ion.","markscheme":"- Sums the three test results and divides by $3$: $\\frac{1.4 + 1.7 + 1.4}{3}$ M1\n- Calculates the mean $X = 1.5$ A1","marks":2,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"calculate_mean","label":"Calculate the mean","steps":[{"type":"text","order":0,"title":"Choose the test values","content":"Use the three results in the **dilute sugar solution** row: $1.4\\text{ g}$, $1.7\\text{ g}$ and $1.4\\text{ g}$. The mean is found by adding all repeats and dividing by the number of repeats, which here is $3$.","highlights":[{"text":"Dilute sugar solution","location":"specification"}]},{"type":"hyper_latex","block":{"nodes":[{"latex":"X=\\frac{\\htmlData{anchor=tests}{1.4+1.7+1.4}}{3}"},{"latex":"X=\\htmlData{anchor=mean}{1.5\\text{ g}}"}],"connections":[{"to":"mean","from":"tests","color":"sky","label":"add, then divide by 3"}]},"order":1,"title":"Calculate the mean","description":"Examiner: writing the calculation shown earns M1. Examiner: obtaining the final mean shown earns A1."}]}],"generatedAt":"2026-07-21T04:13:45.234Z","modelVersion":"gpt-5.6-terra","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"ba9909eb-0566-45ad-9f03-28138227127a","revisionId":"9a0070ae-84fd-4d83-8253-5caf3a389cdd","questionNumber":null,"questionType":"LA","specification":"The table below shows information about four different sizes of cubical agar blocks containing indicator, used in a laboratory experiment to model how cell size affects the rate of diffusion.\n\n| Agar Block | Side length (\$\\text{mm}\$) | Surface area (\$\\text{mm}^2\$) | Volume (\$\\text{mm}^3\$) | Surface area to volume ratio |\n| :--- | :--- | :--- | :--- | :--- |\n| **P** (Smallest) | 3 | 54 | 27 | 2 : 1 |\n| **Q** | 5 | 150 | 125 | 1.2 : 1 |\n| **R** | 8 | 384 | 512 | \$Y\$ : 1 |\n| **S** (Largest) | 12 | 864 | 1728 | 0.5 : 1 |","difficulty":3,"difficultyBand":"easy","totalMarks":3,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"b7dc1cf4-cbab-458f-b924-327d6aed9675","label":"a","content":"Calculate the value of \$Y\$ in the table.","markscheme":"- Uses the ratio of surface area to volume for Block R: \$\\frac{384}{512}\$ M1\n- Obtains \$Y = 0.75\$ (or equivalent fraction \$\\frac{3}{4}\$) A1","marks":2,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"calculate_ratio","label":"Calculate the surface area ratio","steps":[{"type":"hyper_latex","block":{"nodes":[{"latex":"Y = \\frac{\\text{surface area}}{\\text{volume}}"},{"latex":"Y = \\frac{\\htmlData{anchor=surface_area}{384}}{\\htmlData{anchor=volume}{512}}"}],"highlights":[{"color":"sky","anchor":"surface_area"},{"color":"green","anchor":"volume"}]},"order":1,"title":"Form the ratio","description":"Use Block R's surface area, 384 mm², and volume, 512 mm³, in the surface-area-to-volume calculation. Writing this substitution earns the method mark, even if a later division slips."},{"type":"hyper_latex","block":{"nodes":[{"latex":"Y = \\frac{\\htmlData{anchor=fraction}{384}}{512}"},{"latex":"Y = \\htmlData{anchor=answer}{0.75}"}],"connections":[{"to":"answer","from":"fraction","color":"amber","label":"384 ÷ 512"}]},"order":2,"title":"Calculate the value","description":"Divide the surface area by the volume: 384 ÷ 512 = 0.75 = 3/4. Obtaining 0.75, or 3/4, for 384/512 earns the accuracy mark. Therefore Y = 0.75, so the normalised ratio is 0.75 : 1."}]}],"generatedAt":"2026-07-22T11:12:55.611Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]},{"id":"4585bbd9-8ea7-4a71-b5d6-278163d1bab7","label":"b","content":"Describe the relationship between the size of the agar block and its surface area to volume ratio.","markscheme":"- States that as the size (or side length) of the agar block increases, its surface area to volume ratio decreases B1","marks":1,"order":1,"markingRubric":null,"explanation":{"methods":[{"id":"read_the_table","label":"Read the trend","steps":[{"type":"text","order"

Solution	Test 1 (g)	Test 2 (g)	Test 3 (g)	Mean (g)
Dilute sugar solution	1.4	1.7	1.4	$X$
Concentrated sugar solution	-6.2	-6.4	-28.9	-6.3

1.3 Transport in cells

Question 15

1.3 Transport in cells Questions

1.3 Transport in cells

Question 15

1.3 Transport in cells Questions