Reactants may also be present in such low concentrations that it is unlikely they will meet and do what?
melt
explode
depart
collide
Most chemical reactions within organisms would be impossible under the normal conditions within cell. For example, the body temperature of most organisms is too low for reactions to occur quickly enough to carry out life processes. Reactants may also be present in such low concentrations that it is unlikely they will meet and collide. Therefore, the rate of most biochemical reactions must be increased by a catalyst. A catalyst is a chemical that speeds up chemical reactions. In organisms, catalysts are called enzymes .