BIO 1306 Practice Exam 2 – Step-by-Step Study Guidance (Chapters 26–31)

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Topic: Phylogenetics and Evolutionary Relationships

This question tests your understanding of what information a phylogenetic tree conveys about species and their evolutionary history.

Phylogenetic tree: A diagram showing hypothesized evolutionary relationships among species or groups.
Evolutionary relationships: Patterns of descent and common ancestry among organisms.

Review what a phylogenetic tree is and what it is used for in biology.
Consider whether a phylogenetic tree shows direct morphological similarity, rates of molecular evolution, or time of divergence, or if it is more about hypothesizing relationships.
Recall that phylogenetic trees are constructed based on data (morphological, molecular, etc.) but are ultimately hypotheses about how species are related.

Topic: Phylogenetic Terminology

This question checks your understanding of how closely related groups are described in evolutionary trees.

Sister taxa: Two groups that share an immediate common ancestor not shared by any other group.
Common ancestor: The most recent ancestral species from which two taxa diverged.

Recall the definition of sister taxa in the context of a phylogenetic tree.
Think about how sister taxa are represented on a tree (they branch from the same node).
Eliminate options that refer to more distant relationships or unrelated traits.

Topic: Interpretation of Phylogenetic Trees

This question tests your ability to distinguish between what phylogenetic trees do and do not show.

Branch rotation: Rotating branches around nodes does not change relationships.
Patterns of descent: The sequence of branching events showing ancestry.
Hypothesis: Trees are scientific hypotheses about relationships.
Branch length: Sometimes, but not always, indicates amount of change or time.

Review what information is always, sometimes, or never represented by a phylogenetic tree.
Consider whether all trees show evolutionary change or time, or if some only show relationships.
Eliminate statements that are always true for all trees.

Topic: Homology vs. Analogy (Convergent Evolution)

This question asks you to distinguish between traits that arise from shared ancestry and those that arise independently due to similar environments.

Homology: Similarity due to shared ancestry.
Convergent evolution: Independent evolution of similar traits in distantly related lineages due to similar selective pressures.
Adaptive radiation: Diversification of a group into new ecological niches.

Consider whether the two moles are closely related or if their similarities evolved independently.
Recall the definitions of homology and analogy, and how convergent evolution leads to analogous traits.
Eliminate options that refer to shared ancestry if the groups are not closely related.

Topic: Molecular Phylogenetics

This question tests your understanding of the technical difficulties in comparing DNA sequences across species.

Homologous genes: Genes inherited from a common ancestor.
Insertions and deletions (indels): Mutations that add or remove bases, complicating sequence alignment.
Sequence alignment: Arranging DNA sequences to identify regions of similarity.

Recall what happens to DNA sequences over evolutionary time (mutations, insertions, deletions).
Think about how insertions and deletions can make it difficult to line up homologous regions.
Eliminate options that are not true about DNA sequence comparison (e.g., all genes being identical, or computers being unable to detect similarity).