Cell Signalling and Transduction
Why is it that inhaling nitric oxide reduces blood pressure only in the lung tissue and not elsewhere in the body*?

Because nitric oxide cannot cross cell membranes and enter the blood
None of these
Because nitric oxide breaks down quickly and thus cannot travel far
Because other body tissues use a different signaling molecule

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Cell Signalling and Transduction
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?

Nitric oxide would no longer be produced
All of these
Smooth muscle cells could not be made to relax
It would be more difficult to increase blood flow and reduce blood pressure

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Cell Signalling and Transduction
The signaling molecules called steroid hormones

never enter the blood of humans
are hydrophilic and so cannot penetrate the plasma membrane
are made in one location of the body but have their effects some distance away
bind to cell surface receptors to trigger chemical cascades

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Cell Signalling and Transduction
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
changes the shape and thus the enzymatic activity of the proteins involved
allows hydrophilic signaling molecules to cross the plasma membrane

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Cell Signalling and Transduction
A cell is known to respond to a particular signaling molecule. Which of the following must be true of this cell?

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

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