The most commonly used diagnostic tool for tuberculosis is a simple skin test, though blood tests are becoming more commonplace. A small amount of a substance called PPD tuberculin is injected just below the skin of your inside forearm. You should feel only a slight needle prick.
The structure has a double bond and an adjacent atom with a lone pair, so it could have resonance. The possible resonance structures are below. The first structure has the most common bonding pattern for all of its atoms, so it is a reasonable Lewis structure.
When the structures are homologous, they have similar functions and have a common ancestry in evolution. When the structures are analogous, they have similar functions but hav â¦ e a different evolutionary origin.nalogous structures are structures that are similar in appearance and function but are not the result of shared ancestry. For example, the wings of a birds and insects have the same function, but they do not reflect a shared ancestry. + 30 others found this useful.