AQA A-level BIOLOGY 7402/2 Paper 2 Question Paper + Mark scheme [MERGED] June 2022 *jun* IB/M/Jun22/E12 7402/2 For Examiner’s Use Question Mark 1 2

AQA A-level BIOLOGY 7402/2 Paper 2 Question Paper + Mark scheme [MERGED] June 2022 *jun* IB/M/Jun22/E12 7402/2 For Examiner’s Use Question Mark 1 2 3 4 5 6 7 8 9 10 TOTAL Time allowed: 2 hours Materials For this paper you must have: • a ruler with millimetre measurements • a scientific calculator. Instructions • Use black ink or black ball-point pen. • Fill in the boxes at the top of this page. • Answer all questions. • You must answer the questions in the spaces provided. Do not write outside the box around each page or on blank pages. • If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). • Show all your working. • Do all rough work in this book. Cross through any work you do not want to be marked. Information • The marks for the questions are shown in brackets. • The maximum mark for this paper is 91. Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature I declare this is my own work. A-level BIOLOGY Paper 2 2 *02* IB/M/Jun22/7402/2 Do not write outside the Answer all questions in the spaces provided. box 0 1 . 1 In the following passage the numbered spaces can be filled with biological terms. During photosynthesis, plants produce (1) compounds which contain carbon, such as carbohydrates, lipids and proteins. Most of the sugars synthesised by plants are used by the plant in (2) . The rest are used to make other groups of biological molecules. These biological molecules form the biomass of the plants. Biomass can be measured in terms of mass of (3) per given area per given time. The chemical energy store in dry biomass can be estimated using (4) . Write the correct biological term beside each number below, that matches the space in the passage. [2 marks] (1) (2) (3) (4) 3 *03* Turn over ► IB/M/Jun22/7402/2 Do not write outside the box 0 1 . 2 Describe the light-independent reaction of photosynthesis. [6 marks] 8 4 *04* IB/M/Jun22/7402/2 Do not write outside the box 0 2 . 1 Put a tick ( ) in the box next to the equation that shows how the net production of consumers, N, can be calculated where I represents the chemical energy store in ingested food F represents the chemical energy lost to the environment in faeces and urine R represents the respiratory losses to the environment. [1 mark] N = (I – F) + R N = I – (F + R) N = I + (F + R) N = I – (F – R) In the UK, some female cattle are only used for breeding. This female breeding herd has dairy cows and beef cows. Table 1 shows data on dairy cows and beef cows in the UK female breeding herd in December 2013 and December 2017. Table 1 Date Total number in female breeding herd / millions Percentage of total female breeding herd Dairy cows Beef cows December 2013 3.35 54 46 December 2017 3.45 55 45 5 *05* Turn over ► IB/M/Jun22/7402/2 Do not write outside the box 0 2 . 2 In December 2017, the female breeding herd was 48% of all female cattle in the UK. Use Table 1 to calculate the percentage of all female cattle that were beef cows in the UK in December 2017. [1 mark] Answer % 0 2 . 3 Use Table 1 to calculate the increase in the number of dairy cows in the UK female breeding herd between December 2013 and December 2017. Show your working. [2 marks] Increase in number 0 2 . 4 Farming cattle for humans to eat is less efficient than farming crops because of energy transfer. Explain why. [2 marks] 6 6 *06* IB/M/Jun22/7402/2 Do not write outside the box 0 3 Nitrogen-fixing bacteria such as Azotobacter chroococcum use the enzyme nitrogenase to produce ammonia from nitrogen gas in the air. A. chroococcum can use ammonium chloride as a direct source of ammonia. When a source of ammonia is not available this bacterium uses nitrogen fixation. A scientist investigated the effect of an increase in the concentration of ammonium chloride on the activity of nitrogenase in this bacterium. He prepared several liquid medium cultures of the bacterium. Each liquid culture had the same volume. He grew each culture in a different concentration of ammonium chloride. In each culture: • he recorded the nitrogenase activity in arbitrary units • he removed the bacteria and then recorded the concentration of ammonium chloride remaining in each liquid medium. Table 2 shows the scientist’s results. Table 2 Concentration of ammonium chloride / µg cm–3 Nitrogenase activity / arbitrary units Concentration of ammonium chloride remaining in liquid medium / µg cm–3 0 45 0 20 30 0 40 17 0 60 7 0 80 0 6 100 0 14 120 0 20 0 3 . 1 Apart from temperature and pH, give two variables the scientist would have controlled when preparing the liquid medium cultures. [2 marks] 1 2 7 *07* Turn over ► IB/M/Jun22/7402/2 Do not write outside the box 0 3 . 2 A student concluded that this investigation showed that ammonia inhibits nitrogenase activity in nitrogen-fixing bacteria. Use all the information to evaluate the student’s conclusion. [3 marks] 0 3 . 3 Nitrogenase catalyses the reduction of nitrogen during nitrogen fixation. The reaction requires 16 molecules of ATP for each molecule of nitrogen that is reduced. When ammonia inhibits nitrogenase activity, nitrogen-fixing bacteria may benefit. Explain how. [2 marks] 7 8 *08* IB/M/Jun22/7402/2 Do not write outside the box 0 4 . 1 Put a tick ( ) in the box next to the process that occurs in anaerobic respiration but does not occur in aerobic respiration. [1 mark] Phosphorylation of glucose Reduction of NAD Reduction of pyruvate Substrate-level phosphorylation A student used the apparatus shown in Figure 1 to measure the rate of aerobic respiration of seeds for 48 hours. Figure 1 9 *09* Turn over ► IB/M/Jun22/7402/2 Do not write outside the box 0 4 . 2 During the 48 hours, the coloured liquid moved to the