Fruit fly eyes are of the compound type, structurally very different from the camera-type eyes of mammals. Even the camera-type eyes of mollusks, such as octopi, are structurally quite different from those of mammals. Yet, fruit flies, octopi, and mammals possess very similar versions of Pax-6. The fact that the same gene helps produce very different types of eyes is most likely due to

#Question id: 10918

#Unit 6. System Physiology – Plant

The import into sinks such as developing roots, tubers, and reproductive structures, In many ways the events in sink tissues are simply the reverse of the events in sources. The following steps are involved in the import of sugars into sink cells such as;

#Question id: 10919

#Unit 6. System Physiology – Plant

Both of these observations—________X__________and________Y__________—support the existence of mass flow in the sieve elements of the phloem.

#Question id: 10920

#Unit 6. System Physiology – Plant

The pressure-flow model, first proposed by Ernst Münch, Phloem loading at the source and phloem unloading at the sink establish the pressure gradient.

a.) In source tissues, an accumulation of sugars in the sieve elements generates a lower or negative solute potential (ψs).

 b.) source tissue, causes a steep drop in the water potential (ψ), due to water potential gradient, water enters the sieve elements and causes turgor pressure (ψp ) decrease.

c.) In sink tissues, phloem unloading leads to a lower sugar concentration in the sieve elements, generating a higher or less negative solute potential.

d.) As the water potential of the phloem rises above that of the xylem, water tends to leave the phloem in response to the water potential gradient, causing a decrease in turgor pressure in the sieve elements of the sink.

Which of the following statements of sink and source tissue is FALSE?

#Question id: 10921

#Unit 6. System Physiology – Plant

The mechanism of phloem translocation in angiosperms is best explained by which method?

#Question id: 10922

#Unit 6. System Physiology – Plant

The non-reducing sugar sucrose is most commonly translocated in the phloem rather than reducing sugar. Why?

 a.) because they are less reactive than their reducing counterparts

 b.) because sucrose contains more energy than a monosaccharides

 c.) because the ketone or aldehyde group is reduced to an alcohol or combined with a similar group on another sugar so as not to be oxidized

 Which one of the following statements is true about translocation of non-reducing sugar?

#Question id: 10923

#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