Cell Signalling and Transduction
In paracrine signaling, the signaling molecules affects only

both (a) and (b)
target cells distant from its site of synthesis in cells of an endocrine organ
target cells close to the cell from which it was secreted
None of these

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Cell Signalling and Transduction
In terms of cell communication, what do bacterial pathogens such as cholera and anthrax have in common?

They destroy the receptors for key signaling molecules
They prevent the production of key signaling molecules
They alter the chemical structure of key signaling molecules
They block the normal functioning of signal transduction mechanisms

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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?

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

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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
The binding of ligands to many G-proteins linked receptors leads to shortlived

increase in the concentration of certain intracellular signaling molecules called second messenger
decrease in the concentration of certain extracellular signaling molecules called first messenger
increase in the concentration of certain extracellular signaling molecules called first messenger
decrease in the concentration of certain intracellular signaling molecules called second messenger

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