be in a logical order. The plan would not allow another person to determine the effect of pH on breakdown of starch by amylase. 0 marks: No relevant content. Indicative content Mark schemes range of at least 3 pH values / use of buffer • solutions control variables / keep amount or concentration of • Q1. starch and amylase the same keep temperature the same using water bath / (a) to show the experiment was more repeatable • electric heater 1 use iodine test to make qualitative observations • (b) (circle) 0.0 at 20 °C observe colour changes at different temperatures • 1 do repeats at each pH • 4 (c) ignored it / did not use it [10] ignore repeated it 1 Q3. (d) increases the rate of reaction up to 30 °C (a) any one from: 1 ignore control variables that are not given in the method, such as (e) 60 °C or same time 1 ‘equally crushed’ do not accept volume of apple (f) do the experiment at 30 °C, 35 °C and 40 °C juice 1 20 g (of apple) or (same) mass / amount / weight of • (g) Level 2 (3–4 marks): apple A detailed and coherent plan covering all the major steps ignore volume / size is provided. The method is set out logically taking into account control variable and crushed (apple) • appropriate measurements. The plan could be repeated by another person to determine 10 drops (of solution) or (same) number / amount / • the effect of pH on breakdown of starch by amylase. volume of drops Level 1 (1–2 marks): do not accept 10 drops of Simple statements relating to relevant apparatus or steps amylase alone are made but they may not
Mark schemes Q1. (a) to show the experiment was more repeatable 1 (b) (circle) 0.0 at 20 °C 1 (c) ignored it / did not use it ignore repeated it 1 (d) increases the rate of reaction up to 30 °C 1 (e) 60 °C 1 (f) do the experiment at 30 °C, 35 °C and 40 °C 1 (g) Level 2 (3–4 marks): A detailed and coherent plan covering all the major steps is provided. The method is set out logically taking into account control variable and appropriate measurements. The plan could be repeated by another person to determine the effect of pH on breakdown of starch by amylase. Level 1 (1–2 marks): Simple statements relating to relevant apparatus or steps are made but they may not be in a logical order. The plan would not allow another person to determine the effect of pH on breakdown of starch by amylase. 0 marks: No relevant content. Indicative content • range of at least 3 pH values / use of buffer solutions • control variables / keep amount or concentration of starch and amylase the same • keep temperature the same using water bath / electric heater • use iodine test to make qualitative observations • observe colour changes at different temperatures • do repeats at each pH 4 [10] Q3. (a) any one from: ignore control variables that are not given in the method, such as ‘equally crushed’ or same time do not accept volume of apple juice • 20 g (of apple) or (same) mass / amount / weight of apple ignore volume / size • crushed (apple) • 10 drops (of solution) or (same) number / amount / volume of drops do not accept 10 drops of amylase alone
practical-5-food-tests.docx