BIOL4. General Certificate of Education Advanced Level Examination June Unit 4 Populations and environment

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1 Centre Number Surname Candidate Number For Examiner s Use Other Names Candidate Signature Examiner s Initias Genera Certificate of Education Advanced Leve Examination June 2012 Question 1 2 Mark Bioogy Unit 4 Popuations and environment Friday 15 June am to am For this paper you must have: a ruer with miimetre measurements. a cacuator. BIOL TOTAL Time aowed 1 hour 30 minutes Instructions Use back ink or back ba-point pen. Fi in the es at the top of this page. Answer a questions. You must answer the questions in the spaces provided. around each page or on bank pages. You may ask for extra paper. Extra paper must be secured to this booket. Do a rough work in this book. Cross through any work you do not want to be marked. Information The maximum mark for this paper is 75. You are expected to use a cacuator where appropriate. The marks for questions are shown in brackets. Quaity of written communication wi be assessed in a answers. You wi be marked on your abiity to: use good Engish organise information ceary use scientific terminoogy accuratey. (JUN12BIOL401) BIOL4

2 2 Question 1 starts on the next page DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED (02)

3 3 Answer a questions in the spaces provided. 1 The diagram shows the dominant pants in communities formed during a succession from bare soi to pine forest. Time in years Bare fied Grassand Shrub Forest Key Crabgrass Aster Broomsedge Dogwood Pine 1 (a) Name the pioneer species shown in the diagram. (1 mark) 1 (b) The species that are present change during succession. Expain why. 1 (c) The pine trees in the forest have eaves a year. Expain how this resuts in a ow species diversity of pants in the forest. (1 mark) 4 Turn over (03)

4 4 2 In a species of snai, she coour is controed by a gene with three aees. The she may be brown, pink or yeow. The aee for brown, C B, is dominant to the other two aees. The aee for pink, C P, is dominant to the aee for yeow, C Y. 2 (a) Expain what is meant by a dominant aee. (1 mark) 2 (b) Give a the genotypes which woud resut in a brown-sheed snai. (1 mark) 2 (c) A cross between two pink-sheed snais produced ony pink-sheed and yeow-sheed snais. Use a genetic diagram to expain why. (3 marks) (04)

5 5 2 (d) The shes of this snai may be unbanded or banded. The absence or presence of bands is controed by a singe gene with two aees. The aee for unbanded, B, is dominant to the aee for banded, b. A popuation of snais contained 51 % unbanded snais. Use the Hardy-Weinberg equation to cacuate the percentage of this popuation that you woud expect to be heterozygous for this gene. Show your working. Answer... % (3 marks) 8 Turn over for the next question Turn over (05)

6 6 3 (a) Expain what is meant by the ecoogica term community. (1 mark) 3 (b) Scientists investigated the distribution of three species of fish in a ake. They recorded the range of depths where each species was found. The tabe shows their resuts. Species of fish Range of depths / m White bass 6.0 to 18.4 Waeye 6.8 to 10.0 Sauger 7.2 to (b) (i) Use information from the tabe to give the range of depths at which a three species of fish may be found iving together. Answer... m (1 mark) 3 (b) (ii) Suggest and expain one advantage to the fish of occupying different depths in the ake. (06)

7 7 3 (c) The graph shows the reationship between the depth and the temperature of the water in the ake. Temperature / C Depth / m A student concuded that the temperature of the water in the ake determined the depth at which the species of fish were found. Use the tabe and the graph to evauate this concusion. (3 marks) (Extra space)... 7 Turn over (07)

8 8 4 A scientist investigated the uptake of radioactivey abeed carbon dioxide in choropasts. She used three tubes, each containing different components of choropasts. She measured the uptake of carbon dioxide in each of these tubes. Her resuts are shown in the tabe. Tube Contents of tube Uptake of radioactivey abeed CO 2 / counts per minute A Stroma and grana B Stroma, ATP and reduced NADP C Stroma (a) Name the substance which combines with carbon dioxide in a choropast. (1 mark) 4 (b) Expain why the resuts in tube B are simiar to those in tube A. (1 mark) 4 (c) Use the information in the tabe to predict the uptake of radioactivey abeed carbon dioxide if tube A was paced in the dark. Expain your answer. (08)

9 9 4 (d) Use your knowedge of the ight-independent reaction to expain why the uptake of carbon dioxide in tube C was ess than the uptake in tube B. 4 (e) DCMU is used as a weed kier. It inhibits eectron transfer during photosynthesis. The addition of DCMU to tube A decreased the uptake of carbon dioxide. Expain why. 8 Turn over for the next question Turn over (09)

10 10 5 (a) Insect pests of crop pants can be controed by chemica pesticides or bioogica agents. Give two advantages of using bioogica agents Two-spotted mites are pests of strawberry pants. Ecoogists investigated the use of predatory mites to contro two-spotted mites. They reeased predatory mites on strawberry pants infested with two-spotted mites. They then recorded the percentage of strawberry eaves occupied by two-spotted mites and by predatory mites over a 16-week period. The resuts are shown on the graph Key Two-spotted mites Predatory mites Percentage of eaves occupied Time / weeks 16 5 (b) Describe how the percentage of eaves occupied by predatory mites changed during the period of this investigation. (10)

11 11 5 (c) The ecoogists concuded that in this investigation contro of the two-spotted mite by a bioogica agent was effective. Expain how the resuts support this concusion. 5 (d) Farmers who grow strawberry pants and read about this investigation might decide not to use these predatory mites. Suggest two reasons why (e) The ecoogists repeated the investigation but sprayed chemica pesticide on the strawberry pants after 10 weeks. After 16 weeks no predatory mites were found but the popuation of two-spotted mites had risen significanty. Suggest an expanation for the rise in the two-spotted mite popuation Turn over (11)

12 12 6 A student investigated the rate of gas exchange in aerobicay respiring seeds using the apparatus shown in the diagram. She carried out two experiments. In Experiment 1, she put potassium hydroxide soution in the beaker. Potassium hydroxide soution absorbs carbon dioxide. In Experiment 2, she put water in the beaker. Manometer 0 Seeds 2 Scae marked in cm 3 Beaker containing either 4 potassium hydroxide or water Cooured iquid 6 (a) Both experiments were carried out at the same temperature. Expain why. 6 (b) (i) The eve of cooured iquid in the right-hand side of the manometer tube went down during Experiment 1. Expain why. (3 marks) (12)

13 13 (Extra space)... The resuts from both experiments are shown in the tabe. Experiment Soution in beaker Fa in voume of cooured iquid in right-hand side of manometer / cm 3 1 Potassium hydroxide 5 2 Water 1 6 (b) (ii) Use these resuts to cacuate the voume of carbon dioxide produced during Experiment 1. Answer =... cm 3 (1 mark) 6 (c) The student repeated Experiment 1 using seeds which were respiring anaerobicay. What woud happen to the eve of cooured iquid in the right-hand side of the manometer tube? Expain your answer. 8 Turn over (13)

14 14 7 Biofues are fues which can be produced from pants. Scientists have deveoped a standard method caed net ife-cyce carbon dioxide production (NLP) to find the overa effect of producing and using particuar biofues on carbon dioxide production. 7 (a) Petroeum is used as a comparison when evauating NLPs of biofues. Suggest two reasons why (b) Biofues are produced by a variety of different companies. The scientists who deveoped the method of cacuating NLPs are funded by the government s environmenta agency. Suggest two advantages of this method being deveoped by these scientists (14)

15 15 Scientists compared the percentage change in carbon dioxide production if different biofues repaced petroeum. Their resuts are shown in the tabe. Biofue Percentage change in carbon dioxide production if this fue repaced petroeum Corn ethano 18 Soy-based biodiese +4 Switch-grass ethano 124 Sugar-cane ethano 26 7 (c) (i) The scientists suggested that using biofues woud have a great effect on imiting cimate change. Use the data in the tabe to evauate this suggestion. (4 marks) (Extra space)... Question 7 continues on the next page Turn over (15)

16 16 7 (c) (ii) Producing and using biofues from corn ethano resuts in a negative percentage change in carbon dioxide production. Expain why. 7 (d) Ethano can be produced from ceuose. It is produced by anaerobic respiration of ceuose-based biomass by microorganisms. The ceuose is pre-treated by adding ceuose-digesting enzymes before it is used in anaerobic respiration. Suggest why pre-treatment is necessary. (3 marks) (Extra space)... 7 (e) Large areas of and have to be used to grow the pants to make biofues. Ecoogists have suggested that changes in and use coud ead to a decrease in biodiversity. Suggest how changes in and use coud ead to a decrease in biodiversity. 15 (16)

17 17 8 (a) Expain how farming practices increase the productivity of agricutura crops. (5 marks) (Extra space)... Question 8 continues on the next page Turn over (17)

18 18 8 (b) Describe how the action of microorganisms in the soi produces a source of nitrates for crop pants. (5 marks) (Extra space)... (18)

19 19 8 (c) Expain how the use of pesticides can resut in resistant strains of insect pests. (5 marks) (Extra space) END OF QUESTIONS (19)

20 20 There are no questions printed on this page DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED Copyright 2012 AQA and its icensors. A rights reserved. (20)