ABA is transported by both the xylem and the phloem, but it is normally much more abundant in ___

TLS Online TPP Program

#Question id: 12967

#Unit 10. Ecological Principles

Which of the following is the best explanation for why net primary productivity in terrestrial ecosystems tends to increase toward the tropics?

TLS Online TPP Program

#Question id: 12968

#Unit 10. Ecological Principles

Most terrestrial ecosystems have a pyramidal structure of where biomass of producers > primary consumers > secondary consumers > tertiary consumers. However, some aquatic ecosystems have an inverted pyramidal structure where the standing biomass of producers < primary consumers. An explanation for this is:

TLS Online TPP Program

#Question id: 12969

#Unit 10. Ecological Principles

In which of the following habitats would one expect to find the highest diversity of vascular plants? 

TLS Online TPP Program

#Question id: 12970

#Unit 10. Ecological Principles

In deep-sea hydrothermal vents near the Galapagos Islands, bacteria obtain energy by oxidizing hydrogen sulphide released from the vents. Giant tube worms, which lack mouths and digestive systems, harbour the bacteria in their tissues and use them as a source of organic molecules. Clams obtain energy by filtering bacteria directly from the water, and numerous crabs and octopi feed on the clams. In this unique ecosystem, the bactena are playing the role of

TLS Online TPP Program

#Question id: 12971

#Unit 10. Ecological Principles

One group of ecologists has suggested that producers are limited by competition for resources, primary consumers (herbivores) are limited by predation, and secondary consumers (carnivores) are limited by food. If this were true, at which of the following trophic levels would one expect to find substantial evidence for competitive exclusion?

TLS Online TPP Program

#Question id: 12972

#Unit 10. Ecological Principles

Under  some  circumstances a  population  can  split  into  two  or  more  species  without  the  existence of  geographic barriers. All of the following genetically determined behaviours could provide conditions leading to speciation EXCEPT