root cap meristem elongation region Fig. 1 shows a student using a light microscope to examine the growing tip of a garlic root. Cells near the root tip div...
Question 1 Report
Fig. 1 shows a student using a light microscope to examine the growing tip of a garlic root. Cells near the root tip divide rapidly. The student used an eyepiece graticule to measure the length of cells in different regions. Table 1 shows the mean results from 20 cells in each region. The student kept the same objective lens and eyepiece lens for every measurement.
| Region of root | Mean cell length / micrometres | Number of cells observed dividing |
|---|---|---|
| Root cap | 42 | 1 |
| Meristem | 39 | 14 |
| Elongation region | 126 | 3 |
(a) Which region has the greatest number of dividing cells? [1]
(b) Describe the difference in mean cell length between the meristem and the elongation region. [2]
(c) Use the table to calculate the mean cell length increase from the meristem to the elongation region. [2]
(d) Suggest why the root cap cells are unlikely to contain chloroplasts. [2]
(e) What is the name of the process that produces genetically identical daughter cells in the meristem? [1]
Answer Details
(a) The meristem has the greatest number of dividing cells, with 14 observed [1].
(b) Cells in the elongation region are longer [1]: 126 micrometres compared with 39 micrometres in the meristem, which is about three times longer [1].
(c)
\[126-39=87\]
Mean cell length increases by 87 micrometres [2].
(d) Root-cap cells are below ground and receive little or no light [1]. Photosynthesis cannot occur effectively there, so chloroplasts are not needed [1].
(e) The process is mitosis [1].
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