7040 Biology Subject Report Mark Scheme June 2004

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Mark Scheme and Examiner’s Report

Mark Scheme with Examiner’s ReportGCE O Level Biology (7040)

London ExaminationsJune 2004Scheme and Examiner’s Re

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Page 1 of 20 Edexcel International, O Level Mark Scheme with Examiners’ ReportBiology 7040, June 2004

BIOLOGY 7040, MARK SCHEME

Symbols used in the mark scheme

; indicates separate mark points/ indicates alternativeseq allow for correct equivalent__ word underlined means no alternatives allowedmax maximum

Paper 1

Section A

1 (a) digested;straight into the blood / quicker;

(1 max)

(b) level/amount of oxygen (1)

(c) larger lumen;closer to surface / easier to see;thinner walls;lower pressure / less bleeding; (2)

(d) more (once) red blood cells/haemoglobin produced;(more) oxygen;

(more) respiration;no/less anaerobic respiration;no/less lactic acid / oxygen debt; (3 max)

(e) rapid breakdown / levels too low;

occurs naturally / no difference between natural and injectederythropoietin/EPO;no difference between natural and injected EPO; (2)

(f) loss of water;increase in viscosity/thickness/concentration; (2)

(g) improves/more gas exchange;more red blood cells;(more) oxygen absorbed/taken up; (2 max)

(h) replace red cells / not enough red cells; (1)

(Total 14 marks)


2 (a) (i) exhale into syringe;both clips opened then closed; (2)

(ii) less carbon dioxide;more oxygen;less moisture;cooler; (or converse) (3 max)

(b) (i) 11+12+14+15+17 ÷ 5;13.8 ÷ 14;

(2)

(ii) (55 – 35 ÷ 35) x 100 or (20 ÷ 35) x 100 or eq;57.1 or 57.14 (2)

(c) more ventilation in exhaled than in atmospheric /increased rate in exhaled;rate goes down in pure oxygen / rate faster in 90% oxygen; (2)

(Total 11 marks)

Section B

3 (a) (i) Oestrogen;Progesterone / follicle stimulating hormone/FSH;luteinising hormone/LH; (2 max)

(ii)Hormone Site of Production Target organ / cells Effect

Oestrogen Ovaries uterus /pituitary /site of namedsecondary sexualcharacteristic;

uterus lining thickens /repair / stimulatesdevelopment ofsecondary sexualcharacteristics / namedcharacteristic / inhibitFSH / stimulate LHrelease;

Progesterone Corpus luteum /yellow body /Placenta;

uterus / pituitary; maintains uterine lining /inhibits ovulation /maintains pregnancy /inhibits FSH/LH;

FSH Pituitary gland; ovaries; initiates development offollicle / stimulatesoestrogen release;

LH Pituitary gland; ovaries; ovulation / developmentof corpus luteum /stimulates progesteronerelease;

(6 max)

(iii) named hormone increases / decreases;same named hormone decreases / increases; (2)


(b) (i) auxins; (1)(ii) shoot/root tips / apical meristems;

Stimulates/inhibits cell elongation/growth (allow appropriate tropicresponse); (2)

(c) (i) front (of brain) / forebrain;intelligence / learning / memory / senses etc; (2)

(ii) back (of brain) / hind brain;balance / posture / coordinated movements; (2)

(iii) lower part of the brain / below cerebellum;reflexes / heart rate / breathing rate / etc; (2)

(d) Experimental design questions are often marked to the following scheme.See the Chief Examiner’s report at the end of this booklet for a fullerdescription.

two named areas; Control (C) mark

repeat stimulus / use several people; Replication (R)mark

observed response (qualitative or quantitative); Measurement (M)mark

identify / describe stimulus;uniform stimulus (same pressure/temperature etc);

Standardised (S)mark

different sensitivity; Results markmore receptors/nerve endings;

(6 max)

(Total 25 marks)


4 (a) Peristalsis;Oesophagus / gullet;churning action;pepsinogen;pepsin / protease;digestion / breakdown;protein;Polypeptides / amino acids;Hydrochloric acid/HCl;optimum/best pH;kills bacteria/pathogens; (8 max)

(b) glucose;amino acids;fatty acids;glycerol; (4)

(c) diffusion;active uptake/transport; (2)

(d) hepatic vein;vena cava;right atrium;right ventricle;atrio ventricular/tricuspid valve;heart;Pulmonary artery;semi lunar valve; (5)

(e) Experimental design questions are often marked to the following scheme.See the Chief Examiner’s report at the end of this booklet for a fullerdescription.

coffee and no coffee / range of doses; Control (C) mark

same age/sex/mass/diet; Organism used (O)mark

several people / same person several times; Replication (R) mark

how rate measured; (take pulse / use heartmonitor etc)measure before and after coffee;

stated time delay;stated other control factor;(volume of coffee / time of day /activity level etc)

Measurement (M)mark


(6 max)

(Total 25 marks)


5 (a) no oxygen;less energy/ATP;lactic acid;in animals; (linked)ethanol (and carbon dioxide);in plants; (linked) (or converse) (5 max)

(b) Experimental design questions are often marked to the following scheme.See the Chief Examiner’s report at the end of this booklet for a fullerdescription.

seeds and no seeds; (dead seeds / glass beads etc) Control (C) mark

mass/number/volume/species of seeds; Organism used (O)mark

thermometer; Measurement (M)mark

left for stated time ( 1 hour – 1 week);sterile conditions;‘sealed’ air access / cotton wool;soaked/moist seeds;


(6 max)(c) (i) producer carries out photosynthesis / is plant /

autotrophic;herbivore consumes producers/plants;carnivore consumes animals/meat / is predator; (3)

(ii) shape as pyramid;each trophic level labelled correctly (names fromfood chain or technical terms); (2)

(iii) loss of energy;between trophic levels / along food chain / betweenorganisms;example of how energy is lost egrespiration/movement/excretion/undigested/uneaten; (3)

(d) carbon dioxide (in air);Photosynthesis;plants;eaten by animals;correct reference to respiration;decay / decomposition / rotting;combustion; (6 max)


6 (a) nitrate; (ignore nitrogen)protein/amino acids;Phosphate;ATP/DNA;Magnesium;Chlorophyll;calcium;cell walls;Potassium;active transport / stomatal opening / protein synthesis /photosynthesis / respiration;iron;chlorophyll / respiration / photosynthesis; (6)

(b) Experimental design questions are often marked to the following scheme.See the Chief Examiner’s report at the end of this booklet for a fullerdescription.

both brands used; Control (C)mark

same crop plant / seeds same age; Organism used(O) mark

same/stated number/mass seeds /same/stated number of plants;

Replication (R)mark

height/length/mass/yield/number of leaves (quantitative); Measurement(M) mark

stated time (1 week to 6 months);same medium/soil;stated factor (light/temperature/carbon dioxide etc)

Standardised(S) mark

(6 max)(c) leaching;

soil erosion;Eutrophication / algal bloom;water cycle – less transpiration;

less rainfall;flooding;loss of habitat;species extinction / food chain problem;less photosynthesis / less CO2 absorbed / build up ;Greenhouse effect / global warming; (7)

(d) plant survives / not eaten;no need for chemical pesticide; (2)

(e) (i) (living organism/predator) used;eat/kill pest; (2)

(ii) lasts longer;specific;non polluting / environmentally friendly;no reapplication; (2 max)

(Total 25 marks)


7 (i) outside of/around cell;maintains shape/rigidity/turgidity of the cell; (2)

(ii) located inside cell wall / surrounds cytoplasm;controls / lets substances entering and leaving cell; (2)

(iii) inside cell membrane / surrounds vacuole;chemical reactions carried out; (2)

(iv) in cytoplasm;controls cell division/cell development/protein synthesis; (2)

(b) animal cell has no chloroplasts/chlorophyll;animal has no cell wall;animal stores glycogen;animal has small/no vacuole; (or converse) (4)

(c) (i) iodine solution;blue/black colour; (2)

(ii) Benedict’s solution;heat;red colour; (3)

(iii) Biuret solution (NaOH + CuSO4);Purple/lilac/mauve/violet colour; (2)

(d) Experimental design questions are often marked to the following scheme.See the Chief Examiner’s report at the end of this booklet for a fullerdescription.

two or more different concentrations; Control (C) mark

same potato or same type of potato; Organism used (O)mark

repeat experiment or several pieces in eachconcentration;

Replication (R)mark

length / mass / volume;initial and final measurement;

Measurement (M)mark

blotting / left for ( 20 mins - 24 hours) /same temperature;


mass/length/volume increases in dilute solution;(or converse)

Results mark

(6 max)

(Total 25 marks)


Paper 2

1 a) A Right atrium; (1)B Vena cava; (1)C Aorta; (1)D Pulmonary vein; (1)

b) (i) Lungs; (1)

(ii) Increase in oxygen / into blood;Decrease in carbon dioxide / out of blood; (2)

(Total 7 marks)

2(a) (i)

Food Carbohydrate Fat Protein

(peas) 7.7 0.0 5.0

Lamb; 0.0 22.1 23.0

Wine; 0.3 0.0 0.0

Rice; 86.8 1.0 6.2(3)

(ii) 87.3 (g); (1)

(b) vitamins / named vitamin;minerals / named mineral; (2 max)

(c) eitherethanol;water + white / cloudy / milky;

or

or

or

Sudan III;red;

osmic acid;black;

rub on paper;translucent / lets light through; (2)

(Total 8 marks)


3 (a) Compound eyes;one pair/two antennae;three pairs/six legs;three body parts / head, thorax and abdomen;wings; (3 max)

(b) (i) B – egg(s);C – larva(e) / maggot;D – pupa(e) / chrysalis;; (3)

(ii) D; (1)

(iii) takes longer / eq;less/slower respiration/metabolism / reactions / enzyme activity; (2)

(Total 9 marks)

4 (a) (i) amylase; (1)

(ii) maltose; (1)

(iii) Denatures/deforms/destroys enzymes; (1)

(b) glucose; → alcohol/ethanol + carbon dioxide; (2)

(c) kill/prevent growth of pathogens/bacteria/micro-organisms/yeast;prevent further fermentation/reactions; (1 max)

(Total 6 marks)


5 (a) Graph axes; (correct orientation and label and units )points;;line; (straight line through points no extrapolation)scale; (linear and half both axes) (5)

(b) 440 high(est);560 low(est ) / decrease from;680 high / increase from;720 low / decrease from; (3 max)

(c) dark blue;red; (2)

(d) Condition Change in rate of photosynthesis

Decrease in temperature Decrease in rate

Increase in carbondioxide / light; Increases in rate

Increase/decrease lightintensity/carbon dioxide;

Increasing/decreasing light intensity / carbon dioxideincreases / decreases photosynthesis;

(4)

(Total 14 marks)

6 (a) transpiration;stomata / stoma;evaporation;diffusion / high to low concentration; (3)

(b) (i) increased amount collected (0-3h);stops / no more water collected; (2 max)

(ii) light intensity lower;stomata close;less diffusion; (or converse)

amount of water in air increases;gradient / less difference;less diffusion; (or converse)

temperature lower;less kinetic energy;less diffusion; (or converse) (3)

(c) surface area/number/size of leaves/shoot/plant;light intensity;temperature;water supply;time; (2)

(Total 10 marks)


7. (a) as a control;to observe behaviour of beetles in normal conditions;no other factor affects distribution;to compare distribution with Experiment 2; (2)

(b) so light does not affect the Tribolium/experiment/results: (1)

(c) either

or

cobalt chloride paper;pink on moist;

anhydrous copper sulphate;blue on moist; (or converse) (2)

(d) (i) beetles show a preference for the dry side/avoid the moist side;found in dry conditions / flour is dry / survive better in dry; (2)

(Total 7 marks)

8. (a) (i) producer;flowers / stems and roots / fruits and seeds / plankton;voles / molluscs / insect larvae / field mice / crustacean;skylarks / field mice / sprats / owl;tertiary consumer; (5)

(ii) flowers → insect larvae → skylarks → short eared owl;;stems and roots → molluscs → skylarks → short eared owl;mistake in food chain = 0 (2)

(b) if one source of food is reduced other is available;this ensures owl survives / maintain population/numbers; (2)

(c) claws; to hold / grab / kill prey;beak; to rip flesh etc;eyes at front; 3-D / distance / depth;eyes/pupils large; see in dark/see clearly/further;wings; catch prey in air / fly after prey;feathers; camouflaged / dark not seen by prey; (4)

(Total 13 marks)


9 gene / allele / DNA;restriction / endonuclease;plasmid;ligase;DNA;fermenter / bioreactor;diabetes; (7)

(Total 7 marks)

10 (a) D;G;F; (3)

(b) attract insects; (1)

(c) nectar; (1)

(d) transfer of pollen by insect;from anther to stigma; (2)

(Total 7 marks)

11 (a) (i) HH;Hh; (2)

(ii) Parents:Gametes:Offspring:

hh and Hh;hhh

H, h;Hh; (3)

(b) Phenotype ratio Tick1:13:11:2:1 �

1:1:1:1 (1)

(c) block/narrow blood vessels / atheroma;coronary artery;stop/decrease oxygen;anaerobic respiration / lactic acid / angina;heart attack; (3 max)

(d) (i) neutralise stomach acid / maintain alkaline pH / raise pH;emulsify fat / large drops to droplets;increase surface area;speeds up digestion / enzyme action; (2 max)

(ii) reference to nerve (cells) / neurones; (1)

(Total 12 marks)


BIOLOGY 7040, CHIEF EXAMINERS REPORT

The examiners were once again impressed by the knowledge and understanding shown bythe candidates on both of the papers. The candidates were able to describe and explainbiological processes and apply their knowledge and understanding to related areas. We werepleased to note the continuing improvement in candidates’ scores on those items involvingexperimental design.

Paper 1

Most candidates were able to answer the questions in the time allowed and there was littleevidence of them running out of time. A few candidates failed to follow the rubric andattempted to answer more than three questions from Section B. These candidates penalisethemselves by wasting time on questions which will not yield them any marks. We askcentres to remind candidates to follow the rubric and therefore maximise their chances of ahigher grade.

Section A

Question 1

This referred to a printed passage on erythropoietin (EPO), a protein hormone produced bythe kidney. Candidates generally performed quite well on this item with several gaining fullmarks.

In part (a) candidates often recognised that the hormone acts quicker if injected, but fewerrealised that if taken by mouth, the hormone, being a protein, would be digested.

Most candidates gained credit for stating that the level of oxygen stimulated EPO productionbut some failed to earn the mark in part (b) because they did not specify level, concentrationor amount of oxygen.

The better candidates usually earned at least two out of the three marks available in part (c)but very few made points about larger lumen, being closer to the surface, having thinnerwalls or having a lower blood pressure.

In part (d) most responses correctly identified that an increase in red blood cells would leadto better transport of oxygen and therefore increased respiration rate, less anaerobicrespiration and lactic acid build up.

In part (e) candidates needed two reasons why cheats are hard to detect. Most recognisedfrom the passage that EPO is rapidly broken down, few noted that it is naturally releasedfrom the kidney.

In part (f) responses that were worthy of credit noted the loss of water from the blood and theresulting increase in blood viscosity or concentration.

Candidates were able to describe the increase in red blood cells in part (g), but only the bestwere able to link this to improved absorption of oxygen in the lungs.

In part (h) some answers did not earn credit because they described a shortage of blood butdid not specify red blood cells.


Question 2

This required candidates to interpret experimental data from a study of locust gas exchange.

In part (a) most candidates were able to suggest blowing into the syringe as a method offilling it with exhaled air. To gain the second mark candidates needed to explain that bothclips needed to be opened then closed. Very few gained this mark. Almost all candidatescould cite three ways in which atmospheric and exhaled air differed.

In part (b) many candidates were able to correctly calculate the percentages.

For part (c) some candidates did not refer to the data in the table while others merely quotedfigures without comment. To gain credit candidates needed to point out that the rate ofventilation increased in exhaled air compared to atmospheric air and that the rate in 100%oxygen was less than in 90% oxygen and 10% carbon dioxide.

Section B

Candidates need to spend time selecting which three of the five questions will yield them themost marks. They should be encouraged by centres to spend several minutes reading all ofeach of the questions and thinking or planning their responses to each part.

Question 3

This was the least popular question, being answered by about 40% of the candidates.

In part (a) most chose to describe oestrogen or progesterone with few opting for FSH or LH.The site of production was well known but the site of action and the effects were less wellknown. Few candidates were able to describe negative feedback in relation to thesehormones.

In part (b) most correct answers named auxin and described its production and effect. Otherplant growth substances, though not on the syllabus, were credited if correctly described.

Candidates were able to describe in part (c) the location of the cerebral cortex andcerebellum correctly, but many could not accurately locate the medulla oblongata. Theyfaired better at the functions of these components.

For the experimental design those candidates that had carried out, discussed with teachersor considered such an experiment, performed very well. The very weakest candidates merelydescribed the withdrawal reflex.

Question 4

This was quite popular, chosen by about 55% of the candidates.

Part (a) was well answered by many candidates who had learned this topic very well. Somescripts failed to confine their descriptions to the stomach but described the whole alimentarycanal and all the processes therein. This did not cost them credit but meant that they spentlonger on this item than they needed to.

Most responses to parts (b) and (c) earned credit and often full marks.

Almost all candidates gained full credit in part (d) for correctly describing the route taken byfood molecules from the liver to the lungs.


In part (e), experimental design, responses varied from the very accurate to the very weak.When answering experimental design questions students should be taught to write to aformula that considers the following aspects:

• Control (C) In this case, providing some males with coffee others with water• Organism used (O) In this case, human males of the same age and mass• Replication (R) In this case, using, for example, five males who drink coffee

and five who are given water• Measurement (M) In this case, how the heart rate was measured, using the pulse

recorded for one minute and recorded before and afterconsuming the liquid

• Standardised (S) In this case, the delay between the drink and the measurement say one hour to let the coffee be absorbed or giving the same volume of drink to all the subjects.

If we take the first letter of these words, they spell out CORMS, a biological term that can beused as a prompt to students.

Question 5

This was the second most popular question being chosen by about 69% of candidates.

In part (a) most candidates were very familiar with the differences between aerobic andanaerobic respiration.

In part (b), experimental design, the same approach, CORMS, can be used as for question4 with the prompts leading to the following points:

• Control (C) The use of living and dead seeds or seeds and boiled seeds• Organism used (O) The same mass of seeds, the same species of seed• Replication (R) The same number of seeds used in each condition or the experiment repeated• Measurement (M) Using a thermometer to record the change in temperature• Standardised (S) Leaving seeds set up for stated time say twelve hours or sterilising the seeds to prevent microbial growth or soaking the seeds to ensure germination.

Most candidates were able to explain the meaning of herbivore and carnivore in part (c) butseveral were unable to explain producer, with only the better responses describingphotosynthesis or the autotrophic nature of producers. Most were able to draw a pyramid ofbiomass but very few could explain its shape in terms of energy losses between trophiclevels.

In part (d) most responses showed a good knowledge of the processes in the carbon cycle.Decomposition and combustion were the processes most often omitted from the answers.

Question 6

This was quite a popular question, chosen by about 54% of candidates.

In part (a) many candidates were able to correctly name three minerals and describe theirfunctions in plants.


In part (b), experimental design, the same prompt of CORMS, as described underquestions 4 and 5, can be applied to the experiment to compare two brands of fertiliser:

• Control (C) Both brands of fertiliser used• Organism used (O) The same named species of crop plant is used, the plants are at the same stage of development• Replication (R) The same number of plants are grown in each fertiliser• Measurement (M) The heights of the plants are measured• Standardised (S) The plants are measured after 3 months, they are grown in the same soil type and exposed to the same sunlight.

Although there were several reasonable responses to part (c) few candidates gained fullmarks with only the very best candidates quoting six or seven consequences.

In part (d) most correctly identified that the farmer would not need to apply pesticide butfewer noted that the plant would be protected from being eaten.

The candidates had a good knowledge of biological control and many gained full marks forpart (e).

Question 7

This was the most popular question chosen by about 75% of candidates.

In part (a) many candidates drew a labelled sketch of a plant cell and this enabled the awardof the location marks. Some students did not precisely describe the location so they did notearn credit. The functions of the cell components were generally known but stating that thenucleus is the ‘brain of the cell’ did not gain marks.

For part (b) we were expecting simple structural differences between the plant and animalcells. Almost all candidates were able to do this with many responses getting full marks.

The tests in part (c) were familiar to most candidates. However in some centres candidatesalways added starch to the iodine for the starch test and protein to the Biuret solution in theprotein test. Although these candidates have some knowledge of the tests they seem unlikelyto be able to carry out such tests as they will always find positive results!

In part (d), experimental design, the same prompt of CORMS, as described above, ishelpful:

• Control (C) Two or more stated concentrations eg 10% and 20%• Organism used (O) Same type of potato or same potato used• Replication (R) Several pieces of potato used in each solution• Measurement (M) Measurement of length or mass of potato pieces before and after immersion in the solutions• Standardised (S) The pieces left in the solutions for one hour and carefully blotted dry before weighing. Marks were also available for stating the expected results.


Paper 2

The paper discriminated very well and allowed the candidates to show their biological ability.Questions 5, 6, 7 and 9 were the most difficult for candidates, whilst questions 1, 2, and 10were the most accessible. There was evidence that the weaker candidates were not able toattempt parts of the more difficult questions.

Question 1

All parts of this question were attempted by all the candidates. The better candidates gainedfull marks. In part (a) some confused the aorta and the pulmonary vein, but most appreciatedthat the organ in part (b) was the lung and that the role it plays in gas exchange enables theblood to increase its oxygen content and decrease its carbon dioxide content.

Question 2

Only weaker candidates were unable to correctly identify the foods though a surprisingnumber struggled to calculate 87.3 as the total mass of the other nutrients in 100g of peas. Inpart (b) vitamins and minerals, or a named vitamin and a named mineral, were credited andmost gained the marks. Many were familiar with the emulsion test for fat involving the use ofethanol as a solvent and the milky white appearance when added to water. Those who wroteabout the grease spot test, where the food is rubbed onto paper with fat giving a translucentappearance, were duly rewarded.

Question 3

Many were familiar with the features of insects, though candidates need to be remindedabout the importance of being precise with their answers. As such, antennae alone as ananswer was not rewarded because the answer demanded candidates to state that there is apair of antennae, or two antennae. Answers which stated that the body is divided into threesegments were not credited. A common error in part (b) was to reverse the order for thelarval and pupal stage, and a surprising number of candidates were unaware of the stage inwhich metamorphosis takes place. Most candidates appreciated that the colder temperaturewould lengthen the time taken to complete the life cycle though some lost the mark becausethey were unable to express their answer clearly. The better candidates offered anacceptable explanation for the second mark, appreciating the impact of low temperature onenzyme-controlled metabolic reactions.

Question 4

The role of amylase in digesting starch into maltose was understood by the bettercandidates, as was the denaturing effect of high temperatures. Candidates who referred toenzymes being killed by high temperatures were not credited. In part (b) it was hoped thatthe word ‘fermentation’ in stage 6 would assist candidates and provide a clue for them towrite the word equation for anaerobic respiration in plants. However, weaker candidateswere unaware of this, and many wrote the word equation for aerobic respiration. Chemicalequations were credited. Part (c) was well answered with many appreciating the need tosterilise the beer.

Question 5

The graph was challenging for all but the best candidates. Credit was given for correctalignment of the axes and their labelling, sensible use of the grid space, correct plotting ofpoints and the use of straight lines to join the points neatly and correctly. In part (b)candidates needed to refer to wavelengths in order to gain credit. Part (c) was accessible formost. Most candidates appreciated that a decrease in temperature would decrease the rate


of photosynthesis but only the better candidates did well with the other parts of (d),appreciating the influence of light intensity or carbon dioxide levels on the rate ofphotosynthesis.

Question 6

There were many very good answers to part (a) mentioning transpiration and the role ofstomata in the evaporation of water. Candidates were also able to describe the changes inthe volume of water collected in the bag over time, appreciating that the volume collectedshowed a steady increase for the first three hours and then stopped with no more watercollected. Attempts to explain this pattern of change tended to be poor with only the bestcandidates appreciating the role of light intensity on the opening or closing of stomata,the role of temperature on the kinetic energy of molecules and consequent diffusion rate orthe influence of diffusion gradients on the ability for water molecules to pass out of the plantshoot leaves into the bag. In part (c) the better candidates understood the influence of lightintensity, temperature, surface area of leaves and time, but a large number of candidatesmentioned wind, failing to appreciate that the leaves were shielded from this factor.

Question 7

This was a challenging question for many candidates. Most were able to recognise thatExperiment 1 was a control, but struggled to explain why it was important to carry out acontrol. The fact that it is important to establish that there are no other factors influencing themovement of the beetles, so that the results in Experiment 2 have validity seemed beyond allbut the most able. This idea could be expressed in a variety of ways in order to gain credit. Inpart (b) it was anticipated that candidates would appreciate the importance of ensuring thatlight would not have an effect on the behaviour of the beetles, a point that only the most ableappreciated. The use of cobalt chloride paper and its colour change from blue to pink wasknown by many and in part (d) candidates demonstrated a clear understanding of thebehaviour of the beetles and many were able to relate the behaviour to the natural habitat ofthese animals.

Question 8

Part (a) was well answered by most candidates with the naming of the tertiary consumertrophic level posing most difficulty. The food chain caused little difficulty, but somecandidates misread the question and created a food web. In part (b) many candidatesappreciated the survival value to an owl in being able to feed on other organisms should onefood source become scarce. In part (c) it was important for candidates to select two featuresand then state how they helped the owl catch its prey. Most candidates were able to fulfil thistask, though many lost credit by restating the stem of the question and writing, for example,that the owl has claws which it uses to ‘catch its prey’. A more detailed qualification wasexpected such as to hold or grab its prey.

Question 9

This question was posed almost verbatim with the wording in the syllabus and yet manycandidates struggled to answer it fully. Most were familiar with diabetes as the disease andthat DNA was the molecule that was cut out. However, many struggled to recall the role ofrestriction enzymes, plasmids and ligase enzymes in producing recombinant DNA in bacteriathat are cultured in a fermenter.

Question 10

Part (a) discriminated very well with weaker candidates opting for C as the part where pollengrains germinate. The attractiveness of petals to insects was well known as was the fact thatnectar is produced by part H. Some candidates did not read the question carefully and lost


credit by writing ‘nectary’ as their answer to part (c). Weaker candidates simply rewrote thestem of the question as their answer to part (d), but most appreciated that insects areinvolved in the transfer of pollen, and that the transfer takes place between the anther andthe stigma.

Question 11

This genetics question was well answered by most candidates. However, more care isneeded to ensure that a gap is evident when the genotypes of gametes are written on thepaper. Part (b) discriminated well. The biology of heart disease is well known by candidatesthough their understanding of the cause of a heart attack is sometimes obscure. A surprisingnumber of candidates believe that bile emulsifies fat into fatty acids and glycerol, thoughmost appreciated its role in increasing the surface area for lipase and neutralising acidchyme. In part (d) (ii) the liver was often quoted possibly because candidates are aware ofthis organ’s role in bile production. Those who read the question carefully correctly referredto the association between myelin and nervous tissue.


BIOLOGY 7040, GRADE BOUNDARIES

Grade A B C D E

Lowestmark foraward of

grade140 119 99 89 65

Note: Grade boundaries may vary from year to year and from subject to subject, dependingon the demands of the question paper.

Further copies of this publication are available fromEdexcel International Publications, Adamsway, Mansfield, Notts, NG18 4FN, UKTelephone: +44 (0) 1623 450 781Fax: +44 (0) 1623 450 481Email: [email protected]

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7040 Biology Subject Report Mark Scheme June 2004