A Level Biology A H420/03 Question Paper 2021

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Tuesday 19 October 2021 – Afternoon A Level Biology A H420/03 Unified biology 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 24 pages. ADVICE • Read each question carefully before you start your answer Answer all the questions. 1 (a) The figure below shows a light micrograph of an insect’s gas exchange system. B A Name the structures labelled A and B in the figure. A ............................................................................................................................................... B ............................................................................................................................................... [2] (b) Fish use gills as specialised gas exchange surfaces. (i) In ventilation, water moves into the buccal cavity, across the gills and out of the opercular cavity. Complete the table by placing ticks (3) in the appropriate boxes to show which of the processes occur at each stage of ventilation. Mouth closes Buccal cavity floor lowers Operculum opens Highest rate of oxygen diffusion int [Show More]

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