Download 2.3 Reading Study Guide answers

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2.3 Reading/Study Guide
1. Why is it important for your body to produce millions of new cells by the time
you finish reading this sentence?
Allows you to grow and replace cells that have died.
THE LIFE OF A CELL
A __ 2.When does the cell cycle begin?
a. when the cell is formed
c. when the cell uses energy
b. when the cell divides
d. when the cell takes in oxygen
B __ 3.When does the cell cycle end?
a. when the cell is formed
new cells
c. when the cell uses energy
b. when the cell divides and makes
d. when the cell takes in oxygen
4. What must a cell do before it can divide to make a new cell?
Before a cell divides it must make copies of the DNA.
5. What makes sure that each new cell will be an exact copy of its parent cell?
Copying of chromosomes
6. A cell without a nucleus is a(n) prokaryotic cell.
7. A cell with a nucleus is a(n) eukaryotic cell.
8. A chromosome is the ring of DNA in a(n) prokaryotic cell.
9. A chromosome is made up of DNA and protein in the nucleus of a(n)
eukaryotic cell.
10. Are bacteria prokaryotic cells or eukaryotic cells?
Prokaryotic
11. Bacteria create new cells through a kind of cell division called binary fission.
12. When binary fission is complete, the result is two cells that each contain one
copy of . DNA
13. The chromosomes of eukaryotic cells have more DNA than do the
chromosomes of prokaryotic cells.
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The Cell in Action
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14. Humans have 46 chromosomes, while fruit flies have only 8. Potatoes have 48
chromosomes.
15. Chromosomes that line up in pairs are called homologous chromosomes.
16. What do pairs of homologous chromosomes have in common?
The have the same gene sequence and structure.
17. In the beginning of the eukaryotic cell cycle, the cell grows and duplicates its
organelles and chromosomes.
18. After a chromosome is duplicated, the two copies are called chromatids.
19. Where are chromatids held together? centromere
20. Chromatids in eukaryotic cells separate during a process called mitosis.
21. Describe what happens during the first stage of the cell cycle in a eukaryotic
cell.
A cell grows and copies organelles and chromosomes. Chromosomes split
into copies called chromatids. Chromatids twist into a X shape.
22. Describe what happens during the second stage of the cell cycle in a
eukaryotic cell.
Chromatids line up at the middle of the cell.
23. Describe what happens during the third stage of the cell cycle in a eukaryotic
cell.
Chromotids begin to move to opposite sides of the cell.
MITOSIS AND THE CELL CYCLE
B _ 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
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
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The Cell in Action
Name ______________________________ Class ___________________ Date __________________
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.”
Mitosis Phase 3 Anaphase
25. Chromatids separate and move to opposite
sides of the cell.
Mitosis Phase 2 Metaphase
26. The chromosomes line up along the equator of
the cell. Homologous chromosomes pair up.
Interphase ____________
27. Before mitosis begins, chromosomes are
copied.
Mitosis Phase 4 Telophase
28. A nuclear membrane forms around the two
sets of chromosomes, and the chromosomes
unwind. Mitosis is complete.
Mitosis Phase 1 Prophase
29. Mitosis begins. The nuclear membrane
dissolves. Chromosomes condense into rodlike
structures.
Cytokinesis ________ 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.
31. Describe how animal cells and eukaryotes without cell walls divide their
cytoplasm during cytokinesis.
The cell membrane pinches inward until the cytoplasm completely splits into
two new cells. These cells are called daughter cells.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
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The Cell in Action
Name ______________________________ Class ___________________ Date __________________
Match the correct definition with the correct term. Write the letter in the space
provided.
D _ 32.the process of cell division that forms two
nuclei
a. cytokinesis
b. chromosome
C _ 34.the life stages of a cell
c. cell cycle
E _ 35.pairs of similar chromosomes
B _ 36.the structure in which DNA, the hereditary
material that controls cell activities, can
be found
d. mitosis
e. homologous
chromosomes
A _ 37.the division of cytoplasm
Write the letter of the correct answer in the space provided.
B _ 38.Cells need to produce new cells in order to
a. create new chromosomes.
b. replace cells that have died.
c. obtain energy from sunlight.
d. release energy from food.
A _ 39.Organelles and chromosomes are copied during
a. the first stage of the eukaryotic cell cycle.
b. the second stage of the eukaryotic cell cycle.
c. the third stage of the eukaryotic cell cycle.
d. cytokinesis.
C _ 40.During cytokinesis in plant cells,
a. a cell plate forms inside the two new cells.
b. the cell loses some of its DNA.
c. a cell plate forms, and the cell splits in two.
d. the cell wall breaks.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
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The Cell in Action