Which statement best describes the mechanism by which enzymes catalyze a reaction? a. enzymes absorb the change in enthalpy (δh), permitting a reaction to proceed. b. enzymes lower the concentration of the substrates, thereby driving the equilibrium to favor product formation. c. enzymes are completely used up in the course of the reaction and therefore favor product formation. d. enzymes lower the energy barrier necessary to achieve the transition state of a reaction. e. enzymes lower the concentration of the products, thereby driving the reaction to favor product formation.

Option E,  Enzymes lower the energy barrier necessary to achieve the transition state of a reaction.

Explanation:

Enzymes  just act like bio catalyst to favor the formation of final product at a given physical and chemical condition. Thus these enzymes reduces the energy required for reaching the transition stage through a process called catalysis.  Enzymes do not modify or change the final products however they enhance the rate of biochemical reaction.

Thus, option E is correct

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.