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TLS Online TPP Program

#Question id: 1295

What signal is released by endothelial cells to recruit circulating leukocytes?

#Unit 4. Cell Communication and Cell Signaling

  1. Vesicle-sequestered P-selectins are moved to the cell surface.

  2. Vesicle-sequestered αLβ2 molecules are moved to the cell surface.

  3. Integrins are cleaved from the plasma membrane so that the extracellular domain can bind leukocytes.

  4. Secreted glycoproteins trigger leukocytes to initiate “rolling” motility.

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TLS Online TPP Program

#Question id: 12285

#Unit 10. Ecological Principles

The principle of competitive exclusion states that
TLS Online TPP Program

#Question id: 12286

#Unit 10. Ecological Principles

Keystone predators can maintain species diversity in a community if they
TLS Online TPP Program

#Question id: 12287

#Unit 10. Ecological Principles

Food chains are sometimes short because
TLS Online TPP Program

#Question id: 3296

#Unit 10. Ecological Principles

Some beetles and flies have antler-like structures on their heads, much like male deer. The existence of antlers in beetle, fly, and deer species with strong male-male competition is an example of
TLS Online TPP Program

#Question id: 12349

#Unit 10. Ecological Principles

Males in a population differ in the time they spend displaying to females. A researcher hypothesizes that predators are responsible for these differences. Males display for longer durations when there are no predators in the vicinity and for shorter durations when there is a predator nearby. Which of the following study designs is the most appropriate test of this hypothesis?
TLS Online TPP Program

#Question id: 12347

#Unit 10. Ecological Principles

A team of conservation biologists, surveying a population of frogs on an island, captured and marked 312 individuals in the first sample. In a second sampling, 3 days later, the team caught 140 individuals of which 26 were previously marked. The total number of frogs on the island is estimated to be . (Use decimal notation, not fractions or percentage)