Page 1 of 1: MCQ "1"

wasem · Credits: 8632 My Scrapbook

Question 1. In a homeostatic control system:

A. There is a detector sensitive to the controlled variable.
True False

B. Positive FEEDBACK is important.
True False

C. The measured value of the controlled variable is compared with a reference value.
True False

D. The controlled variable tends to oscillate around a mean value known as the set point.
True False

E. Open loop control systems are frequently involved.
True False

Question 2. The plasmalemma:

A. Consists of a bilayer of phospholipids.
True False

B. Is readily permeable to ionic substances.
True False

C. Contains glycoproteins.
True False

D. Is readily permeable to water.
True False

E. Makes use of facilitated diffusion to maintain ionic gradients between the cytoplasm and the extracellular fluid.
True False

Question 3. With regard to osmosis across the plasmalemma:

A. Water moves up its potential gradient.
True False

B. Cells will swell in hypotonic solutions.
True False

C. The osmolality of a solution dictates its tonicity.
True False

D. Proteins are the most important osmotically active solutes in the extracellular fluid.
True False

E. Increased intracellular hydrostatic pressure would help to oppose osmotic swelling.
True False

Question 4. G-proteins:

A. Diffuse into the cell cytoplasm when activated.
True False

B. Bind to GDP when activated by agonist-receptor complexes.
True False

C. Consist of three main subunits.
True False

D. May activate membrane-bound enzymes, leading to second messenger production.
True False

E. Split off the α-subunit when active.
True False

Question 5. Depolarization:

A. In response to an electrical stimulus will be slower in cells with long time constants.
True False

B. Refers to an increase in membrane potential.
True False

C. During an action potential is caused by opening of voltage-activated ion channels.
True False

D. Is associated with an increased membrane permeability to Na+ in nerves and striated muscle.
True False

E. Will close voltage-gated Na+ channels.
True False

Question 6. Action potentials:

A. Are graded electrical events.
True False

B. Are conducted over the surface of excitable cells.
True False

C. Are produced by sub-threshold stimuli.
True False

D. Inhibit further stimulation during or immediately after the action potential.
True False

E. Are associated with a repolarization phase caused by outward movement of Cl- ions.
True False

Question 7. In excitable cells:

A. The conduction velocity is increased as the space constant increases.
True False

B. Hypocalcaemia promotes spontaneous firing of action potentials.
True False

C. The resting membrane potential is largely dictated by the Na+ concentration gradient across the membrane.
True False

D. GTP-energized ion pumps are used to maintain the transmembrane ion gradients.
True False

E. Unidirectional propagation of the action potential is possible because of the refractory period.
True False

Question 8. With regard to junctions between cells:

A. Tight junctions help limit epithelial permeability.
True False

B. Gap junctions are regions where cells are more widely spaced than normal.
True False

C. Electrical syncytia depend on ion channels which connect the cytoplasm of adjacent cells.
True False

D. Nexi show up as five lines in electron micrographs because the outer coats of the lipid membrane are fused.
True False

E. Desmosomes promote the transmission of tension from cell to cell.
True False

Question 9. Membrane-bound receptors:

A. Bind to agonists according to the law of mass action.
True False

B. May be structurally integrated into ligand-gated ion channels.
True False

C. For acetylcholine may be classified as muscarinic or nicotinic.
True False

D. Consist largely of carbohydrate.
True False

E. Are frequently linked to G-proteins.
True False

Question 10. Second messengers:

A. Often activate specific kinases inside the cell.
True False

B. Are usually manufactured by cytoplasmic enzymes.
True False

C. Allow for amplification of an extracellular signal.
True False

D. Include the cyclic nucleotides which are degraded by phosphatase enzymes.
True False

E. Include Ca2+ which can be released from intracellular stores.
True False

Question 10. Second messengers:

A. Often activate specific kinases inside the cell.
True False

B. Are usually manufactured by cytoplasmic enzymes.
True False

C. Allow for amplification of an extracellular signal.
True False

D. Include the cyclic nucleotides which are degraded by phosphatase enzymes.
True False

E. Include Ca2+ which can be released from intracellular stores.
True False

aungnyein · Credits: 561 My Scrapbook

Q.2.(a)True.Cell membrane consists of phospholipid bilayer.
(b)False.It is selective permeable to ionic substances.
(d)True.It is readily permeable to water.
(e)True.
Q.3.(b)True.Cell will swell in hypotonic solution due to water diffused into the cell.
(d)False.Proteins are majoer anion within the cell and they do not diffuse.
Q.4.(c)False.Two subunits;Gi and Gs.
Q.5.(d)True.Positive FEEDBACK cycle of Na entry into the cell cause depolarization.
(e)False.It causes opening of sodium channels.
Q.6.(a)False.Action potentials are not graded but local potentials are graded.
(c)False.Action potential obeys all or none law.

		Sign In New User? Sign Up Sign in to access your control panel and messenger!
				TechZone \| SpiderNevi \| HowTo? \| Scrapbook!