1.1. Figure 1 shows a micrograph of cells in actively dividing tissue from the tip of a plant root.

Figure 1

i) Name the process by which many of the cells in Figure 1 are dividing.

(1)

ii) Using Figure 1, complete Table 1

(3)

Table 1

1.2. Regarding Figure 1:

i) Identify the cells (U, V, W, X, Y or Z) that vesicles fuse to form new cell membranes across the cytoplasm to separate the cell into two daughter cells.

(2)

ii) Identify the stage of cell division that these cells are in.

(1)

1.3. The mitotic index is a measure of the proliferation status of a cell population (i.e. the proportion of dividing cells).

A student prepared a root tip squash and observed the cells under a microscope. A total of 147 cells were observed and 95 of these cells were observed in various stages of mitosis.

(i) Calculate the mitotic index for this dividing root tissue.

(1)

The teacher wanted to double-check this. The student had counted the total number of cells correctly but the teacher calculated a mitotic index of 81.

(ii) Calculate the number of cells undergoing mitosis that the teacher observed.

(1)

1.4. When the student prepared the root tip squash in part c), the root tip was placed on a microscope slide with a stain.

Explain why a stain was used.