Signal Transduction Mechanisms Practice Questions

Question 1

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 2

All the following  hormones have receptors on the plasma membrane of target tissues except:

Accepted Answer

Estradiol

Answer

Epinephrine

Answer

Glucagon

Answer

Thyrotropin

Question 3

A primigravida at 38 weeks of gestation has gone into labor. Oxytocin was started to augment labor. The second messenger system through which oxytocin acts is:

Accepted Answer

Phospholipase C (IP3/DAG pathway)

Answer

Tyrosine kinase

Answer

cGMP

Answer

cAMP

Question 4

Absolute refractoriness of a neuron is due to?

Accepted Answer

Inactivation of Na channels

Answer

Hyperpolarization of Cl channels

Answer

Opening of rectifier K+ channels

Answer

Closure of activated Na channels

Question 5

Which of these is true about the highlighted transporter?

Accepted Answer

One molecule goes in, other molecule goes out

Answer

Both molecules go in

Answer

Both molecules go out

Answer

One molecule goes in and two exit

Question 6

Which of these hormones activate catalytic receptors?

Accepted Answer

IGF1

Answer

All of these

Answer

Leptin

Answer

GH

Question 7

All the following mediate their action using cAMP as second messenger except:

Accepted Answer

Vasopressin

Answer

Glucagon

Answer

Dopamine

Answer

Corticotropin

Question 8

Which of the following is correct about the feedback hormone marked as $X$ ?

Accepted Answer

Inhibin B

Answer

Inhibin A

Answer

Progesterone

Answer

Estrone

Question 9

Serum prolactin levels are highest

Accepted Answer

During third trimester of pregnancy

Answer

24 hrs after parturition

Answer

REM sleep

Answer

In actively lactating mothers

Question 10

Thyroid hormone binds to which receptor ?

Accepted Answer

Nuclear

Answer

Membrane

Answer

Cytoplasmic

Answer

None of the options

Signal Transduction Mechanisms — MCQs

Signal Transduction Mechanisms — MCQs

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