Receptors for most lipid-soluble hormones are located
A. in the cytoplasm of their target cells.
B. on the plasma membrane of their target cells.
C. in the lysosomes of their target cells.
D. on the nuclear membrane of their target cells.
E. in the nucleus or cytoplasm of their target cells.
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Question 2) Which of the following is a regulatory protein associated with membrane-bound receptor molecules?
A. ATP
B. calcium
C. M protein
D. G protein
E. DNA
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Question 3) The role of cAMP when it acts as an intracellular mediator in cells is to
A. bind to and activate protein kinase.
B. activate genes in the nucleus to produce mRNA.
C. directly activate structural enzymes in the cytoplasm of the target cell.
D. catalyze a cascade reaction that ultimately activates genes on the DNA.
E. control levels of calcium in the cell.
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Question 4) A water-soluble hormone binds to its receptor on the plasma membrane. Arrange the events that follow in correct sequence.
(1) alpha subunit-GTP complex alters cell activity
(2) GTP binds to the alpha subunit replacing GDP
(3) G-protein subunits separate from the receptor
(4) alpha subunit separates from other two subunits
(5) G-protein subunits bind to the receptor
A. 5, 2, 3, 4, 1
B. 4, 2, 1, 3, 5
C. 5, 2, 1, 4, 3
D. 5, 4, 2, 1, 3
E. 3, 4, 1, 2, 5
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Question 5) Most hormones are regulated by
A. negative-feedback mechanisms.
B. neural-feedback mechanisms.
C. positive-feedback mechanisms.
D. hormonal-feedback mechanisms.
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Question 6) In some forms of diabetes, an insensitivity to insulin seems to be present. This insensitivity could be the result of
A. up-regulation.
B. over-regulation.
C. down-regulation.
D. a lack of regulation.
E. modulation.
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Question 7) Up-regulation
A. results in a decrease in the number of receptor sites in the target cell.
B. produces an increase in the sensitivity of the target cell to the hormone.
C. is found in target cells that maintain a constant level of receptors.
D. produces insensitivity to the hormone in the target tissue.
E. moves the receptors up on the membrane.
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Question 8) Hormone receptor molecules may be ____ in order to change the target cell's sensitivity to a given hormone.
A. increased in number
B. decreased in number
C. chemically altered
D. moved
E. increased in number, decreased in number and chemically altered
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Question 9) Parathyroid hormone is released when blood calcium levels decrease. This is an example of control by __________ stimuli.
A. hormonal
B. neural
C. humoral
D. visceral
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Question 10) Receptors for most water-soluble hormones are located
A. in the cytoplasm of their target cells.
B. on the plasma membrane of their target cells.
C. in the lysosomes of their target cells.
D. on the nuclear membrane of their target cells.
E. on the endoplasmic reticulum of their target cells.
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