AP Biology 7.9.B: Phylogenetic Trees and Cladograms
Practise AP Biology 7.9.B questions by constructing and interpreting trees and cladograms from morphological, DNA and protein evidence.
- Syllabus
- Effective Fall 2025
- Course
- AP Biology
Exam points
- interpret nodes as most recent common ancestors and use branching patterns to infer evolutionary relatedness
- construct or revise phylogenetic trees and cladograms from morphological, fossil, DNA or protein similarities
- apply outgroups and parsimony to evaluate character origins and competing evolutionary hypotheses
7.9.B—Explain how phylogenetic trees and cladograms can be used to infer evolutionary relatedness question 1
Ruminants are hoofed animals, including cattle and sheep, that have a unique four-chambered stomach specialized to digest tough, fiber-filled grasses. Researchers studying ruminants are investigating the morphological and molecular characteristics of different ruminant families in order to determine the evolutionary relationships among the families. Cladograms of several ruminant families were constructed based on morphological data (Figure 1A) and molecular data (Figure 1B). Table 1 shows a sample of the morphological characteristics present in each family used to construct the cladogram in Figure 1A.
Figure 1. Cladogram of six ruminant families based on (A) morphological data and (B) molecular data
TABLE 1. MORPHOLOGICAL CHARACTERISTICS FOUND IN EACH RUMINANT FAMILY
Question (a)
(a)
Describe how a scientist would use a comparison of the DNA sequences of different organisms to suggest the most likely evolutionary relationship among the organisms.
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Question (b)
(b)
Based on Figure 1, explain why Bovidae is likely to be more closely related to Moschidae than it is to Giraffidae.
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