The herbaceous plant Achillea lanulosa is widespread in the Northern Hemisphere. Phenotypic variation in the species has been extensively studied along an altitudinal gradient from sea level to over 3,000 meters. In California there is conspicuous variation in  height; alpine plants are only several centimeters tall  while  those in  the San Joaquin Valley may reach a height of 1.8 meters. Adaptation to different local environments also results in variation in physiological processes such as photosynthetic rate, resistance to cold, and the timing of dormancy.

Which of the following methods would be best to determine whether the phenotypic variation in Achillea lanulosa is due to genotypic variation?

TLS Online TPP Program

#Question id: 13200

#Unit 6. System Physiology – Plant

In the modification of translocation pathways, Interference with a translocation pathway by wounding or pruning can alter the patterns established by proximity and vascular connections. In the absence of direct connections between source and sink, vascular interconnections, called

TLS Online TPP Program

#Question id: 13201

#Unit 6. System Physiology – Plant

Phloem loading in the apoplastic pathway thought to mediate the transport of sucrose from the apoplast into the sieve element– companion cell complex. Which of the following  are involved in such sucrose transporting by apoplast?

a) Sucrose is at a higher concentration in the sieve element–companion cell complex indicates that sucrose is actively transported against its chemical-potential gradient

b) Sugars transport from the apoplast into the sieve elements and companion cells energy driven process

c) Phloem loading in the apoplastic pathway involves a sucrose–H+ symporter

d) the route of phloem loading is−mesophyll cells→ bundle sheath cells→ phloem parenchyma cell→ ordinary companion cell→ sieve elements

Which of the following is incorrect?

TLS Online TPP Program

#Question id: 13202

#Unit 6. System Physiology – Plant

Which of the following sucrose-H+ symporter appear to be the major sucrose transporters in phloem loading into the companion cells;

TLS Online TPP Program

#Question id: 13203

#Unit 6. System Physiology – Plant

Intermediary cells are specialized companion cells that are involved in phloem loading in the plant. Which of the following pathway that have included the intermediary-type companion cells?

TLS Online TPP Program

#Question id: 13204

#Unit 6. System Physiology – Plant

Many of the carriers of Sucrose–H+ symporters in the phloem play various role in transport, most of the transporters are found in source, path, and sink tissues. Some carriers are characterized such as;

a) SUT1, has high-affinity / low-capacity transporter found in the minor veins of source tissues, appears to be important in phloem loading.

b) Important role of SUT1 in phloem loading appears to be complemented by SUT4, which is low-affinity/high-capacity carrier

c) SUT2, appears to function as a sucrose sensor. This is indicated by findings showing that SUT2 is more highly expressed in sink and path tissues than in source leaves.

d) The major sucrose transporters in phloem loading into the companion cells and final uptake into companion cells appears to be the function of SUT4

Which of the following combination is correct?

TLS Online TPP Program

#Question id: 13205

#Unit 6. System Physiology – Plant

The mechanisms that regulate the loading of sucrose from the apoplast to the sieve elements by the sucrose–H+ symporter await characterization. Possible regulatory factors include the following:

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

Which one of the mechanism that involve to regulate the loading of sucrose?