June 20102 Red blood cells (erythrocytes) transport oxygen from the alveolar surface in the lungs to the respiring tissues. A group of nine athletes (A to I) wanted to see if training for two weeks at a mountain camp, 2000 m above sea level, had an effect on the number of red blood cells in their blood. Samples of blood were taken from each of the athletes at their normal training camp at sea level. Blood samples were taken again after two weeks of training at the mountain camp. A copy of the raw data collected is given below: Number of red blood cells x1012 per dm3 blood before mountain training A 5.0B 5.1C 4.9D 5.3E 5.4 F 5.0 G 4.8 H 5.1I 5.5 Number of red blood cells x1012 per dm3 blood after mountain training A 4.9 B 5.3 C 5.7 D 5.5 E 5.6 F 5.4 G 5.3 H 5.6 I 5.1 (a) Write a null hypothesis for this investigation.(1)..............................................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) Calculate the difference in the number of red blood cells before and after the mountain training for each athlete. Prepare a table to display the raw data and your calculated values.(4)

(c) Identify an anomalous result in the data from the athletes.(2).......................................................................................................................................................... Give one reason for your answer...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................(d) Calculate the mean number of red blood cells per dm3 of blood for the group of athletes before and after mountain training.(2)

Mean number of red blood cells before training ............................................... Mean number of red blood cells after two weeks training at 2000 m ..........................................(e) Present the calculated mean red blood cell counts in a suitable graphical form. (3)

(f) A t-test was applied to the data to test the null hypothesis. The calculated value of t was 2.24. The table below shows the critical values of t with 16 degrees of freedom, at different significance levels.

What conclusion can be drawn from this investigation? Use the information in the table to explain your answer. (3).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for Question 2 = 15 marks)

January 20112 Rennin is an enzyme, found in the stomach of mammals, that can form solid clots in milk. Rennin is often used in the first stage of cheese production. A student was interested in discovering which conditions would be ideal for making cheese. She wanted to determine which concentration of rennin was likely to give her suitable rates of clotting of milk. She prepared the following test tubes: Fourteen test tubes with 5 cm3 milk Twelve test tubes, each containing 5 cm3 of different concentrations of rennin Two test tubes with 5 cm3 distilled water She placed these test tubes in a water bath at 30C and left them for 10 minutes. The content of each test tube containing milk was added to a test tube containing either rennin or distilled water. These were mixed and returned to the water bath. The time taken for the milk to clot (thicken) was recorded. A copy of the students raw results are below.

(a) Explain why the test tubes containing milk, rennin and distilled water were left in the water bath for 10 minutes before they were mixed.(1)..................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(b) Convert the times recorded into the SI units of seconds and prepare a suitable table to display these raw results and each of the following.(i) The mean time for clotting for each concentration of rennin. (ii) The mean rate of milk clotting, calculated using the equation below

(5)

(c) Show the effect of changing the rennin concentration on the mean rate of milk clotting, in a suitable graphical form.(3)

(d) Identify an anomalous result in the data for the different rennin concentrations. (2).......................................................................................................................................................... Give one reason for your answer......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (e) The student applied a Spearman rank correlation to explore the relationship between the rate of clotting and the rennin concentration. From her calculation, she obtained a Spearman rank correlation of 1.0. Table of significance levels for Spearman rank correlation. What conclusion can be drawn from this investigation? Use the information in the table to explain your answer. (2).......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (f) Give an explanation for the relationship between rennin concentration and the rate of clotting of milk.(2).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for Question 2 = 15 marks)

May 20112 A student decided to investigate whether eating breakfast every day had an effect on the body mass of students in her class.She selected twelve students (A to L), measured their body mass and asked if they ate breakfast regularly.A copy of her raw results is shown below.

(a) Write a suitable null hypothesis for this investigation.(1)..............................................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) Prepare a suitable table to display the data obtained and calculate the mean body mass for students who regularly eat breakfast and those who do not.(4)

(c) Using a suitable graphical form, compare the effects of eating breakfast regularly or not on the body mass of these students. (3)

(d) The student applied a t-test to the data she obtained. She obtained a result of t = 3.09 from her calculation. The table below shows critical values of t with 10 degrees of freedom, at different significance levels.

What conclusions can be drawn from this investigation? Use the information provided in the table above and in the graph you have drawn.(3)..............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(e) Suggest why it may not be reasonable to draw a firm conclusion from the results of this investigation.(3).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for Question 2 = 14 marks)

January 20122 A student investigated the effect of caffeine concentration on the heart rate of animals.He selected five Daphnia (A to E), and measured the heart rate, in beats per minute, of each of them in water. This was repeated using six concentrations of caffeine solution (0.01%, 0.1%, 0.5%, 1.0%, 2.0%, 5.0%).A copy of his raw results (starting from water (0%) on the left increasing to 5% caffeine solution on the right) for each Daphnia is shown below.A 176, 240, 256, 260, 268, 274, 282.B 178, 238, 256, 262, 270, 282, 274.C 184, 244, 260, 264, 270, 278, 284.D 172, 236, 248, 254, 260, 270, 278.E 182, 246, 264, 266, 268, 272, 286.(a) Write a suitable null hypothesis for this investigation.(1)..............................................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) State and explain one ethical reason why the student chose to use Daphnia for this investigation.(2)............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(c) Calculate the mean heart rates for each concentration of caffeine.(3)

Mean heart rate at 0.0% caffeine concentration ...................................................................... Mean heart rate at 0.01% caffeine concentration ...................................................................... Mean heart rate at 0.1% caffeine concentration ...................................................................... Mean heart rate at 0.5% caffeine concentration ...................................................................... Mean heart rate at 1.0% caffeine concentration ...................................................................... Mean heart rate at 2.0% caffeine concentration ...................................................................... Mean heart rate at 5.0% caffeine concentration .......................................................................(d) Prepare a table to display the raw data and your calculated values for the mean heart rates.(3)

(e) On the graph paper below, draw a suitable graph to illustrate the effect of caffeine concentration on the mean heart rate of Daphnia. (3)(f) The student used a statistical test to investigate the significance of the correlation between the mean heart rates and the caffeine concentrations. His calculation gave a correlation value of 1.00. The table below shows significance levels and correlation values for this statistical test.

What conclusions can be drawn from this investigation? Use the information provided in the table above and in the graph you have drawn, together with your knowledge and understanding, to explain your answer. (4).................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for Question 2 = 16 marks)

May 20122 A student decided to investigate habituation in Giant African Land snails (Achatina fulica).

The student selected a snail (A) and placed it on a glass plate across which it was able to move. The student tapped the plate with a glass rod, next to the snail, causing the snail to stop moving and withdraw into its shell. The student recorded the time, in seconds, it took for the snail to re-emerge from its shell and start moving again. The student tapped the plate at the start of the investigation and then every two minutes for a total of 12 minutes. The investigation was repeated with two other snails (B and C). A copy of the raw results for each snail is shown below.A 90, 40, 30, 10, 0, 0, 2B 108, 60, 40, 15, 5, 0, 0C 80, 48, 80, 20, 0, 0, 0 (a) Write a suitable null hypothesis for this investigation.(1)..............................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(b) Calculate suitable means from the raw results and prepare a table to display these and the raw data for this investigation.(4)

(c) On the graph paper below, draw a suitable graph to show the effect of repeated tapping on the time taken for a snail to start moving again.(3)

(d) State an anomalous result in the data.(2).......................................................................................................................................................... Give one reason for your answer.....................................................................................................................................................................................................................................................................................................................(e) The student used a statistical test to investigate the significance of the correlation between the mean time for the snails to start moving and the repeated tapping. His calculation gave a negative correlation value of 0.93. The table below shows significance levels and correlation values for this statistical test.

What conclusions can be drawn from this investigation? Use the information provided in the table above and on the graph you have drawn, together with your knowledge and understanding of habituation, to explain your answer.(5).................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for Question 2 = 15 marks)

January 20132 A student decided to investigate the effect of listening to music on short-term memory. She recorded how many numbers were correctly recalled from a grid containing 25 random numbers. She tested 15 members of her class (students A to O) with no music. She repeated the test three times for each student and calculated the mean for each student. She repeated the tests with the same 15 students, while they listened to some loud music. A copy of her mean results for each student is shown below:

(a) Write a suitable null hypothesis for this investigation.(1)..............................................................................................................................................................................................................................................................................................................................................................................................................................................................................(b) Prepare a suitable table to display the data obtained and calculate the overall mean for the numbers recalled by these 15 students, both with music and with no music.(4)

(c) On the graph paper below, draw a suitable graph to show the effect of listening to music on the overall mean for the numbers recalled by these students. Include on your graph an indication of the variability in the overall means.(3)

(d) The student applied a t-test to explore the significance of her results. She obtained a result of t = 3.30 from her calculation. The table below shows some critical values for t-test calculations.

What conclusion can be drawn from this investigation? Use the information provided in the table and in the graph you have drawn, together with your knowledge and understanding to explain your answer.(5)............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(e) Suggest why it may not be reasonable to draw a valid conclusion from the results of this investigation.(3).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for Question 2 = 16 marks)

May 20132 Earthworms are animals that improve the quality of soil needed for plant growth.Farmers often plough the soil before planting crops in a field. A farmer wanted to investigate the effect of ploughing on the presence of earthworms. He used different methods to plough two fields (field A and field B), next to each other. These fields were then left for one month. The farmer then randomly placed quadrats (0.5 m 0.5 m) in field A. In each quadrat he poured a weak detergent solution onto the soil. He then counted the number of earthworms that came to the surface in each quadrat. He repeated this process in field B. A copy of the farmers raw results is shown below: Field A: 10, 4, 13, 9, 9, 3, 8, 5, 4 Field B: 15, 6, 12, 0, 3, 8, 9, 10, 7, 4, 6 (a) Write a suitable null hypothesis for this investigation.(2).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (b) Prepare a suitable table to rank the data obtained. Identify the median number of earthworms from the quadrats in each field.(4)

(c) On the graph paper below, draw a suitable graph to show the effect of different methods of ploughing on the median number of earthworms from the quadrats in each field. Include on your graph an indication of the variability in the data.(3)

(d) The farmer decides to apply the Mann-Whitney U test to the data. This statistical test determines if the difference between the medians is significant. The calculations produced two U values for this set of data. In order to support a difference between the two medians, the smaller U value must be the same as, or less than, the critical value. He obtained a result of U = 50 from the calculation (the smaller value). The table below shows the critical values for the Mann-Whitney U test at the p = 0.05 level.

What conclusions can be drawn from this investigation? Use the information provided in the table above and in the graph you have drawn.(4)..........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(e) Suggest why it may not be reasonable to draw a valid conclusion from the results of this investigation.(3).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for Question 2 = 16 marks)

January 20142 A student decided to investigate whether drinking coffee containing caffeine had an effect on reaction times.She selected 27 students who regularly had drinks containing caffeine.The students did not have any drinks containing caffeine for 24 hours before the investigation. On the morning of the investigation, the students drank either one cup of coffee containing caffeine or one cup of coffee with no caffeine.The students then went to their first lesson. Immediately after the lesson, the reaction times of the students were measured in milliseconds (ms).The raw results are shown below.Group given coffee containing caffeine355 ms, 310 ms, 270 ms, 450 ms, 350 ms, 316 ms, 298 ms, 368 ms, 394 ms,347 ms, 246 ms, 340 ms, 415 ms, 274 ms, 300 msGroup given coffee with no caffeine426 ms, 440 ms, 510 ms, 412 ms, 398 ms, 450 ms, 340 ms, 484 ms, 365 ms,410 ms, 380 ms, 264 ms(a) Write a suitable null hypothesis for this investigation.(2)..............................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(b) Calculate the mean value for each group.Prepare a suitable table to display the mean value and the sample size for each group.(3)

(c) On the graph paper below, draw a suitable graph to show the effect of caffeine on mean reaction times and the variability of the data.(3)

(d) The student applied a t-test to the data she obtained. She obtained a valueof t = 3.03 from her calculation.The table below shows critical values of t with different degrees of freedom at different significance levels.The number of degrees of freedom is calculated using the formula shown below.Degrees of freedom = (n1 1) + (n2 1)where n1 and n2 represent the size of the groups being compared.

What conclusions can be drawn from this investigation?Use the information provided in the table above and in the graph you have drawn to explain your answer.(3)...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (e) Suggest why it is difficult to draw a valid conclusion from the results of this investigation.(3).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for Question 2 = 14 marks)

June 20142 Forced expiratory volume (FEV1), is the maximum volume of air that can be forcibly expired from a persons lungs in one second.Nigel decided to investigate whether the height of a person is related to FEV1.He selected 8 students of different heights. For each student he measured the FEV1 three times. The results of this investigation are shown below.

(a)Write a suitable null hypothesis for this investigation. (2).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (b) Calculate the mean FEV1 for each student. Display the data for the height and the mean FEV1 for each student in a suitable table. (3)

(c) On the graph paper below draw a suitable graph to show the relationship between height and mean FEV1.Include on your graph an indication of the variability in the data. (3)

(d) Nigel used a statistical test to investigate the significance of the relationship between the height of an individual and FEV1. His calculation gave a value of 0.65.The table below shows values for this statistical test at three significance levels of 0.1, 0.005 and 0.01.

Use the information provided in this table and in your graph to draw conclusions from this investigation.(4).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (e) Suggest why it may not be reasonable to draw a valid conclusion from the results of this investigation. (3).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for Question 2 = 15 marks)

January 20152 Ultraviolet (UV) light can be used to kill microorganisms. A student decided to investigate the effect of UV light on the survival of bacteria. The student spread bacteria on three agar plates. Each plate was then exposed to UV light for one minute. She placed the agar plates in an incubator. After 48 hours, she recorded the number of bacterial colonies on each plate. The procedure was repeated for exposure times of 2, 3, 4 and 5 minutes. A copy of her raw results is shown below. 1 minute exposure to UV light: 302, 282 and 322 colonies 2 minutes exposure to UV light: 187, 215 and 231 colonies 3 minutes exposure to UV light: 174, 108 and 129 colonies 4 minutes exposure to UV light: 70, 94 and 82 colonies 5 minutes exposure to UV light: 37, 47 and 21 colonies (a) Write a suitable null hypothesis for this investigation. (2) .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... (b) Calculate the mean number of bacterial colonies for each UV exposure time. (2)

Mean number of bacterial colonies after 1 minute UV exposure ............................ Mean number of bacterial colonies after 2 minutes UV exposure .......................... Mean number of bacterial colonies after 3 minutes UV exposure .......................... Mean number of bacterial colonies after 4 minutes UV exposure .......................... Mean number of bacterial colonies after 5 minutes UV exposure .......................... (c) Prepare a suitable table showing the raw data and your calculated values for the mean number of bacterial colonies. (2) (d) On the graph paper below, draw a suitable graph to show the effect of UV light on the survival of bacteria. Include on your graph an indication of the variability of this data.(3)

(e) The student used a statistical test to investigate the significance of the correlation between the exposure time to UV light and the number of bacterial colonies. A negative correlation with a value of 0.99 was found. The table below shows the critical values for a significance level of p = 0.05 when using this statistical test. Number of meansCritical values for a significance level of p = 0.05

4 1.00

5 0.90

6 0.83

7 0.71

8 0.64

9 0.60

What conclusion can be drawn from the results of this investigation? Use the information given and the graph you have drawn to explain your answer. (4) .............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (f ) Suggest why it may not be reasonable to draw valid conclusions from the results of this investigation. (3) .............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for Question 2 = 16 marks)