Edexcel International A Level (IAL) Chemistry (YCH11) - Unit 4 - 14.22 Biological buffers-Study Notes - New Syllabus

14.22 Importance of Buffer Solutions in Biological Systems

Buffer solutions are essential in maintaining a stable pH in biological and food systems. Even small pH changes can disrupt enzymes, metabolic processes, or lead to spoilage.

(i) Buffers in Cells and Blood

Importance

• Enzyme activity is highly pH-dependent.
• Small pH changes can denature enzymes or slow reactions.
• Cells must maintain a nearly constant internal pH.

Blood Buffer System

The main buffer system in blood is:

\( \mathrm{H_2CO_3 / HCO_3^-} \)

Equilibrium

\( \mathrm{H_2CO_3 \rightleftharpoons H^+ + HCO_3^-} \)

Action

• When acid is added:
  • \( \mathrm{HCO_3^-} \) removes \( \mathrm{H^+} \):

\( \mathrm{HCO_3^- + H^+ \rightarrow H_2CO_3} \)

• When base is added:
  • \( \mathrm{H_2CO_3} \) neutralises \( \mathrm{OH^-} \):

\( \mathrm{H_2CO_3 + OH^- \rightarrow HCO_3^- + H_2O} \)

Outcome

• Blood pH is maintained around 7.4.
• Prevents harmful acidosis or alkalosis.

(ii) Buffers in Foods

Importance

• Food pH can change due to bacterial or fungal activity.
• Microorganisms produce acids or bases during metabolism.
• pH changes can lead to spoilage or deterioration.

Role of Buffers

• Resist pH changes caused by microbial activity.
• Maintain conditions that slow spoilage reactions.
• Help preserve taste, texture, and safety.

Examples

• Buffering agents in processed foods.
• Natural buffers in milk and biological tissues.

Key Features

• Buffers maintain stable pH in sensitive systems.
• Essential for enzyme activity and metabolism.
• Prevent harmful effects of pH fluctuations.
• Important in both living systems and food preservation.