Which organism is structurally similar to this organism?

With regard to enzymes, key is to lock as a) substrate is to activation energy eliminate b) product is to substrate. c) enzyme is to active site. d) substrate is to active site.

Atype of organism that no longer exist on earth is said to be

Nitrogen-14 and nitrogen-15 are isotopes of the same element. how do these two isotopes differ? a. they have different numbers of nuclei. b. they have different numbers of protons. c. they have different numbers of neutrons. d. they have different numbers of electrons.