BRAINCAKEImportant Anions
Inorganic ions are needed by all organisms in small amounts, but each has specific roles. Anions are negatively charged ions. Four are especially important at A level.
Nitrate (NO3−). Plants absorb nitrate from the soil through their root hair cells, usually by active transport. The nitrogen is used to make amino acids (and so proteins), nucleic acids (DNA and RNA), ATP and chlorophyll. A plant short of nitrate shows stunted growth and yellow older leaves.
Phosphate (PO43−). Phosphate is part of nucleotides, so it is found in DNA, RNA and ATP. It forms the phosphate head of phospholipids in membranes, and calcium phosphate makes bones and teeth hard. Adding and removing phosphate groups also switches many enzymes on and off.
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More in Chemistry for Life
- Ionic Bonding
- Covalent Bonding
- Important Cations
- Water
- Water as a Polar Solvent
- Water as a Transport Medium
- Water as a Habitat
- Water in Plant Transport Systems
All 10 lessons in Chemistry for Life · All Edexcel AS-level Biology topics