science: chpt. 9 test Flashcards
True/false: the cell cycle is divided into interphase and mitosis
False (interphase mitosis and cytokinesis)
True/false: Diffusion over large distances is slow and inefficient because it relies on random movement of molecules and ions
True
True/false: During prophase in an onion root tip cell, centrioles migrate to the poles of the cell.
False, because centrioles are not present in plant cells, only spindle fibers
True/false: In plant cells, cytokinesis begins with a furrow that pinches the cell.
False
True/false: stem cells are only of one type: embryonic
False, there are two types of stem cells: embryonic and adult
True/false: embryonic stem cells are found in various tissues in the body and might be used to maintain and repair the same kind of tissue in which they are found
False, the answer is adult. Embryonic cells are unspecialized.
True/False: A cell such as a nerve cell, that exits the cell will do so after Gap2
False, it will exit after gap one before DNA is replicated
True/false: the structure on a chromosome where sister chromatids attach is the centromere
True
True/false: after telophase, the process of cell division is complete.
False, cell division is complete after cytokinesis.
True/false: prokaryotes divide by mitosis
False, prokaryotes divide by binary fission
True/false: cyclins bind with cyclin-dependent kinases to initiate different stages of mitosis.
False, they initiate the different stages in the cell cycle
Which of the following does not occur as a cell grows larger and larger in size?
A. Difficulty obtaining nutrients
B. Difficulty eliminating wastes
C. Ratio of surface area to volume increases
D. Diffusion across the cell membrane is impaired
C. Ratio of surface area to volume increases
Why is the synthesis stage called this?
Because DNA synthesis is taking place
Which of these has occurred by the end of prophase?
A. Sister chromatids are separated
B. The spindle is beginning to form
C. The cell membrane has begun to pinch inward
D. The nuclear membrane has disappeared
D. The nuclear membrane has disappeared
A cell has 12 chromosomes. How many chromosomes will each daughter cell have?
12
A cell that is undergoing mitosis is examined with a light microscope. An observation that would allow for identification of the cell as an animal cell rather than a plant cell would be…
The centrioles migrating
Cancer cells can reproduce rapidly because they…
Spend less time in interphase
What is the role of the cyclin-dependent kinases in the cell cycle?
They initiate various stages of the cell cycle.
DNA replication occurs during…
Interphase
Which of the phases of mitosis has the shortest duration?
Metaphase
A cell that undergoes repeated mitosis without cytokinesis would have…
Many nuclei
The typical growth period of a cell occurs during which stage of the cell cycle?
Gap 1
A stem cell has potential medical uses because it…
Is not specialized in structure and function
Interphase is divided into three stages: G1, __________, and G2
Synthesis
The longest stage of mitosis is __________.
Prophase
Cytokinesis is division of the ___________.
Cytoplasm
Once the cell cycle begins, there are built in ___________ that can stop it at any time.
Checkpoints
During development some cells go through a programmed cell death called _________.
Apoptosis
In an animal cell undergoing mitosis, the spindle first appears as two asters, a structure in which fibers radiate out from each centriole. Would you expect to find asters in plant cells? Why or why not?
No, because the plant cells have no centrioles, there would be no structures from which the fibers could radiate.
How does a high ratio of surface area to volume benefit a sale?
A smaller cell can more efficiently transport substances. In addition waste will be expelled better and it will be easier to obtain nutrients. For the cytoskeleton to be in efficient transport mechanism, the cell must be small.
Prokaryotes divide by binary fission, a form of asexual reproduction in which…
A cell divides into two cells with identical genetic info
