What is an allosteric site?
a) the site on an enzyme where the substrate binds
b) the active part of a non-competitive inhibitor of an enzyme reaction
c) the area on an enzyme that binds the end-product of a metabolic pathway
d) the area on a competitor molecule that inhibits an enzyme reaction

The correct answer is C the area on an enzyme that binds the end product of a metabolic pathway.

Explanation:

Some enzymes contain an additional site beside an active site.The additional site is known as allosteric site.

    The allosteric site act as a binding site of many regulatory compounds called mediator which may be either activator or inhibitor according to action they generates after interacting with the target enzyme.

  The high level end product of some metabolic pathway binds to the allosteric site of the regulatory enzyme that controls the committed step of that pathway thereby blocking that pathway.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.