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Skills Worksheet
Directed Reading A
Section: The Cell Cycle
1. Why is it important for your body to produce millions of new cells by the time
you finish reading this sentence?
THE LIFE OF A CELL
______ 2. When does the cell cycle begin?
a. when the cell is formed
b. when the cell divides
c. when the cell uses energy
d. when the cell takes in oxygen
______ 3. When does the cell cycle end?
a. when the cell is formed
b. when the cell divides and makes new cells
c. when the cell uses energy
d. when the cell takes in oxygen
4. What must a cell do before it can divide to make a new cell?
5. What makes sure that each new cell will be an exact copy of its parent cell?
6. A cell without a nucleus is a(n)
cell.
7. A cell with a nucleus is a(n)
cell.
8. A chromosome is the ring of DNA in a(n)
cell.
9. A chromosome is made up of DNA and protein in the nucleus of a(n)
cell.
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Directed Reading A continued
10. Are bacteria prokaryotic cells or eukaryotic cells?
11. Bacteria create new cells through a kind of cell division called
.
12. When binary fission is complete, the result is two cells that each contain
one copy of
.
13. The chromosomes of eukaryotic cells have more
than do the chromosomes of prokaryotic cells.
14. Humans have
chromosomes, while fruit flies have
only
. Potatoes have
chromosomes.
15. Chromosomes that line up in pairs are called
.
16. What do pairs of homologous chromosomes have in common?
17. In the beginning of the eukaryotic cell cycle, the cell grows and duplicates
its
and
.
18. After a chromosome is duplicated, the two copies are
called
.
19. Where are chromatids held together?
20. Chromatids in eukaryotic cells separate during a process called
.
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Directed Reading A continued
21. Describe what happens during the first stage of the cell cycle in a
eukaryotic cell.
22. Describe what happens during the second stage of the cell cycle in a
eukaryotic cell.
23. Describe what happens during the third stage of the cell cycle in a eukaryotic
cell.
MITOSIS AND THE CELL CYCLE
______24. Before mitosis begins, what paired cell structures are copied?
a. the cell plates
b. the chromosomes
c. the cell membranes
d. the nuclear membrane
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Directed Reading A continued
Use the diagram below to help answer questions 25-30, which describe the phases
of the cell cycle. Write the correct phase in each blank, using “Interphase,”
“Mitosis Phase 1,” “Mitosis Phase 2,” “Mitosis Phase 3,” “Mitosis Phase 4,” or
“Cytokinesis.”
Interphase
Mitosis Phase 1
Mitosis Phase 2
Mitosis Phase 3
Mitosis Phase 4
Cytokinesis
_______________________ 25. Chromatids separate and move to opposite sides of
the cell.
_______________________ 26. The chromosomes line up along the equator of the
cell. Homologous chromosomes pair up.
_______________________ 27. Before mitosis begins, chromosomes are copied.
_______________________ 28. A nuclear membrane forms around the two sets of
chromosomes, and the chromosomes unwind.
Mitosis is complete.
_______________________ 29. Mitosis begins. The nuclear membrane dissolves.
Chromosomes condense into rodlike structures.
_______________________ 30. In cells that lack a cell wall, the cell pinches in
two. In cells that have a cell wall, a cell plate forms
between the two new cells.
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Directed Reading A continued
31. Describe how animal cells and eukaryotes without cell walls divide their
cytoplasm during cytokinesis.
Place the following structures in the order in which they form in eukaryotic cells
with cell walls during cytokinesis. Write the appropriate number in the space
provided.
______32. cell wall
______33. cell plate
______34. cell membrane
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Skills Worksheet
Section Review
The Cell Cycle
USING KEY TERMS
1. In your own words, write a definition for each of the following terms: cell
cycle and cytokinesis.
UNDERSTANDING KEY IDEAS
______ 2. Eukaryotic cells
a. do not divide.
b. undergo binary fission.
c. undergo mitosis.
d. have cell walls.
3. Why is it important for chromosomes to be copied before cell division?
4. Describe mitosis.
MATH SKILLS
5. Cell A takes 6 h to complete division. Cell B takes 8 h to complete division.
After 24 h, how many more copies of cell A would there be than cell B? Show
your work below.
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Section Review continued
CRITICAL THINKING
6. Predicting Consequences What would happen if cytokinesis occurred
without mitosis?
7. Applying Concepts How does mitosis ensure that a new cell is just like its
parent cell?
8. Making Comparisons Compare the processes that animal cells and plant cells
use to make new cells. How are the processes different?
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