stpm trials 2009 biology answer scheme (pahang).pdf

964/1

PEPERIKSAAN PERCUBAAN

SIJIL TINGGI PERSEKOLAHAN MALAYSIA

NEGERI PAHANG DARUL MAKMUR 2009

BIOLOGY

PAPER 1

MULTIPLE-CHOICE

ANSWERS

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1 A 11 B 21 A 31 C 41 B

2 B 12 A 22 C 32 B 42 D

3 D 13 C 23 A 33 A 43 C

4 A 14 A 24 A 34 A 44 B

5 C 15 B 25 D 35 C 45 B

6 C 16 D 26 C 36 C 46 B

7 D 17 B 27 D 37 C 47 D

8 B 18 D 28 D 38 D 48 B

9 A 19 B 29 C 39 D 49 C

10 D 20 B 30 B 40 B 50 A

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PEPERIKSAAN PERCUBAAN SIJIL TINGGI PERSEKOLAHAN MALAYSIA

NEGERI PAHANG DARUL MAKMUR 2009

BIOLOGY PAPER 2

MARKING SCHEME

CONFIDENTIAL* 2

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

1. (a) - during S phase / interphase 1 1

(b) - enzyme C : DNA polymerase 1

- function : adds complementary nucleotides to the growing strand 1 - enzyme D: DNA ligase 1 - function : links Okazaki fragments by forming phosphodiester 1 4

bonds between the fragments (c) - strand X : lagging strand, which is synthesized discontinuously 1 - strand Y : leading strand, which is synthesized continuously 1 2 (d) - because each new DNA molecule contains one old and 1 1

one new strand (e) - the template for strand X is in the 5 to 3 end direction 1 - DNA polymerase only adds nucleotides at the 3 of a growing 1

Strand - therefore, strand X has to be synthesized away from replication fork 1

any 2 2

-------

total 10

CONFIDENTIAL* 3


2 (a) A: Resting potential 1 B: depolarization 1 C: repolarisation 1 D: refractory period 1 4 (b) - The active transport of sodium and potassium ions in 1 and out across the membrane/ 3Na+ out, 2 K + in - The membrane is more permeable to potassium ions 1 compared to sodium ions ; thus more potassium ions

diffuse out of the neurone compared to sodium ions diffuse in 2 (c)

B / depolarization C / Repolarisation Sodium-gated channels open

Potassium-gated channesl open

Sodium ions enter the neu-rone

Potassium ions leave the neurone

The inside of a neurone becomes positive

The inside of a neurone becomes negative

Any 2 pairs 2 (d) - the potassium-gated channels remain open / slow to close 1 1 This allows further efflux of potassium ions (e) - Limits the frequency in which impulses may flow 1 - Ensures that impulses flow in one direction 1

along the nerve any 1 1 --------- total 10

CONFIDENTIAL* 4


3 (a) - graph S : absolute growth curve 1 - graph T : absolute growth rate curve 1 2 (b) - graph S : actual increase in size / area/ growth over a period of time 1 - graph T : the increase in size / area / growth per unit time over a period of time 1 2 (c) - annual plant 1 1 (d) (i) - Limited growth 1 - the growth curve is a sigmoid curve 1 2

(ii) - woody plants are perennial plants 1 - display unlimited growth 1

- the growth curve is a series of sigmoid curve 1 3 ----- Total 10

CONFIDENTIAL* 5


4 (a) - DNA that contains genes from more than one source 1 1 (b) - step I : Insertion of the DNA fragment into the plasmid 1 - step II : Transformation / introducing recombinant DNA into 1 host cell - step III: DNA cloning / amplification making multiple copies 1 3 of target gene (c) - to produce the same sticky / blunt ends which are 1 1

complementary to each other (d) - cultured in a medium containing antibiotics/ ampicillin and X-gal 1 1 before a blue-white screening

- hybridization by using genetics / radioactive probes 1 1 (e) (i) - insulin produced through genetic engineering is similar 1 to human insulin - insulin produced is non allergic 1 - cheaper / not costly 1 Any 2 2

(ii) - because DNA / gene only codes for the synthesis of a 1 1 protein and blood is not a protein ----- Total 10

CONFIDENTIAL* 6


5. (a)

answer marks i. polymerization is formation of long repeated units of monomer

1

ii. by condensation with the removal of water molecules

1

iii. in cellulose the monomer unit is -glucose

1

iv -glucose linked together by - 1,4 glycosidic bonds

1

[any 3] maximum

3

Polysaccharide polypeptide marks i. does not involve ribosome Involve ribosome

1/0

ii. only involve one type of monomer hexose molecule

Involve 20 different types of amino acid 1/0

iii. formation of glycosidic bonds between the monomers

formation of peptide bonds between the mo-nomers

1/0

iv. does not involve gene / DNA Involve gene / DNA to code the amino acid sequences

1/0

v. does not involve mRNA and tRNA Involve mRNA and tRNA

1/0

vi. no transcription and translation stages

Involves transcription and translation stages

1/0

[ Any 4 pairs] maximum 4

CONFIDENTIAL* 7


(b)

Answer marks i. the active site of an enzyme is flexible

1

ii. and not exactly complementary / fitting to the shape of the substrate

1

iii. the active site of an enzyme can be modified when its interacts with substrate

1

iv. the active site changes its shape slightly as the substrate enters

1

v. the active site continues to change until the substrate is completely bound and final shape is determined

1

vi making the fit more precise

1

vii these structural changes may help to stabilized the transition state

1

viii. when the substrate binds to the enzyme, it forms an enzyme substrate complex

1

ix the substrate is then converted into products

1

x. the products are released from the active sites

1

xi, the enzymes return to its original conformation

1

xi. Products are released from the active sites

1

xii. the enzymes return to its original conformation

1

[any 8] maximum 8

CONFIDENTIAL* 8


6. (a)

Plants Animals marks i. occurs in roots / seed / storage organ /tuber

Occurs in skeletal muscles 1/0

ii. occurs when root are submerged // oxygen supply decreases

Occurs when muscles are actively Contracting

1/0

iii. products are ethanol and carbon dioxide

Product is lactic acid 1/0

iv. pyruvate changed / reduced to ethanal first then to its final product, ethanol

Pyruvate directly changed / reduced to its final product , lactic acid

1/0

v. ethanol is poisonous / can kill the plant cells

Lactic acid is still useful / not poisonous 1/0

vi. ethanol cannot be converted back to glucose

Lactic acid can be converted back to glucose 1/0

vii. anaerobic respiration is not needed to sustain the supply of ATP

anaerobic respiration is useful to sustain the supply of ATP

1/0

Any 6 pairs maximum

6

6 (b)

Answer marks i. NAD involved in cellular respiration

1

ii. 2 molecules of reduced NAD / NADH produced in glycolysis

1

iii. 1 / 2 molecules of NADH produced in link reaction

1

iv. 3 / 6 molecules of NADH produced in Kreb cycle

1

v. NAD accepts hydrogen / electron and transfers / carry to the inner mitochondrial membranes / cristae / cytochromes / ETC / matrix

1

vi. NADP involved in photosynthesis

1

vii NADP accept electron and hydrogen ion forming NADPH in non-cyclic photophosphorylation / light dependent reaction / light reaction

1

viii. NADPH used in Calvin cycle / dark reaction / light independent reaction

1

ix. NADPH is used to reduce CO2 / in reduction phase

1

x. NADPH reduces glycerate -1,3-diphosphate into 1

CONFIDENTIAL* 9


glyceraldehydes- 3-phosphate / PGAL [ Any 9] maximum 9 7. (a)

Answer marks i. cocaine present in the synaptic cleft

1

ii. cocaine bind to the transporter molecules

1

iii. cocaine delays the breakdown of norepinephrine / dopamine / noradrenaline

1

iv. reuptake/reabsorption of the norepinephrine / dopamine / noradrenalin from syn-aptic cleft is prevented / blocked

1

v. norepinephrine / dopamine / noradrenalin remains / accumulates in the synaptic cleft

1

vi. norepinephrine / dopamine / noradrenalin keep on binding to the receptors on the post-synaptic membrane

1

vii. impulses will be generated repeatedly

1

viii. causes continuous euphoria / intense pleasure

1

[ Any 6] maximum 6

CONFIDENTIAL* 10


(b)

Answer marks i. HIV glycoprotein (gp 120) binds to CD4 receptor on the surface of the helper T

cell / TH cell / host cell

1

ii. HIV protein envelope / lipoprotein / fuse with / to host cell membrane

1

iii. Reverse transcriptase and viral RNA enter the host / TH cell by endocytosis

1

iv. reverse transcriptase makes a DNA copy (cDNA) of the viral DNA // The first DNA strand is formed from RNA viral by using reverse transcriptase

1

v. DNA copy (cDNA) / the first DNA strand becomes a template for the synthesis of complementary / second strand of viral DNA

1

vi. the double stranded viral DNA formed then enters the nucleus and incorporated into the DNA of the host cell called provirus

1

vii. each time the hosts DNA divides / replicates, viral DNA / provirus also replicates

1

viii. this carries on for six years without any symptoms of disease are exhibited

1

ix. the activated provirus will direct the host cell to synthesis new viral protein and vir-al RNA

1

x. new viral protein and RNA assembled into new retroviruses

1

xi. new retrovirus particles bud off from host cell membrane by exocytosis

1

xii. finally, the virus spreads to all the helper T cells and destroys them

1

xiii. resulting the destruction of the immune system

1

Any 9 Maximum 9

CONFIDENTIAL* 11


8. (a)

answer marks i. these types of plants are short day plants

1

The plants require a period of darkness equal to / longer than critical night ii. length

1

iii. light / spotlight flashes from vehicles interrupt / shorten the period of darkness

1

iv. causes the conversion of Pr into Pfr

1

v. Pfr is the (biological) active form

1

vi. high concentration / level of Pfr inhibit flowering in SDPs [any 5]

1

Maximum 5

CONFIDENTIAL* 12


(b) Explain the changes happens and action of hormone on the onset of labour in human [10marks]

answer marks i. estrogen level high in the end / last week of pregnancy

1

ii. stimulate the development of oxytocin receptor in uterine wall // increase the sensitivity of uterus muscle/myometrium to oxytocin

1

iii. babys head / growing fetus press against the mother cervix

1

vi. causing the cervix and uterine wall to stretch

1

v. this stimulates maternal posterior pituitary to release oxytocin

1

vi. and also stimulates fetal pituitary gland secretes ACTH

1

vii. ACTH triggers fetal adrenal gland to secrete corticosteroids hormone

1

viii. corticosteroids hormone triggers placenta to secrete prostaglandin

1

ix. oxytocin also stimulates placenta / fetal to produce prostaglandin

1

x. both prostaglandin and oxytocin stimulates a powerful contraction of myometrium / uterus wall

1

xi. The more frequent the myometrium contracts, the more oxytocin / prostaglandin produced

1

xii. the uterus contraction also stimulates stretch receptors in the uterine wall and the cervix to trigger further release of oxytocin

1

xiii. the cervix dilates / widen, its tissue softens and become more flexible and amniotic bag burst

1

xiv. contractions become stronger and stronger / more frequent help to push baby down/out

1

(Any 10) Maximum 10

CONFIDENTIAL* 13


9.(a) Multiple alleles:

Answer marks i. one particular characteristic / phenotype is controlled by three or more alleles

1

ii. each allele can occupy the same gene locus on a pair of homologous chromosomes

1

iii. only two alleles can occupy a locus on a pair of homologous chromosomes at any time

1

iv. e.g. human ABO blood group

1

Maximum 3 Polygenic inheritance:

Answer Marks

i. one particular characteristic is controlled by two or more than two different genes

1

ii. genes located at different loci on different chromosomes

1

iii. each dominant allele has a small quantitative effect individually on the phenotype// phenotype produced is the total effect of all dominant genes present

1

iv. e.g. height in human

1

Maximum 3

CONFIDENTIAL* 14


(b) [9 marks]

Parents (p)

Phenotype Red smooth seed White wrinkled seed x

Genotypes

R R

S S

r r

s s

x

Meiosis

Gametes

R

S

r

s

Fertilisation

R r

S s

F1 generation genotype

Phenotype All red and smooth seed

1

1

1

1

CONFIDENTIAL* 15


Test cross for F1 progeny

]

R r

S s

r r

s s

x Genotype

Phenotype Red smooth seed White wrinkled seed x

R

S

r

s

R

s

r

S

r

s

Gametes

Recombinant/new combination of genes

Genotype offspring

R r

S s

r r

s s

R r

s s

r r

S s

Red smooth

White wrinkled

Red wrinkled

White smooth

Prental combination

Recombinants forms as a result of crossing over

Phenotypes

346 335 40 39

1

1

1

1

1

1

CONFIDENTIAL* 16


Maximum 9 10. (a)

answer marks

i. to sustain the biodiversity / flora and fauna of ecosystems

1

ii. to maintain / improve the quality of life

1

iii. to prevent the useful biological resources that have economical /medicinal value from extinct

1

iv. to prevent the biogeochemical cycles from disrupted by the extinction of some species

1

v. to prevent an extreme global climatic changes

1

vi. to keep the ecosystems in their natural state (e.g. ecotourism) which provides aesthetic values for humans

1

vii. to protect the environment for future generation

1

maximum 5 (b)(i)

answer marks i. is development that can continue indefinitely

1

ii. can be achieved by minimizing the use of non-renewable resources

1

iii. and controlling the use of renewable resources of the earth

1

Maximum 2

CONFIDENTIAL* 17


(b) (ii)

techniques benefits marks i. Replanting trees in areas that have been logged

Can decrease the carbon dioxide level in the Atmosphere // can reduced the greenhouse Effect

1+1

ii. Creating forest reserves

- Able to avoid the complete destruction and maintain the biodiversity of the forests. - to keep the ecosystems in their natural state(e.g. ecotourism) which provides aesthetic values for humans - to avoid lost of wildlife and potential resources [any 1]

1+1

iii. Selective logging / only selects tree with certain diameters / species can be felled

- to maintain soil fertility - to prevent flood, soil erosion - to avoid species extinct - to avoid loss of watershed areas - to avoid water pollution

1+1

iv. Enforcement of laws and surveillance

To prevent illegal logging 1+1

iv. Recycling of paper

To reduce the demand for new raw materials 1+1

Any 4 pairs Total

8

BIOLOGY P1 ANSWERSBIOLOGY_ANSWERS_P2

stpm trials 2009 biology answer scheme (pahang).pdf

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