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ADVANCED GCE

BIOLOGYControl, Genomes and Environment

F215

Candidates answer on the question paper.

OCR supplied materials:None

Other materials required:. Electroniccalculator. Ruler (cm/mm)

Monday 13 June 201 1

Afternoon

Duration: t hour 45 minutes

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Candidateforename

Candidatesurname

Centre number Candidate number

INSTRUCTIONS TO CAN DTDATES

' Write your name, centre number and candidate number in the boxes above. Please writeclearly and in capital letters.

. Use black ink. Pencil may be used for graphs and diagrams only.' Read each question carefully. Make sure you know what you have to do before starting

your answer.

' Write your answer to each question in the space provided. lf additional space is required,you should use the lined pages at the end of this booklet. The question number(s) mustbe clearly shown.

. Answer all the questions.

. Do not write in the bar codes.

INFORMATION FOR CANDIDATES

' The number of marks is given in brackets [ ] at the end of each question or partquestion.

. The total number of marks for this paper is 100.where you see this icon you will be awarded marks for the quality of writtencommunication in your answer.. You may use an electronic calculator.. You are advised to show all the steps in any calculations.

' This document consists of 24 pages. Any blank pages are indicated.

@ ocR 2011 [F/500/8554]DC (LEO/SW) 26898i6

OCR is an exempt Charity

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(i)

2-lAnswer all the questions.

Knowledge of the nitrogen cycle can be used to make decisions about management of farmland.A farmer uses her grass meadow to raise sheep. In a separate field she grows cabbages.

(a) Fig. 1.1 shows part of the nitrogen cycle.The four boxes on the bottom line of the diagramrefer to substances in the soil.

Fig. 1.1

Briefly describe the steps that must occur for plant protein to be converted to animalprotein in the farmer's sheep, as shown by arrow A on Fig. 1.1.

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(ii) List the processes which contribute to B in the meadow where sheep are raised.

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Name the bacteria that carry out processes C and D, and explain the significance ofthese bacteria for the growth of plants.

(iii)

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Use the letters on Fig. 1.1 to explain why the soil nitrate concentration will decrease inthe cabbage field if it is used to grow repeated crops of cabbages year after year.

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(v)

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The farmer does not wish to use inorganic fertiliser to replace the nitrate in the soil of thecabbage field. She wishes to make use of process F.

Suggest a crop she could plant that would allow process F to occur and explain how thiswould add nitrate to the soil.

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-'l5lThe sheep on this farm belong to a rare breed called Greyface Dartmoor. The Rare BreedsSurvivalTrust (RBST) gives advice on looking after these sheep and keep records to monitorthe breeding of these sheep, in order to maintain a healthy population.

Why is the continued existence of rare breeds of farm animals desirable?

................ I2l

North Ronaldsay sheep are listed as 'endangered' by the Rare Breeds Survival Trust. Thesesheep were raised on a small Scottish lsland where they were kept along the seashore formost of the year. The sheep developed an unusual metabolism that allowed them to surviveby eating seaweed. They are, however, susceptible to copper poisoning when fed on grass.

(i) State the two essential steps that must have occurred for a breed to develop a distinctivemetabolism, such as the ability to eat mainly seaweed.

(ii) Suggest what particular problems make the North Ronaldsay breed one of the mostendangered sheep breeds in the United Kingdom.

[Total:20]

(c)

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6-lAnimals behave in ways that enhance their survival and reproductive capacity. This behaviour maybe innate or learned.

(a) Describe what is meant by:

(i) innate behaviour

. ...............t2l

(ii) learned behaviour.

(b) Describe the advantages to animals of innate and learned behaviour, with reference tospecific examples of each type of behaviour.

Your answer should include both types of behaviour and make clear the advantaqesto the animals of your chosen examples.

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IMolecular evidence has shown that all specimens of the English Elm tree, Lllmus procera,a genetically isolated clone. English Elms developed from a variety of elm brought to BritainRome in the first centurv A.D.

Although English Elm trees make pollen, they rarely produce seeds. Instead they spread bydeveloping structures known as suckers from their roots. Each sucker can grow into a new tree.

This tendency of elms to create suckers has been exploited by humans, who have separated thesuckers, with roots attached, and used them to plant hedges and establish new woodlands.

(a) (i) Suggest a technique that could be used to provide molecular evidence that all EnqlishElm trees form a clone.

:'.....'.......'.. ........t11

(ii) State why the English Elm clone is genetically isolated from other varieties of elm.

......... .. ....t1l

(iii) State the name given to the process in which plants reproduce asexually by means suchas suckers.

..,........ t1l

In 1967, a new, virulent strain of an elm disease fungus arrived in Great Britain on importedtimber. Beetles that lived under the bark of elm trees spread the fungus.

The saws used to cut down dead branches were not sterilised after use. When the saws wereused to prune healthy trees, these trees became infected. Approximately 25 million elm trees,most of the English Elm population, died within a few years of the arrival of this fungus.

Explain why there was such a rapid loss of elm trees in Britain as a result of this elm disease.

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e-l(c) Elm trees respond to fungal infection by plugging their xylem vessels. The leaves on the upper

branches of the tree then turn yellow and die. When most of the branches have lost theirleaves and died, the roots are weakened and may also die.

(i) Explain why the plugging of xylem vessels will result in the leaves of the upper branchesturning yellow.

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(ii) Explain why the loss of leaves from the tree may result in the death of the tree's roots.

QUESTTON 3(d) STARTS ON PAGE 1o

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(d) Many ornamental plants for gardens can be cloned by tissue culture.

Describe the process of cloning plants by tissue culture.

ln your answer you should make clear the order in which the steps of the processoccur.

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(e) List two advantages and two disadvantages of cloning plants by tissue culture.

advantage 1

advantage 2

disadvantage 1

disadvantage 2

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Wading birds (waders) are birds that feed in shallow water. Table 4.1 shows changes in thepopulation size of four species of wader in two areas of the Western lsles off the coast of Scotland'

. Area 1 is an area that has remained free of hedgehogs.

. Area 2 is an area where four hedgehogs were introduced from the mainland in 1974.

Since then, they have established a large population.

Hedgehogs eat the eggs of ground-nesting birds like waders.

Table 4.1

number of breeding pairs of wader birds

area 1 (hedgehogs absent) area 2 (hedgehogs present)

year

specresof wader

1 983 2000 1 983 2000

lapwing 1 104 1 364 1 869 1287

redshank 486 733 1 288 760

dunlin 803 558 201 6 884

snipe 172 154 655 280

(a) (i) Calculate the percentage decrease in the number of breeding pairs of snipe in area 2

between 1983 and 2000.

Show your working.

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Use the data in Table 4.1 to describe and explain the effect of the introductionhedgehogs on the number of breeding pairs of waders in area2.

.........t61

Suggest two factors that might have allowed a large population of hedgehogs to increasefrom just four individuals in area2.

Explain how each factor has led to an increase in the hedgehog population.

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Three suggested methods to reduce the effect of hedgehogs on the numbers of waders in

area 2 were considered. These were:

. trapping and moving hedgehogs to the mainland

. trapping hedgehogs and keeping them in captivity indefinitely

. trapping of hedgehogs followed by humane killing.

The third method was judged to be the most effective and likely to succeed in reducinghedgehog numbers.

Comment on the ethical issues involved in making this decision.

[Total:15]

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BLANK PAGE

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QUESTION 5 STARTS ON PAGE 16

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Fig.5.1 is a circular representation of the genetic code.

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(a) Fig. 5.2 shows a sequence of bases coding for a sequence of amino acids. The name ofthird amino acid in the sequence has been filled in.

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(c) ldentify the type of nucleic acid that holds the sequence of bases shown in Fig. 5.2.

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(d) Using the information in Fig. 5.1, list the three triplet codons that would cause termination ola polypeptide chain (stop codons) and explain why these codons have this effect.

......t21

(e) What name would be given to a mutation that resulted in a change of the codonUUU to UUC?

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Describe the differences between:

(a) somatic cell gene therapy and germ line cell gene therapy

(b) the central nervous system and the peripheral nervous system

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Two-spot ladybirds, Adalia bipunctata, show a colour polymorphism. They are normally red withtwo black spots. However, melanic individuals occur which are black with two red spots.

A student investigated the proportion of these colour forms in the ladybird population along atransect going up a hill near his school.

(a) (i) Suggest a suitable technique by which the student might have collected his samples ofladybirds along this transect.

.........t1I

The student's teacher suggested he should make several transects up the hill rather thanjust one transect.

Explain why this is good experimental design.

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QUESTTON 7(b) STARTS ON PAGE 20

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(b) The student's results are shown in Table 7.1.

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height abovesea level (m)

total number ofred form of ladYbird

total number ofblack form of ladybird

100 oe a

200 78 13

300 71 16

400 54 14

(i) Suggest a method of processing this data to make comparisons between the frequency

of th-e red form and black form of ladybird at the different altitudes more valid.

Explain why your method is an improvement'

12)

(ii) Evaluate whether the student was correct to conclude as follows:

,,My data showed a positive correlation between increasing altitude and the frequency of

the black form of the ladybird. I therefore concluded that high altitude causes the black

form to survive better."

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The black, melanic, form of the ladybird is caused by an allele (B) that is dominant.

The red form of the ladybird is therefore homozygous recessive at this locus (bb).

(i) State what is meant by the lerm recessive.

.................t11

(ii) The data in Table 7.1 give the total number of the red form of ladybird found as 296, andthe total number of the black form of ladybird as 50.

The Hardy-Weinberg principle states that:

P+Q=1

P2 +2Pq+ 92 = 1

Use the Hardy-Weinberg principle and the figures given above to calculate the frequencyof the dominant allele, p, and the recessive allele, q, in the two-spot ladybird population.

Show each step in your working. Give your answers to 2 decimal places.

p-

Q=

END OF QUESTION PAPER

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