Final answer:
A dichotomous key is a tool used in biology to identify organisms based on observable characteristics. It consists of a series of questions with two possible answers, leading to the correct identification of the organism.
Step-by-step explanation:
A dichotomous key is a tool used in biology to identify organisms based on observable characteristics. It consists of a series of questions with two possible answers, leading to the correct identification of the organism.
For example, in the case of differentiating between bacilli and cocci bacteria, the key would ask questions about characteristics such as shape, arrangement, and staining reactions, narrowing down the options until the correct identification is reached.