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AP Biology 7.9: Phylogeny

Practise AP Biology 7.9 questions by using evidence, trees, cladograms, common ancestors and molecular comparisons to infer relatedness.

Syllabus
Effective Fall 2025
Course
AP Biology

Exam points

  • identify molecular, morphological, fossil and geological evidence used to infer evolutionary relationships
  • interpret nodes, monophyletic groups, outgroups and shared derived characters in phylogenetic trees
  • construct cladograms from trait, DNA, RNA or protein-difference matrices and justify taxon placement
  • evaluate conflicting phylogenies using data breadth, convergence, common ancestry and parsimony

Covered syllabus points

7.9.A—Describe the types of evidence that can be used to infer an evolutionary relationship7.9.B—Explain how phylogenetic trees and cladograms can be used to infer evolutionary relatedness

7.9 Phylogeny question 1

[Maximum number: 3]

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

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

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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Question (c)

(c)

Using the template in the space provided for your response, represent the point(s) at which characteristic 1, listed in Table 1, evolved by marking "X" on the line(s) of the cladogram in the correct location(s).

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