Question

how is a dichotomous key used?
the organism is compared to paired pictures of organisms until a match is found in the key.
the organism’s dna is sequenced and compared to the dna sequences that are listed in the dichotomous key.
observable characteristics of the organism are checked through a sequence of two - part steps until an identification is listed in the key.
observable characteristics of the organism are listed in a group and compared to different groups of observable characteristics listed in the key.

Explanation:

A dichotomous key uses a series of two - part (dichotomous) questions about observable characteristics of an organism. By answering these two - part questions step - by - step, one can identify the organism.

• The first option is incorrect because dichotomous keys don't rely on paired pictures in this way.
• The second option is wrong as dichotomous keys don't involve DNA sequencing.
• The fourth option is incorrect because it's not about grouping characteristics and comparing groups, but about answering two - part questions sequentially.
• The third option correctly describes the process: checking observable characteristics through a sequence of two - part steps until identification.

Answer:

C. Observable characteristics of the organism are checked through a sequence of two - part steps until an identification is listed in the key.