The Mechanisms That Regulate the Loading of Sucrose from the Apoplast

question 26

Multiple Choice

The mechanisms that regulate the loading of sucrose from the apoplast to the sieve-tube members by sucrose-H⁺ symporters are not well understood.Of the following possible regulatory factors,which is least likely to be of direct importance?

• A)turgor pressure of sieve-tube members
• B)sucrose concentration in the apoplast
• C)density of direct cytoplasmic connections between companion cells and sieve-tube members
• D)number of available symporter protein molecules in the plasma membranes of sieve-tube members

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Definitions:

Long-Term Memory

Long-term memory is a type of memory responsible for the storage of information over an extended period, ranging from days to decades, and includes both conscious and unconscious information.

Classical Conditioning

A learning process where two stimuli are repeatedly paired: a response that is at first elicited by the second stimulus is eventually elicited by the first stimulus alone.

Eyeblink Response

A reflex action of closing the eyelids quickly to protect the eyes from threats or stimuli.

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Part of the brain that regulates motor movements, including coordination, precision, and timing.