## ** Chapter 21 **

Cell, tissue and tumour kinetics

**1. Which of the following statements is false? **

a. The mitotic index (MI) gives the proportion
of cells that are dividing, i.e. the duration of mitosis as a fraction of the cell cycle.

b. The labeling index (LI) gives the proportion
of cells that are synthesizing DNA, i.e. the duration of the S phase as a fraction of the cell cycle.

c. Cells are distributed linearly in time
around the cell cycle.

**2. The "percent-labeled mitoses technique" entails: **

a. the feeding of a population of cells
in the S-phase and the subsequent observation of the stained cells in the M phase.

b. the determination of the fraction
of dividing cells at a given time after irradiation.

c. the determination of the relative duration
of mitosis.

**3. By the term "percentage of labeled mitoses" is meant: **

a. the percentage of mitoses occuring
at a given time as a fraction of the total number of mitoses occuring in the cell cycle.

b. the percentage of cells at mitosis
as a fraction of the total number of cells in the studied population.

c. the percentage of mitotic cells that
carry a radioactive label.

**4. All cells in a population have indentical cell cycle times.**

a. True.

b. False.

**5. By using the percent-labeled mitoses technique, one
determines the duration of the various cell cycle phases. **

a. True.

b. False.

**6. In the percent-labeled mitoses technique, the time interval
before any mitotic cells appear gives the duration of:**

a. the S phase.

b. the G_{1} phase.

c. the G_{2} phase.

d. the M phase.

**7. In practice, the data obtained using
the percent-labeled mitoses technique can determine precisely: **

a. the peaks and 50% levels of the curves.

b. the peaks of the curves.

c. the duration of the S period.

**8. In the cases where at least two peaks are discernible in the
data collected by using the percent-labeled mitoses technique,
the duration of all phases in the cell cycle can be
determined if one combines these data with: **

a. the labeling index.

b. the mitotic index.

**9. In the cases where only one peak is discernible in the
data collected by using the percent-labeled mitoses technique,
the duration of all phases in the cell cycle can be
determined if one combines these data with: **

a. the labeling index.

b. the mitotic index.

**10. Cancer cells of a given tissue type have: **

a. shorter cell cycles than the normal cells
of this tissue type.

b. longer cell cycles than the normal cells
of this tissue type.

c. about equal cell cycles than the normal cells
of this tissue type.