The effect of competitive inhibitors can be nullified by increasing the concentration of substrate. Competitive inhibitors are molecules that bind to the active site of an enzyme, preventing the substrate from binding and inhibiting the enzyme's activity. However, increasing the concentration of substrate can overcome the inhibitory effect of competitive inhibitors.

Explanation:

1. Competitive Inhibition:
When a competitive inhibitor binds to the active site of an enzyme, it competes with the substrate for binding. This reduces the probability of the substrate binding to the active site, consequently reducing the enzyme's activity. The inhibitor and substrate are structurally similar, which enables them to compete for the same binding site on the enzyme.

2. Effect of Increasing Substrate Concentration:
Increasing the concentration of substrate can nullify the effect of competitive inhibitors. This is because by increasing the substrate concentration, the probability of substrate molecules binding to the active site of the enzyme also increases. As a result, the substrate molecules outcompete the inhibitor for binding to the enzyme's active site.

3. Competitive Inhibition Curve:
The effect of increasing substrate concentration on competitive inhibition can be observed on a graph known as a competitive inhibition curve. This curve plots the rate of enzyme activity against the concentration of substrate, in the presence and absence of a competitive inhibitor.

4. Increasing Substrate Concentration Shifts the Curve:
When a competitive inhibitor is present, the curve depicting the enzyme activity versus substrate concentration is shifted to the right. This indicates that higher substrate concentrations are required to achieve the same enzyme activity in the presence of the inhibitor.

5. Nullifying the Effect:
By increasing the concentration of substrate, the curve can be shifted back to the left, towards the original curve without the inhibitor. This means that higher enzyme activity can be achieved at lower substrate concentrations, overcoming the inhibitory effect of the competitive inhibitor.

6. Practical Applications:
Understanding the nullifying effect of increasing substrate concentration on competitive inhibition is important in various fields. For example, in pharmacology, it can help in designing drugs that can overcome the inhibitory effects of competitive inhibitors. Similarly, in industrial enzymology, optimizing substrate concentration can enhance the efficiency of enzymatic reactions, even in the presence of competitive inhibitors.

In conclusion, increasing the concentration of substrate can nullify the effect of competitive inhibitors by outcompeting the inhibitor for binding to the enzyme's active site. This knowledge can be applied in various fields to overcome the inhibitory effects of competitive inhibitors.