Question

dichotomous key
1
2 3
4 5 organism x 9
6 7 organism y 8 10 organism z
which number on the dichotomous key represents the point of differentiation between organism x from organism z?
branch 1
branch 3
branch 5
branch 9

Explanation:

Step1: Analyze the dichotomous key structure

A dichotomous key splits organisms based on traits. We need to find where Organism X and Z diverge.

Step2: Trace the paths of X and Z

• Organism X is under branch 3 (from branch 1, one path is branch 3).
• Organism Z is under branch 9, which is a sub - branch of branch 3. So the first point where their paths differ is branch 3, because from branch 3, one path leads to X and the other leads to 9 (which then leads to Z).
• Branch 1 splits into 2 and 3, but X and Z are both under the branch 3 path from branch 1, so branch 1 is not the differentiation point. Branch 5 is part of the branch 2 path (Organism Y's path), so not related. Branch 9 is a sub - branch of 3, so the differentiation between X and Z starts at branch 3.

Answer:

B. branch 3