1 Copy and complete the following paragraph about enzymes. Enzymes are __ which speed up the biochemical __ in living organisms . The enzymes themselves are not changed in these reactions, that is they are biological __ Enzymes are __ - - each one controls only one type of reaction. They are __ by high temperatures and by extremes of pH.

## Step 1<br />The first blank in the paragraph is about what enzymes are. Enzymes are biological catalysts, which means they speed up chemical reactions in living organisms.<br /><br />## Step 2<br />The second blank is about what enzymes speed up. Enzymes speed up biochemical reactions in living organisms.<br /><br />## Step 3<br />The third blank is about what enzymes are not changed in. Enzymes themselves are not changed in these reactions, that is, they are biological catalysts.<br /><br />## Step 4<br />The fourth blank is about what enzymes are. Enzymes are proteins, each one controls only one type of reaction.<br /><br />## Step 5<br />The fifth blank is about what enzymes are affected by. They are affected by high temperatures and extremes of pH.