AQA as biology 2019 paper 1

Tuesday 21 May 2019 Afternoon 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. • 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. Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature AS BIOLOGY Paper 1 2 *02* IB/M/Jun19/7401/1 Do not write outside the Answer all questions in the spaces provided. box 0 1 . 1 The nucleus and a chloroplast of a plant cell both contain DNA. Give three ways in which the DNA in a chloroplast is different from DNA in the nucleus. [3 marks] 1 2 3 0 1 . 2 Some DNA nucleotides have the organic base thymine, but RNA nucleotides do not have thymine. RNA nucleotides have uracil instead of thymine. Give one other difference between the structure of a DNA nucleotide and the structure of an RNA nucleotide. [1 mark] 3 *03* Turn over ► IB/M/Jun19/7401/1 Do not write outside the Figure 1 shows a tRNA molecule. box Figure 1 0 1 . 3 Name the structures labelled W and X in Figure 1. [1 mark] W X 0 1 . 4 Not all mutations in the nucleotide sequence of a gene cause a change in the structure of a polypeptide. Give two reasons why. [2 marks]