A laboratory protocol lists the following ingredients: 1 g sucrose, 16.4 g Na2HPO4, 1.5 g (NH4)3PO4, 0.02 g CaCO3, KNO3, water to 1 liter and autoclave. This recipe is for a medium. A laboratory protocol lists the following ingredients: 1 g sucrose, 16.4 g Na2HPO4, 1.5 g (NH4)3PO4, 0.02 g CaCO3, KNO3, water to 1 liter and autoclave. This recipe is for a medium. reducing agar defined agar complex enrichment broth defined broth complex broth

1 g sucrose, 16.4 g Na₂HPO₄, 1.5 g (NH₄)₃PO₄, 0.02 g CaCO₃, KNO₃, water to 1 liter and autoclave. This recipe is for a DEFINED BROTH medium.

Explanation:

A medium is classified as defined when it is known its exact composition ( we know which are all its ingredients). In this case, the medium contains sucrose as carbon source, salts (Na₂HPO₄, (NH₄)₃PO4,CaCO₃, KNO₃) as nitrogen and minerals sources, and water. Undefined media commonly contains animal or plant extracts, whose exact composition is unknown (we cannot know which quantity of salts, aminoacids and other components contains the extract). Furthermore, the medium lack of agar, which is a component which is added to make solid the medium. Thus, this medium is liquid and it is a broth. It does not contain reducing substances (so it is not a reducing medium) neither antibiotics (so it is not a selective medium).