What is the biological importance of …

• Importance of pH in Everyday life:

pH change and survival of animals -

1. Our body works well within a narrow pH range of 7.0 to 7.8.
2. When the pH of rain water is less than 5.6, it is known as acid rain.
3. When  this  acid  rain  flows  into  rivers,  it  lowers  the  pH  of the river  water making the survival  of aquatic life difficult.

pH in our digestive system

1. Our stomach produces hydrochloric acid which helps in the digestion of food without harming the stomach.
2. Sometimes excess acid is produced in the stomach which causes indigestion.
3. To get rid of this pain, bases called antacids are used.
4. Antacids are a group of mild bases which react with the excess acid and neutralise it.
5. Commonly used antacids are magnesium hydroxide [Mg(OH)2] and sodium bicarbonate[NaHCO₃]

pH change - Cause of tooth decay:

Tooth decay starts when the pH in the mouth falls below 5.5. Tooth enamel is made up of calcium phosphate which is the hardest substance in the body. It is insoluble in water but gets corroded when the pH in the mouth falls below 5.5. The bacteria present in the mouth produce acids due to the degradation of sugar and food particles after eating. Hence, to prevent tooth decay, the mouth should be rinsed after eating food and toothpastes which are basic should be used for cleaning teeth to neutralise the excess acid.