How do aquaporins allow the passage of H2O but not H3O+?

TLS Online TPP Program

#Question id: 13212

#Unit 6. System Physiology – Plant

The water at the top of a tree develops a large tension (a negative hydrostatic pressure), and this tension pulls water through the xylem this mechanism is called ,

TLS Online TPP Program

#Question id: 13210

#Unit 6. System Physiology – Plant

In Cohesion–Tension Theory, the pressure gradients needed to move water through the xylem could result from

TLS Online TPP Program

#Question id: 13209

#Unit 6. System Physiology – Plant

After unloading, the sugars are transported to cells in the sink by means of a short-distance transport pathway. This pathway has also been called,

TLS Online TPP Program

#Question id: 13208

#Unit 6. System Physiology – Plant

The polymer trapping model explains that, Plasmodesmata between the  Bundle sheath cell  and intermediary cells must be smaller that allows only selective sugar to diffuse from this Plasmodesmata such as;

TLS Online TPP Program

#Question id: 13207

#Unit 6. System Physiology – Plant

The polymer-trapping model explains symplastic loading in plants with intermediary-type companion cells, this model makes three prediction; which one of the following prediction is INCORRECT?

TLS Online TPP Program

#Question id: 13206

#Unit 6. System Physiology – Plant

Given below are some of the statements that regulate the sucrose loading mechanism;

A) The solute potential or, more likely, the turgor pressure of the sieve elements

B) Sucrose concentration in the apoplast

C) The available number of symporter protein molecules

Possible observation given on how to avoid regulation;

i) increase in sieve element turgor above a certain threshold would lead to a compensatory increase in loading

ii) High sucrose concentrations in the apoplast would increase phloem loading

iii) SUT1 transporter mRNA and protein have been lower after 15 hours of darkness than after a light treatment. These data suggest that the concentration of SUT1 transporter molecules could regulate loading

iv) Decrease in sieve element turgor below a certain threshold would lead to a compensatory increase in loading

v) The transporter mRNA and protein high in darkness than lower in the light treatment

Which of the following combinations represents correct observation?