Questions and answers for exam Preparation

MCQs

Total Questions : 121 | Page 10 of 13 pages

Question 91. Self-phosphorylation is an excellent mechanism for triggering specific catalytic function of the proteins involved in signal cascades because it

changes the shape and thus the enzymatic activity of the proteins involved
makes the receptor more likely to capture the signaling, molecule
allows hydrophilic signaling molecules to cross the plasma membrane
None of the above

Discuss Question

Answer: Option A. -> changes the shape and thus the enzymatic activity of the proteins involved

Question 92. Which of the following statements about G proteins is false?

They are involved in signal cascades
They bind to and are regulated by guanine nucleotides
They become activated when bound to GDP
They must be active before the cell can make needed cAMP

Discuss Question

Answer: Option C. -> They become activated when bound to GDP

Question 93. When a __________ reaches its __________ , there is a specific means of receiving it and acting on the message. This task is the responsibility of specialized proteins called __________ .

signaling molecule; receptor; G proteins
signaling molecule; target cell; G proteins
signaling molecule; target cell; receptors
kinase; receptor; proteases

Discuss Question

Answer: Option C. -> signaling molecule; target cell; receptors

Question 94. Why is it that inhaling nitric oxide reduces blood pressure only in the lung tissue and not elsewhere in the body*?

Because other body tissues use a different signaling molecule
Because nitric oxide cannot cross cell membranes and enter the blood
Because nitric oxide breaks down quickly and thus cannot travel far
None of the above

Discuss Question

Answer: Option C. -> Because nitric oxide breaks down quickly and thus cannot travel far

Question 95. . Which of the following comes under the category of cell surface receptor?

Enzyme linked receptors
Ion-channel linked receptors
G protein linked receptors
All of these

Discuss Question

Answer: Option D. -> All of these

Question 96. . Which of the following is true about a hydrophilic signaling molecule?

Its receptor is located in the cytosol of the target cell
It might trigger a signal cascade that causes some effect in a cell
Since it can enter the cell, it directly affects some specific cell process
It is a steroid

Discuss Question

Answer: Option B. -> It might trigger a signal cascade that causes some effect in a cell

Question 97. . Nitroglycerin has long been administered to human patients suffering from chronic chest pain (angina). This medication works because it

mimics the action of signal receptors
is broken down into hormones that affect the heart
interferes with chemical cascades that trigger contraction of heart muscle
breaks down into nitric oxide, which increases blood flow to the heart

Discuss Question

Answer: Option D. -> breaks down into nitric oxide, which increases blood flow to the heart

Question 98. . cAMP and cGMP are derived from

ATP and GTP by the actions of adenylate cyclase and guanylate cyclase respectively
GTP and ATP by the actions of adenylate cyclase and guanylate cyclase respectively
ATP and GTP by the actions of guanylate cyclase and adenylate cyclase respectively
none of the above

Discuss Question

Answer: Option A. -> ATP and GTP by the actions of adenylate cyclase and guanylate cyclase respectively

Question 99. . If a disease of the blood vessels caused the endothelial cells of the vessel to die, what effect would that have on the cellular activities associated with vasodilation?