Which of these is not a characteristic of white dwarfs? choose the correct answer.
a long period of existence
a hot, extremely dense core
a ring-like planetary nebula
a position in the lower left of the h-r diagram

answer; a muscle cell, another neuron and a of the above

where is the scientific experiment?

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products