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Câu 53:
Câu 53:
What is the “quiescent center” and where is
What is the “quiescent center” and where is
it located? What is known about the
it located? What is known about the
function of the quiescent center?
function of the quiescent center?



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
This structure is located
This structure is located
just behind the root cap and
just behind the root cap and
consists of 500-1,000 seemingly
consists of 500-1,000 seemingly
inactive cells.
inactive cells.






These cells are usually in
These cells are usually in
the G1 phase of the cell cycle

the G1 phase of the cell cycle
and divide only about once
and divide only about once
every 15-20 days.
every 15-20 days.



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


Quiescent and
Quiescent and
meristematic cells are different
meristematic cells are different
in sensitivity to environmental
in sensitivity to environmental
problems such as radiation.
problems such as radiation.


For example, meristematic
For example, meristematic
cells stop dividing when
cells stop dividing when
exposed to x rays while
exposed to x rays while
quiescent cells are unaffected by
quiescent cells are unaffected by

radiation and soon begin
radiation and soon begin
dividing to reform the
dividing to reform the
meristem.
meristem.



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


Cells in the quiescent
Cells in the quiescent
center function as a reservoir
center function as a reservoir
to replace damaged cells of
to replace damaged cells of
the meristem.
the meristem.


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


Its important because it
Its important because it
organizes the patterns of

organizes the patterns of
primary growth in roots.
primary growth in roots.