They say how an enzyme perfectly fits into its substrate is alike a "lock and key".
Only one specific enzyme can fit a specific substrate.
Answer:
Must have lived before.
Explanation:
For an organism to be classified as once living, an object must have been part of a living organism or is now dead. When a flower is plucked from a plant it is hard to distinguish between when it is considered alive and when it is now considered once living. An example of a nonliving object is an apple or a dead leaf.Apr 22, 2013
Utah Education Network › view
Release of a neurotransmitter across the synapse is triggered by the entry of Ca++ into the presynaptic axon. No Ca++ entry means no transmission across the synapse.