Hypothesize some situations where it would be necessary for signal transduction to happen very rapidly, as happens after the activation of either a kinase cascade or a second-messenger pathway?

Answer 1

Fight or flight! If an animal, for example, is suddenly in danger, adrenaline is released into the bloodstream, causing a fight-or-flight response. This triggers a STP that releases more glucose into the blood for fast energy, increases blood to muscles in case a physical response is necessary... If it's a case of survival, the organism needs to act quickly, thus the response must be quick.