Chapter 10 Section Review Answer Key
Section Review 10-1
1. cell membrane 2. surface area 3. cell division
4. The information contained in the DNA would not
be able to meet the needs of the larger cell. 5. Food,
oxygen, and water enter the cell, and waste products
exit the cell via the cell membrane. 6. The ratio of
surface area to volume decreases as the cell’s size
increases. 7. Cells divide because of the problems of
DNA“overload” and of increasing size that decreases
the ratio of surface area to volume. 8. 6 cm3 9. 6:1
10. 80 cm2
Section Review 10-2
1. The four phases of the cell cycle are the M phase
(mitosis), G1 phase (cell growth), S phase (DNA replication), and G2 phase. 2. The cell replicates its chromosomes. 3. During cytokinesis, the cytoplasm
divides from one cell into two cells. 4. metaphase
5. prophase 6. prophase 7. anaphase 8. telophase
9. prophase 10. metaphase 11. anaphase
12. Mitosis refers only to the division of the nucleus,
while cell division also includes cytokinesis, or division
of the cytoplasm. 13. There would be 64 cells
after 7.5 hours. 14. Possible student answers may
include any reference to incorrect movement of chromosomes during mitosis, lack of cytokinesis, or DNA duplication without cell division. 15. An animal cell has centrioles, while a plant cell has regions known as centromeres. During cytokinesis, in most animal cells
the cell membrane moves inward and pinches the
cytoplasm into two equal parts. In a plant cell, a cell
plate forms midway between the two divided nuclei.
Section Review 10-3
1. Cyclin regulates the timing of the cell cycle in
eukaryotic cells. 2. Internal regulators prevent a
cell from entering mitosis until all chromosomes
have been replicated. 3. External regulators, such
as growth factors, direct cells to speed up or slow
down the cell cycle. 4. The abnormal growth of
cancer cells is caused by the failure to respond to
signals that regulate growth. 5. No. Some cells
complete the cell cycle more quickly than other
cells, or spend more time in one phase than another.
External regulators can also alter the growth rate.
For example, when there is an injury to the skin,
the cells will increase their growth rate. Another
example is when molecules on the surface of neighboring cells cause a cell to decrease its growth rate. 6. Possible student answer: How much cyclin is in
cancer cells? 7. Both internal and external regulators
regulate the timing of the cell cycle. The external
regulators respond to stimuli from outside the
cell, and the internal regulators respond to stimuli
within the cell. 8. Possible student answer: A cut
or injury is followed by a period of increased cell
growth. After healing is complete, the cells return
to a normal rate of growth.
Chapter Vocabulary Review
1. cell division 2. centromere 3. interphase 4. cell
cycle 5. spindle 6. Mitosis 7. prophase, metaphase,
anaphase, telophase 8. cytokinesis 9. cyclins
10. cancer 11. a 12. c 13. b 14. a 15. a 16. b
17. d 18. G2 phase 19. prophase 20. metaphase
21. anaphase 22. telophase 23. cytokinesis
24. G1 phase 25. S phase