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AQA As LEVEL (7401/2) BIOLOGY PAPER 2 QUESTION PAPER+ MARK
SCHEME JUNE 2024
AS
BIOLOGY
Paper 2
Thursday 23 May 2024 Morning Time allowed: 1 hour 30 minutes
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 75. For Examiner’s Use Question Mark 1 2 3 4 5 6 7 8 9 TOTAL
Do not write outside the Biologists have concluded that the experiment in Figure 1 supports the^ box (^0 1). 3 An air bubble was introduced into the glass tubing in Figure 1. The air bubble moved a distance (d) of 1.5 cm in 120 minutes. The radius of the lumen (hole) of the glass tubing was 0.6 cm Use this information and the formula πr^2 d to calculate the rate of water movement in the glass tubing in cm^3 hour–^1. Use π = 3.14 in your calculation. [1 mark] Answer cm^3 hour–^1^6 cohesion–tension theory of water transport in the xylem. Explain how this conclusion is supported by the experiment in Figure 1. [3 marks] Turn over ►
Do not write outside the box (^0 2). 1 Figure 2 shows an image of a red blood cell at a magnification of × 5500 Figure 2 Calculate the actual diameter in μm of the red blood cell between points P and Q. Show your working. [2 marks] Answer μm
Do not write outside the 4 (^0 2). 5 Using Table 1 , give the blood groups of people who could accept a donation of blood group O without causing agglutination of the donated red blood cells. [1 mark] Blood groups^9
. There are four main blood groups in the human ABO blood group system. Table 1 shows the basis on which each of these blood groups is classified. Table 1 ABO blood group Antigens present on red blood cells Antibodies present in blood plasma A A Anti-B B B Anti-A AB A and B No anti-A and no anti-B O No A and no B Anti-A and anti-B A transfusion of blood from a blood group A donor to a blood group B recipient would cause agglutination of the donated red blood cells. box Use information in Table 1 to explain why. [2 marks]
Do not write outside the box (^0 3). 1 Describe how you would use cell fractionation and ultracentrifugation to obtain a sample of mitochondria from muscle tissue. [4 marks] Question 3 continues on the next page Turn over ►
Do not write outside the Using all the information, evaluate whether 12 weeks of RET would improve athletic^ box performance in the general population. [5 marks] Turn over for the next question Turn over ►
Do not write outside the box [1 mark] (^0 4). 2 The genome of an adenovirus is a single, linear molecule of double-stranded DNA. Adenoviruses use eukaryotic host cells to transcribe their genes in protein synthesis. The process of transcription of adenovirus genes is similar to the process of transcription of genes in eukaryotes. Scientists investigated the process of transcription of this viral DNA. Figure 4 shows one of the experiments carried out by these scientists. Figure 4 (^0 4). 1 Where does transcription occur in a eukaryotic cell?
Do not write outside the box (^0 5). 1 Orchids form a large family of flowering plants. Scientists analysed genes coding for ribosomal RNA in orchids. Explain how this analysis allowed the scientists to determine the phylogenetic relationships between species of orchids. [2 marks] (^0 5). 2 Suggest one reason why analysing genes coding for ribosomal RNA allows phylogenetic relationships to be studied between all cellular organisms. [1 mark] (^0 5). 3 Most orchid species are found in tropical rainforests. Two common features found in many of these species are: they grow up trees to reach the upper branches they only open their stomata at night. Suggest how each of these two features benefits these orchids. [2 marks] They can reach the upper branches of trees They only open their stomata at night
Do not write outside the box (^0 5). 4 A student used an optical microscope to observe a piece of tissue from the lower surface of an orchid leaf. The piece of leaf tissue observed was very thin. Explain why this was important. [2 marks] (^0 5). 5 The student produced a biological drawing of the leaf tissue they viewed through an optical microscope. Give three ways the student could ensure they produce a correct biological drawing of the leaf tissue. Assume the student uses a sharp pencil. [3 marks] 1 2 3 Turn over ►
Do not write outside the box (^0 6). 2 The student used a sterile pipette with 0.1 cm (^3) graduations to transfer 2 cm (^3) of B. subtilis into each test tube. What is the uncertainty in measuring 2 cm^3 with this pipette? Calculate the percentage uncertainty of this 2 cm^3 measurement. [2 marks] Uncertainty cm^3 Percentage uncertainty (^0 6). 3 Use Table 2 to evaluate the effectiveness of disinfectant X at killing microorganisms on non-living surfaces. [4 marks] Turn over ►
Do not write outside the box (^0 7). 1 Edwards’ syndrome is a condition resulting from an extra chromosome 18. A chromosome mutation in the second meiotic division is the most frequent cause of Edwards’ syndrome. Explain how a chromosome mutation in the second meiotic division could result in an extra chromosome 18. In your answer, name the type of chromosome mutation which would result in the extra chromosome. [2 marks] (^0 7). 2 Complete trisomy 18 is the most common type of Edwards’ syndrome. This occurs when all the cells of the body have an extra chromosome 18. Explain why all the cells of the body have an extra chromosome 18. [2 marks]
Do not write outside the box 8 (^0 7). 5 A ventricular septal defect (VSD) is a common feature of Edwards’ syndrome. A VSD is a hole in the wall between the two ventricles of the heart. A VSD can cause higher blood pressure in the lungs. Explain how a VSD can cause higher blood pressure in the lungs. [2 marks]
Do not write outside the box (^0 8) Lyme disease is most frequently caused by the bacterium Borrelia burgdorferi. Lyme disease can be difficult to diagnose. Figure 5 shows an ELISA test that is used to find out if a person has antibodies to B. burgdorferi. Figure 5 A false positive in this test is a result which incorrectly indicates that antibodies to B. burgdorferi are present. (^0 8). 1 Failure to thoroughly wash the well in Step 4 can result in a false positive. Explain why. [2 marks] Turn over ►
