What are the characteristics of allosteric enzymes?
a. They conform to Michaelis–Menten kinetics.
b. They may have binding sites for regulatory molecules that are separate from active sites.
c. They tend to have a sigmoidal (S‑shaped) curve of V 0 vs. [S].
d. They interconvert between a more active form and a less active form.
e. They are generally small single subunit proteins.

b, c and d

Explanation:

Allosteric enzymes are enzymes whose activity is changed by the binding of a molecule at a site other than the active site. The molecule bonded is  

called allosteric effector  

Allosteric enzymes possess multiple subunits and show sigmoidal ‘S’ shape curve for rate of reaction (V0) and substrate concentration [S].

Kinetics of allosteric enzymes cannot ne studied by Michaelis- Menten relationship as their activities are affected by variation in the concentration. So, they show interconversion between a more active form and a less active form.

Therefore, the correct options are b, c and d.

b. They may have binding sites for regulatory molecules that are separate from active sites.

c. They tend to have a sigmoidal (S shaped) curve of V 0 vs. [S].

d. They interconvert between a more active form and a less active form.

i believe the answer is a.

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.