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AP Biology Practice Quiz: Phylogeny

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 16 questions to check your progress.

Question 1 of 16

Which of the following represents a primary type of evidence used to construct a phylogenetic tree?

All Questions (16)

Which of the following represents a primary type of evidence used to construct a phylogenetic tree?

A) Geographical distribution of species

B) Reproductive behaviors of species

C) Molecular sequence similarities

D) Ecological niche of each lineage

Correct Answer: C

The provided content explicitly states that phylogenetic trees can be constructed using morphological similarities and molecular sequence similarities.

According to the principles of phylogeny, what does a node (a branching point) on a cladogram represent?

A) A single species that has gone extinct

B) The most recent common ancestor of the descendant lineages

C) A trait that has been lost in all subsequent lineages

D) The point in time when a species first appeared in the fossil record

Correct Answer: B

The content specifies that nodes on phylogenetic trees and cladograms represent the most recent common ancestor of the lineages that branch from that point, illustrating a speciation event.

What is the key distinction between a phylogenetic tree and a cladogram?

A) Phylogenetic trees use molecular data, while cladograms use morphological data.

B) Phylogenetic trees show the amount of change over time, while cladograms do not.

C) Phylogenetic trees represent hypotheses, while cladograms represent proven facts.

D) Phylogenetic trees show relationships of living species, while cladograms show relationships of fossils.

Correct Answer: B

The provided text directly states that 'Phylogenetic trees show the amount of change over time, whereas cladograms do not show a time scale.'

Why are phylogenetic trees and cladograms described as 'dynamic hypotheses'?

A) Because they are considered absolute and unchangeable facts of evolution.

B) Because they only depict relationships between species that are still living.

C) Because they are constantly revised based on new evidence that emerges.

D) Because they cannot be tested or falsified through scientific methods.

Correct Answer: C

The content states that phylogenetic trees and cladograms are 'dynamic hypotheses that are constantly revised based on new evidence,' meaning they are not static.

When constructing a cladogram, biologists focus on shared derived characters. What are these?

A) Traits present in all organisms being studied, including the common ancestor.

B) Traits that are gained or lost during evolution and are shared by descendant lineages.

C) Similarities in morphology that arise from convergent evolution.

D) Random mutations that do not affect an organism's phenotype or survival.

Correct Answer: B

The provided text specifies that 'Traits that are gained or lost during evolution, particularly shared derived characters, are used to construct phylogenetic trees and cladograms.'

The primary purpose of a phylogenetic tree is to illustrate a hypothesis about the...

A) exact population size of ancestral species.

B) geographical range of each species.

C) evolutionary relationships among lineages.

D) complete genetic code of a common ancestor.

Correct Answer: C

The content explains that phylogenetic trees and cladograms are used to 'infer evolutionary relatedness' and are 'hypotheses illustrating evolutionary relationships among lineages.'

A scientist builds a phylogenetic tree for a group of extinct mammals based on the structure of their fossilized skeletons. This is an example of using which type of evidence?

A) Molecular sequence similarities

B) Morphological similarities from fossil species

C) Behavioral patterns inferred from fossils

D) Developmental similarities in modern species

Correct Answer: B

The content states that trees can be constructed using 'morphological similarities (from living or fossil species).' Using fossilized skeletons fits this description.

The branching patterns on a cladogram are intended to show...

A) the level of physical similarity between organisms.

B) the flow of energy through an ecosystem.

C) the sequence of speciation events.

D) the geographic location of different species.

Correct Answer: C

The content states that trees 'can illustrate speciation events, with nodes representing the most recent common ancestor of descendant lineages.' The branching pattern is a map of these events.

If new DNA evidence reveals that a species was incorrectly placed on a phylogenetic tree, the most scientifically sound action would be to...

A) ignore the new DNA evidence because the original tree is already established.

B) revise the phylogenetic tree to reflect the new evidence.

C) conclude that molecular data is not useful for inferring relationships.

D) create a new, separate tree for that one species and leave the original unchanged.

Correct Answer: B

This reflects the principle that phylogenetic trees are 'dynamic hypotheses that are constantly revised based on new evidence.' The correct response is to update the hypothesis.

Which statement accurately reflects the scientific standing of a phylogenetic tree?

A) It is a definitive and unchangeable record of evolutionary history.

B) It is a testable hypothesis subject to change with new data.

C) It is a model based on speculation that cannot be supported by evidence.

D) It is an exact timeline showing the date of every speciation event.

Correct Answer: B

The content explicitly describes phylogenetic trees and cladograms as 'testable hypotheses illustrating evolutionary relationships' that are 'constantly revised based on new evidence.'

Both morphological and molecular data can be used to...

A) determine the exact age of a living organism.

B) predict the future evolution of a species.

C) clone extinct species from the fossil record.

D) infer an evolutionary relationship and construct a cladogram.

Correct Answer: D

The provided text states that trees can be constructed using 'morphological similarities (from living or fossil species) and molecular sequence similarities' to infer evolutionary relationships.

On a cladogram, two lineages are considered to be most closely related if they...

A) are positioned next to each other at the tips of the diagram.

B) share the most recent common ancestor.

C) have the fewest shared derived characters.

D) are both extinct and found in the same rock layer.

Correct Answer: B

Evolutionary relatedness is determined by how recently two lineages shared a common ancestor. The node closest to the tips for any two species represents their most recent common ancestor.

The loss of a trait, such as the loss of legs in snakes, can be used to place a group on a phylogenetic tree because it represents a...

A) shared derived character.

B) random mutational event.

C) failure of the fossil record.

D) trait common to all vertebrates.

Correct Answer: A

The content specifies that 'Traits that are gained or lost during evolution, particularly shared derived characters, are used to construct phylogenetic trees.' The loss of a trait is a type of shared derived character.

A researcher is studying a diagram that shows the evolutionary relationships among several species of fish, but the lengths of the branches do not indicate the passage of time. This diagram is best described as a...

A) phylogenetic tree.

B) fossil record.

C) cladogram.

D) karyotype.

Correct Answer: C

The key information is that the diagram does not show a time scale. The provided content distinguishes between phylogenetic trees, which 'show the amount of change over time,' and cladograms, which 'do not show a time scale.'

What type of event in evolutionary history is indicated by the branching of a single lineage into two on a phylogenetic tree?

A) A mass extinction

B) A speciation event

C) A genetic mutation in an individual

D) A period of evolutionary stasis

Correct Answer: B

The content clearly states that 'Phylogenetic trees and cladograms can illustrate speciation events, with nodes representing the most recent common ancestor of descendant lineages.'

Which of the following statements best synthesizes the core principles of phylogeny presented?

A) Phylogeny uses only molecular data to create fixed, unchanging diagrams of speciation.

B) Phylogeny creates testable hypotheses about evolutionary relationships using shared derived characters from morphological or molecular evidence.

C) Cladograms are superior to phylogenetic trees because they use fossil evidence to establish an exact timeline of evolution.

D) The main goal of phylogeny is to prove common ancestry using only the traits gained, not lost, during evolution.

Correct Answer: B

This option correctly combines multiple concepts from the text: that trees are 'testable hypotheses,' they illustrate 'evolutionary relationships,' they are built using 'shared derived characters' (which can be gained or lost), and the evidence can be 'morphological' or 'molecular.'