Answer:
a} Allosteric regulation is just any form of regulation where the regulatory molecule (an activator or inhibitor) binds to an enzyme someplace other than the active site.The shape of the active site is changed, allowing substrate to bind at a higher affinity.
b) The molecules that bind cellular respiration enzymes act as signals, giving the enzyme information about the cell's energy state. ATP, ADP, and NADH are examples of molecules that regulate cellular respiration enzymes. ATP, for instance, is a "stop" signal: high levels mean that the cell has enough ATP and does not need to make more through cellular respiration.
c) This is a case of feedback inhibition i in which a product feeds back to shut down its pathways.