3. Enzyme-linked receptors: A. allow ions to cross the cell membrane B. activate

Question

3. Enzyme-linked receptors:
A. allow ions to cross the cell membrane
B. activate a second messenger in the cytoplasm
C. interact with a G-protein complex
D. generate active proteins within the cytosol to effect a functional change in the cell

4. c-AMP (cyclic AMP) is a second messenger associated with which of the following?
A. Ligand-gated channel receptors
B. G-protein–coupled receptors
C. Enzyme-linked receptors
D. Lipophilic signal molecules

5. Antagonists frequently:
A. bind the receptor without inducing a cellular response.
B. increase the ability of the endogenous ligand to bind the receptor.
C. activate receptors and induce a cellular response in the absence of the endogenous ligand.
D. act as enzymes that digest the receptor.

6. The resting membrane potential is negative because:
A. sodium ions are always leaking out of the cell.
B. sodium ions are always leaking into the cell.
C. potassium ions are always leaking into the cell.
D. potassium ions are always leaking out of the cell.

7. Which of the following is true about neurons?
A. Axons transmit electrical signals to the nucleus
B. Axons are covered in places by myelin
C. The terminal end of a dendrite is the cite of signal transduction to a postsynaptic cell
D. Axons outnumber dendrites


8. If an excess of cations accumulates in the cytosol,
A. the extracellular fluid acquires an excess of anions
B. the extracellular fluid acquires an excess of cations
C. the membrane potential is at rest.
D. the cell hyperpolarizes.

9. Resting membrane potential is
A. -70 mV
B. 0 mV
C. +70 mV
D. +32 mV

10. A cell has a very strong electric gradient, with a relative excess of anions inside the cell. The membrane potential of this cell is most likely:
A. -100 mV
B. -30 mV
C. +30 mV
D. +90 mV

Explanation / Answer

On # 6 remember that a potassium ion is negative, and sodium is positive. #7 I believe C is the best choice. its worded a little strange. But, recall that the axon hillock is covered in the myelin sheath not the 'axon' itself. The axon is one small region of the neuron, so D is wrong. Dendrites receive the signal, and the synaptic cleft relays the message to the muscle or whatever its attached to. Use power of elimination. #9. B resting membrane potential refers to equal number of ions on each side of a membrane. So there should be no charge. #10 . Best choice A or B . Recall that anions are negatively charged and cations are positive. So the result must be negative. Hope this helps a lil'

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