Following statements are given regarding to the genes in Drosophila.

A. The anterior posterior compartment of each segment of drosophila is regulated by the expression of engrailed and wingless genes.

B. The gap genes are activated or repressed by the maternal effect genes, and are expressed in one or two broad domains along the anterior-posterior axis.

C. The transcription patterns of the anterior gap genes are initiated by the different concentrations of the Hunchback and Bicoid proteins.

D. The segment polarity genes encode proteins that are constituents of the delta-notch and Hedgehog signaling pathways.

E. After the segmental boundaries are set, the pair-rule and gap genes interact to regulate the homeotic selector genes, which specify the characteristic structures of each segment.

Which one of following option has all the correct statements?

#Question id: 2243

#Unit 2. Cellular Organization

Features of the fluid mosaic model of membrane structure include:

A. a lipid bilayer.

B. dynamic motion of both membrane lipids and proteins.

C. proteins that may either rest on the surface or penetrate the membrane.

D. the hydrophobic core of the bilayer prevents the unassisted movement of water-soluble substances from one side to the other.

E. Covalent interactions between phospholipids, and between phospholipids and proteins, lend strength and resilience to the membrane.

Which of the following is correct?

#Question id: 2244

#Unit 2. Cellular Organization

Arrange the statements below in the proper sequence of events that occur in an action potential:

I. The resting potential is re-established.

II. A stimulus depolarizes the membrane to threshold.

III. Na+ gates open and Na+ rushes into the cell.

IV. K+ gates open and K+ rushes out of the cell.

#Question id: 2245

#Unit 2. Cellular Organization

Which of these statements is generally true of integral membrane proteins?

#Question id: 2246

#Unit 2. Cellular Organization

Which of the following statements describe(s) the typical biomembrane?

a. It may include different types of lipid molecules.

b. The lipid molecules in the membrane are attached to each other though covalent bonds.

c. All lipids and proteins in the biomembrane are equally mobile.

d. It contains a hydrophilic core.

e. It has a cytosolic face and an exoplasmic face.

#Question id: 2247

#Unit 2. Cellular Organization

When computing the osmotic pressure that must be placed across the membrane to stop the flow of water, what is the glucose osmotic equivalent of 1 M CaCl₂?

#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.