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6134/01Edexcel GCEBiology (Salters-Nuffield) (Pilot)AdvancedUnit Test 4Tuesday 20 June 2006 – MorningTime: 1 hour 15 minutes

Materials required for examination Items included with question papersRuler NilCalculator

Instructions to CandidatesIn the boxes above, write your centre number, candidate number, your surname, initial(s) andsignature.The paper reference is shown above. Check that you have the correct question paper.Answer ALL SIX questions in the spaces provided in this booklet.If you need to use additional answer sheets, attach them loosely but securely inside this booklet.Show all the steps in any calculations and state the units. Calculators may be used.Include diagrams in your answers where these are helpful.

Information for CandidatesThe marks for individual questions and parts of questions are shown in round brackets: e.g. (2).The total mark for this question paper is 60.

Advice to CandidatesYou will be assessed on your ability to organise and present information, ideas, descriptions andarguments clearly and logically, taking into account your use of grammar, punctuation and spelling.

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Question LeaveNumber Blank

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Answer ALL questions in the spaces provided

1. Give the meaning of the following biological terms:

(a) allele

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(b) climax community

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(c) abundance

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Q1

(Total 6 marks)

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2. The diagram below shows energy flow measured during a study of a grassland ecosystem.The values shown are kJ m–2 year–1× 104. Values of energy lost through respiration (R)and other means (L) are shown for some organisms. The biomass of the organisms in theecosystem remained unchanged during the study.

(a) Name one primary consumer and one secondary consumer shown in this diagram.

Primary consumer .........................................................................................................

Secondary consumer .....................................................................................................(2)

(b) (i) Calculate the gross primary productivity (GPP) for the grasses in this system.Show your working.

.................................... kJ m–2 year–1× 104

(2)

(ii) Describe how this figure could be used to calculate the net primary productivity(NPP) of the grasses.

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Otherorganisms

Seed eating birds

Grasses 0.07

L=25.4

L=3.7

R=12.5

R=2

1980

R=3600

11.6

44.4

6

Grasshoppers Spiders

Field mice

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

Answer ..............................................(3)

(ii) Give two ways in which energy is lost by the grasshoppers other than inrespiration.

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(d) Use your calculated figures from parts (b)(i) and (c)(i) to explain why food chains areof limited length.

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Q2

(Total 12 marks)

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3. The graphs below show changes in the quantities of an antibiotic used in a hospital andthe percentage of infections caused by bacteria resistant to the antibiotic over the sametime period.

(a) Explain how bacteria become resistant to antibiotics. Use the information in thegraphs to support your answer.

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14121086420

Resistance /%

14121086420

87 88 89 90 91 92 93 94Year

Antibiotic used /kg

87 88 89 90 91 92 93 94Year

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(b) Bacteria were grown on an agar plate and incubated with four different antibiotics.The antibiotics were placed on paper discs. The resulting plate is shown in thediagram below.

(i) Give one piece of evidence that suggests that antibiotic B is more effective atkilling these bacteria than antibiotic C.

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(ii) Antibiotic C is a much larger molecule than antibiotic B. Explain why thismethod might not be appropriate when comparing the effectiveness of antibioticsB and C.

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(iii) Antibiotic C acts by inhibiting the growth of bacterial cell walls. Antibiotic Dacts by interfering with the activity of bacterial ribosomes. Use this informationto explain why neither antibiotic would be effective against viruses.

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Q3

(Total 11 marks)

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A

C D

Paperwith

antibiotic

Areas withno

bacteriaB

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4. Tuberculosis (TB) is an infection of the lungs caused by the bacterium Mycobacteriumtuberculosis. TB can often be overcome by the immune system. Macrophages destroythe bacteria by phagocytosis.

(a) Explain how phagocytosis destroys bacteria.

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(b) An investigation into infection with TB was carried out on mice with very few Thelper cells (CD4 depleted mice). The mice were infected with M. tuberculosis.Some of the mice were injected with T helper cells taken from mice that wereimmune to TB.

The diagram below summarises the experiment.

Result TB develops No TB develops

Using the information above, explain:

(i) the role of T helper cells in the immune response.

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CD4 depletedmouse

CD4 depletedmouse

T helper cellsinjected

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(ii) the effects of HIV infection on the ability of humans to combat TB.

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(c) In a separate investigation, T helper cells infected with HIV were exposed to fluidfrom the lung of a TB patient. This fluid contained chemicals secreted bymacrophages, which activate T helper cells. The results are shown in the table below.

Explain the results shown in the table above.

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(d) Many people are now infected by both M. tuberculosis and HIV (co-infection). Usethe results of both studies above to suggest the effect of co-infection on the rate atwhich each disease develops.

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Q4

(Total 12 marks)

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Fluid taken from

Healthy lung

TB infected lung

Rate of HIV production

No change

Increased

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5. Following the introduction of DNA fingerprinting into forensic testing, many people havebeen freed from prison as a result of new evidence provided by the technique.

(a) Give reasons why confidence in the new evidence was strong enough to enable therelease of these prisoners.

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(b) Give one example of physical evidence that could be retained from the originalinvestigation and explain why the sample is suitable for a DNA test to be carried out.

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(c) Explain how the results of DNA fingerprinting could be used to find the identity of adead person.

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(d) Give two other ways in which the identity of a dead person could be determined.

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Q5

(Total 9 marks)

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6. A study of mammals in West Africa has found that populations have decreased by up to76% in 41 different species. Some species have become extinct in the area, reducing thebiodiversity.

Source: www.news.bbc.co.uk

(a) Explain why extinction of species reduces biodiversity.

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(b) It is thought that this loss of biodiversity is an indirect result of European legislationwhich limits fishing in European waters. Rather than lose their way of life, Europeanfishermen now fish off the West African coast, and this has reduced fish stocksdramatically. The highest density of human populations in West Africa is along thecoast.

(i) Suggest one reason why fish stocks are important for the human population inWest Africa.

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(ii) Suggest reasons why changes in European legislation have had an effect on thewild mammal populations of West Africa.

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(c) With reference to the information given, describe the importance of consideringcultural issues when using legislation for conservation of organisms.

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(d) Explain why local legislation is likely to be less effective than internationalagreements for major conservation projects.

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TOTAL FOR PAPER: 60 MARKS

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Q6

(Total 10 marks)

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