#Question id: 10905
#Unit 6. System Physiology – Plant
The rate of movement of materials in the sieve
elements can be expressed in two ways: as velocity, or as mass transfer rate.
In early publications reporting on rates of transport in the phloem, what is
the velocity and the mass transfer rate?
i)
velocity-centimeters per hour (cm h-1) and mass transfer- grams per
hour per square centimeter (g h-1 cm-2)
ii)
velocity-the linear distance traveled per unit time and mass transfer rate-the
quantity of material passing through a given cross section of phloem or sieve
elements per unit time.
iii) velocity- the
quantity of material passing through a given cross section of phloem or sieve
elements per unit time and mass transfer rate- the linear distance traveled per
unit time
iv) velocity- per hour per square centimeter (h-1 cm-2) and mass transfer- kg centimeters per hour (cm h-1)
#Question id: 10906
#Unit 6. System Physiology – Plant
The pressure-flow model explains phloem translocation as a flow of solution (bulk flow) driven by an osmotically generated pressure gradient between source and sink.
a) Phloem translocation, both active and passive mechanisms were considered. All theories, both active and passive, assume an energy requirement in both sources and sinks.
b) In sources, energy is necessary to move photosynthate from producing cells into the sieve elements. This movement of photosynthate is called phloem loading.
c) In sinks, energy is essential for some aspects of movement from sieve elements to sink cells, which store or metabolize the sugar. This movement of photosynthate from sieve elements to sink cells is called phloem unloading.
d) The Active mechanisms of phloem transport further assume that energy is required in the sieve elements of the path between sources and sinks simply to maintain structures.
From the given statements find out the correct for pressure-flow model.
#Question id: 10907
#Unit 6. System Physiology – Plant
The mechanism of phloem translocation in angiosperms is best explained by the pressure-flow model, this model is an example of,
#Question id: 10908
#Unit 6. System Physiology – Plant
The energy is necessary to move photosynthate from producing cells into the sieve elements. This movement of photosynthate is called
#Question id: 10909
#Unit 6. System Physiology – Plant
The energy is essential for some aspects of movement from sieve elements to sink cells, which store or metabolize the sugar. This movement of photosynthate from sieve elements to sink cells is called
#Question id: 10910
#Unit 6. System Physiology – Plant
In early research on phloem translocation, both active and passive mechanisms were considered. All theories, both active and passive, assume an energy requirement in both sources and sinks. What will be the INCORRECT explanation of active and passive mechanism?