Enzymes are (a) which speed up the biochemical (b) in living organisms. The enzymes themselves are not changed in these reactions, that is they are biological (c). Enzymes are (d)- each one controls only one type of reaction. They are (e)by high temperatures and by extremes of ph.

Enzymes are biological catalysts. Catalysts lower the activation energy for reactions. The lower the activation energy for a reaction, the faster the rate. Thus enzymes speed up reactions by lowering activation energy.

Explanation:

Maybe this will help?

a tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.