M1)}"},{"latex":"\\text{M-phase}=\\htmlData{anchor=answer}{\\color{@green}{120\\text{ minutes}}}\\qquad\\text{(A1)}"}],"highlights":[{"color":"green","style":"text-color-with-background","anchor":"answer"}],"connections":[{"to":"subtraction","from":"total","color":"red","label":"subtract other stages","style":"solid"}]},"order":5,"title":"Calculate the remaining time","description":"The given cell-growth time is 330 minutes. Subtract both interphase times from the total; this subtraction setup earns M1."}]}],"generatedAt":"2026-07-21T03:57:10.976Z","modelVersion":"gpt-5.6-terra","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":{"percent":63}},{"id":"67b5ace7-7789-4b30-97c2-fc8d23b55328","revisionId":"b76d944c-f0f0-4506-9b66-24552ac4fc8c","questionNumber":null,"questionType":"LA","specification":"A scientist is studying the cell cycle of onion root tip meristem cells (*Allium cepa*), where one complete cycle takes 20 hours.\n\nFigure 1 shows the relative proportion of time spent in each of the three stages of this cell cycle (Stage X, Stage Y, and Stage Z).\n\n![Figure 1: Cell cycle of onion root tip cells](https://assets.mathsgenie.co.uk/aqa-qb/131f0b4d-cffe-4c51-9b9a-bf08a75ca1d6.png)","difficulty":5,"difficultyBand":"medium","totalMarks":5,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"9730ba6c-e29c-49d5-80e3-13bcbe06ddf4","label":"a","content":"What percentage of the total time of the cell cycle is spent in Stage X?","markscheme":"- Identifies that there are 20 total sectors and that Stage X covers 17 of them M1\n- Calculates the percentage: $\\frac{17}{20} \\times 100\\% = 85\\%$ A1","marks":2,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"sector_fraction","label":"Count sectors and convert","steps":[{"type":"text","order":0,"title":"Count the sectors","content":"The circle is split into **20 equal sectors**. Stage X runs from sector 1 to sector 17, so it covers **17 sectors**.\n\nThis is the key observation for **M1**: use the number of equal sectors, rather than trying to estimate the angle by eye.","highlights":[{"text":"What percentage of the total time of the cell cycle is spent in Stage X?","location":"specification"}]},{"type":"hyper_latex","block":{"nodes":[{"latex":"\\text{Fraction of cycle in Stage X}=\\frac{\\color{@sky}{17}}{20}"},{"latex":"\\frac{17}{20}\\times 100\\%=\\color{@green}{85\\%}"},{"text":"A1: This correctly calculates the percentage as 85%."}],"highlights":[{"color":"sky","style":"text-color","anchor":"17"},{"color":"green","style":"text-color-with-background","anchor":"85"}]},"order":1,"title":"Convert to a percentage","description":"Use the sectors for Stage X over all the sectors, then convert that fraction to a percentage."}]}],"generatedAt":"2026-07-21T03:55:12.347Z","modelVersion":"gpt-5.6-terra","explanationVersion":"v3"},"options":[]},{"id":"218376a3-9ea8-4529-8780-9ca8bbb518cb","label":"b","content":"If a sample starts with 2 active meristematic cells, and each divides to form two new cells every 20 hours, how many hours will it take for this sample to reach a total of 64 cells?","markscheme":"- Sets up the cell division sequence: $2 \\rightarrow 4 \\rightarrow 8 \\rightarrow 16 \\rightarrow 32 \\rightarrow 64$, or uses $2 \\times 2^n = 64$ M1\n- Identifies that $n = 5$ cycles of division are required A1\n- Calculates the total time: $5 \\text{ cycles} \\times 20 \\text{ hours/cycle} = 100$ hours A1","marks":3,"order":1,"markingRubric":null,"explanation":{"methods":[{"id":"doubling_sequence","label":"Follow the doubling sequence","steps":[{"type":"text","order":0,"title":"Track each division","content":"Each complete cell cycle ends with every active cell dividing into two. Start at $2$ cells and double the **total** after each cycle:\n\n$$2 \\rightarrow 4 \\rightarrow 8 \\rightarrow 16 \\rightarrow 32 \\rightarrow 64$$\n\nWriting this cell-division sequence earns **M1**.","highlights":[{"text":"starts with 2 active meristematic cells,

1.2 Cell division

Question 2

1.2 Cell division Questions

1.2 Cell division

Question 2

1.2 Cell division Questions