The secondary compound cyanide (Figure 1) is a toxic, bitter-tasting chemical that is found in apple seeds. Cyanide in seeds is only released and tasted if the seed is crushed. When animals eat apples, they typically eat the sweet fleshy part of the fruit and spit out the seeds or swallow them whole.

Based on the chemical structure of cyanide, identify ONE type of biological macromolecule that could serve as a chemical precursor for the production of cyanide in a plant. Justify your choice.


The macro protein biological molecule can act as a precursor for cyanide production.


Cyanides are chemical compounds containing the cyanide group (C≡N). Based on the elements attached to the cyanide group cyanides can be classified into organic and inorganic cyanides.

Inorganic cyanides the cyanide group is present as CN ^ - ions that make them toxic. In organic cyanides CN ^ - no group is present and therefore less toxic.

Because nitrogen is the essential component of cyanide, a biomolecule containing nitrogen acts best as a precursor of cyanide formation.

The biomolecule protein is a long chain polymer of amino acids containing a nitrogen group. So proteins can act as a precursor to cyanide formation.