Following statements are regarding to the microtubules.

A. Tubulin is the major structural component of microtubules

B. Microtubule-associated proteins (MAPs) associate with tubulin and help mediate the assembly, dynamics, and function of microtubules.

C. Free tubulin exists as a dimer in which the α-subunit contains a trapped and hydrolyzable GTP and theβ-subunit binds an exchangeable and nonhydrolyzable GTP

D. All microtubules are nucleated from microtubule-organizing centers (MTOCs), and many remain anchored with their (−) ends there. Thus the end away from the MTOC is always the (+) end.

Which of the following statements is incorrect?

#Question id: 2248

#Unit 2. Cellular Organization

The movement of Na+ ions into an animal cell

a. has a positive ΔG value.                 

b. is energetically favorable.

c. is chemically favorable.                  

d. drives the export of Ca2+ in muscle cells.

#Question id: 2249

#Unit 2. Cellular Organization

In intestinal lumen epithelial cells, which of the following occurs by passive transport?

a. import of Na+ on the apical side    

b. export of Na+ on the basal side

c. import of glucose on the apical side           

d. export of glucose on the basal side

#Question id: 2250

#Unit 2. Cellular Organization

Which of the following is true about cystic fibrosis?

#Question id: 2251

#Unit 2. Cellular Organization

Differences between cotransport and active ion transport include

#Question id: 2252

#Unit 2. Cellular Organization

The generation and maintenance of a membrane electric potential requires which of the following:

a. active pumping of ions       

b. ion-specific membrane channel proteins

c. ATP                                    

d. a generally permeable membrane

#Question id: 2253

#Unit 1. Molecules and their Interaction Relevant to Biology

Match the following lipid linked proteins (column I) with their function (Column II).