(a) (i) A (biological) catalyst or explained (ii) (A measure of) how acidic or alkaline a solution is [allow 'neutral or not'] (b) (i) Name of enzyme: amylase or pepsin or catalase (ii) 1 - Leaving Cert Biology - Question 8 - 2009

pH is the scale used to measure how acidic or alkaline a solution is. A pH less than 7 indicates acidity, a pH of 7 is neutral, and a pH greater than 7 indicates alkalinity.

The enzyme can be amylase, which breaks down starch into sugars, or pepsin, which digests proteins, or catalase, which decomposes hydrogen peroxide into water and oxygen.

The substrate for amylase is starch, for pepsin it is protein, and for catalase it is hydrogen peroxide.

The products formed are glucose from starch by amylase, peptides from proteins by pepsin, and water and oxygen from hydrogen peroxide by catalase.

The diagram should illustrate a test tube containing the substrate along with the enzyme, labeled appropriately to show the interaction.

Label the diagram with the name of the enzyme being used, such as 'Amylase', 'Pepsin', or 'Catalase'.

To alter the pH of the solution, you should add an appropriate acid, such as hydrochloric acid (HCl), or a base, such as sodium hydroxide (NaOH), or different buffer solutions to maintain a specific pH.

Enzyme activity is affected by temperature. Typically, there is an optimal temperature range, around 37°C for human enzymes, where the reaction rate is maximized.

A water bath is often used to maintain a constant temperature for enzyme reactions, preventing fluctuations that could affect enzyme activity.

The graph should depict enzyme activity against varying substrate concentrations or pH levels, showing a curve that indicates changes in rate of reaction rather than a flat or 'V' shaped line.