** mark."}]}],"generatedAt":"2026-07-22T08:53:07.976Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"72019bef-8f12-4b70-b953-116b393ac983","revisionId":"19e0ea3d-c3c3-49f8-8f32-1630bb3d6c1b","questionNumber":null,"questionType":"LA","specification":"","difficulty":5,"difficultyBand":"medium","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"1c6e00a3-8f64-4727-a6aa-85e7c8461fb5","label":null,"content":"Explain how stem cells located in the crypts of the human small intestine contribute to the ongoing maintenance and repair of the intestinal lining.","markscheme":"- Stem cells divide by mitosis to produce a constant supply of new cells M1\n- These cells differentiate (or specialise) into functional cell types of the intestinal epithelium (such as absorptive or secretory cells) A1","marks":2,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"stem_cell_renewal","label":"Stem cell renewal","steps":[{"type":"text","order":1,"title":"State the cell division","content":"The lining continually needs replacement cells. Stem cells in the crypts **divide by mitosis**, producing a constant supply of genetically identical new cells.\n\nThis earns **M1**: mitosis is the type of cell division used for growth and repair.","highlights":[{"text":"stem cells located in the crypts of the human small intestine","location":"specification"},{"text":"ongoing maintenance and repair","location":"specification"}]},{"type":"text","order":2,"title":"Explain their specialisation","content":"The new cells then **differentiate** (specialise) into functional epithelial cells of the intestinal lining, for example absorptive cells or secretory cells.\n\nThis earns **A1** because these specialised cells maintain the lining and replace cells after damage.","highlights":[{"text":"maintenance and repair of the intestinal lining","location":"specification"}]}]}],"generatedAt":"2026-07-22T08:48:12.969Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"7bfaccb6-be56-4d71-b8da-2e069aba9ccf","revisionId":"da15828e-daa5-4278-a103-aceb826bbcbe","questionNumber":null,"questionType":"LA","specification":"Scientists have developed techniques to reprogramme adult human skin cells into induced pluripotent stem cells (iPSCs), which behave almost identically to embryonic stem cells.","difficulty":4,"difficultyBand":"medium","totalMarks":4,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"f81c96d4-7f6a-401f-af68-607926511548","label":null,"content":"Describe three benefits of using these reprogrammed adult body cells in medical treatments and clinical research compared to using embryonic stem cells.","markscheme":"- Avoids the ethical or moral objections associated with the destruction of human embryos B1\n- Lower risk of immune rejection if the patient's own cells are reprogrammed to create genetically matched tissues B1\n- Easier or less complex to obtain/harvest skin cells compared to acquiring fertilised human embryos from IVF clinics B1\n- Can be used to model specific genetic diseases or test new drug safety in vitro using patient-specific cells B1","marks":4,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"identify_comparative_benefits","label":"Identify comparative benefits","steps":[{"type":"text","order":1,"title":"Avoid embryo destruction","content":"Adult skin cells can be taken and reprogrammed without destroying a human embryo. This avoids the ethical or moral objections that some people have to embryonic stem-cell use. **This is one distinct benefit (B1).**","highlights":[{"text":"adult human skin cells","location":"specification"},{"text":"embryonic stem cells","location":"specification"}]},{"type":"text","order":2,"title":"Match the patient","content":"A patient's own skin cells can be reprogrammed into iPSCs

Mitosis, growth and stem cells

Question 10

Mitosis, growth and stem cells Questions

Mitosis, growth and stem cells

Question 10

Mitosis, growth and stem cells Questions