OCR AS Level Biology A H020/02 Depth in biology JUNE 2022 QUESTION PAPER.

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AS Level Biology A H020/02 Depth in biology JUNE 2022 Time allowed: 1 hour 30 minutes INSTRUCTIONS • Use black ink. You can use an HB pencil, but only for graphs and ... diagrams. • Write your answer to each question in the space provided. If you need extra space use the lined pages at the end of this booklet. The question numbers must be clearly shown. • Answer all the questions. • Where appropriate, your answer should be supported with working. Marks might be given for using a correct method, even if your answer is wrong. INFORMATION • The total mark for this paper is 70. • The marks for each question are shown in brackets [ ]. • Quality of extended response will be assessed in questions marked with an asterisk (*). • This document has 28 pages. ADVICE • Read each question carefully before you start your answer. © OCR 2022 [601/4261/3] DC (ST/CB) 301082/4 OCR is an exempt Charity Turn over BLANK PAGE PLEASE DO NOT WRITE ON THIS PAGE Answer all the questions. 1 The cells in beetroot contain a red pigment called betalain. The plasma membrane of the beetroot cell is impermeable to betalain. A group of students set out to investigate how temperature affects the structure and permeability of the plasma membrane of beetroot cells. The method they used is shown below. • Cut some pieces of beetroot. • Place them in a flask containing 100 cm3 of distilled water. • Stand this flask in a water bath and increase the temperature at 10 °C intervals. • Take a sample of water from the flask 5 minutes after each new temperature is reached. • Measure the absorbance of the water samples taken using a blue filter in the colorimeter. (a) A second group of students made improvements to this method. One of the improvements they made was to carry out two further trials at each temperature. Suggest two further improvements they could have made and give a reason for the improvements you have suggested. Improvement and reason 1 ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Improvement and reason 2 ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... [4] (b) Name the independent variable in this investigation. .............................................................................................................................................. [1] (c) (i) The table shows the results obtained by the second group of students. Temperature (°C) Absorbance (%) Trial 1 Trial 2 Trial 3 Mean 10 0 0 0 0.0 20 0 0 0 0.0 30 2 3 2 2.3 40 6 5 7 6.0 50 9 7 7 7.7 60 46 45 47 46.0 70 78 78 80 78.7 Plot a graph of the results from the table on the grid. [3] (ii)* Explain the results between 20 °C and 70 °C using your knowledge of the structure and properties of phospholipid molecules in the plasma membrane. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [6] Additional answer space if required. ........................................................................................................................................... [Show More]

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