Welcome to the Quiz!
This quiz contains 9 questions from a mix of 1 subtopics.
What is the primary purpose of translocation?
to actively load solutes into companion cells
to move water through the xylem
to transport dissolved sugars and amino acids through the phloem
to maintain a concentration gradient using enzymes
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According to the mass flow hypothesis, what happens at the source to initiate translocation?
solutes are actively removed from sieve tube elements
solutes like sucrose are actively loaded into sieve tube elements
hydrostatic pressure decreases in the sieve tube elements
water exits the sieve tube elements by osmosis
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What happens to the water potential in sieve tube elements when solutes are actively loaded at the source?
it decreases
it fluctuates
it increases
it remains unchanged
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According to the mass flow hypothesis, what creates the pressure gradient that drives translocation?
(Select all that apply)
diffusion of solutes through plasmodesmata into companion cells from sieve tube elements at the source
movement of water by osmosis into sieve tube elements at the source and out at the sink
osmosis of water out of sieve tube elements at the source and in at the sink
active loading of solutes at the source and removal of solutes at the sink
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Which of the following is NOT a feature of translocation?
it maintains a concentration gradient using enzymes
it occurs through the xylem
it transports substances from sources to sinks
it requires energy
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What happens to the hydrostatic pressure in sieve tube elements at the source during translocation?
it remains unchanged
it increases
it decreases
it fluctuates
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Which of the following is a source of assimilates for translocation?
leaves
flowers
roots
stems
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Explain how the mass flow hypothesis proposes that translocation occurs, including the roles of the source and sink.
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How are hydrogen ions (H+) involved in the active loading of sucrose into the phloem?
H+ is actively transported into companion cells from surrounding source cells
H+ is co-transported with sucrose into companion cells
H+ is not involved in the active loading of sucrose
H+ diffuses through plasmodesmata from companion cells to sieve tube elements
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