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Pearson Edexcel Centre Number Candidate Number Level 3 GCE Biology B Advanced Subsidiary Paper 2: Core Physiology and Ecology
Tuesday 7 June 2016 – Afternoon Paper Reference Time: 1 hour 30 minutes 8BI0/02
You may need a ruler, a pencil and a calculator. Total Marks
Instructions • Use black ink or ball-point pen. • Fill in the boxes at the top of this page with your name, centre number and candidate number. • Answer all questions. • Show your working in any calculation questions and include units in your answer where appropriate. • Answer the questions in the spaces provided – there may be more space than you need. • You may use a scientific calculator. • In questions marked with an asterisk (*), marks will be awarded for your ability to structure your answer logically, showing how the points that you make are related or follow on from each other where appropriate.
Information • The total mark for this paper is 80. • The marks for each question are shown in brackets – use this as a guide as to how much time to spend on each question.
Advice • Read each question carefully before you start to answer it. • Try to answer every question. • Check your answers if you have time at the end. Turn over P49832A ©2016 Pearson Education Ltd. *P49832A0136* 3/3/2/2/2/
Answer ALL questions.
Write your answers in the spaces provided. DO NOT WRITE IN THIS AREA Some questions must be answered with a cross in a box . If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .
1 Cholera is a disease caused by a bacterial infection that affects the absorption of water in the small intestine. (a) The photograph shows part of one epithelial cell from the wall of the small intestine. DO NOT WRITE IN THIS AREA WRITE IN DO NOT DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA WRITE IN DO NOT This cell is adapted to absorb substances by active transport. State what is meant by the term active transport. (2)
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(b) The bacteria that cause cholera release a toxin.
DO NOT WRITE IN THIS AREA This toxin affects the CFTR protein found in the membrane of intestinal epithelium cells. The toxin causes the CFTR protein to pump more chloride ions out of these cells into the intestine. This causes a lot of water to be lost in the faeces. Explain how the toxin causes this water loss. (3)
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(c) The CFTR protein is also found in the membrane of epithelial cells in the lungs. Cystic fibrosis is a recessive genetic condition caused by mutations of the allele for the CFTR protein. DO NOT WRITE IN THIS AREA WRITE IN DO NOT This can result in the production of thick, highly viscous mucus in the bronchioles and bronchi. Explain why the blood of people with cystic fibrosis has a low oxygen concentration. (2) DO NOT WRITE IN THIS AREA ......
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(d) There is a high frequency of mutated CFTR alleles in some human populations.
In an experiment, three groups of genetically modified mice were infected with DO NOT WRITE IN THIS AREA cholera bacteria. The relative volume of water in their faeces was measured. The results are shown in the table.
Relative volume of Group water in faeces Mice with two normal CFTR alleles 1.0
Mice with one normal and one mutated THIS AREA WRITE IN DO NOT 0.5 CFTR allele Mice with two mutated CFTR alleles 0.1
Use the information in the table to explain why the mutated CFTR allele has a
high frequency in some human populations. DO NOT WRITE IN THIS AREA (3)
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2 The rate of transpiration in plants can be measured using a potometer.
(a) (i) Explain why the stem of a plant should be cut under water before it is inserted DO NOT WRITE IN THIS AREA into a potometer. (2)
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(ii) Which combination of the following factors would increase the rate of transpiration the most? (1) A high wind speed, low humidity, high temperature
B low wind speed, low humidity, high temperature DO NOT WRITE IN THIS AREA C high wind speed, high humidity, high temperature D high wind speed, low humidity, low temperature
(b) Which of the following shows the order of the structures a water molecule would pass through as it moves from the soil along the symplastic pathway in a root? (1) A cell wall only B cell wall, cell membrane, cytoplasm DO NOT WRITE IN THIS AREA WRITE IN DO NOT C cytoplasm only D cell membrane, cytoplasm, cell wall RAFT DO NOT WRITE IN THIS AREA Dexemplar DeRxeAmFpTlar DO NOT WRITE IN THIS AREA WRITE IN DO NOT
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*(c) Scientists investigated the transpiration of pine trees over a 24-hour period.
DO NOT WRITE IN THIS AREA The mass of water lost per second and the total area of the leaves were measured. The decrease in diameter of xylem vessels was also measured over the same 24 hours. The results are shown in the graph.
10 – 0.05 –1 s –2 8 – 0.04 O m 2 Key 6 – 0.03 transpiration / –2 –1
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DO NOT WRITE IN THIS AREA 0 – 0 – – – – – – – – – – – – – – – – – 00:00 01:30 03:00 04:30 06:00 07:30 09:00 10:30 12:00 13:30 15:00 16:30 18:00 19:30 21:00 22:30 00:00
Time (24 hour clock)
Using your knowledge of cohesion-tension theory, explain the changes in xylem diameter and transpiration rate over the 24-hour period. (6)
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3 Organic farming does not use artificial insecticides, herbicides or fertilisers, all of which are used in conventional farming. DO NOT WRITE IN THIS AREA Students investigated the effect of organic farming on the species diversity of butterflies. They compared fields used for growing crops on an organic farm and on a conventional farm. Butterflies were sampled three times on both farms during July. They were collected by walking around the fields using a sweep net. On each sampling exercise, the butterflies were collected until no more butterflies were seen. Sampling was only carried out when the temperature exceeded 25°C and the wind speed was low. DO NOT WRITE IN THIS AREA WRITE IN DO NOT The results are shown in the table.
Number of butterflies Species of butterfly Organic farm Conventional
Cabbage white 22 44 DO NOT WRITE IN THIS AREA Common blue 12 0 Large skipper 4 0 Monarch 3 0 Painted lady 11 0 Peacock 14 5 Red admiral 35 6
Small copper 2 0 THIS AREA WRITE IN DO NOT Swallowtail 14 4
(a) (i) The index of diversity for the conventional farm is 1.54 Use the formula to calculate the index of diversity for the organic farm. DO NOT WRITE IN THIS AREA N(N1− ) D = Σn(n1− )
N = total number of organisms of all species R n = totalA number ofF organismsT of a particular species Dexemplar (2) DeRxeAmFpTlar DO NOT WRITE IN THIS AREA WRITE IN DO NOT
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(ii) Explain why the organic farm has a higher index of diversity than the conventional farm. DO NOT WRITE IN THIS AREA (3)
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(iii) Criticise the method used by the students to obtain these results.
DO NOT WRITE IN THIS AREA (4)
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(b) Some conventional farms have converted to organic farming.
A further experiment was carried out to investigate the effect on species diversity of DO NOT WRITE IN THIS AREA how long the farms have used organic methods. (i) Butterflies and plant species were sampled from a range of farms that had used organic farming methods for different lengths of time. The number of plant species and the number of butterfly species were recorded. The results are shown in the table.
Years of organic Number of Number of butterfly
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0 17 4
1 to 5 38 12
6 to 15 42 14 DO NOT WRITE IN THIS AREA
16 to 25 39 12
Explain how the number of years of organic farming affects the biodiversity of butterfly species. (3)
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(ii) Creeping thistle is considered to be a weed.
DO NOT WRITE IN THIS AREA Creeping thistle has a deep root system and takes many years to be completely removed by organic farming methods. The moth population and the number of creeping thistle plants were counted. The results are shown in the table.
Years of organic Number of moth Number of creeping farming species thistle plants
0 15 10 DO NOT WRITE IN THIS AREA WRITE IN DO NOT 1 to 5 27 235
6 to 15 20 74
16 to 25 10 14 DO NOT WRITE IN THIS AREA Explain the changes in the number of moth species. (2)
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4 The mammalian circulatory system transports materials to and from cells.
DO NOT WRITE IN THIS AREA (a) (i) State how the double circulatory system of mammals ensures a higher hydrostatic blood pressure than a single circulatory system. (1)
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(ii) The diagram shows a section through a mammalian heart during part of the cardiac cycle. DO NOT WRITE IN THIS AREA WRITE IN DO NOT DO NOT WRITE IN THIS AREA
Which of the following statements is true for this stage in the cardiac cycle? (1)
DO NOT WRITE IN THIS AREA WRITE IN DO NOT A the pressure in the aorta is higher than the pressure in the left ventricle B the atrioventricular valves are open and the semilunar valves are closed C the pressure in the left ventricle is higher than the pressure in the left atrium D the atrioventricular node is about to send an impulse along the bundle of His DO NOT WRITE IN THIS AREA RxeAmFpTlar DeRxeAmFpTlar De DO NOT WRITE IN THIS AREA WRITE IN DO NOT
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(b) Lymphoedema is a condition that causes severe swelling of body tissues due to the accumulation of tissue fluid. DO NOT WRITE IN THIS AREA This occurs when lymphatic ducts are blocked. The diagram shows how the hydrostatic blood pressure and oncotic plasma pressure vary along the length of a capillary.
Key hydrostatic pressure oncotic pressure DO NOT WRITE IN THIS AREA WRITE IN DO NOT
Pressure DO NOT WRITE IN THIS AREA
Distance along the capillary
(i) With reference to the diagram, explain how tissue fluid is produced and reabsorbed by the capillaries. (4) DO NOT WRITE IN THIS AREA WRITE IN DO NOT ......
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(ii) Lymphatic ducts remove proteins that are secreted by cells.
DO NOT WRITE IN THIS AREA Explain how a blockage of a lymphatic duct could lead to lymphoedema. (2)
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5 Blood contains a variety of cells, plasma and clotting factors.
Smoking can increase the risk of blood clot formation. DO NOT WRITE IN THIS AREA An investigation was carried out to determine the effects of smoking on the contents of blood plasma. In the first part of the investigation, blood samples were taken from male smokers and non-smokers aged between 35 and 50. All males were matched for health status, body mass and diet. The concentration of fibrinogen in their blood plasma was measured. The results are shown in the table. DO NOT WRITE IN THIS AREA WRITE IN DO NOT
Mean blood plasma Number of Sample Standard concentration of fibrinogen cigarettes per day size deviation / mg 100 cm–3
0 30 241.8 ± 3.0 DO NOT WRITE IN THIS AREA 1 to 10 10 329.0 ± 7.4
11 to 20 22 361.0 ± 4.7
> 20 8 376.9 ± 6.6
In the second part of the investigation, blood samples were taken from men aged between 35 and 50 just after waking. Another blood sample was taken just after the men had smoked their first cigarette. DO NOT WRITE IN THIS AREA WRITE IN DO NOT The concentration of thrombin present in both blood samples was measured. The concentration of thrombin present in the blood of the non-smokers was also measured. The results are shown in the table. DO NOT WRITE IN THIS AREA Mean thrombin Sample Standard Group concentration size deviation / arbitrary units RNon-smokersA after wakingFT9 56 ± 1 Smokersx eafter wakingmp10lar121 ± 47 DeSmokers after first cigarette 10 365 ± 76 DeRxeAmFpTlar DO NOT WRITE IN THIS AREA WRITE IN DO NOT
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(a) Analyse the data to explain why smoking can increase the risk of blood clot formation. DO NOT WRITE IN THIS AREA (4)
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(b) The diagram below shows some of the cells found in blood. DO NOT WRITE IN THIS AREA
R
Q S DO NOT WRITE IN THIS AREA WRITE IN DO NOT
(i) Which row of the table correctly identifies the cells labelled Q, R and S ? (1) DO NOT WRITE IN THIS AREA
Q R S A erythrocyte monocyte neutrophil B neutrophil lymphocyte monocyte C monocyte neutrophil erythrocyte D monocyte neutrophil lymphocyte
(ii) Describe the function of a neutrophil in defence. THIS AREA WRITE IN DO NOT (2)
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6 Gills are the site of gas exchange in fish.
DO NOT WRITE IN THIS AREA (a) The diagram shows some of the gill lamellae from a bony fish.
blood entering blood gill leaving gill DO NOT WRITE IN THIS AREA WRITE IN DO NOT
lamella
Draw one arrow on the diagram to show the direction of water flow across the lamellae. DO NOT WRITE IN THIS AREA (1) (b) The diagram shows a section through the head of a bony fish. The graph shows the pressure changes in the buccal cavity and opercular cavity during ventilation.
Pressure change / Pa +125 buccal DO NOT WRITE IN THIS AREA WRITE IN DO NOT cavity operculum 0 0.1 0.2 0.3 0.4 0.5 0.6 Time / s –125 opercular cavity Key DO NOT WRITE IN THIS AREA pressure in buccal cavity pressure in opercular cavity
The operculum will be closed between RAFT (1) xA 0.4 se and 0.5m s plar DeRxeAmFpTlar e B 0.0 s and 0.4 s D C 0.4 s and 0.6 s DO NOT WRITE IN THIS AREA WRITE IN DO NOT D 0.2 s and 0.4 s
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(c) The table shows some information for five species of fish. DO NOT WRITE IN THIS AREA Surface area of Comparison of Mass of fish Fish species Activity level gill lamellae surface area to / g / mm2 mass / cm2 g–1 toadfish low 46 055 305 1.51 butterfish medium 120 321 261 4.61 sheepshead medium 254 048 544 4.67 mullet high 252 500 250 mackerel high 235 040 226 10.40 DO NOT WRITE IN THIS AREA WRITE IN DO NOT
(i) The comparison of surface area to mass of mullet is (1) A 1010 cm2 g–1 B 10.10 cm2 g–1 DO NOT WRITE IN THIS AREA C 1.01 cm2 g–1 D 0.99 cm2 g–1
(ii) Analyse the data to explain the difference in the activity levels of these fish species. (3)
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(d) Water polluted with heavy metal ions can cause the death of fish.
DO NOT WRITE IN THIS AREA The photographs show cross-sections of the lamellae from a fish caught in unpolluted water and from a fish caught in water polluted with heavy metal ions. DO NOT WRITE IN THIS AREA WRITE IN DO NOT
Gill lamellae from a fish in Gill lamellae from a fish in water unpolluted water polluted with heavy metal ions DO NOT WRITE IN THIS AREA Use the photographs to explain why fish die in water polluted with heavy metal ions. (2)
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7 There are currently only three surviving species of elephant:
● Asian elephant, Elephas maximus DO NOT WRITE IN THIS AREA ● African bush elephant, Loxodonta africana ● African forest elephant, Loxodonta cyclotis (a) Complete the table showing the classification of the African bush elephant. (2)
Domain ...... DO NOT WRITE IN THIS AREA WRITE IN DO NOT Kingdom Animalia
Phylum Chordata
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Order Proboscidae
Family Elephantidae
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(b) All African elephants used to be classified as a single species.
DO NOT WRITE IN THIS AREA Recent comparisons of African elephants demonstrated that they are two separate species. The diagrams show the appearance and locations of the two African elephant species. DO NOT WRITE IN THIS AREA WRITE IN DO NOT DO NOT WRITE IN THIS AREA African bush elephant DO NOT WRITE IN THIS AREA WRITE IN DO NOT
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(i) Give one reason why scientists used to classify African elephants as a single species. (1)
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(ii) Scientists agreed to separate the African elephants into two species based on new evidence from DNA sequencing. DO NOT WRITE IN THIS AREA State how scientists reach agreement on new evidence. (1)
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(c) Recently, scientists extracted mitochondrial DNA from a frozen Arctic mammoth. DO NOT WRITE IN THIS AREA WRITE IN DO NOT This DNA was sequenced and compared with the mitochondrial DNA from the Asian elephant and from the African bush elephant. The percentage similarities in the DNA sequences are shown in the table.
Percentage similarity in DNA sequence (%) DO NOT WRITE IN THIS AREA Species African bush Mammoth Asian elephant elephant
Mammoth 100 98 96
Asian elephant 98 100 95
African bush elephant 96 95 100
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Which diagram shows the correct evolutionary relationship for these three species, based on the data in the table? DO NOT WRITE IN THIS AREA (1)
African Asian African Asian elephant elephant elephant elephant mammoth mammoth DO NOT WRITE IN THIS AREA WRITE IN DO NOT A B
Asian African African elephant elephant Asian elephant elephant mammoth mammoth DO NOT WRITE IN THIS AREA
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(d) Scientists also investigated the effect of temperature on the percentage saturation of haemoglobin with oxygen, using blood from an Asian elephant. DO NOT WRITE IN THIS AREA The oxygen dissociation curves are shown in the graph.
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Haemoglobin saturation (%) Haemoglobin saturation 10°C 20 – 20°C 38°C 43°C
0 – – – – – – – – – 0 2 4 6 8 10 12 14
pO2 / kPa
(i) In the alveolar capillaries, the partial pressure of oxygen is 12 kPa at a THIS AREA WRITE IN DO NOT temperature of 38 °C and haemoglobin is fully saturated with oxygen. In active muscle tissue, the partial pressure of oxygen is 2 kPa at a temperature of 43 °C. Use the graph to determine the percentage saturation of haemoglobin in
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(ii) When 1g of haemoglobin is fully saturated it carries 1.3 cm3 of oxygen.
DO NOT WRITE IN THIS AREA Calculate the volume of oxygen released by 1 g of haemoglobin to this active muscle tissue. Show your working. (2) DO NOT WRITE IN THIS AREA WRITE IN DO NOT DO NOT WRITE IN THIS AREA Answer ......
(iii) Scientists extracted the genes for mammoth haemoglobin and used them to produce mammoth haemoglobin. The oxygen dissociation curve for mammoth haemoglobin at 38 °C was found to be the same as for the Asian elephant at 38 °C. Lowering the temperature did not shift the oxygen dissociation curve. Explain how these observations show that this haemoglobin enabled mammoths to be adapted for life in cold Arctic regions. DO NOT WRITE IN THIS AREA WRITE IN DO NOT (3)
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8 Sucrose is synthesised and transported through plants.
DO NOT WRITE IN THIS AREA The diagram represents the mass-flow hypothesis for sucrose transport in a plant.
sugar transport in phloem
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DO NOT WRITE IN THIS AREA (a) Which row in the table shows the conditions present in the sink and the source of a plant carrying out rapid photosynthesis? (1)
Sink Source
Sucrose Water Sucrose Water concentration potential concentration potential A high low high low
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(b) The effect of root temperature and oxygen on the movement of sucrose through a plant was investigated using the apparatus shown in the diagram. DO NOT WRITE IN THIS AREA
Plant leaves placed into a sealed glass chamber with an atmosphere consisting of radioactive 14 carbon dioxide ( CO2) and air
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Plant roots in a thermostatically controlled water bath
The water bath was set at 10°C and a solution from each of the small tubes was collected. The time taken for radioactive sucrose to travel the first 200mm and the second 200 mm was recorded. The experiment was repeated at 20°C and 30°C. DO NOT WRITE IN THIS AREA WRITE IN DO NOT
The whole experiment was then repeated replacing the air with nitrogen gas (N2). The results are shown in the table. RAFT DO NOT WRITE IN THIS AREA Dexemplar DeRxeAmFpTlar DO NOT WRITE IN THIS AREA WRITE IN DO NOT
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DO NOT WRITE IN THIS AREA travel 200mm / hr chamber of roots sucrose transport From From –1 containing / °C Mean / mm hr A to B B to C 14 CO2 + air 10 3.25 3.50 3.38 59.17 14 CO2 + air 20 2.35 2.45 2.40 83.33 14 CO2 + air 30 1.75 1.83 14 CO2 + N2 10 6.50 6.25 6.38 31.35 14 CO2 + N2 20 6.25 6.10 6.18 32.36 14 DO NOT WRITE IN THIS AREA WRITE IN DO NOT CO2 + N2 30 6.45 6.11 6.28 31.85
14 (i) Calculate the mean rate of sucrose transport when the plant is kept in CO2 + air whilst at 30°C. Show your working. (1) DO NOT WRITE IN THIS AREA
–1 Answer ...... mm hr (ii) Analyse the data in the table to explain the effect of temperature and oxygen on sucrose transport. (4)
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9 Before the twentieth century, tigers were once widespread across the whole of South and South East Asia. Over the last hundred years, their geographical distribution has been reduced by over 90%. The diagram shows the current distribution of three varieties of tiger. DO NOT WRITE IN THIS AREA
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Key: Sumatran tigers Indian Ocean Indochinese tigers Bengal tigers DO NOT WRITE IN THIS AREA Sumatra
(a) Use the map to explain how the different varieties of tiger may eventually become separate species. (4)
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(b) The development of palm oil plantations in Sumatra has removed areas of forest that provided the natural habitat for these tigers. DO NOT WRITE IN THIS AREA Many tigers in Sumatra suffer from inherited disorders. Explain why planting strips of trees to link the remaining patches of forest would have an effect on the frequency of genetic disorders in these tigers. (2)
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Every effort has been made to contact copyright holders to obtain their permission for the use of copyright material. Pearson Education Ltd. will, if notified, be happy to rectify any errors or omissions and include any such rectifications in future editions.
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