The rate of movement of materials in the sieve elements can be expressed in two ways: as velocity, or as mass transfer rate. In early publications reporting on rates of transport in the phloem, what is the velocity and the mass transfer rate?

i) velocity-centimeters per hour (cm h^-1) and mass transfer- grams per hour per square centimeter (g h^-1 cm^-2)

ii) velocity-the linear distance traveled per unit time and mass transfer rate-the quantity of material passing through a given cross section of phloem or sieve elements per unit time.

iii) velocity- the quantity of material passing through a given cross section of phloem or sieve elements per unit time and mass transfer rate- the linear distance traveled per unit time

iv) velocity- per hour per square centimeter (h^-1 cm^-2) and mass transfer- kg centimeters per hour (cm h^-1)

TLS Online TPP Program

#Question id: 12099

#Unit 10. Ecological Principles

According to the competitive exclusion principle, two species cannot continue to occupy the same

TLS Online TPP Program

#Question id: 12100

#Unit 10. Ecological Principles

Prairie dogs once covered the expanses of the Great Plains. Their grazing made the grass more nutritious for the huge herds of bison, and a variety of snakes, raptors, and mammals   preyed on the rodents. In fact, the black- footed ferret (now endangered) specialized in prairie dog predation. Today, growing housing and agricultural developments have covered many prairie dog towns. Which of the following statements about prairie dogs is true?

TLS Online TPP Program

#Question id: 12101

#Unit 10. Ecological Principles

The sum total of an organism's interaction with the biotic and abiotic resources of its environment is called its

TLS Online TPP Program

#Question id: 12102

#Unit 10. Ecological Principles

Use the following diagram of Joseph Connell's study of barnacle distribution in Scotland to answer the following two questions

Which of the following is the most logical conclusion about the distribution of the two species of barnacle, Chthamalus and Balanus?

TLS Online TPP Program

#Question id: 12103

#Unit 10. Ecological Principles

Which of the following is a good description of an ecological niche? 

TLS Online TPP Program

#Question id: 12104

#Unit 10. Ecological Principles

Two barnacles, Balanus and Chthamalus, can both survive on the lower rocks just above the low-tide line on the Scottish coast, but only Balanus actually does so, with Chthamalus adopting a higher zone. Which of the following best accounts for this niche separation?