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?

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

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Cell Signalling and Transduction
The signaling molecules called steroid hormones

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

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

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

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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
allows hydrophilic signaling molecules to cross the plasma membrane
None of these
changes the shape and thus the enzymatic activity of the proteins involved

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