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In a two-compartment model of a cell with a K+-permeable membrane and a 10-fold

ID: 271464 • Letter: I

Question

In a two-compartment model of a cell with a K+-permeable membrane and a 10-fold excess K+ in the inside compartment, the membrane potential is experimentally made more negative than the K+ equilibrium potential. How would K+ ions flow across the membrane?

a. They would flow from the inside compartment to the outside compartment.

b. They would flow from the outside compartment to the inside compartment.

c. There would be no flow of K+ ions. d. They would flow in both directions at the same time in equal molar quantities.

e. They would flow in both directions, but the flow would be negligible.

The most important factor determining whether a receptor-operated ion channel is inhibitory or excitatory is

a. the ligand-binding properties of the receptor.

b. whether the permeant ion is positively or negatively charged.

c. whether the permeant ion’s reversal potential is positive or negative to threshold.

d. the number of different ions that can pass through the receptor.

Which statement about cell signaling pathways is true?

a. Cellular responses are always short-lived.

b. Cellular responses are always long-lived.

c. Signaling is always initiated by membrane-bound receptors.

d. Signaling is always initiated by intracellular receptors.

e. Intracellular signal transduction pathways are always activated by a chemical signaling molecule

From which structure do the neural crest cells arise?

a. Notochord

b. Pre-somitic mesoderm

c. Lateral endoderm

d. Dorsal aspect of the neural tube

e. Ventral aspect of the neural tube

Explanation / Answer

They would flow from inside to outside because the concentration gradient is high inside and low outside thus they move down the concentration gradient via diffusion

C is the correct answer. If the potential is negative it would be inhibitory, positive excitatory

Cellular responses are short lived

Dorsal aspect of neural tube

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