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Additional questions calculate stage duration from proportional cell counts, analyse cell-cycle timing across three cell types, compare adaptations of specialized cells, and apply mitosis/meiosis to moss life-cycle chromosome and DNA strand counts.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/exam/","Exam",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/cell-division-and-specialisation-question-23-29/457221/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/cell-division-and-specialisation-question-23-29/457221.png","ImageObject",300,407,{"name":42,"@type":43},"anakgang17","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-22","2026-09-30",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",7,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"What abnormality might be seen if the metaphase checkpoint is not working?","Question",{"text":63,"@type":64},"Cells may progress from metaphase without proper chromosome alignment and control. This can allow division to continue even when chromosomes are not correctly prepared.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"In flow cytometry, how do fluorescence levels relate to DNA amount and interphase stages?",{"text":68,"@type":64},"Fluorescence is proportional to DNA content. The stage with the least fluorescence corresponds to the earliest interphase stage with the lowest DNA content, while the most fluorescence corresponds to the interphase stage where DNA has been replicated.",{"name":70,"@type":61,"acceptedAnswer":71},"Why is fluorescent dye use inappropriate for analysing red blood cells?",{"text":72,"@type":64},"Red blood cells do not contain nuclei, so they lack DNA for the dye to stain. 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The eukaryotic cell cycle is regulated by three checkpoints. Mutations can occur in genes that control the cell cycle checkpoints.  \nScientists recorded observations of two different tissues.  \ni. In one tissue, the scientists found a genetic mutation that stopped the metaphase checkpoint from working.  \nSuggest an abnormality the scientists might observe in the cells of this tissue.  \n[1]  \nii. In the other tissue, the scientists observed cells with chromosomes that had been replicated despite containing damaged DNA.  \nSuggest which cell cycle checkpoint is no longer working in this tissue and justify your answer.  \n[1]  \n24. The figure is a diagram that represents the different phases of the cell cycle.  \nX, Y and Z represent checkpoints in the control of the cell cycle.  \nFig. 2.3  \ni. State all the letters in the figure that represent the phases of interphase.  \nCell Division and Specialisation  \nii. Suggest what is being checked at checkpoint Y on the figure .  \n\n|  |\n| --- |\n|  |\n\n[1]  \n25. Cells can be counted and analysed using a technique called flow cytometry. DNA in the cells is stained with a fluorescent dye before analysis. The degree of fluorescence is dependent on the amount of DNA present.  \ni. Use your knowledge of the cell cycle to name the stages of interphase that match the following descriptions.  \nThe stage in which a cell produces the least fluorescence  \n\n| The stage in which a cell produces the most fluorescence |\n| --- |\n| The stage in which the highest number of cells is recorded |\n\n[3]  \nii. Scientists analysed a sample of liver cells. Of these cells, 27.2% were found to be undergoing cell division or nuclear division. An adult human's liver contains approximately 180 billion cells.  \nEstimate the number of cells in interphase in an adult human's liver.  \nWrite your answer in standard form to two significant figures.  \nAnswer = ................................................................... [1]  \niii. Suggest why the use of fluorescent dyes in flow cytometry is inappropriate when analysing red blood cells.  \nCell Division and Specialisation  \n26. A student observed a prepared slide of an onion root tip under a microscope.  \nThe total number of cells in the field of view was 265.  \nThe number of cells at the different stages of the cell cycle are shown in Table 23.  \n\n| Stage of cell cycle | Number of cells |\n| --- | --- |\n| interphase | 207 |\n| prophase | 42 |\n| metaphase | 4 |\n| anaphase | 6 |\n| telophase | 6 |\n\nTable 23  \nThe cell cycle takes 20 hours. The number of cells visible at each stage is proportional to how long each stage of the cell cycle lasts.  \nCalculate the time taken for prophase to occur.  \nGive your answer in minutes to the nearest whole number.  \ntime taken = ......................................... min [2]  \nCell Division and Specialisation  \n27. indicates the relative time spent in different phases of the cell cycle for three different types of cell, P, Q and R.  \n\n| Cell type | Relative time spent in a phase |  |  |  |\n| --- | --- | --- | --- | --- |\n|  | G1/G0 | S | G2 | M/C |\n| P | 18 | 50 | 13 | 19 |\n| Q | 18 | 25 | 11 | 16 |\n| R | 100 | 0 | 0 | 0 |\n\ni. Which of the cells P, Q or R takes the shortest time to divide?  \n[1]  \nii. Suggest why cell P spends twice as much time in phase S than cell Q.  \n\n|  |\n| --- |\n|  |\n\n[1]  \niii. What can be deduced about the behaviour of cell R?  \nGive reasons for your answer.  \n\n|  |\n| --- |\n|  |\n|  |\n|  |\n\n[2]  \nCell Division and Specialisation  \n28. The table describes adaptations of three types of specialised cell.  \n\n|  | Erythrocytes | Neutrophils | Palisade cells |\n| --- | --- | --- | --- |\n| A | biconcave shape with flattened nucleus to allow them to squeeze through narrow capillaries | a large, spherical nucleus and cytoplasm that contains many lysosomes | thick cell walls to maintain turgor |\n| B | biconcave shape with no nucleus and flexible to allow them to squeeze through narrow capil","cbCaigHUDr8wFq3X","https://ap.wps.com/l/cbCaigHUDr8wFq3X","pdf",1876840,38,"English","# Cell cycle checkpoints and mutations\n# Interphase phases and checkpoint functions\n# Flow cytometry and interphase fluorescence\n# Estimating interphase cell number\n# DNA staining in flow cytometry (red blood cells)\n# Onion root tip timing calculations\n# Relative phase timing across cell types\n# Adaptations of specialized cells\n# Moss life cycle and DNA strand calculation\n## DNA strands before mitosis\n## Identifying meiosis on a diagram\n## Adaptations in moss sperm cells","[{\"question\":\"What abnormality might be seen if the metaphase checkpoint is not working?\",\"answer\":\"Cells may progress from metaphase without proper chromosome alignment and control. This can allow division to continue even when chromosomes are not correctly prepared.\"},{\"question\":\"In flow cytometry, how do fluorescence levels relate to DNA amount and interphase stages?\",\"answer\":\"Fluorescence is proportional to DNA content. The stage with the least fluorescence corresponds to the earliest interphase stage with the lowest DNA content, while the most fluorescence corresponds to the interphase stage where DNA has been replicated.\"},{\"question\":\"Why is fluorescent dye use inappropriate for analysing red blood cells?\",\"answer\":\"Red blood cells do not contain nuclei, so they lack DNA for the dye to stain. As a result, fluorescence cannot reliably indicate DNA content or cell-cycle stage.\"}]","Cell Division and Specialisation - Question 23-29 | PDF",1790748652,96]