Questions and answers for exam Preparation

MCQs

Total Questions : 121 | Page 2 of 13 pages

Question 11. The enzyme that catalyzes the splitting of PIP2 into two molecules of inositol triphosphate (IP3) and diacylglycerol in cell signaling, is

phosphokinase C
phospholipase C
phosphodiesterase C
lipokinase

Discuss Question

Answer: Option B. -> phospholipase C
Answer: (b).phospholipase C

Question 12. Which of the following processes involve the combining of a message from one signaling molecule with that of another to either enhance or inhibit a cellular effect?

Signal transduction
Signal reception
Signal integration
Signal amplification

Discuss Question

Answer: Option C. -> Signal integration
Answer: (c).Signal integration

Question 13. A cell is known to respond to a particular signaling molecule. Which of the following must be true of this cell?

It is in the heart muscle
It is also the site of production for the signaling molecule
It contains the receptor for the signaling molecule
It is incapable of signal transduction

Discuss Question

Answer: Option C. -> It contains the receptor for the signaling molecule
Answer: (c).It contains the receptor for the signaling molecule

Question 14. The binding of ligands to many G-proteins linked receptors leads to shortlived

increase in the concentration of certain intracellular signaling molecules called second messenger
decrease in the concentration of certain intracellular signaling molecules called second messenger
increase in the concentration of certain extracellular signaling molecules called first messenger
decrease in the concentration of certain extracellular signaling molecules called first messenger

Discuss Question

Answer: Option A. -> increase in the concentration of certain intracellular signaling molecules called second messenger
Answer: (a).increase in the concentration of certain intracellular signaling molecules called second messenger

Question 15. A signal cascade induced by adrenaline or thyroxine

must begin with receipt of the signal molecule by a surface receptor
involves the activation of a G protein
results in the activation of a sequence of enzymes needed for the cell effect
all of the above

Discuss Question

Answer: Option D. -> all of the above
Answer: (d).all of the above

Question 16. 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
Answer: (a).changes the shape and thus the enzymatic activity of the proteins involved

Question 17. 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
Answer: (c).signaling molecule; target cell; receptors

Question 18. 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
Answer: (c).They become activated when bound to GDP

Question 19. 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
Answer: (c).Because nitric oxide breaks down quickly and thus cannot travel far

Question 20. Which of the following comes under the category of cell surface receptor?