TLS Online TPP Program

#Question id: 9217


Which of the following conditions is the most likely indicator of a population in an extinction vortex?

#Unit 9. Diversity of Life Forms
  1. The species in question is found only in small, stable pockets of its former range.
  2. The effective population size of the species falls below 1,000.
  3. Genetic measurements indicate a loss of genetic variation over time.
  4. The population is permanently small.
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TLS Online TPP Program

#Question id: 2149

#Unit 2. Cellular Organization

A ligand-gated ion channel (such as the nicotinic acetylcholine receptor) is:

TLS Online TPP Program

#Question id: 2150

#Unit 2. Cellular Organization

Which of the following increase(s) membrane fluidity?

TLS Online TPP Program

#Question id: 2151

#Unit 2. Cellular Organization

Which of the following statement(s) is (are) true of transmembrane proteins?

a. All contain a hydrophobic α helix.

b. Some serve as membrane attachment sites for peripheral membrane proteins.

c. Some contain more than one membrane-spanning domain.

d. All are asymmetrically oriented in the lipid bilayer.

TLS Online TPP Program

#Question id: 2152

#Unit 2. Cellular Organization

Precursors of membrane phospholipids are

a. soluble in the cytosol.                    

b. incorporated into biosynthetic intermediates.

c. sometimes complexed with fatty-acid-binding proteins.

d. stored in glycerolosomes.

e. sometimes activated by conjugation with CDP.

TLS Online TPP Program

#Question id: 2153

#Unit 2. Cellular Organization

Membrane phospholipids include

a. cholesterol.            

b. plasmologens.        

c. sphingolipids.         

d. triglycerides.                      

e. bile acids.

TLS Online TPP Program

#Question id: 2154

#Unit 2. Cellular Organization

Membrane lipids are distributed appropriately between the two leaflets of a given membrane by

a. dockases.    

b. trumpases.              

c. fatty acid desaturases.        

d. flippases.    

e. transmembrane tunnelases.