roscopy/questions","formulaUrl":null,"initialIndex":26,"initialQuestionWindow":[{"id":"0ac0938f-a022-45bf-8769-5a134df1fc3f","revisionId":"5b2c7fb6-8db0-4a60-905f-dce70219a3eb","questionNumber":null,"questionType":"LA","specification":"A student prepared a temporary slide of human cheek epithelial cells, staining them with methylene blue to observe their structures. They obtained an image similar to the one shown in Figure 1.\n\n![Stained human cheek cells under a light microscope](https://assets.mathsgenie.co.uk/aqa-qb/0073c921-e164-43b5-a1c8-e0f3d33e9c31.png)","difficulty":5,"difficultyBand":"medium","totalMarks":3,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"e019dfe2-7d9f-4448-b681-016131ce1178","label":null,"content":"Describe how the student should use the light microscope to view these cells clearly at a total magnification of $\\times 600$.","markscheme":"- Selects and states the use of a $\\times 15$ eyepiece lens combined with a $\\times 40$ objective lens (or a $\\times 10$ eyepiece lens and a $\\times 60$ objective lens) to achieve $\\times 600$ magnification B1\n- Starts by focusing on a low-power objective lens using the coarse adjustment knob/dial to find and align the cells M1\n- Rotates to the high-power ($\\times 40$) objective lens and uses the fine adjustment knob/dial to obtain a sharp, clear image A1","marks":3,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"light_microscope","label":"Using the light microscope","steps":[{"type":"hyper_latex","block":{"nodes":[{"latex":"\\text{total magnification}=\\text{eyepiece magnification}\\times\\text{objective magnification}"},{"latex":"600=15\\times40"}]},"order":0,"title":"Choose the lens pair","description":"Use a ×15 eyepiece lens with a ×40 objective lens, because 15 × 40 = 600. Alternatively, use a ×10 eyepiece lens with a ×60 objective lens. This earns B1 because the eyepiece and objective magnifications are multiplied to give ×600."},{"type":"text","order":1,"title":"Start with low power","content":"Begin with a low-power objective lens. Use the coarse adjustment knob or dial to focus until the cells are found and aligned. This earns M1 because the cells are located before changing to the high-power objective."},{"type":"text","order":2,"title":"Refine the focus","content":"Rotate to the high-power ×40 objective lens. Use the fine adjustment knob or dial to obtain a sharp, clear image. This earns A1."}]}],"generatedAt":"2026-07-22T11:16:03.367Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"1166c2a8-c2a9-4edf-bf97-08ab2bbd611f","revisionId":"56a23d2a-ec32-4795-b852-68e9a921502d","questionNumber":null,"questionType":"LA","specification":"A student prepared a temporary wet mount of onion epidermal cells to view under a light microscope, as shown in the diagram.\n\n![Preparation of onion epidermis slide](https://assets.mathsgenie.co.uk/aqa-qb/ca5c6c48-d25f-4473-a2c6-0a6fd6141dd0.png)","difficulty":3,"difficultyBand":"medium","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"fac0cab0-4971-45b3-a1c3-b6d534cc2c8f","label":null,"content":"Explain why the student must use a single-cell-thick epidermal peel (Step 1), rather than a chunk of onion bulb scale, when viewing the cells with a light microscope.","markscheme":"- Explains that a thin peel allows light to easily pass/transmit through the specimen (as light microscopes rely on light passing through the object to the lens) B1\n- Explains that it ensures there is only a single layer of cells, preventing them from overlapping so that individual cell structures can be clearly resolved and observed B1","marks":2,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"11aaae88-057f-47e0-86e8-6e7daf45465c","revisionId":"8ab2f71a-cb7e-4ad6-b403-f447edc5939a","questionNumber":null,"questionType":"LA","spe

Cells and microscopy

Question 6

Cells and microscopy Questions

Cells and microscopy

Question 6

Cells and microscopy Questions