Question

macromolecule test

an enzyme (catalase) is found in liver cells. its function is to break down its substrate (hydrogen peroxide) into harmless water and oxygen.

$$2 h_2o_2 \xrightarrow{\text{catalase}} 2 h_2o + o_2$$

what will happen to the enzyme (catalase) if the amount of substrate (hydrogen peroxide) keeps increasing?

○ it will be used up, and the cells will be poisoned.

○ it will be used up, and more of the enzyme will be produced.

○ it will be denatured by the hydrogen peroxide.

○ it will be reused to break down the hydrogen peroxide.

Explanation:

Enzymes are biological catalysts that speed up reactions without being consumed or permanently altered. When substrate (hydrogen peroxide) increases, initially the reaction rate increases as more enzyme - substrate complexes form. But once all enzyme active sites are occupied (saturation), further substrate increase doesn't use up the enzyme. Enzymes aren't used up in reactions, so options saying it will be used up are wrong. Hydrogen peroxide (substrate) doesn't denature catalase under normal substrate - increasing conditions (denaturation is due to factors like extreme pH/temperature). As substrate increases, the enzyme is reused to break down the additional substrate as long as active sites are available (and after saturation, rate plateaus but enzyme is still there to react with substrate).

Answer:

It will be reused to break down the hydrogen peroxide.