AP Biology Flashcards: Phylogeny
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 16 cards to help you master important concepts.
A scientist is building a tree based on the presence or absence of a jawbone in a set of fossils. What type of evidence is being used?
The scientist is using morphological similarities from fossil species to construct the phylogenetic tree.
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A scientist is building a tree based on the presence or absence of a jawbone in a set of fossils. What type of evidence is being used?
The scientist is using morphological similarities from fossil species to construct the phylogenetic tree.
In what way is a cladogram a 'hypothesis'?
A cladogram is a hypothesis because it represents a proposed explanation of evolutionary relationships that is subject to testing and revision with new data.
How do cladograms illustrate speciation events?
Cladograms illustrate speciation at the nodes, where a single ancestral lineage splits into two or more distinct descendant lineages.
What is the key difference between a phylogenetic tree and a cladogram regarding time?
Phylogenetic trees show the amount of change over time, often indicated by branch length, whereas cladograms do not show a time scale.
If a new fossil is discovered that contradicts an existing phylogenetic tree, what does this imply about the tree?
This implies that the tree is a testable hypothesis that must be revised based on the new evidence presented by the fossil.
What is the fundamental nature of a phylogenetic tree?
A phylogenetic tree is a testable hypothesis that illustrates the proposed evolutionary relationships among various lineages.
What does a node on a phylogenetic tree represent?
A node represents a speciation event and the most recent common ancestor of the descendant lineages that emerge from it.
What is the most recent common ancestor in the context of a phylogenetic tree?
The most recent common ancestor is the lineage, represented by a node, from which two or more descendant lineages diverged.
What are the two main types of evidence used to construct phylogenetic trees?
Phylogenetic trees are constructed using morphological similarities (from living or fossil species) and molecular sequence similarities.
Why are phylogenetic trees and cladograms considered 'dynamic'?
They are considered dynamic because they are hypotheses that are constantly revised and updated based on new evidence.
How is evolutionary relatedness inferred from a phylogenetic tree or cladogram?
These diagrams are used to infer evolutionary relatedness by showing how recently lineages shared a most recent common ancestor.
What types of data can be used to infer an evolutionary relationship?
Evolutionary relationships can be inferred from evidence such as morphological similarities in living or fossil species and molecular sequence similarities.
A researcher compares the amino acid sequences for a specific protein across several species. What type of evidence is being used to infer relatedness?
The researcher is using molecular sequence similarities to infer evolutionary relatedness and construct a phylogenetic tree.
What are shared derived characters?
Shared derived characters are traits that are gained or lost during evolution and are used to construct phylogenetic trees and cladograms.
What is the role of traits gained or lost during evolution in phylogeny?
These traits, especially shared derived characters, form the basis for constructing phylogenetic trees and cladograms by grouping related organisms.
An evolutionary diagram shows branch lengths that are proportional to the number of DNA mutations. Is this a phylogenetic tree or a cladogram?
This is a phylogenetic tree because it shows the amount of change over time, a feature that cladograms do not represent.