AQA A LEVEL BIOLOGY PAPER 1 2021

AQA A LEVEL BIOLOGY PAPER 1 2021 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 1 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 wantto be marked. Information • The marks for the questions are shown within brackets. • The maximum mark for this paper is 91. For Examiner’s Use Question Mark 1 2 3 4 5 6 7 8 9 10 TOTAL 2 *02* IB/H/Jun21/7402/1 Do not write outside the box . 1 Describe the induced-fit model based on enzyme action and how an enzyme acts as a catalyst. [3 marks] . 2 Scientists investigated the action based on the enzyme ATP synthase. They made reaction mixtures each containing: • ATP synthase • buffer (to control pH) • substrates. One based on the substrates required within these reaction mixtures is inorganic phosphate (Pi). Tick ( ) one box to show which other substrate the scientists must add to the reactionmixtures to produce ATP. [1 mark] Adenine Adenosine diphosphate Glucose Ribose 0 1 0 1 . 3 3 4 8 . The scientists investigated the effect based on concentration based on inorganic phosphate (Pi) onATP synthase activity. After 2 minutes, they stopped each reaction and then measured the concentration based on ATP. Do not write outside the box Figure 1 shows the scientists’ results. Figure 1 Suggest and explain a procedure the scientists could have used to stop each reaction. [2 marks] . Explain the change within ATP concentration with increasing inorganic phosphate concentration. [2 marks] Turn over ►