BRS-HISTO CH. 1

Question 1

A herpetologist is bitten by a poisonous snake and is taken to the emergency depart- ment with progressive muscle paralysis. The venom is probably incapacitating his
(A) Na

Answer 1

D. acetylcholine receptors

Question 2

Cholesterol functions in the plasmalemma to
(A) increase fluidity of the lipid bilayer.
(B) decrease fluidity of the lipid bilayer.
(C) facilitate the diffusion of ions through
the lipid bilayer.
(D) assist in the transport of hormones
across the lipid bilayer.
(E) bind extracellular matrix molecules.

Answer 2

B.

Question 3

The cell membrane consists of various components, including integral proteins. These integral proteins
(A) are not attached to the outer leaflet.
(B) are not attached to the inner leaflet.
(C) include transmembrane proteins.
(D) are preferentially attached to the E-face.
(E) function in the transport of cholesterol-
based hormones.

Answer 3

C.

Integralproteinsarenotonlycloselyassociatedwiththelipidbilayerbutalsotightly bound to the cell membrane. These proteins frequently span the entire thickness of the plasmalemma and are thus termed transmembrane proteins (

Question 4

Which one of the following transport processes requires energy?
(A) Facilitated diffusion (B) Passive transport (C) Activetransport
(D) Simple diffusion

Answer 4

C. Active Transport

Question 5

hich one of the following substances is unable to traverse the plasma membrane by simple diffusion?
(A) O2
(B) N2
(C) Na

Answer 5

C. Na+

Question 6

Symport refers to the process of transporting
(A) a molecule into the cell.
(B) a molecule out of the cell.
(C) two different molecules in opposite
directions.
(D) two different molecules in the same
direction.
(E) a molecule between the cytoplasm and
the nucleus.

Answer 6

D. same direction

Question 7

One of the ways that cells communicate with each other is by secretion of various molecules. The secreted molecule is known as
(A) a receptor molecule. (B) a signaling molecule. (C) aspectrintetramer. (D) an integrin.
(E) ananticodon.

Answer 7

B. signaling molecule

Question 8

Adrenocorticotropic hormone (ACTH) travels through the bloodstream, enters connective tissue spaces, and attaches to specific sites on target-cell membranes. These sites are
(A) peripheral proteins.
(B) signaling molecules.
(C) Gproteins.
(D) G protein–linked receptors. (E) ribophorins.

Answer 8

D.
Gprotein–linkedreceptorsaresiteswhereACTHandsomeothersignalingmolecules attach. Binding of ACTH to its receptor causes Gs protein to activate adenylate cyclase, set- ting in motion the specific response elicited by the hormone

Question 9

Which of the following statements con- cerning plasma membrane components is TRUE?
(A) All G proteins are composed of three subunits.
(B) The glycocalyx is usually composed of phospholipids.
(C) Ion channel proteins are energy depend- ent (require adenosine triphosphate).
(D) Gated channels are always open.
(E) Ankyrinbindstoband3oftheredblood
cell plasma membrane.

Answer 9

E