Which segments of the attenuator together form the repression loop?

TLS Online TPP Program

#Question id: 12234

#Unit 10. Ecological Principles

All of the following have been used by plants to avoid being eaten except

TLS Online TPP Program

#Question id: 12235

#Unit 10. Ecological Principles

Which  of  the  following  are  important  biotic  factors  that  can  affect  the  structure  and  organization of  biological communities?

TLS Online TPP Program

#Question id: 12236

#Unit 10. Ecological Principles

A  plant species arrives at  an  island  for the first time, where it  is  exposed to  a  new set of  pollinators.  Over the course of 20 generations, the characteristics of its flowers change. The figures above show the frequency distribution of petal length in the original colonizing population (Figure 1) and 20 generations later (Figure 2). Which of these explanations is consistent with the observed change in petal length?

TLS Online TPP Program

#Question id: 12237

#Unit 10. Ecological Principles

Which of the following occurred first during the separation of the elements of Pangaea through continental drift? 

TLS Online TPP Program

#Question id: 12238

#Unit 10. Ecological Principles

The mussel Mytilus edulis thrives in saline habitats, in both the highly salty seawater of tidal zones and the less salty estuaries. This results in two kinds of populations: one adapted to the higher salt concentrations of the tidal zone, and one adapted to the lower salt concentrations of the estuary. It has been found that the more salt-tolerant populations have high frequencies of an allele that produces an enzyme involved in maintaining osmotic equilibrium. Conversely, estuarine mussels having the same enzyme seem to be disfavoured and have a much higher death rate than mussels without the allele. Adult estuarine populations do have lower frequencies of this allele. Each spring, large numbers of larvae from  the salty habitats pour into the estuaries.

The invasion of the seawater larvae would be expected to facilitate change in the genetic structure of the estuarine population by a process called

TLS Online TPP Program

#Question id: 12239

#Unit 10. Ecological Principles

The figures above show the results of an experiment in which two microbial species, A and B, were grown in three treatments. In treatment I, species A was grown alone. In treatment II, species B was grown alone. In treatment III, both species were grown together at the same starting densities as in (I) and (II). The results suggest the interaction is best described as