TOPIC FIVE - Stafford Papers (Marking Schemes)

7/28/2019 TOPIC FIVE - Stafford Papers (Marking Schemes)

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TOPIC FIVE ON THE WILD SIDE

SAQ 514

(a) (i) A stroma B starch (grain) / lipid droplet C thylakoid (membrane) / chlorophyll

D granum (2) for all correct

(1) for 2 or 3 correct 2 marks

(ii) C / thylakoid / granum / D ; 1 mark

(iii) photolysis/splitting water using light energy ; release of electrons to chlorophyll ;

releases hydrogen ions ; oxygen released ;

OH source of oxygen ; 3 marks

(b) reduced production (of carbohydrate) ; less carbon dioxide fixed ; ref RuBP ; ref Calvin cyc

eq ; less carbon available for reduction to carbohydrate ; ref to enzyme / RuBPcarboxylase ; 3

marks

(c) high light intensity ; ref. to change in wavelength ; high temperature ; high humidity ;

high carbon dioxide concentration ; 2 marks Total 11 marks

SAQ 515

(b) Treated have fewer lamellae/grana/thylakoids/membranes; Less chlorophyll for absorbin

sunlight/ less LDR; Treated have fewer ribosomes;

Produce fewer enzymes/carriers (For LIR)/ fewer proteins for membranes; 4SAQ 516

(a) photolysis (of water) ;

(b)light / enzyme / chlorophyll /eq ;

1. passed to chlorophyll / photosystem / replace electrons lost by chlorophyll / eq ;

2. light energy {promotes electrons to higher energy level / excites electrons } / electrons

emitted ;

3. ATP production ;

4. reduction of NADP / production of NADPH / eq ;

5. reference to electron carriers / electron transport chain ;6. reference to redox / eq ;

(d)1. GP ;

2. reduced ;

3. using H from reduced NADP ;

4. and ATP as source of energy

(e)1. 10/12 GALP /eq ;

2. (regeneration of) RuBP /eq ;

3. (rest used to form) glucose ;

4. and starch / other organic chemicals /eq ;


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SAQ 516

(a) (i) chlorophyll molecule/electron gains energy/becomes excited/is raised higher energy le

chlorophyll molecule loses (excited) electron/becomes positively charged; 2

(ii) energy lost by electrons (is used to .drive. reaction between ADP and Pi.); 1

(b) reduction/described; of GP to triose phosphate; 2

Tot

SAQ517

(a) Grana/thylakoids/ lamellae; 1

(b) A = oxygen/O2

B = ADP and phosphate/Pi /phosphoric acid/correct formula;

C = reduced NADP; ALLOW NADPH/NADPH2 /NADPH + H+ 3

(c) (i) Absorbs light/energy; Loses electrons/becomes positively charged/is oxidised; Acceptselectrons from water/from OH ; Causes more water to dissociate/pulls equilibrium to the rig

max 3

(ii) Electrons raised to higher energy level/electrons excited; Use of electron

carriers/cytochromes/acceptors;

For production of ACT [ REJECT .energy production.] 3

(d) (i) GP formed from RuBP + CO2; GP TP/sugar-phosphate/sugar/to RuBP; GP formed at

same rate as it is used; 3

(ii) No CO2 to combine with/not enough CO2 to combine with; RuBP not changed into GP

RuBP reformed from GP/TP; max 2 Total 15 m

SAQ 518

SAQ 519

(a) electrons; from chlorophyll / photolysis; 2

(b) (i) RuBP combines with carbon dioxide to produce 2 x GP; 1

(ii) less used to combine with carbon dioxide / less used to form glycerate 3-phosphate; 1

(c) (i) used in photosynthesis allows detection of products; 1

(ii) ATP and reduced NADP not formed; GP is not being used to form RuBP / is being formedfrom RuBP; 2

(iii) used in respiration / formation of starch / cellulose; 1

Tot

SAQ 520

(a) Reduced NADP;Accept NADPH2/NADPH) ATP; 2

(b) Oxygen produced / carbon dioxide uptake; 1

(c) Ensure high rate of photosynthesis / enough product formed / neither factor limiting; 1

(d) More photosynthesis when dark period increased from 3 to 17 ms; (Even though) amount

light is the same; 2


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SAQ 521

(a) 1. 5C/RuBP combines with CO2;

2. to form 3C compound / TP / GP;

3. using ATP;

4. and reduced NADP / eq;

5. 2 molecules of 3C compound/ TP / GP form hexose;

6. all RuBP is regenerated;

7. 10 molecules of 3C/TP/GP form 6 molecules of 5C/RuBP; 6 max

(b) 1. electron transport chain accepts excited electrons;

2. from chlorophyll / photosystem;

3. electrons lose energy along chain;

4. ATP produced;

5. from ADP and Pi;

6. reduced NADP formed;7. when electrons (from transport chain) and H+ combine with NADP;

8. H+ from photolysis; 6 max

(c) 1. some hexose/biomass/eq. used in respiration; growth cancels this point

2. CO2 produced (is lost to air);

3. some parts of the plant are eaten;

4. some parts lost to decomposers / in leaf fall; 3 max

Tota

SAQ 522(a) (i) 100/reference to original value / blank reading . light meter reading (%); 1

(ii) Oxygen produced (per unit) time/change in oxygen concentration per unit time; 1

(b) (i) Suitable factor kept constant: e.g. Light intensity/type of glass/distance of meter/ carbo

dioxide concentration/ concentration of algae; 1

(ii) Decrease in carbon dioxide/hydrogencarbonate ions; 1

(c) Light-dependent reaction/chlorophyll absorbs light/physical reaction; No (direct) enzyme

involvement; 2

Tot

SAQ 523

(a) NADPH / reduced NADP; 1

(b) (i) 2; 1

(ii) 1 Less GP;

2 Reduced amount of TP / GALP / carbohydrate;

3 Less RuBP regenerated / made;

4 Less CO2 taken up / less fixation; 3 max

(iii) High levels of oxygen reduce photosynthetic rate, effect greater at higher temperatures;

Higher concentration more effective competitor / more RuBP combines with oxygen (instead


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SAQ 524

(a) (i)What name is given to the relationship between wavelength of light and the rate

of photosynthesis, as shown by this graph? action spectrum;

(1 m

(ii)From the graph, state the optimum wavelength of light for photosynthesis.450 nm;

(1 m

(iii)Explain the effect on the rate of photosynthesis of varying the wavelength of

light from 550 to 700 mm. 625 gives max rate / rate fluctuates / steep fall

after675; reference to secondary pigments;

different pigments absorb different wavelengths / eq.; chlorophyll a peak

absorption 600 650; chlorophyll a peak absorption at 650 675;

pigments do not absorb wavelengths above 675;(2 ma

(b) (i) Name the stage of photosynthesis the produces oxygen. light dependent stage /

eq.;

(ii) State where in a chloroplast this stage would occur. grana / thylakoids;

(1 m

[Total 6 m

SAQ 525

SAQ 526

SAQ 527

(a). oxygen has low solubility in water ; given off as gas / as bubbles // allow converse;

easy to / can collect // easy to / can measure volume // allow converse ;

max 2

(b) use hydrogen carbonate / bicarbonate / HCO3 /eq ; several / 3 or more stated

concentrations ; measure length / volume of bubble ; over a specified / stated

time ; repeat at each concentration /eq ; maintain same temperature / any

named factor /eq ; equilibration/eq at each concentration ;max 4

(c) (i) rate (of photosynthesis / oxygen production) increases as current increases;

greatest effect between no current and 2 cm s1 / suitable manipulation of

figures ; reaches a plateau / little change after 2 or 3 cm s1 / shallower

gradient / suitable manipulation of figures ; max 2(ii) carbon dioxide dissolved in water ; plant will use up all local /eq supplies if


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supply equals / is greater than rate of use/eq // another stated factor is limiting /

CO2 is no longer limiting /eq ; oxygen produced is removed /eq ;max 3

SAQ 527

(a) Shade leaves thinner / sun leaves thicker ;

Fewer layers of cells / two / three layers of palisade cells ; Sun leaves darker

green in colour / shade leaves paler ; Larger number of chloroplasts / more

chlorophyll pigment / less in shade leaves ;

Sun leaves glossier / more shiny ; Thicker cuticle on sun leaves ;Max 4

(b) (Cuticle) reduces loss of water (by evaporation) // protection from abrasion /eq

entry of pathogens /eq ; 1

(c) (Spongy mesophyll) allows gaseous exchange / diffusion / (limited)

photosynthesis ; 1

(d) Shade leaves lower rate than sun leaves // sun leaves higher ; Less

photosynthetic tissue / only one layer of palisade cells ; 2

SAQ 528

SAQ 529

a) It is a factor which limits the rate (of photosynthesis / of a reaction) ; Increasing this

factor increases the rate (of photosynthesis) ; Until another factor limits the rate

/ eq ; 2

(b) (i) 1. Increase in rate from 0 to 300 / 350 (light intensity) ;

2. Reference to manipulatedfigures to support increase ;3. Light is the limiting factor / eq ; [accept converse]

4. Rate levels off / eq above 300 / 350 (light intensity) ;

5. Another factor has become limiting ;

6. Named limiting factor: carbon dioxide / temperature /

chloroplasts / chlorophyll ; 4

(ii) 1.(Provides) carbon dioxide ;

2. Rate of, O2 production / photosynthesis, is greater

(at all light intensities) above 50 for higher carbonate / CO2 concentration / eq ;

3. Reference to comparative figures for rates / approx. double ;

4 For both concentrations rate starts to levels off at 300 / 350 light intensity / lower


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5. Hydrogen carbonate / CO2 concentration is a limiting factor / not limiting up to light

intensity 50 ; 3

(iii) Keep temperature constant / place tube containing pond weed in a water

bath ; Reference to rate of reaction / enzymes being affected by

temperature

changes / temperature affects, solubility / diffusion / volume of oxygen /

kinetic energy ;

Repeat / replicate ; To avoid anomalous / eq results ; Use the same piece /

length of pond weed throughout ; A different piece could have, more /

fewer, leaves / different surface area / eq (and so affect the volume of

oxygen produced) ; Reference to equilibration / eq ; To make sure pond

weed is acclimatised to new conditions ; No air bubbles in equipment ; So

measuring only gas / oxygen given off ; Same type of light source ; So keep

wave length the same ; No external light sources ;To control the experimental light intensities ; 1+1

(c) 1. Splitting water in (presence of) light ;

2. H2O O2 + 2e- + 2H+ ; [allow words]

3. Electrons replace the electrons lost from PS11 / P680 / chlorophyll ;

4. Hydrogen ions picked up by NADP / hydrogen ions reduce NADP ;

5. NADPH / eq used, in light-independent reaction / Calvin cycle / to reduce

carbon dioxide ; 3

SAQ 530

(a) Two {peaks / eq} at 425 - 440 and 665 - 675 nm ;Little {absorption / eq} between 450

and {600 / 650} nm ;

Second peak {smaller / lower than first} / quoted difference / no absorption 470 480

nm ; [units at least once] 2

(b) 1. Each (pigment) absorbs a different wavelength of light ;

2. (more pigments) gives a greater range of absorption / plant able to absorblight of greater range of wavelengths ;

3. Reference to protective nature of carotenoids / accessory pigment

qualified ; 2

(c) 1. Use chromatography ;

2. {Grind up / crush / eq} sample of plant tissue in {propanone / organic

solvent

/ eq} ;

3. Place drops of {pigment / eq} on {paper / gel / column / silica} ;


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SAQ 531

(a) Affects (rate of) enzyme activity / affects (rate of) enzyme {controlled / catalysed}

reaction / correct reference to kinetic energy of molecules / reactants / eq ; In

light-independent stage / Calvin cycle ; 2(b) A Starch (grain) ;

B Stroma ;

C Granum / stack of thylakoid ; 2

[All correct for two marks, two correct for one mark]

(c) (i) X CO2 / carbon dioxide ;

Y PGA / phosphoglyceric acid / phosphoglycerate / GP /

glycerate 3-phosphate / unstable 6-carbon compound ; 2

(ii) Light-dependent reaction / grana / thylakoid /non-cyclic photophosphorylation ; 1

SAQ 532

SAQ 533

SAQ 535

SAQ 536

(a) 1. Factor which {controls / eq} the rate

2. Increasing this factor increases the rate (of photosynthesis) ;

3. Factor {not at optimum / nearest its {threshold / minimum} value / eq} ;

2 m

(b) [condition + control for two marks]

1. Temperature ; Use water bath / description of heat filter / eq ;

2. Carbon dioxide ; adding sodium hydrogen carbonate / bubble through carbon dioxide / 3. {Wavelength / colour} of light ;

Use same {light source / filter / gel } ;

4. pH ; [not acidity /alkalinity]

Buffer ;

4 m

(c) 1. {Equilibrate / eq} before timing ;

2. {Clear / remove} bubbles from capillary tube at start / eq ;

3. Use syringe to move {oxygen / gas bubble} into capillary tube / eq;

4. measure length of bubble / eq;

5. Correct reference to determining volume of oxygen / eq ;


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2. Reference to appropriate qualification e.g. filters placed in correct position / keeping light

intensity the same / all other factors the same ;

2 m

Total 12 m

SAQ 537

SAQ 538

(a) Habitat/environment + community (/described) / (all the) biotic and abiotic factors in an

area/in an environment; 1

(b) Reflected / absorbed by water; Reflected from producers; Transmitted / passes between

chloroplasts/ between plants / too few chloroplasts; (Reject .not absorbed. unqualified) Wro

wavelength / some = heat / some = UV / used to evaporate water; Used to drive reactions of

photosynthesis / lost in photosynthesis;

Other limiting factor / named example . carbon dioxide / temperature; 2 max(c) Loss of energy/heat / use of energy / less energy to be passed on; In respiration; In excret

excretion / urine / carbon dioxide; Inedible parts / indigestible parts / egesta / egestion / to

decomposers; 2 max

Tot

SAQ 539

(a) Primary consumer - seed eating birds / grasshopper / field mice ; Secondary consum

spider ; 2 marks

(b) (i) 1980 + 3600 + 62 ; = 5642 ; Allow full marks for correct answer with no working show

marks

(ii) Either: subtract respiration / 3600 ; Or: 2042; NPP=(GPP R)/GPP=NPP + R; 1 mark

(c) (i) 44.4 - (12.5 + 25.4) ; 6.5 out of 44.4 ; 14.6% ; Allow full marks for correct answer wit

working shown 3 marks

(ii) Faeces/ indigestible material ; Reject inedible parts Nitrogenous waste / eq ; 2 marks

(d) An explanation to include two from: 1. Small proportion reaches next level / converse

Correct use of figures ; 3. Insufficient energy to support another level ; 2 marks Total 12 m


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SAQ 540

(a) (i) Energy in B = 80 x 1.5 = 120 AND energy in C = 140 x 0.1 = 14 ; 1 mark(ii) Percentage = 14 120 x 100 ; = {11.67 / 11.7} % ; 2 marks(b)1. Less energy in C than in B or A / converse ;

2. Reference to 10% rule / only about 10% of energy of B in C / small proportion passed;3. Energy lost between trophic levels ;

4. Example of loss (e.g. inedible parts, respiration, heat etc) ;3 marks

Total 6 marks

SAQ 541

(a) (i) GPP and NPP similar to start with ; both increase ; After 2 days) GPP and NPP diverge/e

figures in support ; 2 marks

(ii) more energy is used in metabolism/eq in {older / bigger} plants ; figures in support ; suita

explanation e.g. protein synthesis/flower initiation/differentiation / ref. to herbivores ; more

photosynthesis tissue ; (as grows) / eq ; 2 marks

(b) GPP-NPP=R /eq ; biomass production reduced by respiration / eq ; 2 marksTotal 6 marks

SAQ 542

(a) kJ m-2 yr -1; 1 (all 3 units needed, accept J, any area, any time)

(b) (i) 0.64 / 0.636 (%); 1

(ii) Heat / respiration; (Reject respiration uses energy) Movement / muscle contraction;

Faeces / indigestible material / food not eaten; Excretion; 1 max

(c) (i) Some light reflected / not absorbed / refracted; Some light misses chloroplasts /

chlorophyll;

Only certain wavelengths of light used; 1 max

(ii) Excites electrons from chlorophyll; Electrons passes down carriers; Energy released duringtransfer;

ADP + P forms ATP; 3 max Total 7

SAQ 543

(a) (i) respiration; 1

(ii) decomposers; (accept bacteria/fungi) 1

(b) 87402 x 100 = 5.14/ 5.1%; 1.7 x 106 2 (correct answer = 2 marks)(principle: energy in

producers energy of light absorbed = 1 mark)

(c) excites chlorophyll/electrons; release electron(s); 2 max(d) reduced NADP; reduces GP / to change GP to TP; ATP; provides the energy to reduce GP /

convert GP to TP / TP to RuBP/ provides phosphate to convert TP to RuBP; 4 Total 10

SAQ 544

(a) (i) dogwhelks move more; 1

(ii) their food contains more material that cannot be digested / no enzymes to digest;

such as cell walls/cellulose; 2

SAQ 545

a) (i) 130 x 22 = 2860kJ. (1)

(ii)Energy absorbed by chlorophyll = (45 100) x 3150000 = 1417500 kJ


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(iii)Some of the energy is lost due to biochemical inefficiency during the photosynth

reactions. Some of the organic compounds are used for plant respiration and the remain

energy is used for producing plant biomass. (2)

b)Only a small proportion of the heather is eaten by the herbivore. All the food that is eate

not digested. Energy is lost in the undigested food as faeces. Some amount of energy is los

heat energy due to respiration.(3) (Total 8 marks)

SAQ 546

a) Herbivore = (6 16) x100 = 37.5% Carnivore = (3 14) x100 = 21 %(2)

b) Cellulose is present in the faeces of herbivores. Cellulose is not completely digestable

contains a lot of energy.(2) (Total 4 marks)

SAQ 547

a)From May to July.(1)

b)There is loss of energy during transfer between trophic levels. Some energy is lost as h

from respiration. Some energy is lost during excretion and egestion. Thus at higher trophic le

there will be less energy left to sustain higher trophic levels.(3)

c).Phytoplankton reproduce at rate rate of their consumption. (Total 5 marks)(1)

SAQ 548

a)Some of the energy is lost due to biochemical inefficiency during the photosynthetic reacti

Some of the organic compounds are used for plant respiration and some energy is lost due to

Transpiration. Only about 1% of the remaining energy is used for producing plant biomass. (

b). 44090 (20000 + 15330 + 5840) = 2920 kJm-2

(1)

c)Ammonium is converted into nitrite by Nitrosomonas. The nitrite is then converted into nit

by Nitrobacter, under aerobic conditions. (3)

SAQ 549

a)It is the energy fixed into the mass of organisms at each trophic level per unit area of

ground in one year. It is the rate of production of biomass in a trophic level. The gross prim

productivity is the rate of energy fixation during photosynthesis. The rate of formation

biomass of producers is called as the net primary productivity. (2)

b)Sustainable management of forests involves the techniques used to utilize the resource

the forest without destroying the forests. The wood is cut at the same rate at which it regroShort rotation coppicing is a good example of sustainable management of forests. (2)


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SAQ 550

(i) Ecosystem -This refers to living world and its non-living environment interacting with each

other. The biotic and abiotic factors interact with each other enabling the flow of energy and

nutrients between the components of an ecosystem. It is a reasonably self-contained area

together with all its living organisms. Eg: Pond ecosystem, grassland ecosystem. (2)

(ii) Trophic level -This is the feeding level of an organism in a food chain or food web. It show

the energy transfer in a food chain. Producers - 1st trophic level, Herbivores - 2nd trophic leve

Carnivores - 3rd trophic level. (2)

(i).((600 38) 600) x 100 = 93.67%(2)

(ii).Not all parts of the plants or animals are consumed by the next trophic level. The ro

bones, teeth, claws are not always eaten. All the consumed food is not assimilated in to

body. A large part remains undigested and is lost in faeces ( E F). A lot of the assimilated foo

used up for respiration (ER). Some energy is lost in urine ( EU ). (2)(iii)The productivity of the producers is very high. This prevents the producers from comple

being consumed by the herbivores. Moreover, the biomass takes into account the mas

organisms present at the time of the investigation. The producers can be replaced as rapidl

they are consumed, so their population is not depleted. (3)

c)Use a 0.25 m2 quadrat and place it randomly on the grassland. Collect all the consumers f

within the quadrat and separate them as herbivores and carnivores. Then uproot all the pla

from within the quadrat and remove the soil from the roots. Repeat the procedure twenty ti

and find the mean mass. (4) (Total 15 marks)

SAQ 551

a)(i) ((2250 240) 2250) x 100 = 89.3%(2)

(ii)Not all parts of the plants or animals are consumed by the next trophic level. The roots bo

teeth, claws are not always eaten. All the consumed food is not assimilated in to the bod

large part remains undigested and is lost in faeces (EF). A lot of the assimilated food is used

for respiration (ER). Some energy is lost in urine (EU). (2)

b) The experiment has not been repeated or the dead organisms may not be collected or so

organisms may feed at two or more trophic levels. (3)

c)Some of the energy is lost due to biochemical inefficiency during the photosynthetic reacti

Some of the organic compounds are used for plant respiration and some energy is lost du

Transpiration. (2) (Total 9 marks)


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SAQ 552

(i)In a temperate forest there is lower rainfall and reduced light intensity compared to a trop

forest.This results in lower productivity in the temperate forests. Moreover, the decidu

forests which shed their leaves during autumn are found in temperate regions, where as trop

regions have evergreen trees. (2)

(ii)The intensively cultivated land has plants which are artificially selected to produce a h

yield. Artificial fertilizers are also used to improve the yield. Moreover, the crops are replan

after harvesting. All these factors ensure that the intensively cultivated land produces a hig

yield than the grassland. (3)

b). Use a 0.25 m2 quadrat and place it randomly on the grassland. Collect all the consumers f

within the quadrat and separate them as herbivores and carnivores. Then uproot all the plafrom within the quadrat and remove the soil from the roots. Repeat the procedure twenty ti

and find the mean mass. Then divide the mass of each trophic level by the area of the grassl

to find the biomass. (4)

c) . The biomass includes the inorganic component, like water and ions. The water conten

variable and leads to inaccuracy. The measurement of productivity is a true reflection of

energy capture. (2) (Total 11 marks)

SAQ 553

a) Use a sweep net and sample a 10m2 of the pond to collect all the organisms in the a

Separate the organisms into trophic levels and find the mass of organisms in each trophic le

Calculate the mass of organisms per unit area of the pond. (3)

b) (i)((418-26.8) 418) x 100 = 93.6%(2)

(ii)Not all parts of the plants or animals are consumed by the next trophic level. The ro

bones, teeth, claws are not always eaten. All the consumed food is not assimilated in to

body. A large part remains undigested and is lost in faeces (EF). A lot of the assimilated foo

used up for respiration (ER). Some energy is lost in urine (EU). (2) (Total 7 marks)

SAQ 554

a) (i)The primary production is the amount of energy fixed into the chemical bonds of org

compounds, like glucose, produced during photosynthesis. (2)

(ii)[(14.5 x 104) (251 x 104)] x 100 = 5.77%(2)

b) Not all parts of the plants are consumed by the next trophic level The roots and wo


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SAQ 555

a) (i) On the figure draw a ring around the number which indicates the energy entering

system via photosynthesis. (1)

(ii)(45500 1880000) x 100 = 2.4%(2)

b) Some energy is reflected from the surface of the leaf. Some energy is transmitted thro

the leaf. Some of the energy is lost due to biochemical inefficiency during the photosynth

reactions. Some of the organic compounds are used for plant respiration and some energy is

due to transpiration. (4)

c) As heat energy. (1)

SAQ 556

a) Methane(1)

b) The organic matter is first hydrolysed by aerobic bacteria in the fermenter. The simple su

are then converted into acetic acid by anaerobic acetogenic bacteria. The low pH and anaer

conditions stimulate the methanogenic bacteria to produce methane. (2)

c)Biogas is used as a domestic cooking fuel. (1)

d)The sludge can be used as a fertilizer for agriculture. (1) (Total 5 marks)

SAQ 557

a) The closed container prevents the biogas from escaping out of the container. It also help

maintain anaerobic conditions in the fermenter, which favours the formation of methane.

closed container also ensures that heat cannot escape easily from the container. This help

maintain a suitable temperature for biogas formation. (2)

b) (i)0 to 10 days- The pH falls rapidly because the bacteria produce carbon dioxide, wh

dissolves in the water to form carbonic acid. Acetogenic bacteria also produce acetic acid, w

further lowers the pH. (3)

10 to 45 days.-The pH rises due to the conversion of acetic acid to methane

methanogennesis.

(ii) There is an initial increase in the rate of gas production due to carbon dioxide produ

from aerobic bacteria. Then the rate of gas production further increases due to meth

production by methanogenic bacteria, under anaerobic conditions. As the temperature rises

pH becomes unsutable for methanogenesis, the gas production decreases. (3)

c). It is a good way of producing cheap fuel and getting rid of organic waste at the same tim

is a renewable source of energy, which recycles CO2 in a relatively short period of time. It d

not contribute to acid rain as it produces only carbon dioxide & water vapour. It is a clean fof fuel. No soot or Carbon dust is formed. The sludge from the waste outlet can be used

d t l f tili f i lt (3) (T t l 11 k )


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SAQ 558

a) The starch stored in the corn is hydrolysed into maltose by amylase. The amylase is furt

hydrolysed into glucose. The glucose is broken down under anaerobic respiration of yeas

produce ethanol and carbon dioxide. (2)

b)The ethanol is mixed with petrol to form a mixture of 20%ethanol and 80% petrol, cagasohol. (2)

c) (i) There is a general rise in the production of ethanol. There is a slight decrease from 199

1996. The production remains constant between 1982 to 1984 and 1988 to 1990. (3)

(ii) This may be due to a decrease in the production of corm or due to more use of pu

transport. The cost of fossil fuels may have decreased. (2)

d)Ethanol is a renewable fuel which recycles carbon dioxide in a relatively short period of ti

where as fossil fuels release carbon dioxide that was removed millions of years ago. Moreo

the fossil fuels release acidic gases which contribute to acid rain, but ethanol only produ

carbon dioxide and water vapour. (2)

e)Methane(1) (Total 12 marks)SAQ 559

(a) (i) Oldest / biggest/ four-year-old trees; 1

(ii) Maintains a range of habitats/ not all habitats destroyed; Species/organisms not lost/

maintains biodiversity; OR Willow plantation is sustainable; So reduce demands on other

woodlands; OR Willow plantation is sustainable/ allows continuous production; Continuous

source of income/energy; 2

(b) Willows take in carbon dioxide; By photosynthesis; Little/No net increases in carbon dioxi

in atmosphere; Burning fossil fuels also releases sulphur dioxide; 3 max Total 6

SAQ 560

(a) Any three from: Loss of habitat / nest sites / shelter / niche; ignore homes Loss of food

Exposure of soil leads to erosion / leaching of ions; Change in (micro)climate / levels of light /

temperature / humidity; Animals move away / higher death rate / extinction; 3 max

(b) Any three from: Absorb carbon dioxide; (extra carbon-sources CANCEL) In photosynthesis

Carbon (dioxide) is used in forming permanent plant tissues / biomass / plant structures; Caris incorporated in organic molecules / named e.g.; 3 max

(c) (i) Any four from: Less oxygen can enter the soil (from the air); For saprobionts / soil

microorganisms /bacteria / fungi / decomposers / correctly named soil organisms; For use in

aerobic respiration; Less breakdown of organic matter / humus / dead plants / dead animals

other e.g.; Less carbon dioxide released / formed; 4 max

(ii) Any five from: Oxygen enters the soil / use of oxygen; Nitrifying bacteria are aerobic;

Ammonia / ammonium ions _ nitrite; Nitrite _ nitrate; (Ammonia_ nitrate = 1 mark) (If formu

used, worth 1 mark only if correct) Nitrate is absorbed / used by plants; To make named orga

N e.g. protein / amino acids / DNA / ATP / NAD(P) / chlorophyll; Increased yield / growth; 5max Total 15 marks


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SAQ 561

(a) (i) photosynthesis;

(ii) decomposition;

(iii) respiration;

(iv) combustion; 4 marks

(b) (i) (coal contains) carbon that has been taken from the atmosphere (in the past) /carbon t

has been taken out of circulation (in the carbon cycle); 1 mark

(ii) burning wood does not add to the amount of CO2 in the atmosphere / does not cause a n

increase;

carbon dioxide in (roughly) equals carbon dioxide out; burning wood releases carbon recently

absorbed (by photosynthesis) / burning fossil fuels releases CO2 trapped a long time ago / eq

marks

(c) not enough room to keep planting enough forest to use up all the surplus CO2; a

{mature/fully grown} forest is carbon neutral / only {young / growing} forest is a net absorbeeq; in the end the forest will die and decay / be burnt by humans; 2 marksTotal 9 marks

SAQ 562

(a) (i) A Photosynthesis

B Combustion / burning

C Respiration

[Write a cross by each error in right hand margin]

[One error = 1 mark, two errors = 0 marks] 2

(ii) (Willow) coppice / wood / trees / straw / agricultural waste; 1[do not credit sunflower oil / peat]

(b) (i) Idea that: can be carried on long into the future / we can carry on doing it indefinitely /

biomass renewable (unlike fossil fuel) will not get used up /fossil fuel will get used up (unlike

biomass); 1

(ii) For up to one mark:

Any valid reference to {less atmospheric pollution / less greenhouse effect / less acid rain} (w

biomass) / can grow some more wood;

For up to two marks:

EITHERBiomass is {renewable / eq};

And going on to explain that fossil fuel (on the other hand) {is getting used up / being used up

faster that its being formed} / eq;

OR

Less carbon dioxide pollution;

Because its just replacing what has recently been absorbed in photosynthesis / other valid

explanation of carbon neutrality / contributes less to {global warming / greenhouse effect};

OR

Biomass is renewable;

And contributes less to {global warming / greenhouse effect};


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Whereas fossil fuel represents carbon being returned to the system after being out of circula

for a long time;

Therefore (use of biomass) contributes less to {global warming / greenhouse effect / climate

change} (than fossil fuel); 3

(c) Computer / data logger;

Light / infra red / heat source;

(Stop) clock / timer; 2

(d) (i) Increased {enzyme / microbial} activity; 1

[Do not credit increased population]

(ii) (Increased enzyme activity / decay) means more CO2 released / CO2 released faster than

being used up in photosynthesis;

Due to increased (microbial) respiration;

More CO2 (in the atmosphere) therefore more {global warming / greenhouse effect}; 2 [12]

SAQ 563(a) (i) Respiration / decomposition; 1

(ii) Nitrogen fixation / death of animals / organisms / excretion; 1

(b) Increase in photosynthesis; As enzyme activity increased; 2

SAQ 564

(a) (i) ecosystem is (self-supporting) system in which all organisms / community interact with

physical environment / community + environment / biotic + abiotic; 1

(ii) A + B + E + F + G + I; 1

(b) pygmy weed competes for CO2 / light / nutrients; reduction in numbers of original plantssome of original plant species lost; loss of habitats / niches / shelter / food sources; consume

die / some migrate; 3 max

Total 5

SAQ 565

(a) Tubifex/ sludgeworm / rat-tailed larva / midge larva / Chironomus larva / bloodworm

/ gnat larva / mosquito larva; 1

(b) Haemoglobin / respiratory pigment (in blood) ; Picks up oxygen (at low external

oxygen concentrations) / very high affinity for oxygen ;

Very thin body wall ; Short oxygen (diffusion) pathway ;

Blood (vessels) near body surface ; Short oxygen (diffusion) pathway ;

Waving tail ; Circulates water next to body / eq. ;

Reference to breathing tube / eq ; Goes to surface / to obtain oxygen from the

air ; 2 + 2 max 4

Presence of hairs / wing cases / elytra ; To trap an air bubble ;Credit other correct example]

SAQ 566


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Take a mean; Use stats to check results; eg Chi2, t -test or other suitable method; 4

(b) Lower light intensity/temperature; Reduces the rate of growth because less sugars

made/other suitable idea;

(Reject food) Wouldnt reproduce to produce more plants; 2 maxTotal 6

SAQ 568

(a) Decrease in pH linked to decrease in population; 1

(b) Use of pH meter / indicator / pH probe; 1 (Reject litmus)

(c) Quadrats; Large number / random sampling; Calculate the mean; 3

(d) (i) Provides oxygen for (aerobic) respiration; (by) bacteria / microorganisms; 2

(ii) Fewer bacteria / decomposers; Acid conditions inhibit enzymes / enzymes denatured; (H+

ions) affects enzymes active site; 2 max Total 9

SAQ 569(a) (i) many small trees with low mass (at start) and fewer trees surviving but with much grea

mass (to the left); 1

(ii) closer the trees are/larger the population, the more limited the resources per plant; 1

(b) reduces transpiration/evaporation of water from leaves; stomata do not open as much;

guard cells photosynthesise less/water potential changes; less water moves in transpiration

stream/drawn up xylem; 2 max Total 4

SAQ 570

a) The weasels and stoats belong to the third trophic level because they feed upon herbivores, which feed upon plants. The weasels and stoats are eaten by the foxes

cats(tertiary consumers) (3)

b). The stoats are larger than weasels. The mean mass of weasels is 75.56g and the mean m

of the weasels is 251.08g. So, the stoats are about 3 times larger than the weasels. (2)

c). Biomass is the mass of organisms. A large number of small organisms is equivalent to a s

number of large organisms. Since the prey organisms are of different sizes it is more meanin

to compare the biomass as it gives an idea of the energy consumed. (2)

d). The mice and voles are the main food of weasels and the hares are the main food of

stoats. Both eat more or less the same quantity of eggs and birds and other prey. (2)e)Both the populations have decreased during this period. The population begins to fall m

rapidly from 1975. The population of stoats levels off from 1990 but the weasel populatio

still decreasing. The number of foxes and cats will decrease as there will be less food for th

The number of herbivores will increase because fewer will be consumed. (3) (Total 12 marks)

SAQ 571


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(b) Increases sample size; More representative sample / reduces impact of anomalies; Increa

reliability; 2 max Total 4

SAQ 572

1Award 2 marks if the method would provide reliable quantitative data;;Award 1 mark if the

method would provide quantitative data but with some concernsabout reliability, such as tha

the method is subjective; 2 max

2(No mark awarded for number of trees)Sample large enough to minimise the effect of

anomalies / extremely large orsmall results;Sample sufficient for statistical test;Sample not to

large that work could not be completed in the time available; 2 max

3Height from ground;Diameter of treeSpecies of tree;Exposure to light/wind; 2 max(not quad

size or number of quadrats)4Any two fromTexture;Affects ability of species to attach / hold

water / other valid answer relating to texture;Run off of water down bark/water content of

bark;Affects nutrient availability / affects supply of water;pH;Affects enzyme activity inphotosynthesis/respiration 4 max

5(a) Light intensity;Temperature;Wind speed; 2 max

(b) Either affects rate of photosynthesis or desiccation/water content of cells; 1

6If percentage cover used as a measure of abundanceMeasurements are subjective;Some

squares are only partly covered;If frequency used as a measure of abundanceOnly recording

presence at a point;

Might not be representative; 2 max Total 15

SAQ 573 SN4 JAN 007 (2)SAQ 574(a) 1. Changes in (tree species I communities I eq) with trnme:

2. Seral stages I predictable changes I directional changes I eqr:g

3. changes bought about by trees themselves I eq:

4. Reference to climax

5. Relevant example from the data

2 marks

(b) 1. None at outset.,e

2. Biomass increase (with time)::e

3. Fall after 200 years4. Greatest rate ol increase between 80 and 120 years

5. Any other quantitative descnption:

3 marks

(C) 1. Soil conditions not suitable I lack c water I Lack of minerals I other abiotic factor:

2. Cannot compete with (alder Iwillow):

3. Didn't happen to coloniser::

4 Other (climatic I extemal} factor:

5. Species before (Hemlock spruce) change conditions: 2 marks Total 7 marks


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(a) (i) (Ecosystem) Abiotic factors/ environment / habitat and community/ biotic factors/ the

living organisms; Place must be stated or implied by .environment. / .habitat. / .community.

(ii) (Population) All the individuals of one species in an area / habitat /ecosystem /community

(b) (i) Use random numbers from e.g. calculator / computer / tables / phone book / etc;Allow

random number generatorUse of grids/ as coordinates; 2

(ii) (Large number) Need representative / .typical. / .reliable. / .valid. value / anomalies are le

significant/more detectable/ chance variations are less significant / allows statistical

test; Reject .remove. anomalies. Ignore .accurate. or .mean.. (At random) Overcome bias /

independent of observer/ is representative; 2 Ignore .fair.

(iii) Correct answer: 4.24/ 4.2 ;; = 2 marks OR Understanding ofn(n-1) + wrong answer/ 4.23

1 mark 2 max

(iv) Takes account of number of individuals / of population sizes; 1

(v) 1. Plants change conditions;Accept suitable example examples: add humus to soilimprov

water retentionprovide shelter

2. Competition/ environment more hostile/harsh/ some species make environment unsuitab

for other species;

3. Lack of/competition for named resource . water/ ions/ nutrients [ignore food]/ light;

4. Succession occurs;

5. Reduction in number of species; 4 max

(c) Animal diversity falls because: OR Animal diversity increases because:Any two from: Any t

from:

More exposure to climate / less shelter; Larger plants " more shelter / are more stable; Fewefood types/ less food;Fewer niches / habitats; " more niches / (micro)habitats;Fewer animal

species survive/stay; More animal species survive/enter; " more food types; 2 max Total 15

SAQ 576

(a) Place quadrats at random coordinates / described; (Ignore throwing) Score mean no. of

thistles per quadrat / total for all quadrats; Mean x 5000 / mean x (ratio of area of field : area

quadrat) / / total x (ratio of area of field : area of all quadrats); 3

(b) Initial sample too small / marked recapture sample too small; Small change in data would

give large change in population estimate / leads to overestimate of population; Or Paint on

shells ! more visible to predators / paint toxic / paint comes off; ! overestimate of populationsize; Or One day too short; Too many marked snails recaptured ! underestimate of populatio

size / too few marked snails recaptured ! overestimate of population size; 2 max Total 5

SAQ 577

(a)1. fixed / constant area ;

2. reference to sampling ;

3. valid comparisons possible ;

4. easy so can be repeated ;

(b)1. sampling along changing conditions / environmental gradient ;

2 systematic sampling /random sampling does not show distribution / eq ;


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4. different species present ;

5. credit figures (e.g. 3 times more plants, 2.4g more matter, 17 more species) ;

SAQ 578

(a) Suitable method with detail;; For example: Kick sampling with net; Detail, such as time of

kicking/area kicked/number of kicks; 2

(b) (i) Breed together organisms (of different colours), if fertile offspring then same species; 1

(ii) 1.068, 1.07;; 2

(62 x 61/(60 +59) + 2 OR 3782/3542 gains 1 mark)

(c) Two suitable advantages For example: Takes account of number of individuals and numbe

species; Species do not have to be identified; Do not have to know oxygen requirement of

individual species; 2 max Total 7

SAQ 579

(a) Quadrat placed (along line) at 1 metre / regular intervals; Count number / calculate per m

(b) pH; Linked to nutrient availability / enzyme activity; Nutrient; Effect of named nutrient on

growth;

Light; Adapted to lower light availability for photosynthesis;

Air movement; Notadapted to water loss; 2 max (Allow other abiotic factors with explanation

e.g. temperature and enzymeactivity)

(c) (i) Number of seeds; Amount of nutrients; pH; Temp; Light; Carbon dioxide; Size of pots;

Spacing of seeds; 2 max(ii) A Ranunculus bulbosus B Ranunculus acris C Ranunculus repens 1

(iii) Breed together; Production of fertile offspring (if same species); OR Use of DNA; Similar b

sequence / fingerprint; 2Total 9

SAQ 580

a) Dead cells contains hollow like tubes

2. (No I reduced1 (end I cross} watts:

3. Lignin qualified with reference to water e.g. waterproofing / strengthens to withstand

pressure.:s4. Pits for lateral movement (of water): 2 mark

b) (Forces of) adhesion:Intermotecutar force between water and (celluloseI(ignin):

(Forces of) cohesion: Intermolecular force between water molecules: Putted up xylem b

transpiration /correct reference to evaporation as driving force: Difference in water

potential /(hydrostatic) pressure.:i Root pressure/described in terms of osmosis in roots

mark

c) (i) InterceLlular cement I calcium pectate I middle LameUa / helps to hold cells togeth

(ii) For making chlorophyll I enzyme cofactors: (hi) Making (protein I DNA I RNA I ATP}: 3

mark


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4. Not enough time between tides to eat a mussel:

5. Reference to explanation of the one dog whelk at site 3:

6. Identify one biotic or abiotic factor in context: 3 marksTotal 11 marks

SAQ 581(a) (i) Organic matter increases with distance ; Number of species rises ; Up to {500 m / site 4

falls {beyond 500 m / site 4 / at 650 m / site 5}; 2 marks

(ii) 1. Less organic matter, fewer nutrients ;

2. Unstable substrate ;

3. Few species can tolerate ;

4. Reference to pioneer species ;

5. Increased organic matter suits more species ;

6. Reference to increased competition ;

7. Fewer species where good soil due to climax community established ;

4 marks

(b) (Plant community that) no longer changes (in species) composition / eq ; (Due to) success

;

Dominant species (for climate) most abundant ; 2 marks

(c) In both change to conditions to suit other species / community / eq ; In both changes in

{species / distribution of species} with time ; In sandy shore see all stages, in body see only on

stage / eq ; 2 marks

(d) Defined area / quadrat ; Method for choosing position (e.g. random, transect) ; Method oestimating cover described ; 2 marks Total 12 marks

SAQ 582

(a) (i) change in community over time; either due to change environmental/abiotic factors /

change is due to species

present; 2

(ii) stable community/no further succession/final community; 1

(b) (increased) interspecific competition; for light/nutrients/named nutrient/water;

(c) fewer leaves/lower surface area/shading of leaves; less photosynthesis to produce newbiomass/glucose/growth;

competition with other species for nitrates/named nutrient; reduced synthesis of protein or

named compound; ratio of leaves to woody parts and roots decreases; so higher respiration

relative to photosynthesis; 3 max Total 8

SAQ 583

(a) (Grass) not mowed / grazed by domestic animals / livestock /eq ; Shrub seedlings

allowed to grow / not eaten /eq ;Reference to leaf lifter from shrubs smotheringgrasses / shading effect : Max 2


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number of niches / habitats ;

Increase in different types of food ;Increase in different types of nesting /

roosting site ; Max 2

(d) Accept points in converse but must state in shrub community;More predators

(in pine) ;Birds may have larger territories Greater diversity may cause increased competition

;Decrease in nestin/ roosting sites ; Leaf lifter more acidic, supports fewer (insect)

species as food for birds less food available ; Max 2

(e) (Secondary) succession; 1

(f) Cutting of trees / deforestation /eq ;Introduction of new species / aliens / disease

(e.g. Dutch elm) ;

Natural disaster / flooding / storm damage / volcanic activity / fire /eq

;Climatechange / acid rain; Max 2[11]

SAQ 584

(a) Climax community; 1

(b) One method with explanation e.g. Regular grazing / cutting . young shoots eaten / preven

succession;

Herbicides . kills herbaceous plants; Ploughing / burning - destroys seedlings / plants; 1 max

(c) Rapid process; Large number produced; Only one plant required; No variation linked to

advantageous characteristics; 3 Total 5

SAQ 585

(a) Mowing grassland kills other plants/prevents succession; (Once mowing stops) competitio

occurs;

Changes in community lead to changes in abiotic/edaphic factors; Allowing

trees/woodland/climax community to become established; 3 max

(b) Temperature (of air) may affect transpiration/enzymes/temperature of soil as this may af

enzymes;

Wind speed as this may affect rate of transpiration / seed/pollen dispersal; Light intensity as

may affect (LDR of) photosynthesis; Edaphic factors/named factor as this may affect nutrientavailability / soil

organisms; (Accept pH of soil affecting enzymes, reject pH alone) Humidity as this may affect

of transpiration/water loss; 3 max (Award mark for factor measured and explanation)Total 6

SAQ 586

(a) 1. colonisation/pioneering;

2. microscopic plants at start;

3. death / decomposition;

4. named change in environment e.g. increase in organic matter/ stabilisation;

5. new species colonise once there is a change;

6 increase in number of species/diversity;


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one mark . direct result of removing forest cover;e.g. soil erosion/leaching one mark . specific

effect on organisms in lake; e.g. more sediment/nutrients (for plants to grow) 2

(c) 1. named nutrient availability;

2. numbers of producers providing energy (for a food chain);

3. light intensity affecting the rate of photosynthesis;

4. disease killing (weaker) members of species;

5. space for nest building / niches;

6. reproductive rate balancing death rate;

7. competition for a named limited resource;

8. (intra and interspecific) competition explained;

9. predation described; 5 max Total 13

SAQ 587

(a) (i) (collect and) dry all above ground plant material; (reject collect one/ small sample/who

plants)

in an oven at or just below 100 oC; weigh and repeat until constant mass; other precaution, e

cooling in desiccator; 3 max

(ii) large number of sample areas / repeats; randomly selected; 2

(iii) drying destroys plants, so different samples needed; large area, so difficult to get

representative samples; difficult to measure biomass of trees; variability in growing conditionvariability of abiotic conditions in different areas of forest; 2 max

(b) (i) 1:25 1

(ii) most of the plants are trees/large; high proportion of dead / non-photosynthesising biom

herbs grow rapidly/small so large percentage increase; herbs have higher productivity, so rat

lower at 10 years; 2 max Total 10

SAQ 588

(a) two suitable examples, e.g.

reduction in insect predators from ponds, because ponds kept shallow;reduction in animals that prefer pH outside 5-7, because lime added;

reduction in species that feed on/live on trees/shrubs,

because these are removed/eaten by sheep/rabbits; 2 max

(b) conservation (measures) tends to stop this;

keep communities the same;

(adding lime) stops abiotic change/pH change;

no climax community/community of trees and shrubs;

sheep/rabbits prevent growth of shrubs/trees; 3

SAQ 589


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effect is how the sun keeps the Earth warm whereas global warming is an increased greenho

effect / greenhouse effect causes global warming;

Two marksAs for one mark plus further detail: Global warming is {an increase in global me

surface temperature/ average of measurements made in many different places throughout t

world} / current global warming may be due to (anthropogenic) burning of fossil fuel / global

warming is a fact whilst greenhouse effect is a theory / two greenhouse gases named;;

Three marks (makes the contrast with some detail and which clarifies fact and conjecture and

clearly disentangles global warming, greenhouse effect and the possible role of burning fossi

fuels):

As for two marks but also: widely believed that (some clear implication that it may not be th

only explanation) current global warming is due to {enhanced/increased} greenhouse effect d

to raised CO2 concentration (of the atmosphere) / global warming may be caused by someth

other than greenhouse gases e.g. changes in solar radiation;;; 3

(b) (i) any reasonable attempt at a J shaped curved best fit line; 1(ii) credible attempt at extrapolating the line as a curve; for correctly reading both points off

candidates own extrapolated graph; (would expect 0.5 C for 2000 and around 1.2 C for 2020

extrapolated as a curve or 1.0 C extrapolated as a straight line) for subtracting to get increas

using own figures (e.g. 1.1-0.5 = 0.6 C) including units; 3

(iii) assumes present trend continues; line not based on long enough series of data / older da

may be less accurate / reliable; (graph shows) that temperature has fluctuated (over period

18802000); numerical evidence taken from graph to illustrate an occasion when the

temperature fell approx 1900 to 1908 or approx 1945 to 1970; ALLOW any reasonable attem

to use figures to make a valid point about predicting future climate from these data; someunpredictable event may affect trend e.g volcanic eruption / sharper than expected change in

fossil fuel consumption / changes in solar radiation; 3

(c) enzymes temperature sensitive / damaged by high temperature; damage to enzymes may

affect respiration / metabolic activity / photosynthesis / supply of energy; may give competit

an advantage; may affect water availability; may affect supply of food plants / prey species /

predators; change of sex ratio in reptiles / crocodiles; 2 [12]

SAQ 590

SAQ 591

(a) 1. Long term weather datasets / (direct) temperature records;

2. Pollen analysis / use of pollen;

3. Dendrochronology / study of tree rings;

4. Melting of {polar ice / glaciers};

5. Phenological records;

6. Coral bleaching; 2

(b) (i) 1. Dust cloud;

2. Less {sunlight / solar radiation} / blocks out sun;

3 Got colder / global cooling;


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(ii) 1. Increased volcanic activity; Leading to {more sulphurous gases released / reflection of s

radiation / more carbon dioxide / change in greenhouse effect};

2. Competition from {other types of animal / mammals}; {Newly evolved animals / mammals

{are better adapted to / can adapt faster to} changing conditions;

3. {Temperature / climatic} changes caused by factors other than meteorite collision / named

alternative cause of {temperature / climate}; An example of a valid consequence of this;

4. Disease; 2

(c) Become more {common / abundant} / grow in different places / altered distribution / spre

further {north / south / to different altitudes} / change in breeding patterns; 1

(d) (i) Water vapour; Oxides of nitrogen / {NOx / NO2 / N2O / NO / named compound};

Methane; CFCs / chlorofluorocarbons; 2

(ii) Increase in solar radiation / change in earths magnetic field / change in earths angle of

rotation / decrease in snow cover / increase in greenhouse gases from a source other than fo

fuels e.g. {volcanic activity / biological methane production / more water vapour in atmosphe/ more use of CFCs} / deforestation; 1 [11]

SAQ 592

(a) Remote sensing / satellite (images) / GIS / Global imaging system / OTCS; 1

(b) (Algae supply polyps) with {sugar / carbohydrates / energy / food}; (Algae supply polyps) w

oxygen; Any credible suggestion why colour is an advantage to the polyp; 2

(c) 1. Some (species of) coral become less common / other types become more common (and

take over);2. Reference to competition;

3. Existing species {become adapted to change / evolve};

4. Correct reference to mutation;

5. Improved conservation measures (to alleviate effects of human interference)

6. Increased sea temperature was not the real reason why the reef was in decline suggested

credible alternative e.g. {pollution / predation / disease} / whatever the original cause {has no

declined / no longer the problem it was}; 2 [5]

SAQ 593a)The bacteria and yeast in the rumen produce cellulase enzyme. This enzyme breaks do

cellulose into simple sugars. This mutualistic relation enables the herbivore to obtain ene

from cellulose and provides nutrition for the microorganisms as well. The cattle regurgitate

food and chew it continuously. This increases the surface area for digestion. (3)

b)((175 715 - 160 572) 160 572) x 100 = 9.43%(2)

c)Both emissions of methane and carbon dioxide increase during the period. The emissions f

dairy cattle and sheep have decreased because their numbers have decreased. Ther

increased emission from beef cattle because their numbers have increased. This may be due

change in the human diet, which may have changed to prefer more beef products. (3)

d)Methane may be produced by swamps, landfill sites, leaking biogas tanks, peat bogs, pa


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e).Short wavelength solar radiation (400 to 700nm) penetrates the atmosphere and

converted into longer wavelength infrared radiations (4000 to 100,000nm). These lon

wavelength radiations are trapped by gases in atmosphere and radiated back to the earth.

prevents heat from escaping into space. This is called green house effect. The insulating g

are called green house gases. CO2, CH4, N2O, CFCs, O3, H2O are green house gases. Green ho

effect is a natural phenomenon, necessary to maintain the temperature of the ear

atmosphere, which would otherwise be about 30C lower than today. However, human activ

in recent years have led to an increase in release of green house gases. This may cause

increase in global temperatures called Global warming. (3)

f)The global warming potential of methane is 21 times more than the global warming poten

of carbon dioxide. (2)

g). (i)Because the other gases have increased more than carbon dioxide. (1)

(ii)More rearing of cattle and increases use of landfill sites leads to an increase in meth

production.More fridges, computers, aerosols, fire extinguishers leads to increased use of CFCs. More

engines(more use of fossil fuels) and more use of nitrogen fertilizers leads to more productio

nitrous oxide. (3) (Total 19 marks)

SAQ 594

a) ((5.2 4.7) 4.7) x 100 = 10.6%(2)

b) Increase in the number of motor vehicles and increase in the demand for electricity ffossil fuels. (2)

c) The graphs show a general increase in the global temperature as the fossil fuel use increa

However, there is a decrease in global temperature in 1910 during which period there is

corresponding decrease in fossil fuel usage. (3)

d)Fast growing plants as a fuel will recycle carbon dioxide in a short period of time. this

prevent the carbon dioxide concentration from increasing in the atmosphere. Since,

emission of greenhouse gases decreases, global warming is slowed down. (3) (Total 10 mark

SAQ 595

(a) A suggestion to include three from:

1. reference to seed (not pollen) dispersal by wind / animals;

2. reference to a specific adaptation (of fruits) that aid dispersal by wind for example, wings /

parachute / eq;

3. reference to a specific adaptation (of fruits) that aid dispersal by animals for example, cont

food for animals / may have hooks which stick to animals fur;

[N.B. candidates are not expected to know about how individual species are dispersed but on

about adaptations for dispersal in general therefore examples of methods of dispersal need nrefer specifically to pine, hazel or oak] 3


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2. therefore it will take many generations to cover the distance (750 km);

3. suitable reference to slowness of climate change / temperatures would rise more slowly /

ice would take longer to melt in the {north / Scotland};

4. long time to reach reproductive age / eq; [Reject long to grow unqualified]

5. oak requires warmer conditions than pine / differential response to pine against oak;

6. dispersal limited by low number of animals; 2

(c) (i) An explanation to include:

1. need to find a place nearby with peat / take a peat core / look at layers in the peat / the

deeper the layer the older the pollen / eq;

2. pine and oak pollen look different; [Accept types of pollen are different]

3. reference to method of identifying pollen 2

(ii) pine (pollen) would be in deeper layers than oak; correct reference to relative abundance

pine / oak pollen 1

(d) An explanation to include three from:1. they assume that current trends will continue / we cannot be sure current trends will

continue;

2. there is only limited amount of long term data used to produce them /eq / older records m

have been made with inadequate equipment;

3. something unforeseeable may happen / not all the relevant factors may have been include

the model / appropriate reference to chaos theory;

4. many factors involved / inadequate computing power; 3 [11]

SAQ 596(i) (Arrow pointing) between the bark and the xylem vessels (including grey area) ;1 mark

SAQ 597

(a) The use of satellites to {obtain information about / collect data about / to monitor the

earths} {global environment / biological change};

The satellites carry (electron) sensors;

Over very {large / inaccessible} areas / example;

Example of sensor systems that might be carried in satellites e.g. Ocean Colour and TemperatScanner (OCTS), LANDSAT, Sea WIFS; 3

(b) {Sea / land} surface temperature;

{Distribution / abundance / photosynthetic activity} of phytoplankton;

Distribution of (types of) vegetation cover / eq;

(e.g. cloud / ice cover) 2

(c) 1. Pollen analysis / collect pollen grains preserved in peat bogs;

2. The deeper the layer the older the pollen in it / use of 14C dating to date the layers (the

pollen is found in);

3. Pollen from each species {distinctive / can be identified};

4. Compare with present day distribution of species and climate;


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SAQ 598

(a) Access for {pollinators / pests / parasites}; Wind exposure; Light intensity; Light spectral

composition; Wavelength / spectral composition of light; Rainfall / snow cover / soil moisture

water availability; Grazing by animals; Humidity / water vapour; {Carbon dioxide / oxygen}

concentration; 3

(b) (i) Dendrochronology; 1

(ii) Increases;

Any valid attempt to quantify the increase in growth e.g. more than double, at least 5 (or

more);

Sustained for (at least) three years (at a similar rate); 2

(c) Pollen analysis / use of pollen from peat; Layers dated according to the depth / the deepe

the {sediment / peat layer} the older the specimen / date the peat layer by radiocarbon meth

Identify species in different layers / estimating relative abundance from pollen density / eq; 2(d) More carbon dioxide turned into wood / more photosynthesis; Therefore more carbon

dioxide removed from atmosphere / increased carbon dioxide absorption; Therefore less

greenhouse gas (than there otherwise would be); 2

(e) Increased rate of decay; Due to increased {microbial activity / enzyme activity}; 2 [12]

SAQ 599

SAQ600

(a) (i) Any unambiguous attempt to label the outermost layer (inside the bark) ; 1 mark(ii) 1999 ; [Accept 2001 ifthe candidate has incorrectly labelled the centre as 2003 or 2002

the previous ring inside has been labelled 2003] 1 mark

(b) (i) Three measurements totalled and divided by 3 ;Correct answer with units in the rang

to 4 mm / 0.3 0.4 cm ; 2 marks

(ii) A description to include two from:

1. (generally) the more rainfall the greater tree growth / converse ;

2. specific reference to the fact that the correlation is not a perfect one ;

3. reference to a specific anomaly, for example, 2003 value /

the differences between the size of the rings is much bigger in proportion tothe differences in rainfall ; 2 marks

(c) A suggestion and an explanation to include:

1. increased temperature increases growth / leads to wider annual rings ;

2. reference to enzymes / reference to increases growth within a particular temperature

range / along as the temperature is not so high that it denatures enzymes / unless high

temperature lead to drought ;2 marks

(d) (i) (coppicing is a) renewable (energy source)/ can be replaced by growing some more /

same piece of ground can be used over and over again /reduces reliance on fossil fuels / no

renewables / carbon neutral ; 1 mark

(ii) An explanation to include three from:


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(no net increase of CO2

or CO2

taken up or by CO2

release)

4. (so) no increase in greenhouse effect / no (extra) {heat / infra red} absorbed /

trapped by atmosphere ; 3 marks Total 12 marks

SAQ 601(b) (i) respiration

Photosynthesis

(ii) carbon dioxide removed from air for photosynthesis is converted to plant bio mass /

organic matter/ wood more carbon dioxide taken up than given out in respiration

by living organisms

(c ) increase in carbon dioxide causes global warming

Higher temperature increases (respiration /decay)

Ref to temperature dependency of ( enzymes /bacterial action of decay)

(dead organism ) matter in soil breaks down

(releasing ) carbon dioxide faster than its taken up for photosynthesis

Any correct ref to deforestation

(d) 1. Some other factor has not been ignored sn2 jun 3

SAQ 602

SAQ 603

(a) proportion of total alleles ; for one gene (in a population)/eq ; 2 marks

(b) different alleles exist / ref mutation ;advantage in specific environment ;ref selection

pressure ;more likely to reproduce ;allele passed to offspring more often ;

ref at disadvantage in other environment ;Allow converse argument4 marks(c) faster life cycle of bacteria/converse/ eq ;greater selection pressures on bacteria (eg

antibiotic use) ;

ref plasmid transfer in bacteria/eq ;larger numbers of bacteria hence larger gene pool/eq ;ref

mutation ;2 marks

Total 8 marks

SAQ 604

(a) same genus / reflects close relationship /eq ;

(b)1. isolation of populations; / reproductive isolation /eq ;


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5. (reference to effects of local conditions on) allele

frequencies ;

c)1. requires co-ordination between governments / eq ;

2. (government might have) different approaches to

conservation / e.g. tourism / eq ;3. (government might have) different needs for local

populations / different wealth of countries / eq ;

4. leopards know no boundaries ;

SAQ 605

(a) Kingdom, class, family, genus; 1

(b) (i) (Human)

FishRhesus monkey

Horse; 1

(ii) As animals closely related, more amino acids in sequence; 1

(c) The more similar the DNA, the more similar the base sequences; The greater the number

hydrogen bonds/bonds between base pairs; More energy/heat needed to separate strands; 3

(Q Correct terminology of base, base pair and hydrogen bond must be used as specified in

scheme.) Total8

SAQ 606

SAQ 607

SAQ 608


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TOPIC FIVE - Stafford Papers (Marking Schemes)

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