1.4.5 Maths Skill: Drawing a Graph for Enzyme Rate Experiments

When investigating how different factors affect enzyme activity, drawing an accurate graph is essential to analyse the data effectively. Here's how to plot and interpret a graph for enzyme rate experiments.

Steps to Draw the Graph:

1. Label Axes:

• x-axis: Independent variable (e.g., temperature in °C).
• y-axis: Dependent variable (rate of enzyme activity).

2. Plot Data Points:

• Use the data collected from your experiment to plot points on the graph.
• Make sure each point is marked clearly, as this will allow you to see the trend in enzyme activity.

3. Draw the Curve:

• Connect the data points with a smooth curve to show the relationship between temperature and the rate of enzyme activity.
• In enzyme experiments, you'll often see a bell-shaped curve indicating the rate of reaction as it changes with temperature.

Interpreting the Graph (Example: Rate of Enzyme Activity vs. Temperature):

• Rising Phase (10°C to Optimum Temperature):
  • As temperature increases, kinetic energy of molecules also increases, leading to more frequent enzyme-substrate collisions and a higher rate of reaction.
• Optimum Temperature:
  • The peak of the curve represents the optimal temperature for enzyme activity, where the rate is at its highest.
• Declining Phase (Above Optimum Temperature):
  • Beyond the optimum temperature, the rate of reaction decreases sharply. This is because high temperatures cause denaturation of the enzyme, altering its active site so the substrate can no longer bind effectively.

Drawing and interpreting graphs like this allows you to understand the effect of temperature (or other variables) on enzyme activity, helping to identify the conditions where the enzyme is most effective.