CELL STRUCTURES AND FUNCTION
CELL DIVISION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Cell division is a completely random process
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Once cells divide, they can never divide again
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The controls on cell growth and division can be turned on and off
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There is only a limited amount of DNA available to a given group of cells
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Detailed explanation-1: -Cells grown in a petri dish tend to divide until they form a thin layer covering the bottom of the dish. If cells are removed from the middle of the dish, the cells bordering the open space will begin dividing until they have filled the empty space.
Detailed explanation-2: -Which of the following explains why normal cells grown in a petri dish tend to stop growing once they have covered the bottom of the dish? Contact with other cells stops cell growth.
Detailed explanation-3: -For instance, when normal cells grown in a dish are crowded by neighbors on all sides, they will no longer divide. Cancer cells, in contrast, keep dividing and pile on top of each other in lumpy layers.
Detailed explanation-4: -Metaphase Metaphase is a stage during the process of cell division (mitosis or meiosis). Normally, individual chromosomes are spread out in the cell nucleus. During metaphase, the nucleus dissolves and the cell’s chromosomes condense and move together, aligning in the center of the dividing cell.
Detailed explanation-5: -The cells stick to the bottom of the dishes and spread out as they multiply. In the body, however, cells don’t grow that way. They are surrounded by other cells in three dimensions, forming tissues such as skin, muscle, and bone.