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Describe binary fission in bacteria. [3 marks Question 1 continues on the next page Microbiologists investigated the effect of two temperatures on the population growth of a species of bacterium. They grew separate bacterial cultures in identical nutrient media at 20 °C and 24 °C for 8 hours. Figure 1 shows the estimated final population size of each culture. Figure 1 6.07 I tT mira: 1 t H pe a ae ae + i 4. oe ee sane SeannRaniG Giemnaiad decor | + fo _ - | . q 1 ; os £ po m3 : eee | 4.04----——-- seman eean| ee bees Logi ean rest cass ay number ietea tee mae of bacteria nan Gai aaceaee 4 mated “I re aie im etna evaeane 4 oF 5, 20 Temperature / °C 24 } {o{ 2]. 14] Table 1 shows four statements and the names of four parts of a nephron. 4 Puta tick (“) in each box where the statement is true for that part of the nephron. [2 mark: Table 1 Part of the nephron Statement Proximal Distal ‘ ect Glomerulus | convoluted convoluted Collecting duct tubule tubule ADH receptors are present Water can be absorbed from the filtrate Blood is under high pressure Glucose is absorbed from the filtrate Protein is not normally present in the urine of a person. Explain why. [2 marks] | aed | (0/2) [3] Glomerular sclerosis (GS) is a type of kidney damage that can cause protein to be present in the urine. High-protein diets are linked to GS in adults. Scientists investigated the development of GS in underweight, 5-day-old rats. They fed: e 14 rats a high-protein milk diet e 14 rats a normal-protein milk diet. From day 21, they fed both groups of rats the same diet of solid food. At 160 days old, they examined nephrons in the rats’ kidneys for GS. They identified the number of nephrons with GS for each group of rats. Rats fed a high-protein diet had a larger number of nephrons with GS than rats fed a normal-protein diet. The scientists performed a statistical test on these data and they calculated P < 0.01 A journalist reported on this investigation and stated ‘feeding high-protein milk to underweight human babies could cause kidney damage in adults’. Use all of the information provided to evaluate this statement. [5 marks Ecologists investigated the population size of C. graminis using the mark-release-recapture method. Table 2 shows the ecologists’ results. Table 2 Number of C. graminis | Number of unmarked captured and marked C. graminis captured in first sample in the second sample Number of marked C. graminis captured in the second sample | 405 248 124 3|.[2| The ecologists captured and Marke d the first sample of beetles during the second week of August. They identified th € species of beetle before marking them. Use the information Provided to Suggest: 0|3]./ 3] Use the data provided in Table 2 to estimate the population size of C. graminis. Show your working. [2 marks] Answer = beetles [o|3|.[4] The ecologists repeated the investigation over a five-year period to monitor the population size of C. graminis, State two precautions they would have taken each year to obtain comparable data. [2 marks] 1 Turn over for the next question {0} 4].) 3] Antibodies are proteins produced and secreted by plasma cells. Once activated, a single B cell divides and produces 4000 plasma cells. Each one of these plasma cells produces 2000 molecules of antibody Q per second, A human male has a blood volume of 5.4 dm? Calculate the total number of molecules of antibody Q per cm? of blood 24 hours after the production of these plasma cells, [2 marks] Answer = molecules of antibody Q per cm? of blood Question 4 continues on the next page 10 fo 4|.|4| Scientists investigated the effect of age on the immune response in healthy female mice. The scientists used the following method. 1. Infected a large number of young and old mice with the same strain of influenza virus. 2, Removed the lungs from 6 young and 6 old mice on the day of infection (day 0). 3. Repeated step 2 on 8 different days after infection. 4. Determined the mean number of B cells present per gram of lung tissue for young and old mice. Figure 3 shows the scientists’ results. Figure 3 2.07 Key —e— Young mice —x— Old mice 1.57 Mean number of B cells per gram 1.0- of lung tissue x10" 0.57 °o 12345 67 & 9 1011121314 151617 1619 Time after infection with influenza virus / days 11 Cleft lip and palate (CLP) is a split in the upper lip and/or th CLP is present from birth. ee eee tah, CLP can be caused by various genetic and environmental factors, CDH is a gene involved in lip and mouth development in a fetus before a baby is born. Scientists hypothesised that CLP is caused by a ‘two-hit' model: e a ‘genetic hit’ through loss of CDH7 function e an ‘environmental hit’ leading to CDH7 methylation caused when inflammation affects a fetus. Inflammation can result from the mother having an infection or diabetes. Scientists investigated the ‘two-hit’ model using human cells grown in vitro. They: ¢ grew normal cells and cells with a loss of CDH7 function * treated some of each type of cell with a drug to cause inflammation and left some of each type of cell untreated ¢ measured the percentage CDH7 methylation of the cells. Figure 4 shows the scientists’ results. Figure 4 80 7 Tonk caer 68 60 i Bea bs oe Hig PEs | | Percentage CDH1 40 i methylation | { 20 Normal Human cells with human cells loss of CDH1 function Key | | Untreated cells B Cells treated with drug to cause inflammation 13 0|5|.| 1] The frequency of live births with CLP is 1 in 700 Despite knowing this frequency, the Hardy-Weinberg equation cannot be used to estimate any allele frequencies for CLP, Suggest two reasons why. [2 marks] 1 2 O15 |.[2] Describe one effect methylation could have on CDH1 [1 mark] [o[s|.[3] su iggest and explain three reasons in Fi evidence for the ‘two-hit’ model. why the data in Figure 4 might not provide 4 3 marks] eis Min cas tatty Sana 2 — 3 14 Describe the role of structures A and B in increasing the volume in the thoracic Cavity. [2 marks] Lung volume can be determined with a spirometer using the helium dilution method. The lung volume (V2) is calculated using the equation: V1(C1— C2) C2 V2= where C1 = the initial concentration of helium in the spirometer C2 = the helium concentration in the spirometer when equal with the lungs V1 = volume of gas in the spirometer. A student used a spirometer with a volume of 3250 cm? and an initial concentration of 10% helium. They found C2 was 3.78% Use the equation to calculate this student's lung volume in dm? Show your working, [2 marks] Lung volume = [5] Suggest two advantages of diagnosing asbestosis without a biopsy. Asbestos is a fibrous mineral. If asbestos is inhaled, it can cause a lung disease called asbestosis. The latency period of a disease is the time between exposure to the cause of the disease and the symptoms occurring. The latency period for asbestosis is 15 to 40 years. Asbestosis can be diagnosed using a biopsy. This is where a sample of lung cells is removed from a patient and examined with a microscope. Asbestosis can also be diagnosed without a biopsy. To diagnose asbestosis without a biopsy, five conditions must be met. Three of these are given below. 4. A scan of the lungs showing fibrous scar tissue. 2. Reduced gas exchange. 3. Shortness of breath. These three conditions are also present in many other lung diseases. Using the information provided, suggest the other two conditions that must be met before a diagnosis of asbestosis can be made. [2 marks] [2 marks] AZ The doctors concluded that both drugs increased life expectancy in patients with IPF compared with survival data for previous patients with IPF. Using all the information, evaluate whether nintedanib and pirfenidone should be considered as treatments for asbestosis. [4 marks] 19 tT wm 2 (0) 7) a Se | Either ——, $6") [O}7|.).1} Or apne] (Oj 74,2] Write an essay on one of the topics below. The importance of condensation and hydrolysis reactions in biological systems. (25 marks] The importance of responses to changes in the internal and external environment of organisms. [25 marks] 20 
