Anions

• Nitrate is absorbed from the soil by plants and is also an important source of nitrogen.
• Hydrogencarbonate acts as a buffer, which helps to maintain the pH of the blood.
• Chloride ions are involved in the 'chloride shift' which helps to maintain the pH of the blood during gas exchange.
• Phosphate ions are involved in photosynthesis and respiration reactions.
• Hydroxide ions affect the pH of substances.