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

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Cell Signalling and Transduction
A signal cascade induced by adrenaline or thyroxine

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

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Cell Signalling and Transduction
The signaling molecules called steroid hormones

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

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Cell Signalling and Transduction
In the signal transduction mechanism known as protein phosphorylation

All of these
the signaling molecule binds to a surface receptor
phosphorylated proteins act with enzymes to trigger the signal cascade
receptor kinases play a key role in triggering the signal cascade

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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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