Biology > AQA > A-level BIOLOGY (7402/1) Paper 1 Mark scheme (All)

A-level BIOLOGY (7402/1) Paper 1 Mark scheme

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Question Marking Guidance Mark Comments 01.1 Any two of the following; Concentration of enzyme Volume of substrate solution pH 1 Allow same concentration of substrate 01.2 Ratio between 4:1 and... 5:1;; 2 Initial rates incorrect but correctly used = 1 mark 01.3 At 60 ° C: 1. More kinetic energy; 2. More E–S complexes formed; 2 Allow converse for 37 ° C 01.4 Different times: 1. Higher temperature / 60 ° C causes denaturation of all of enzyme; 2. Reaction stops (sooner) because shape of active site changed; Different concentrations of product (at 60 ° C) 3. Substrate still available (when enzyme denatured); 4. But not converted to product; 4 Accept converse for 37 ° C 2. Reject if active site on substrate Question Marking Guidance Mark Comments 02.1 1. Trachea and bronchi and bronchioles; 2. Down pressure gradient; 3. Down diffusion gradient; 4. Across alveolar epithelium; 5. Across capillary endothelium/epithelium; 4 max 4. Capillary wall neutral 02.2 (About) 80.0%; 1 02.3 1. (Group B because) breathe out as quickly as healthy / have similar FEV to group A; 2. So bronchioles not affected; 3. FVC reduced / total volume breathed out reduced; 3 3. Allow this marking point for group C .................................................................................................continued..................................................................................... [Show More]

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