Select all of the following statements that correctly compare the t and r forms of allosteric enzyme subunits.
a. the t form has a different shape than the r form.
b. both the t form and r form can exist without substrate bound to the active site.
c. a t form and r form cannot exist at the same time in an allosteric enzyme.

Because the earth is not round ,but it may seem round when viewed from ,our planet but true some points earth is not round was an oblate spheroid -a square that it squashed as globe however is not even a perfect oblate spheroid.in fact isaac newton's first proposed that earth was not perfectly round but it was an oblate spheroid instead.that mean a square that is squashed as its poles and swollen at the