lIndex":17,"initialQuestionWindow":[{"id":"3f7ae410-e02e-42f3-a921-e585041f7bc4","revisionId":"cc823ea3-f954-4fdc-a3c1-e7d2aff84cb6","questionNumber":null,"questionType":"LA","specification":"An agricultural scientist is investigating the effect of different concentrations of a nitrogen-based fertilizer on the growth rate of wheat shoots over 10 days. The increase in height of the shoots is recorded for three separate trials at each concentration.\n\nThe table below shows the results of this investigation:\n\n| Fertilizer Concentration ($g\\text{ L}^{-1}$) | Height increase of shoots in 10 days ($\\text{mm}$) | | | | |\n| :---: | :---: | :---: | :---: | :---: | :---: |\n| | **Trial 1** | **Trial 2** | **Trial 3** | **Mean** | **Range** |\n| **1.5** | 22 | 19 | 25 | 22 | 19–25 |\n| **3.0** | 53 | 49 | 54 | *.........* | 49–54 |","difficulty":4,"difficultyBand":"easy","totalMarks":5,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"35beeb9e-d278-45ae-bbca-c0b60323ff60","label":"a","content":"Calculate the missing mean height increase at a concentration of $3.0\\text{ g L}^{-1}$ to complete the table. Show your working.","markscheme":"- Calculates the sum of the trials for $3.0\\text{ g L}^{-1}$: $53 + 49 + 54 = 156$ M1\n- Divides the sum by $3$ to find the mean: $52\\text{ mm}$ A1","marks":2,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"calculate_mean","label":"Calculate the mean","steps":[{"type":"hyper_latex","block":{"nodes":[{"latex":"53+49+54=156\\text{ mm}"}]},"order":1,"title":"Add the trial results","description":"First find the total increase across all three trials. This addition is the method mark (M1)."},{"type":"hyper_latex","block":{"nodes":[{"latex":"156\\text{ mm}\\div 3=52\\text{ mm}"}]},"order":2,"title":"Divide by three","description":"A mean is the total divided by the number of trials. Dividing by 3 gives the answer mark (A1)."}]}],"generatedAt":"2026-07-22T09:03:29.780Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]},{"id":"1ab60a23-1dfc-4782-b0de-81b8234178fc","label":"b","content":"Identify which variable (Fertilizer Concentration or Height increase) should be plotted on the x-axis.","markscheme":"- Identifies the independent variable, **Fertilizer Concentration**, as the variable to be plotted on the x-axis B1","marks":1,"order":1,"markingRubric":null,"explanation":{"methods":[{"id":"identify_independent","label":"Identify the independent variable","steps":[{"type":"text","order":0,"title":"Find the changed variable","content":"Look for the factor the scientist deliberately changes between groups. Here, the investigation uses **different concentrations of a nitrogen-based fertilizer**; this is the **independent variable** (the variable changed by the scientist).","highlights":[{"text":"different concentrations of a nitrogen-based fertilizer","location":"specification"}]},{"type":"text","order":1,"title":"Choose the x-axis","content":"Plot the independent variable on the horizontal, or $x$-, axis. Therefore, plot **Fertilizer Concentration** on the $x$-axis. This identification earns the B1 mark.","highlights":[{"text":"Fertilizer Concentration","location":"specification"}]}]}],"generatedAt":"2026-07-22T09:04:10.316Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]},{"id":"5fe66953-dfc1-4653-9112-b64ff1a36f53","label":"c","content":"Explain how knowing the range of the trials helps the investigator when drawing conclusions from a graph of these results.","markscheme":"- Explains that the range shows the spread, variability, or dispersion of the replicate data points B1\n- Explains that a narrower range indicates greater consistency or reliability in the data, which increases confidence in any conclusions drawn from the graph B1","marks":2,"order":2,"markingRubric":null,"explanation":{"methods":[{"id":"interpret_ranges","label":"Interpret the ranges","steps":[{"type":"text","order":1,"title":"Identify what range shows","content":"

Practical skills

Question 10

Practical skills Questions

Practical skills

Question 10

Practical skills Questions