Ch 11 Cell cycle and division
Practical 11.1 Examination of different stages of the cell
cycle
Questions (p. 11-2)
1
Cell
Mitosis (Nuclear division)
Cell
growth
(Prophase)
Stage 1
Stage 2
(Metaphase)
Cytoplasmic
Stage 4
division
(Anaphase) (Telophase)
✓
A
B
✓
C
✓
D
Stage 3
✓
E
✓
F
✓
✓
G
✓
H
✓
I
✓
J
2
Interphase: Individual chromosomes cannot be distinguished.
Prophase: Chromosomes become visible, each is seen to consist of two
chromatids held together at the centromere. The nuclear membrane disintegrates.
Metaphase: The chromosomes line up in the middle of the cell.
Anaphase: The two chromatids of each chromosome separate and move to the
opposite poles of the cell. The cytoplasm starts to divide.
Telophase: New nuclear membranes form around each set of chromosomes. The
chromosomes uncoil to become chromatin again.
3
The cells near the tips divide actively by mitotic cell division.
Practical 11.2 Investigation of the relative time required
for each stage of the cell cycle
Results (p. 11-6)
1
2
Number of cells in the stage
Area 1 (A1)
Area 2 (A2)
Area 3 (A3)
Relative time spent in the stage
(min)
Interphase
23
25
24
551
Prophase
3
2
3
61
Metaphase
2
2
1
38
Anaphase
1
1
1
23
Telophase
1
2
1
30
Cytoplasmic
division
1
0
1
15
Stage
Total number of cells in each area
T1 = 31
T2 = 32
T3 = 31
3
Questions (p. 11-8)
1
To expose more cells for observation.
2
a
To intensify the stain.
b
To avoid the slide being overheated and broken.
3
The number of cells in each phase is directly proportional to the time required by
the cells in that phase.
4
a
(Answer varies with results.)
b
(Answer varies with results.)
a
The results are different. This is because different students and groups used
slightly different criteria to categorize the phases (i.e. personal judgment
and subjectivity) or different groups collected their data from different
samples.
b
No. The findings are based on an assumption without testing. If the
assumption is wrong, the findings will also be incorrect.
c
Subjectivity; Tentativeness; Observation vs. Inference; Creativity;
Empirically based.
5
Conclusion (p. 11-9)
Interphase takes the longest time in the cell cycle. Phases in mitosis are relatively
short.
Practical 11.3 Examination of meiotic cell division
Questions (p. 11-13)
1
4.
2
8.
3
abdce
a) Homologous chromosomes line up at the middle of the cell. → b) Separation
of homologous chromosomes. → d) Formation of two daughter cells each with
chromosome number halved. → c) Arrangement of chromosomes at the middle
of the cell. → e) Formation of four haploid daughter cells.