Explain the importance of iron ions and phosphate ions to living organisms.

Iron ions are essential because they are a component of haemoglobin, the protein in red blood cells that carries oxygen from the lungs to tissues. Without iron, haemoglobin cannot bind oxygen, so oxygen transport is impaired.

Phosphate ions are important for energy transfer, as they are part of ATP – the molecule that stores and releases energy for cellular work. They are also a structural component of nucleic acids (DNA and RNA) and of phospholipids that make up cell membranes, providing both genetic material and membrane integrity.