AQA As LEVEL (7401/1) BIOLOGY PAPER 1 QUESTION PAPER+ MARK SCHEME JUNE 2024, Exams of Biology

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AQA As LEVEL (7401/1) BIOLOGY PAPER 1 QUESTION PAPER+ MARK

SCHEME JUNE 2024

AS

BIOLOGY

Paper 1

Monday 13 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

• 7 401/

Do not write outside the

. 2 Figure 2 is a diagram of an alveolus and a blood vessel associated with the alveolus. The direction of the movement of substances is shown by the arrows labelled C , D , E , F and G. Figure 2 Complete Table 1 by writing the correct letter, C , D , E , F or G , in the box next to each statement. You may use each letter once, more than once or not at all. box [2 marks] Table 1 Box Statement represents the diffusion of oxygen represents the transport of a gas mixture represents blood moving at the highest pressure Turn over ►

Do not write outside the [2 marks] box 6 (^0 1). 3 Describe and explain one adaptation of a single alveolus for gas exchange.

Do not write outside the box Answer μmol dm–^3 s–^1^10 (^0 2). 3 The student’s test for protein was positive. Explain why. [2 marks]

0 2. 4 An enzyme’s turnover number (kcat) is the number of substrate molecules converted

into product molecules by one enzyme molecule in 1 second. It is determined using this equation.

kcat =^ Maximum^ rate^ of^ enzyme-controlled^ reaction^ /^ μmol^ dm–^3 s–^1

Enzyme concentration / μmol dm–^3 A scientist investigated the action of a protease enzyme. The scientist prepared a

reaction mixture with a protease concentration of 0.0118 μmol dm–^3. The kcat for the

protease is 110 substrate molecules per second. Use this information and the formula to calculate the maximum rate of the protease-controlled reaction. Give your answer to 3 significant figures. Show your working. [2 marks]

Do not write outside the box [4 marks] Question 3 continues on the next page Turn over ► (^0 3). 1 Describe how viruses are replicated.

Do not write outside the box (^0 3). 4 Animal cells replicate during the cell cycle. Figure 4 shows one animal cell at a stage of the cell cycle. Figure 4 Identify the stage of the cell cycle shown in Figure 4. Explain the appearance of the cell shown in Figure 4. Do not refer to organelles in your answer. [2 marks] Identity of stage Explanation Turn over for the next question Turn over ►

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. 1 Complete Table 3 to show whether the feature of DNA is associated with the DNA molecule found in each of these locations. box Tick () the appropriate boxes. [3 marks] Table 3 Feature of DNA Location of DNA molecule Prokaryotic cell Nucleus Chloroplast Is circular Contains four different types of nucleotide Is associated with histones

Do not write outside the Some strains of the bacterium, Escherichia coli , are known to be resistant to^ box antibiotics. Scientists analysed data recording the deaths of people in hospitals across the world during 2019. They used the data to find how many of the bodies of people who died in hospitals contained antibiotic-resistant E. coli bacteria and whether the E. coli were:  not the cause of death ( associated E. coli )  the cause of death ( causal E. coli ). Figure 5 shows their results. Figure 5

Do not write outside the box (^0 4). 2 Using Figure 5 , a student calculated that out of all the people who died when antibiotic-resistant E. coli were present, 25% of those deaths involved causal E. coli. The student’s calculation is incorrect. Use Figure 5 to calculate the correct percentage of deaths involving causal E. coli in people who died when infected with antibiotic-resistant E. coli. Identify the mathematical step the student performed incorrectly in their calculation. [3 marks] Correct answer % Incorrect mathematical step (^0 4). 3 Which method is most likely to be successful in (^) decreasing the frequency of antibiotic-resistant bacteria in populations of people? Tick () one box. [1 mark] Give people lower doses of antibiotics to treat disease. Test more people to determine if they are infected with antibiotic-resistant bacteria. Vaccinate more people to reach herd immunity against bacteria that cause diseases common in human populations. Turn over ►

Do not write outside the box (^0 5). 2 The student wanted to present the results for the distribution of plant heights in a histogram. Figure 6 shows the outline of a results table. Use Figure 6 to design a suitable results table the student should use for a histogram of plant height measurements ranging between 60 cm and 120 cm. [2 marks] Figure 6 Question 5 continues on the next page Turn over ►

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. 3 A student investigated biodiversity in a community of bee species in a field of wild flowers. The student trapped and identified the bee species in the field over 6 months. Table 4 shows some of the student’s results. Table 4 Bee species Total number of trapped bees after 6 months Cuckoo bee 250 Domestic honeybee 800 Clover bee 200 The index of diversity in a community of organisms is determined using the formula where N = total number of organisms of all species and n = total number of organisms of each species. Use the formula and information in Table 4 to calculate the index of diversity in this community of bee species. box [2 marks] Answer

Do not write outside the box (^0 6). 1 Give two roles of phosphate ions in cells. [2 marks] 1 2 (^0 6). 2 Diseased lungs can cause carbon dioxide to build up in the blood plasma. This leads to an increase in hydrogen ion concentration in the plasma. Describe the effect this increase in hydrogen ion concentration has on the plasma and on the proteins in the plasma. Do not refer to the Bohr effect. [2 marks]

Do not write outside the 3 Scientists measured the concentration of inorganic ions in the cytoplasm of mammalian cells and in the tissue fluid surrounding those cells. Figure 7 shows their results. Figure 7 box

. Use Figure 7 to describe two patterns shown in the total concentrations of positively and negatively charged ions in the cytoplasm and in tissue fluid. [2 marks] 1 2 Turn over ►