Oxygen-Evolving Organisms Have two Photosystems that Operate in Series, explain by emerson that is the Photosystem I preferentially absorbs far-red light of wavelengths greater than 680 nm; photosystem II preferentially absorbs red light of 680 nm and is driven very poorly by far-red light; Another difference between the photosystems is that,

a.) Photosystem I produces a strong reductant, capable of reducing NADP+, and a weak oxidant

b.) Photosystem I produces a very strong oxidant, capable of oxidizing water, and a weaker reductant than the one produced by photosystem II

c.) Photosystem II produces a strong reductant, capable of reducing NADP+, and a weak oxidant

d.) Photosystem II produces a very strong oxidant, capable of oxidizing water, and a weaker reductant than the one produced by photosystem I

Which statements would be CORRECT?

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?

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?