phylum Example

I Fungi

II Bryophyta

III Filicinophyta

IV Angiospermophyta

(a)Helianthus

(b)Dryopteris(c)Marchantia(d)Mucor

Which of the following is correct for the phyla and their respective example?

I II III IV

A (a) (b) (c) (d)

B (c) (d) (a) (b)

C (d) (a) (b) (c)

D (d) (c) (b) (a)

43. Which of the following would cause phenotypic variation among organisms of the same

genotype?

A Mutation

B Exposure to different environments

C Continuous variation within the species

D Different varieties of the same species



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44. Which processes result in the greatest amount of genetic variation in a population?

A Natural selection and meiosis

B Meiosis and mutation

C Mutation and mitosis

D Mitosis and natural selection

45. According to Darwins theory of evolution, what causes the struggle for survival in

populations?

A Overproduction of offspring

B Favourable heritable variations

C Natural selection

D Competition between the fittest individuals in the population



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46. The graph below shows the effects of three types of ecological selection.

Which of the following is correct regardingBiston betularia in industrial areas, human

birth weight in developed countries and rabbit population in the Andes mountain?

Biston betularia Human birth weight Rabbit population

in industrial areas in developed countries in Andes mountain

A R P Q

B Q R P

C Q P R

D R Q P

47. Which of the following energy flows in an ecosystem involves the transfer of the greatest

amount of energy?

A Plant to herbivore

B Plant to decomposer

C Herbivore to carnivore

D Carnivore to decomposer



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48. Which of the following are true of an ecosystem?

I Phytoplankton are producers.

II The last consumer obtains the highest energy

III Ecosystem is an open system with input and output of energies.

IV Heterotroph include herbivores, carnivores, decomposers and detritivores

A I and II

B III and IV

C I, III and IV

D II, III and IV

49. Carrying capacity of a population is

A the number of individuals in a population

B the population size when the mortality rate is more than the natality rate

C population size when the natality rate is more than the mortality rate

D the population size of species which can be supported by resources available in a

habitat



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50. In an experiment, a 25cm x 25cm quadrate was used to determine the density of the plant

Mimosa pudica in the area R and S. The results of the experiment were as below.

Quadrat 1 2 3 4 5 6 7 8 9 10

Number of plants in R 5 10 9 0 7 6 5 9 0 9

Number of plants in S 3 4 3 2 1 0 4 1 2 0

What is the density of the plantMimosa pudica per square meter in R and S?

R S

A 40 16

B 60 20

C 96 32

D 120 40



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964/2*This questions paper is CONFIDENTIAL until the examination is over. . CONFIDENTIAL*

PEPERIKSAAN PERCUBAAN

SIJIL TINGGI PERSEKOLAHAN MALAYSIA

NEGERI PAHANG DARUL MAKMUR

2012

BIOLOGY

PAPER 2

Two and a half hours

Instructions to candidates

DO NOT OPEN THIS QUESTION PAPER

UNTIL YOU ARE TOLD TO DO SO

Answer all questions in section A. Write your answer

in the spaces provided.

Answer any four questions in section B. Begin each

answer on a fresh sheet of paper and arrange your

answers in numerical order.

Tie your answer sheets to this question paper.

Answers should be illustrated by large and clearlylabelled diagrams wherever suitable.

For examiners useSection A

1

2

3

4

Section B

Total

964/2 [Turn over

* This question paper is confidential until the examination is over. CONFIDENTIAL*



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Section A [ 40 marks ]

Answeral lquestions in this section.

1 The diagram shows cells taken from the stem of a plant. Cells A , B and C

are adjacent cells and the figures indicate the water potential of each cell.

(a) (i) Draw arrows on the diagram to show the overall direction of water

movement between these three cells. [ 1 mark]

(ii) Explain your answer in terms of water potential. [ 2 marks ]

.



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(b) The diagram below shows two plant cells, X and Y as seen through a

microscope.The figures show the solute potential s and the pressure

potential p for both cells and the water potential for cell Y

(i) Calculate the water potential, , of cell X .Show your working. [ 1 mark]

.........

..................................................................

(ii) State the name of the condition shown by cell Y and explain how thiscondition could have arisen. [ 3 marks ]

.

(c) Cell X has the higher pressure potential p. Explain how this pressurepotential is built up in cell X. [ 3 marks ]

.



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2 Figure 2.1 outlines anaerobic respiration in yeast cells.

Fig. 2.1

(a) Complete Fig. 2.1 by writing in the missing compounds. [ 4 marks ]

(b) Describe how anaerobic respiration in mammalian cells differs fromanaerobic respiration in yeast cells [ 3 marks ]

(c) Explain why anaerobic respiration results in a small yield of ATP comparedwith aerobic respiration . [ 3 marks ]



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3 The diagram below represents transverse sections through three differentanimal phyla, A ,B and C

(a) Identify the body layers 1,2 and 3. [ 3 marks ]

1 :.2 :

3 :

(b) identify which of the transverse sections (A , B or C ) represents a memberof the phylum Platyhelminthes. Give one reason for your decision.

[ 2 marks ]

Section : .

Reason:

(c) Which section ( A ,B or C) represents a phylum that shows radialsymmetry? [ 1 mark]

.

(d) Which section ( A, B or C) represents a phylum in which chaetae would bepresent ? [ 1 mark]



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(e) Describe three features found in members of the phylum Annelida whichare not found in Hydra. [ 3 marks ]

..

..

..

..

..



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4 The diagram below shows energy flow measured during a study of a

grassland ecosystem. The values shown are kJm-2 year-1 104. Values ofenergy lost through respiration (R) and other means (L) are shown for

some organisms. The biomass of the organisms in the ecosystemremained uncharged during the study.

(a) Calculate the gross primary productivity (GPP) for the grasses in thissystem . Show your working. [ 2 marks ]

..

(b) Describe how this figure could be used to calculate the net primaryproductivity (NPP) of the grasses. [ 1 mark]

...



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(c) Calculate the percentage of the energy taken in by the grasshoppers thatis converted into new grasshopper biomass. Show your working.

[ 3 marks ]

(d) Give two ways in which energy is lost by the grasshoppers other than inrespiration. [ 2 marks ]

(e) Use your calculated figures from parts (a) and (c) to explain why foodchains are of limited length. [ 2 marks ]



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Section B [ 60 marks ]

Answer anyfourquestions in this section.

5 (a) Draw and label a simplified diagram to show how DNA is constructedfrom sugars ,phosphates and bases. [ 6 marks ]

(b) Explain why DNA must be replicated before mitosis and the role ofhelicase in DNA replication. [ 4 marks ]

(c) Explain how the base sequences of DNA is conserved during replication.

[ 5 marks]

6 (a) The leaves of plants are adapted to absorb light for photosynthesis.

Draw a labelled diagram to show the arrangement of tissues in a leaf.[6 marks ]

(b) Explain the reaction involving the use of light energy that occurs in thethylakoids of the chloroplast. [ 9 marks ]

7 (a) Outline one example of inheritance involving multiple alleles. [ 6 marks ]

(b) Using an example you have studied, explain a cross between two linkedgenes , including the way in which recombinants are produced.

[ 9 marks ]

8 (a) Draw and label a diagram showing the structure of a glomerulus and anassociated nephron. [ 6 marks ]

(b) Explain how water balance is maintained in the blood. [ 9 marks ]

9 (a) Compare the roles of the endocrine and nervous systems in control andcoordination in animals. [ 8 marks ]

(b) Describe the part played by auxins in apical dominance in a plant shoot.

[ 7 marks ]



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10(a) Explain the role of isolating mechanisms in the evolution of newspecies. [ 8 marks ]

(b) Describe and explain, using an example , the process of artificialselection. [ 7 marks ]



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ANSWER SCHEME FOR STPM TRIAL EXAM , BIOLOGY 2012

NO. ANSWER NO. ANSWER

1 C 26 B

2 A 27 C

3 B 28 A

4 A 29 D

5 D 30 B

6 C 31 A

7 B 32 C

8 B 33 D

9 B 34 C

10 C 35 A

11 D 36 C

12 A 37 B

13 D 38 D

14 A 39 C

15 B 40 D

16 B 41 C

17 C 42 D

18 A 43 C

19 A 44 B

20 A 45 C

21 B 46 A

22 B 47 B

23 A 48 C

24 B 49 D

25 A 50 C



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MARKING SCHEME PERCUBAAN STPM 2012

BIOLOGY KERTAS 2

NEGERI PAHANG

No Answer Mark.1(a)(i) C to B to A 1

(a)(ii) Water moves down a water potential gradient / high to low ;

By osmosis

1

1

(b)(i) = 1000-1800= -800kPa

1

(b)(ii) Plasmolysed;

Cell in concentrated solution / low water potential ;

Water diffuses out;

Cytoplasm / vacuole shrinks.(not : cell membrane comes awayfrom wall )

1

max=2

(c) Water diffuses into cell by osmosis;

Cytoplasm expands ;

Cell become turgid;

As cytoplasm / contents push against wall;

Wall inelastic/ resists further expansion .(not : rigid) Max=3



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No Answer Mark.

22corrects= 1

3corrects= 2

4corrects=3

allcorrects

= 4

b In mammals:

Lactate produced / no ethanol produced;

No decarboxylation / carbon dioxide released;

Single step;

Lactate dehydrogenase;

reversible

Max=3

c In anaerobic respiration

Only glycolysis occurs/ krebs cycle stops/link reaction

stops;glucose , not fully broken down/ still contain energy;

pyruvate does not enter mitochondrion;

(no oxygen) so no final eletron acceptor ( in ETC);

ETC stops;

No oxidative phosphorylation

Max=3

3 (a) 1= ectoderm2= endoterm3= mesoterm

111

(b) B;Triploblastic organism with no coelom(acoelomate).[ both termsrequired]

11

(c) A 1

(d) C 1



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No Answer Mark.

(e) Annelida have three body layers/triploblastic/possess mesoderm;

Possess a coelom;

Body is bilateral symmetrical;

Metamerical segmented;

Through gut/regional specialization;

Other appropriate difference

Any 3Max=3

4(a) 1980+3600+62=5642 ( state units )

2

(b) Subtract respiration / 3600;

Or2042 ( state units )NPP=(GPP-R)/GPP=NPP+R

1

(c) 44.4-(12.5+25.4);6.5 out of 44.4;14.6%

3

(d) Faeces/indigestible material;Reject inedible parts

Nitrogenous waste

1

1

(e) An explanation to include two form:

Small proportion reaches next level/ converse;

Correct use of figures;

Insufficient energy to support another level

1

1

5(a) Labelled phosphate linked to labelled sugar by a single bond;

Labelled base linked to a labelled sugar by a single bond;

Correctly linked base, sugar and phosphate labelled asnucleotide;

Covalent bond(s) labelled between sugar and phosphate/between sugar and base;

At least two nucleotides linked by a single sugar-phosphate bond;

At least two nucleotides linked by base-base bonds;

Hydrogen bonds labelled between bases;

A-T and /or C-G base pairing;

Max =6



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No Answer Mark.

Phosphate and base shown linked to correct carbon atoms onsugar;

5(b) Two genetically identical nuclei/daughter cells formed duringmitosis ( so hereditary information in DNA can be passed on);

Two copies of each chromosome/DNA molecule/chromatidneeded;

Helicase unwinds the DNA /double helix;

To allow the strands to be separated;

Helicase separates the two (complementary) strands of DNA;

By breaking hydrogen bonds between bases;

Max=4

5(c) DNA replication is semi- conservative;

DNA is split into two single/template strands;

Nucleotides are assembled on / attached to each single /template strands;

By complementary base pairing;

Adenine with thymine and cytosine with guanine/A with T and Cwith G;

Strand newly formed on each template strands is identical to othertemplate strand;

DNA polymerase used;

Max=5

6(a) Award 1 mark for each of the following structures,shown in thecorrect relative position and labelled.

Upper epidermis;

Palisade layer/mesophyll;

Spongy layer/mesophyll;

lower epidermis;

xylem ( in a major or minor vein)

phloem ( in a major or minor vein)

collenchyma ( in the midrib);

Max=6



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No Answer Mark.

guard cell;(do not accept stoma/stomata only)

6(b) Chlorophyll/photosystem absorbs light;

Electron raised to higher energy level/photoactivated;

Splitting of water / photolysis replaces electron;

Passing of excited electrons between chlorophyll molecules inphotosystem;

Electron passed from photosystem II ( in thylakoid membrane);

Production of ATP in this way is called photophosphorylation;

Pumping of protons into the thylakoid;

Proton gradient used by ATPase to drive ATP production;

Electron passes to photosystem I at end of carrier chain;

Electron re-excited and emitted by photosystem I;

Electron passed to / used to reduce NADP+;

Cyclic photophosporylation using photosystem I electron carriersand ATPase only;

Max=9

7(a) Multiple alleles means a gene has three or more alleles/ morethan two alleles;

ABO blood groups/other named example of multiple alleles;

ABO gene has three alleles / equivalent for other example;

IA IB and i shown (at some point in the answer) / equivalent forother example;

Accept other notation for alleles if clear.

any two of these alleles are present in an individual;

homozygous and heterozygous genotype with phenotypes (shownsomewhere);

Max=6



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No Answer Mark.

all six genotypes with phenotypes given (shown somewhere);

example / diagram of a cross involving all three alleles

7(b) linked genes occur on the same chromosome / chromatid;

genes (tend to be) inherited together / not separated/do notsegregate independently;

non-Mendelian ratio / not 9:3:3:1 / 1:1:1:1;

real example of two linked genes;

Award[1]for each of the following examples of a cross betweentwo linked genes.

key for alleles involved in the example of a cross;

homozygous parental genotypes and phenotypes shown;

genotype and phenotype shown / double heterozygote genotypeand phenotype; 1 F

possible genotypes and phenotypes shown; 2 F

recombinants identified;

recombinants due to crossing over;

in prophase I of meiosis;

diagram / explanation of mutual exchange of parts of chromatidsduring crossing over;

Max=9

8(a) Award[1]for each of the following clearly drawn and correctlylabelled.

loop of Henle;

ascending and descending;

proximal convoluted tubule; (shown with convolutions)

Bowmans capsule; (shown as a continuation of proximalconvoluted tubule)

afferent arteriole;

efferent arteriole; (with smaller diameter than afferent)

distal convoluted tubule; (shown with convolutions)

Max=5



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No Answer Mark.

collecting duct; (shown with branches)

fenestrated capillaries; (shown as an enlarged diagram)

8(b) ADH released (by the pituitary) when blood solute high;

ADH makes cells of the collecting duct more permeable;

more water is reabsorbed / concentrated urine produced;

solute gradient within the medulla draws water from filtrate;

leads to water reabsorption in the descending loop of Henle;

ascending limb is impermeable to water (at upper reaches);

(lower) ascending limb permeable to sodium ions/ Na+ pumpedout of (upper) ascending limb;

which contributes to the establishment of a solute gradient;

more Na+ at base of loop / deeper in medulla;

some water re-absorbed in proximal convoluted tubule;

capillaries associated with nephron absorb reclaimed water;

once water level returns to normal/low blood solute, release of

ADH stops;

less water is reabsorbed / dilute urine produced;

Max=9

9(a) Compare each aspect :endocrinehormones ;

chemical messengers ; A chemical that transfer information

ductless glands / (released) into blood ;

target, organs / cells ;

ref. receptors on cell membranes ;

example of named hormone and effect ;

nervousimpulses / action potentials ; electrical, signals / current

along, neurones / nerve fibres ; nerves

synapse (with target) / neuromuscular junction ;

Max =8



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No Answer Mark.

ref. receptor / effector / sensory / motor, neurones ;

differences endocrine / nervous

slow manifestation/ fast

long lasting effect / short;

widespread effect/ localised;

9(b) IAA / plant growth regulator ;

synthesised in, growing tips / apical buds / meristems ;

moves by diffusion ;

from cell to cell ;

also, mass flow / in phloem ;

stimulates cell elongation ; R cell enlargement

inhibits, side / lateral, buds / growth ; A inhibits branching

plant grows, upwards / taller ; A stem elongates

IAA / auxin, not solely responsible ;

interaction between IAA and other plant growth regulators ;

e.g. role of ABA and lateral bud inhibition

e.g. cytokinins antagonistic to IAA / gibberellins enhance IAA

Max=7

10 (a) allopatric speciation ;

geographical isolation / spatial separation ;

e.g. of barrier ; e.g. of organism ; must relate

sympatric speciation ;

example ;

meiosis problems ;

polyploidy ;

behavioural / temporal / ecological / structural, isolation ;

(isolated) populations, prevented from interbreeding / can onlybreed amongst themselves ;

no, gene flow / gene mixing, (between populations) ;

Max=8



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No Answer Mark.

different selection pressures operate ;

natural selection ;

change in allele frequencies ;

different gene pool ;

over time (differences prevent interbreeding) ;

reproductively isolated ;

10 (b) humans ; must be linked to, choosing / selecting / mating etc

parents with desirable feature ;

e.g. organism and feature ;

bred / crossed ;

select offspring with desirable feature ;

repeat over many generations ;

increase in frequency of desired allele(s) / decrease in frequencyofundesired allele(s) ;

background genes ;

loss of hybrid vigour / increase in homozygosity / ref. inbreedingdepression ;

Max=7

[edu.joshuatly.com] pahang stpm 2012 biology [1ac4debf]

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