Calcium as Second Messenger Practice Questions

Question 1

The following smooth muscle relaxants act by affecting calcium release except:

Accepted Answer

Prazosin

Answer

Dantrolene

Answer

Nifedipine

Answer

Verapamil

Question 2

Which of the following statements is true regarding smooth muscle contraction?

Accepted Answer

Phosphorylation of myosin is essential for contraction.

Answer

None of the options.

Answer

Calmodulin plays no role in smooth muscle contraction.

Answer

Troponin plays a significant role in smooth muscle contraction.

Question 3

What is the PRIMARY mechanism by which the Na+-Ca2+ exchanger functions in cardiac muscle cells?

Accepted Answer

Na+-Ca2+ exchanger acts to remove Ca2+ from heart muscle cells

Answer

Na+-Ca2+ exchanger requires ATP directly

Answer

The Na+-Ca2+ exchanger operates in reverse mode during normal cardiac contraction

Answer

The Na+-Ca2+ exchanger primarily moves Ca2+ into cardiac muscle cells during systole

Question 4

Which of the following protein molecules is responsible for cell-to-cell adhesion?

Accepted Answer

Cadherin

Answer

Laminin

Answer

Fibronectin

Answer

Collagen

Question 5

Which of the following statements best describes the mechanism of action of insulin on target cells?

Accepted Answer

Insulin binds to a transmembrane receptor on the outer surface of the plasma membrane, activating the tyrosine kinase in the cytosolic domain of the receptor.

Answer

Insulin binds to a receptor on the outer surface of the plasma membrane, activating adenylate cyclase through the Gs protein.

Answer

Insulin binds to a cytoplasmic receptor and is transferred as a hormone receptor complex to the nucleus to modulate gene expression.

Answer

Insulin enters the cell and causes the release of calcium ions from intracellular stores.

Question 6

In intracellular fluid, which of the following has least concentration?

Accepted Answer

Calcium

Answer

Potassium

Answer

Magnesium

Answer

Protein

Question 7

Calcium does not bind to

Accepted Answer

Tropomyosin

Answer

Troponin

Answer

Calmodulin

Answer

None of the options

Question 8

In response to changes in Ca2+ concentration, which of the following Ca2+ binding proteins can modify the activity of many enzymes & proteins?

Accepted Answer

Calmodulin

Answer

Collagen

Answer

Kinesin

Answer

Elastin

Question 9

Which one of the following acts to increase the release of Ca²⁺ from endoplasmic reticulum?

Accepted Answer

Inositol triphosphate

Answer

1, 25-dihydroxy cholecalciferol

Answer

Diacylglycerol

Answer

Parathyroid hormone

Question 10

Which of the following substances is present intracellularly in muscle cells?

Accepted Answer

Corticosteroid

Answer

Insulin

Answer

Epinephrine

Answer

Glucagon

Calcium as Second Messenger — MCQs

Calcium as Second Messenger — MCQs

Want unlimited practice?