AQA A LEVEL BIOLOGY PAPER 2 2021

A-level BIOLOGY Paper 2 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 within the boxes at the top based on this page. • Answer all questions. • You must answer the questions within 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 based on this book. Write the question number against your answer(s). • Show all your working. • Do all rough work within this book. Cross through any work you do not want to be marked. Information • The marks for the questions are shown within brackets. • The maximum mark for this paper is 91. *JUN 7402/2 For Examiner’s Use Question Mark 1 2 3 4 5 6 7 8 9 10 TOTAL 2 1 Answer all questions within the spaces provided. Do not write outside the box . Describe the process based on glycolysis. [4 marks] 0 1 . 2 Malonate inhibits a reaction within the Krebs cycle. Explain why malonate would decrease the uptake based on oxygen within a respiring cell. [2 marks] . *02* axonthan along a non-myelinated axon. [3 marks] IB/H/Jun21/7402/2 6 0 0 1 3 Do not write outside the 1 0.2.1 Explain how a resting potential is maintained across the axon membrane within a neurone 0.2.2. Explain why the speed based on transmission based on impulses is faster along a myelinated axonthan along a non-myelinated axon. Question 2 continues on the next page [3 marks] Do not write outside the box Do not write outside the 4 *04* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/2 3 9 . A scientist investigated the effect based on inhibitors on neurones. She added a respiratory inhibitor to a neurone. The resting potential based on the neurone changed from –70 mV to 0 mV. Do not write outside the box Explain why. [3 marks] 0 2 Sl - The Marketplace to Buy and Sell your Study Material 5 Do not write outside the *05* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/2 Figure 1 shows an investigation into growth factors within plants. Figure 1 box . 1 Use your knowledge based on indoleacetic acid (IAA) to explain the growth curvature shown withinFigure 1. [3 marks] Question 3 continues on the next page Turn over ► 0 3 0 3 Sl - The Marketplace to Buy and Sell your Study Material 6 Do not write outside the *06* Downloaded by: BetterAcademics | Distribution of this document is iillllegall IB/H/Jun21/7402/2 A bioassay is a method to determine the concentration based on a substance by its effect on living tissues. Figure 2 shows the practical procedure used within a growth curvature bioassay todetermine the concentration based on IAA within shoot tips. Figure 2 Figure 3 shows the calibration curve for this growth curvature bioassay. Figure 3 box Sl - The Marketplace to Buy and Sell your Study Material 7 Do not write outside the IB/H/Jun21/7402/2 Distribution of this document is illegal . 2 Using the procedure within Figure 2 and the calibration curve within Figure 3, describe howyou could compare the IAA concentration within shoot tips from two different plant species. box In your answer you should refer to all the variables that should be controlled to produce a valid comparison. [5 marks] Question 3 continues on the next page Turn over ► *07* Downloaded by: BetterAcademics | 0 3 Sl - The Marketplace to Buy and Sell your Study Material 8 A scientist investigat ed the effect based on a directiona l light stimulus on the distributi on based on IAA within shoot tips. The scientist set up three experime nts as shown within Figure 4. All variables were controlle d apart from exposure to light. She then used the growth curvaturebioassay to compare the IAA concentrations within the agar blocks from: experiment 1 experiment 2 experiment 3 section A experime nt 3 section B. Table 1 shows thescientist’sresults TABLE 1 Experiment Degree based on curvature within Bioassay / degrees 1 17.69 2 17.61 3A 11.22 3B 6.50 *08* Downloaded by: BetterAcademics | Distribution of this document is illegal IB/H/Jun21/7402/2 S - The Marketplace to Buy and Sell your Study Material