1.4. Dichotomous keys

Keys are used by biologists in the process of identifying organisms.

'Dichotomous' = branching (dividing) into two. 

Each key is made from pairs of contrasting features that help narrow down the options of what an organism might be. One can find out as specific as the species of an organism. That said, the telltale features are not always obvious to the common eye, so look carefully! Don't let hastiness trip you up.

Not only will you need to identify organisms, but you will also be asked to construct your own dichotomous key from given pictures.

As seen above: 

• the keys are mutually exclusive characteristics of biological organisms
• they often begin with general characteristics and lead to more specific characteristics.

[source: workbook]

To try out more exercises from the original post, click here.

And more past papers for this section, click here!