Fig. 6.1 is a photomicrograph of plant cells in stages of the mitotic cell cycle. [Figure 6.1]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2022). The mark or mark type is shown in brackets.

1. [1] (a)(i) anaphase ;
2. [2] (a)(ii) any two from: growth;
3. R growth of cells
4. repair of tissues (by replacement of cells);
5. replacement of, old / dead /damaged / worn out, cells ;
6. R repair of cells
7. asexual reproduction ;
8. production of genetically identical daughter cells ;
9. [4] (b) any four from: as concentration of Paclitaxel increases, the ratio of cells in anaphase to those in metaphase reduces / there are a greater proportion of cells in metaphase than in anaphase ;
10. as the concentration of Paclitaxel increases, the percentage of cells in mitosis is increasing;
11. use of data to support a described trend ;
12. idea that as the concentration increases, more cells, stop in metaphase / spend more time in metaphase / fewer cells are able to move into anaphase ;
13. suggested mechanism for halt in metaphase ; e.g. centromeres do not divide prevents spindle fibres shortening prevents movement of chromatids to opposite poles (because sister chromatids still held together) cells do not pass the (metaphase) checkpoint
14. AVP;