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DP IB Biology: HL

Topic Questions

Home / IB / Biology: HL / DP / Topic Questions / 1. Cell Biology / 1.4 Cells: Division / Structured Questions: Paper 2


1.4 Cells: Division

Question 1a

Marks: 2
a)

Bowel cancer can result from adenoma polyps. Adenoma polyps form as a result of mutations occurring in dividing cells of the colon lining.

Suggest the differences in the cell cycle of a cancer cell compared with that of a normal intestinal cell.

[2 marks]

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    Key Concepts
    Tumour Formation

    Question 1b

    Marks: 3
    b)

    Compare and contrast the process of cytokinesis in plants and animals.

    [3 marks]

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      Key Concepts
      Cytokinesis

      Question 1c

      Marks: 2
      c)

      Before the cell progresses from G1 into S phase, it needs to pass through a checkpoint, which prevents the cell cycle from proceeding if certain conditions are not met. 

      Suggest one reason why a cell might not progress through the checkpoint.

      [2  marks]

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        Key Concepts
        Interphase

        Question 1d

        Marks: 2
        d)
        The graph below shows data produced from a flow cytometer. This measures the number of cells that are labelled with DNA bound to a fluorescent dye, as this is proportional to DNA content. The stages of the cell cycle are indicated.
        1-4-h-1d-paper-2

        Suggest why, during the S phase, that the amount of DNA per cell is between 2n and 4n.

        [ 2 marks]

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          Key Concepts
          Interphase

          Question 2a

          Marks: 2
          a)

          During the cell cycle, there are various checkpoints the cell meets to determine if there are any errors. If an error cannot be repaired then the cell goes through cell death (apoptosis).

          Scientists have developed cancer drugs that can inhibit the cell cycle and cause the cell to carry out apoptosis. Paclitaxel and 5-fluorouracil are two of these cancer drugs.

          • Paclitaxel binds to spindle microtubules preventing the spindle from performing its function
          • 5-fluorouracil prevents the synthesis of thymine nucleotides

          Determine at which stages of the cell cycle these drugs would take effect and inhibit the cell cycle.  

          [2 marks]

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            Question 2b

            Marks: 3
            b)

            Discuss the role serendipity plays in scientific discoveries, using a named example.

            [3 marks]

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              Key Concepts
              Cyclins

              Question 2c

              Marks: 3
              c)

              Sketch a graph to illustrate which cyclin is controlling the different phases of the cell cycle.

              [3 marks]

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                Key Concepts
                Cyclins

                Question 2d

                Marks: 2
                d)

                In order to identify which phase of the cycle a cell is in, other than mitosis, biochemical analysis is used. Radioactive thymidine is one example of a biochemical used. 

                Suggest, giving a reason, which phase is readily identified when radioactive thymidine is used.

                [2 marks]

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                  Key Concepts
                  Interphase

                  Question 3a

                  Marks: 2
                  a)

                  A team of biologists estimated the number of cells in different phases of the cell cycle in Saccharomyces cerevisiae (brewer's yeast). They took two samples, A and B, from different environmental conditions. One sample came from a nutrient-rich environment, the other from a nutrient-poor environment.

                  Their results are shown in the table below.


                  Phase of the cell cycle

                  Sample A 

                  / number of cells counted

                  Sample B 

                  / number of cells counted

                  G1

                  312

                  451

                  S

                  203

                  294

                  G2

                  136

                  196

                  Mitosis

                  27

                  39

                  Total

                  678

                  980


                  In sample A, a full cell cycle took 1 hour and 35 minutes, whereas, in sample B, a full cell cycle took 60 minutes. 

                  Calculate the time, in minutes, that the cells in sample A were in S phase during one cycle. Show your working.

                  [2 marks]

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                    Key Concepts
                    Interphase

                    Question 3b

                    Marks: 2
                    b)

                    The biologists studying the Saccharomyces cerevisiae (brewer's yeast) from part (a) hypothesised that when the yeast was exposed to stressful conditions, the growth rates were low. 

                    Suggest, with a reason, which sample came from the nutrient-rich conditions.

                    [2 marks]

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                      Key Concepts
                      Interphase

                      Question 3c

                      Marks: 2
                      c)

                      The availability of nutrients is also a key factor in regulating the cell cycle of Schizosaccharomyces pombe (fission yeast).  Below is a table containing data scientists collected for two sites which were deficient in nitrogen and phosphate. 


                      Phase of the cell cycle

                      Deficient in nitrogen 

                      / number of cells counted

                      Deficient in phosphate 

                      / number of cells counted

                      G1

                      207

                      181

                      S

                      135

                      118

                      G2

                      90

                      79

                      Mitosis

                      0

                      0

                      Total

                      432

                      378


                      Deduce, giving a reason, the point at which a nutrient-poor environment would arrest the cell cycle of the Schizosaccharomyces pombe.

                      [2 marks]

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                        Key Concepts
                        Interphase

                        Question 3d

                        Marks: 2
                        d)

                        The Saccharomyces cerevisiae (brewer's yeast) nuclei are, on average, 2 µm in diameter, but the DNA molecules packed into them have been measured up to 355 µm in length. 

                        Describe the process that enables the DNA molecules, that comprise the 16 chromosomes of yeast, to be packed into the nuclei.

                        [2 marks]

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                          Key Concepts
                          Chromosomes Condense

                          Question 4a

                          Marks: 1
                          a)

                          The diagram below shows a drawing of an electron micrograph of a cell undergoing mitosis.

                          wlYY9zpU_h-4a

                          Deduce which phase of mitosis this cell is in.

                          [1 mark]

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                            Question 4b

                            Marks: 2
                            b)

                            The diagram below shows a sample of root tissue collected by a researcher.

                            Root tip mitotic index question

                            Calculate the mitotic index.

                            [2 marks]

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                              Question 4c

                              Marks: 2
                              c)

                              A student’s research determined that the cell cycle of the growing tissue in a similar root as part (b) was 1,560 minutes in length, and that on average, cells spent 5 hours in the visible stages of mitosis.

                              Calculate the percentage difference between the data gathered by the student and the mean length of the mitotic stages found by the researcher in part (b).

                              [2 marks]

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                                Key Concepts
                                Phases of Mitosis

                                Question 4d

                                Marks: 2
                                d)

                                Suggest two possible reasons why there may have been differences in the mitotic index the researcher determined and the student’s value.

                                [2 marks]

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                                  Question 5a

                                  Marks: 4

                                  One mark is available for clarity of communication throughout this question.

                                  a)

                                  MPXV is a virus that belongs in the same group as smallpox and cowpox.

                                  Explain why viruses, such as MPXV, do not have a cell cycle.

                                  [4 marks]

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                                    Key Concepts
                                    Interphase

                                    Question 5b

                                    Marks: 5
                                    b)

                                    Some cell biologists believe that the use of the term ‘cell division’ should be discontinued and replaced with ‘cell multiplication’.

                                    Evaluate this claim using your knowledge of the cell cycle.

                                    [5 marks]

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                                      Key Concepts
                                      Interphase

                                      Question 5c

                                      Marks: 6
                                      c)

                                      Human papillomaviruses are the main cause of cervical cancer.

                                      Explain how mutagens can interrupt the cell cycle to cause cancer.

                                      [6 marks]

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                                        Key Concepts
                                        Tumour Formation