:"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"b7a290ed-f065-4dee-87e7-0de853456969","revisionId":"cd22eaba-5f69-47d9-acc3-4f04dafbca8a","questionNumber":null,"questionType":"LA","specification":"Carrot taproots grow entirely underground.","difficulty":4,"difficultyBand":"medium","totalMarks":3,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"b5bec796-a485-4003-9970-cddfe707cce1","label":null,"content":"Explain why the cells of a carrot taproot do not contain chloroplasts.","markscheme":"- States that carrot taproots are located underground where there is no light / they are in darkness B1\n- States that the role of chloroplasts is to absorb light energy to carry out photosynthesis B1\n- Explains that since no light is available, photosynthesis cannot occur, so chloroplasts are not needed or present in these cells B1","marks":3,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"link_light_to_function","label":"Link light to chloroplasts","steps":[{"type":"text","order":0,"title":"Use the location","content":"The taproot **grows entirely underground**, so its cells are in darkness and no light reaches them. This earns the first mark (B1).","highlights":[{"text":"Carrot taproots grow entirely underground.","location":"specification"}]},{"type":"text","order":1,"title":"State chloroplast function","content":"Chloroplasts absorb light energy for photosynthesis. This is the second marking point (B1)."},{"type":"text","order":2,"title":"Finish the explanation","content":"Because no light is available underground, photosynthesis cannot occur, so chloroplasts are not needed or present in the carrot taproot cells. This completes the third marking point (B1)."}]}],"generatedAt":"2026-07-22T09:58:00.336Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"c6b9dc53-1deb-49bf-8005-862bf7ff7297","revisionId":"8e28332f-01e5-4c9c-8b0d-25c844c7cf29","questionNumber":null,"questionType":"LA","specification":"A student cut a thick slice of rhubarb stem, placed it directly onto a dry microscope slide, and lowered a coverslip over it.\n\nThey placed the slide on the stage of a light microscope and looked through the eyepiece, but they could not see any distinct cell structures.","difficulty":3,"difficultyBand":"medium","totalMarks":6,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"89cf70a9-1364-42f7-bd0f-c44e1315d1d5","label":null,"content":"Explain two improvements the student should make to their method to clearly see the details of the cells.","markscheme":"- **Improvement 1:** Cut or prepare an extremely thin section, or peel a single-cell-thick layer of rhubarb epidermis B1\n- **Explanation 1:** This allows light to pass through the specimen so individual cells can be resolved B1\n- **Improvement 2:** Add a drop of chemical stain, such as iodine solution or methylene blue B1\n- **Explanation 2:** This increases contrast or binds to specific cell structures to make organelles (like the nucleus or cell wall) visible B1\n- **Alternative Improvement:** Add a drop of water or mounting medium to the slide before lowering the coverslip B1\n- **Alternative Explanation:** This suspends the specimen, prevents drying out, or prevents air bubbles from obscuring the image B1","marks":6,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"prepare_and_stain","label":"Prepare and stain the slide","steps":[{"type":"text","order":1,"title":"Make the specimen thin","content":"First, **do not use a thick slice**. Cut an **extremely thin section** of the rhubarb stem, or peel off a **single-cell-thick epidermis** (the outer cell layer).\n\nThis is the first improvement mark: it directly fixes the problem caused by the thick specimen.","highlights":[{"text":"cut a thick slice of rhubarb stem","loc

Cells and microscopy

Question 13

Cells and microscopy Questions

Cells and microscopy

Question 13

Cells and microscopy Questions