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GCE MAY 2010 : (A2 1) Physiology and Ecosystems - Revised

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Sp N ec e ifi w ca tio n Centre Number 71 Candidate Number ADVANCED General Certificate of Education 2010 Biology assessing Physiology and Ecosystems AB211 Assessment Unit A2 1 [AB211] TUESDAY 25 MAY, MORNING TIME 2 hours. INSTRUCTIONS TO CANDIDATES Write your Centre Number and Candidate Number in the spaces provided at the top of this page. Write your answers in the spaces provided in this question paper. Answer all nine questions. You are provided with Photograph 4.6 for use with Question 6 in this paper. Do not write your answers on this photograph. For Examiner s use only Question Marks Number 1 2 INFORMATION FOR CANDIDATES 110010 The total mark for this paper is 90. Section A carries 72 marks. Section B carries 18 marks. Figures in brackets printed down the right-hand side of pages indicate the marks awarded to each question or part question. You are reminded of the need for good English and clear presentation in your answers. Use accurate scientific terminology in all answers. You should spend approximately 25 minutes on Section B. You are expected to answer Section B in continuous prose. Quality of written communication will be assessed in Section B and awarded a maximum of 2 marks. 5948 3 4 5 6 7 8 9 Total Marks BLANK PAGE 5948 2 [Turn over Section A Examiner Only Marks 1 Remark The ABO blood grouping system is based on the presence of certain antigens. (a) (i) Describe the precise location of the blood antigens. _________________________________________________________ _______________________________________________________ [1] (ii) State the antigen present when the blood plasma contains antibody b. _______________________________________________________ [1] (iii) Describe the process of agglutination. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] (b) Antibodies to the ABO system are used to identify different blood groups. The table below shows the results of testing for four different blood groups. The first one, blood group A, has been identified. Identify the other three blood groups and name them in the spaces provided. Antibody added to the sample of blood Blood Group Antibody a Agglutination No agglutination No agglutination Agglutination Agglutination Agglutination No agglutination A Antibody b No agglutination [3] 5948 3 [Turn over 2 The diagram below shows the productivity at various trophic levels in an ecosystem. All productivity values are in kJ m 2y 1. Examiner Only Marks Remark Sunlight 7 106 50150 Producers 87400 37250 Key 23050 Gross productivity 7950 Primary Consumers 14200 6250 1300 Respiration 4600 Secondary Consumers 1650 350 80 Productivity minus energy used in respiration 240 Tertiary Consumers 110 30 30 A (a) (i) Using the information in the diagram, state the following values. NPP (net primary productivity) ____________________ kJm 2y 1 The energy available to carnivores ________________ kJm 2y 1 [2] (ii) State two processes which may result in the losses shown by arrow A. 1. _______________________________________________________ 2. _____________________________________________________ [2] 5948 4 [Turn over (b) The energy transfers shown in the diagram are for a natural meadow ecosystem. Suggest how energy transfer would differ in a field of grass cut, on several occasions during the year, and removed for the production of silage. Examiner Only Marks Remark _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [3] 5948 5 [Turn over 3 (a) In an experiment on kidney function, a student drank 700 ml of water. After drinking the water the student produced a sample of urine at 30 minute intervals for a period of 3 hours. The volume of each sample of urine and the mass of solute in each sample were measured. The results are shown in the graph below. 200 Volume of urine/ml Volume of urine /ml 3 Total solute /g 2 100 Total solute/g 1 0 0 30 60 90 120 150 0 180 Time/min (i) Using the information in the graph, determine which sample was the most concentrated. Examiner Only Marks Remark _________________________________________________________ _______________________________________________________ [1] (ii) Compare the samples taken after 60 minutes and 120 minutes and determine which of the two samples has the lower solute potential. Explain your answer. _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] 5948 6 [Turn over (b) Explain the process of osmoregulation in the body after drinking a large volume of water. Examiner Only Marks Remark _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [4] 5948 7 [Turn over 4 Crop rotation is used by farmers to maintain the fertility of the soil. Examiner Only Marks Often crop rotation includes the planting of a grass clover mixture. Clover is a legume with root nodules rich in amino acids and protein. In the autumn the grass clover crop is ploughed into the soil as green manure before the planting of winter wheat. (a) (i) Explain why clover root nodules are rich in amino acids and protein. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] (ii) Following the ploughing of the grass clover crop into the soil, the plants die and the soil subsequently becomes rich in nitrates. Describe the processes involved in the soil becoming rich in nitrates. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ Remark _______________________________________________________ [3] 5948 8 [Turn over (b) The graph below shows the influence of different mixtures of grass clover on the yield of wheat grain following the ploughing-in of the grass clover crop. Examiner Only Marks Remark 6 5 Grain yield from winter wheat/ tonnes ha 1 4 3 2 0 20 40 60 80 100 Percentage of clover in grass clover mixture/% (i) Explain the trend evident in the graph. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] (ii) Describe and explain one additional benefit of crop rotation. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] 5948 9 [Turn over 5 An experiment was set up to investigate the growth of a yeast population. A small number of yeast cells was allowed to multiply in a nutrient medium. The number of cells was estimated by removing a sample of the population at regular intervals and counting the yeast cells using a haemocytometer slide (shown below). Surface of slide type-B square (0.04 mm2) type-C square (0.0025 mm2) type-A square (1 mm2) Central part of slide Section of slide showing coverslip in position edge of field of view (low power) Examiner Only Source: Practical Biology for Advanced Level, M. Roberts, T. King, M. Reiss, Nelson, 1994 Marks Remark (a) The samples removed need to be representative of the yeast population at the time of sampling. Suggest how this is achieved. _____________________________________________________________ ___________________________________________________________ [1] The diagram below represents four type-C squares from a haemocytometer slide. The distance between the surface of these type-C squares and the overlying coverslip is 0.1 mm. A 5948 10 [Turn over (b) (i) Count the number of yeast cells in the type-C square marked A. Examiner Only Marks Remark _______________________________________________________ [1] (ii) Using your answer from (b)(i) above, calculate the number of yeast cells per mm3. (Show your working.) Answer __________________ [2] (c) Towards the end of the experiment there may be too many yeast cells to clearly see the grid lines on the haemocytometer slide. Suggest how such a dense population might be treated to enable a count to be made, and how this count would subsequently be used to obtain an estimate of the population size. _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [2] 5948 11 [Turn over The population was sampled daily and the results are shown in the graph below. Examiner Only Marks Remark carrying capacity number of yeast cells 0 1 2 3 4 5 6 7 8 9 10 Time/days (d) (i) Suggest an appropriate title for the graph shown above. _________________________________________________________ _______________________________________________________ [1] (ii) Indicate on the graph with the letter X, the point at which the growth rate of the population was greatest. [1] (iii) Explain what is meant by the term carrying capacity shown on the graph. _________________________________________________________ _______________________________________________________ [1] 5948 12 [Turn over 6 The Photograph 4.6 shows the eye of a young mammal with the eyelids closed. Examiner Only Marks Remark (a) Identify the structures labelled A to D. A ___________________________________________________________ B ___________________________________________________________ C ___________________________________________________________ D _________________________________________________________ [4] (b) Describe the operation of the iris in bright sunlight. _____________________________________________________________ _____________________________________________________________ ___________________________________________________________ [2] (c) The diagrams E and F below show eyes with different lens thicknesses and so adapted differently for the accommodation (focusing) of light. E F (i) State which of these shows an eye adapted for accommodation of light from a near object. Explain your answer. _________________________________________________________ _______________________________________________________ [1] (ii) Explain how the lens shape in E is produced within the eye. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] 5948 13 [Turn over 7 The importance of the photoperiod in the control of flowering has been known since the early 1900s and phytochrome, the plant pigment responsible, was eventually discovered in 1960. Phytochrome exists in two interchangeable forms P660 (PR) and P730 (PFR). The conversion between the two forms is illustrated below. P660 light Examiner Only Marks Remark P730 slowly in darkness (a) (i) State one other treatment that would cause the conversion of P660 to P730. _______________________________________________________ [1] (ii) State which of the two forms of phytochrome is the active form. _______________________________________________________ [1] (iii) Describe in detail how phytochrome controls flowering in a long-day plant. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] 5948 14 [Turn over Experiments were designed to investigate whether it is the leaves or the apical bud which are sensitive to the photoperiod. In each experiment, the entire plant or a portion of the plant was placed in a light-proof box which allowed the period of light and darkness to be controlled. The plants used were short-day plants. Examiner Only Marks Remark The experiments are shown in the diagram together with the results obtained. Experiment one Experiment two Entire plant receives a short-day Leaves receive a short-day light light treatment within the box treatment within the box Apical bud receives a long-day light treatment outside the box apical bud leaves Result: plant flowers Result: plant flowers (b) (i) How do the results of Experiment two suggest that the photoperiod is perceived by the leaves and not the apical bud? _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] (ii) What is the purpose of Experiment one in this investigation? _________________________________________________________ _______________________________________________________ [1] 5948 15 [Turn over The results suggest that a chemical messenger is involved in flowering. This is supported by the fact that plants, given light treatments to inhibit their flowering, can be caused to flower by grafting or attaching leaves from plants that are already flowering. Examiner Only Marks Remark (c) How do such grafting experiments suggest that a chemical messenger is involved? ______________________________________________________________ ______________________________________________________________ ___________________________________________________________ [2] 5948 16 [Turn over BLANK PAGE (Questions continue overleaf) 5948 17 [Turn over Rivers in Northern Ireland have a wide biodiversity of over 1500 invertebrate aquatic species. However pollution reduces biodiversity. The diagram below illustrates a river in which an organic discharge entered at point A and its subsequent effect on the BOD (Biological Oxygen Demand) downstream. Some of the aquatic animals (Indicator species) sampled along the river are also illustrated. Percentage of mean summer BOD/% 8 500 No animals rat-tailed maggot (Eristalis) sludge worm bloodworm (Tubifex) 400 fresh water shrimp (Gammarus) clean-water animals 300 bloodworm leech mayfly nymph 200 caddis fly larva stonefly nymph water louse Lymnaea clean-water animals mayfly nymph stonefly nymph 100 0 0 5 10 A 15 20 Distance/km Examiner Only (a) Organic discharges, such as slurry, contain many bacteria and fungi as well as dead organic matter. (i) Explain the huge increase in the BOD immediately after the organic discharge at A. _________________________________________________________ _______________________________________________________ [1] (ii) Describe what happens to cause a decrease in the BOD downstream. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] 5948 1 8 Marks Remark [Turn over (b) The first animals sampled after the discharge include the rat-tailed maggot (Eristalis) and the sludge worm (Tubifex). These animals have adaptations: the rat-tailed maggot can extend its tail to the surface of the water and the sludge worm possesses haemoglobin within its tail. Examiner Only Marks Remark (i) Suggest how these adaptations increase their tolerance of the organic pollution. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] (ii) Explain the change in the aquatic communities with distance from the organic discharge. _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [2] 5948 19 [Turn over (c) (i) Explain why eutrophication may occur downstream from the source of this organic pollution. Examiner Only Marks Remark _________________________________________________________ _______________________________________________________ [1] (ii) Explain the consequences of eutrophication. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _______________________________________________________ [3] 5948 20 [Turn over BLANK PAGE (Questions continue overleaf) 5948 21 [Turn over Section B Examiner Only Marks Remark Quality of written communication is awarded a maximum of 2 marks in this question. [2] 9 Give an account of the generation of an action potential, impulse transmission along an axon and subsequent transmission to a post-synaptic neurone. 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_________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 5948 26 [Turn over THIS IS THE END OF THE QUESTION PAPER 5948 27 [Turn over Permission to reproduce all copyright material has been applied for. In some cases, efforts to contact copyright holders may have been unsuccessful and CCEA will be happy to rectify any omissions of acknowledgement in future if notified. 110010 Sp N ec e i w ca tio n GCE Advanced Biology (A2) New Specification Assessment A2 1 Physiology and Ecosystems Summer 2010 Photograph 4.6 (for use with Question 6) } Eyelids A Iris Lens B C D Lutz Slomianka 1998-2009 School of Anatomy and Human Biology The University of Western Australia 5948.02 110011 [Turn over

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