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?

#Question id: 4988

#Unit 11. Evolution and Behavior

If the foods preferred by each species are found on different parts of the island, and if the flies mate and lay eggs on their food sources, regardless of the location of the food sources, then the speciation events involving these fly species may have been driven, at least in part, by which of the following?

#Question id: 4987

#Unit 11. Evolution and Behavior

A female fly, full of fertilized eggs, is swept by high winds to an island far out to sea. She is the first fly to arrive on this island, and the only fly to arrive in this way. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species each of which eats only a certain type of food. None of the species can fly, for their flight wings are absent, and their balancing organs (i.e., halteres) are now used in courtship displays. The male members of each species bear modified halteres that are unique in appearance to their species. Females bear vestigial halteres. The ranges of all of the daughter species overlap.In each fly species, the entire body segment that gave rise to the original flight wings is missing. The mutation(s) that led to the flightless condition could have

#Question id: 4986

#Unit 11. Evolution and Behavior

A female fly, full of fertilized eggs, is swept by high winds to an island far out to sea. She is the first fly to arrive on this island, and the only fly to arrive in this way. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species each of which eats only a certain type of food. None of the species can fly, for their flight wings are absent, and their balancing organs (i.e., halteres) are now used in courtship displays. The male members of each species bear modified halteres that are unique in appearance to their species. Females bear vestigial halteres. The ranges of all of the daughter species overlap. If these fly species lost the ability to fly independently of each other as a result of separate mutation events in each lineage, then the flightless condition in these species could be an example of

#Question id: 4985

#Unit 11. Evolution and Behavior

The loss of ventral spines by modern freshwater sticklebacks is due to natural selection operating on the phenotypic affects of Pitx1 gene

#Question id: 4984

#Unit 11. Evolution and Behavior

A hypothetical mutation in a squirrel population produces organisms with eight legs rather than four. Further, these mutant squirrels survive, successfully invade new habitats, and eventually give rise to a new species. The initial event, giving rise to extra legs, would be a good example of

#Question id: 4983

#Unit 11. Evolution and Behavior

As rat pups mature, the growth of their snouts and tails outpaces growth of the rest of their bodies, producing the appearance of sexually mature males. It is found that sexually mature female rats prefer to mate with mutant, sexually mature males that possess snouts and tails with juvenile proportions. Which of the following terms is (are) appropriately applied to this situation?