Questions and answers for exam Preparation

MCQs

Total Questions : 121 | Page 7 of 13 pages

Question 61. Self-phosphorylation is an excellent mechanism for triggering specific catalytic function of the proteins involved in signal cascades because it

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

Discuss Question

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

Question 62. 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
None of these
Because nitric oxide cannot cross cell membranes and enter the blood
Because nitric oxide breaks down quickly and thus cannot travel far

Discuss Question

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

Question 63. Which of the following comes under the category of cell surface receptor?

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

Discuss Question

Answer: Option B. -> All of these

Question 64. Which of the following statements about G proteins is false?

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

Discuss Question

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

Question 65. 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
kinase; receptor; proteases
signaling molecule; target cell; G proteins
signaling molecule; target cell; receptors

Discuss Question

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

Question 66. Which of the following is true about a hydrophilic signaling molecule?

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

Discuss Question

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

Question 67. In terms of cell communication, what do bacterial pathogens such as cholera and anthrax have in common?

They block the normal functioning of signal transduction mechanisms
They prevent the production of key signaling molecules
They alter the chemical structure of key signaling molecules
They destroy the receptors for key signaling molecules

Discuss Question

Answer: Option A. -> They block the normal functioning of signal transduction mechanisms

Question 68. 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
breaks down into nitric oxide, which increases blood flow to the heart
interferes with chemical cascades that trigger contraction of heart muscle
is broken down into hormones that affect the heart

Discuss Question

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

Question 69. CAMP and cGMP are derived from

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
ATP and GTP by the actions of adenylate cyclase and guanylate cyclase respectively
None of these

Discuss Question

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

Question 70. 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?