Which is the best definition of activation energy?
the energy required to end a chemical reaction
the energy required to bind a substratewo an active site
the energy required to form or break the bonds of reactant molecules
the energy required to re-form bonds in product molecules

This rapid change in species that rarely leaves behind fossil evidence is referred to as

What kind of sugar is found in a nucleotide?

Why are some body cells responsive to a particular hormone, whereas others are not? responsive cells have complex signal transduction pathways, whereas cells that do not respond to a particular hormone lack these pathways. responsive cells express a receptor specific for the hormone. all of these choices are correct. responsive cells are located closer to the gland that releases the hormone. whether or not a cell responds to a hormone depends entirely on what type of cell it is (liver cell vs. fat cell vs. nerve cell), because hormones only activate one type of cell.