Which statement defines enzymatic activity? Enzymes are required to slow down biological reactions within cells.
Specific enzymes can catalyze a wide variety of chemical reactions.
Enzymes regulate cellular functions through feedback mechanisms.
Enzymes bind substrates so that reactive groups have many different orientations.

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later

Variables,control,conclusion and finally scientific theory