AP Biology Quiz: Phylogeny

What this quiz covers

This quiz focuses on Phylogeny, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Biology.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. C is more closely related to A than to D (correct answer)
2. D is more closely related to A than B is to A
3. C and D are sister taxa because both branch after (A,B)
4. A is equally related to C and D because A branches first
5. B is ancestral to A because they are in the same clade

Explanation: This question assesses the skill of inferring phylogenetic relatedness from a described branching pattern in plants. The topology shows ((A,B),C) as a clade sister to D, meaning C shares a more recent common ancestor with A (at the node uniting (A,B,C)) than with D (at the root). A and B are sisters, with C as their outgroup within the larger clade excluding D, and no timing data alters this hierarchical inference. This supports that divergence between C and A occurred after the split from D. A tempting distractor is D, claiming A equally related to C and D due to A's basal position, a misconception of equating branching order with equal genetic distance, a level-of-organization error in tree reading. A transferable strategy for this question type is to identify the most recent shared node for pairs and compare node depths to determine relative closeness without assuming branch lengths.

Question 2

1. M and N
2. N and O (correct answer)
3. M and O
4. M and the outgroup
5. All pairs are equally related because all have jaws

Explanation: This question assesses the skill of inferring phylogenetic relatedness using shared derived traits in vertebrates. Taxa N and O both possess four limbs and a bony skeleton, with O additionally having an amniotic egg, indicating N and O share a more recent common ancestor defined by the limb synapomorphy relative to the outgroup. All taxa share jaws, a basal trait, while M shares only the bony skeleton with N and O but lacks limbs, placing it outside the N-O clade. This assumes each trait evolved once without loss, supporting a parsimonious tree with (N,O) as sisters. A tempting distractor is A (M and N), which might appeal because both have bony skeletons, but this ignores the more exclusive limb trait, a level-of-organization error in clade hierarchy. A transferable strategy for this question type is to map traits onto a tree by grouping taxa with the most nested shared derived characters to identify closest relatives.

Question 3

1. P and Q share a more recent common ancestor than Q and R
2. R and S share a more recent common ancestor than Q and R (correct answer)
3. P and S share a more recent common ancestor than R and S
4. Q and S share a more recent common ancestor than R and S
5. P is most closely related to S because it branches first

Explanation: This question assesses the skill of inferring phylogenetic relatedness from a described cladogram structure. The branching order shows the root splitting to P and a lineage that then splits to Q and another that splits to R and S, meaning R and S are the last to diverge, sharing the most recent common ancestor. This aligns with AP Biology principles of cladogram interpretation, where branch points represent common ancestors, and closer branch points indicate more recent shared ancestry. P branches first, then Q, leaving R and S as sister taxa at the final split. A tempting distractor is choice A (P and Q share a more recent common ancestor than Q and R), but this is incorrect due to a misconception of branch order, specifically a structure-function confusion where earlier branches are mistakenly seen as closer than later sister pairs. For similar questions, trace the branching sequence from the root and identify the pair with the shortest path back to their shared node as most closely related.

Question 4

1. A and B
2. B and C
3. D and E (correct answer)
4. A and E
5. C and D

Explanation: This question assesses the skill of inferring phylogenetic relatedness using shared derived traits in cladistic analysis. The lineages D and E share all five derived traits, including the most nested one (trait 5 present only in E), but since trait 4 is present in D and E while absent in C, and trait 5 distinguishes E further, D and E share the most recent common ancestor as they are the last to diverge in this nested pattern. Traits are assumed to evolve once without loss, following parsimony in AP Biology phylogeny construction, where shared derived traits (synapomorphies) group clades. For example, A lacks all but trait 1, B shares up to trait 2, C up to trait 3, but D and E extend to trait 4, with E having trait 5, confirming their close relationship. A tempting distractor is choice B (B and C), which share traits up to 2 and 3 respectively but not as many as D and E, reflecting a misconception of counting total traits rather than identifying the most nested shared ancestor (clade nesting error). When facing such questions, construct a mental cladogram by nesting groups based on progressively shared derived traits to pinpoint the closest pairs.

Question 5

1. U and V share a more recent common ancestor than either does with W (correct answer)
2. W is the outgroup because it differs most from U and V
3. U is ancestral to V because U has fewer differences from O
4. All three island lineages diverged at the same time because O differs equally
5. V and W are most closely related because both differ equally from U

Explanation: This question assesses the skill of inferring phylogenetic relatedness from nucleotide differences with an outgroup. Among island lineages, U and V differ by only 2 nucleotides, fewer than U-W=6 or V-W=6, indicating U and V diverged most recently from a common ancestor, while all differ equally from outgroup O at 12, establishing ancestral state. This uses the AP Biology concept of molecular divergence, where fewer differences post-colonization reflect recency under neutral evolution. W differs more from both, suggesting earlier split. A tempting distractor is choice E (V and W most closely related because both differ equally from U), but equal differences from a third don't imply closeness, a misconception of teleology assuming symmetry indicates relation. Compare intra-group differences against the outgroup to find the minimal pair for closest island relatedness.

Question 6

1. L and M are sister taxa because both have character A
2. M and N share the most recent common ancestor because both have B
3. N and O share a more recent common ancestor than either shares with M (correct answer)
4. N is least related to the outgroup because it has character D
5. O is ancestral to N because O lacks character D

Explanation: This question assesses the skill of inferring phylogenetic relatedness from derived character distributions. Character C is present only in N and O, indicating they share a more recent common ancestor than either does with M, as this synapomorphy defines their subclade. Character A is basal to all, B groups M, N, O, and D is unique to N, supporting a tree with (N,O) nested within (M,N,O). Assumptions of single evolution and no loss ensure parsimony in interpreting these patterns. A tempting distractor is B (M and N sharing B), which overlooks the more exclusive C, a structure-function confusion mistaking broader shared traits for closer relatedness. A transferable strategy for this question type is to construct a cladogram by progressively grouping taxa based on increasingly exclusive shared characters to reveal nested hierarchies.

Question 7

1. W and X (correct answer)
2. Y and Z
3. W and Z
4. X and Y
5. W and Y

Explanation: This question assesses the skill of inferring phylogenetic relatedness from molecular sequence differences. The data show that species W and X differ at only 1 amino acid position, which is the fewest differences among all pairs, indicating they share a more recent common ancestor under the assumption of a roughly constant substitution rate. Species Y differs from both W and X at 4 positions, while Z differs from them at 6 positions, supporting that W and X diverged most recently. In contrast, Y and Z differ at 5 positions, which is more than W and X, confirming W and X as the closest pair. A tempting distractor is B (Y and Z), which might appeal due to a misconception of averaging differences instead of identifying the minimal pairwise difference, a structure-function confusion in interpreting molecular clocks. A transferable strategy for this question type is to systematically compare all pairwise differences and select the pair with the smallest number as the most closely related, assuming constant evolutionary rates.

Question 8

1. A and B
2. B and C
3. C and D
4. D and E (correct answer)
5. A and E

Explanation: This question tests the skill of inferring phylogenetic relationships using cladistic analysis of derived characters. The characters show a nested pattern where Character 3 (feather-like filaments) is the most derived, present only in species D and E, indicating these two species share the most recent common ancestor. This follows the principle that species sharing the most recently evolved traits diverged most recently from their common ancestor. A common misconception is to group species by total character count rather than identifying which species share the most derived (recently evolved) character. When analyzing cladistic data, identify the most restricted character distribution, as species sharing the most exclusive derived trait are sister taxa.

Question 9

1. P and Q
2. Q and R
3. R and S
4. S and T (correct answer)
5. P and T

Explanation: This question tests the skill of inferring phylogenetic relationships from nested sets of derived characters. The traits show a clear nested pattern where Trait 3 is the most derived, present only in species S and T, indicating these two species are sister taxa sharing the most recent common ancestor. This follows the cladistic principle that species sharing the most recently evolved trait diverged most recently from their exclusive common ancestor. A common misconception is to pair species based on having different numbers of traits rather than identifying which species uniquely share the most derived character. When analyzing nested character data, the most restricted trait distribution identifies the most closely related species pair.

Question 10

1. W and V
2. Y and Z (correct answer)
3. W and Z
4. X and V
5. W and Y

Explanation: This question tests the skill of inferring phylogenetic relationships from molecular sequence differences. The data shows pairwise amino acid differences between five species, where fewer differences indicate more recent divergence according to the molecular clock hypothesis. Species Y and Z differ at only 2 positions, which is the smallest difference among all pairwise comparisons, indicating they share the most recent common ancestor. A common misconception is to focus on the reference species (W) and choose the pair with the smallest difference from W (like W and X with 1 difference), but phylogenetic relatedness requires comparing all species pairs directly. When analyzing molecular data for phylogeny, always create a complete pairwise difference matrix and identify the species pair with the fewest differences.

Question 11

1. S1 and S2 share the most recent common ancestor because both lack trait C
2. S2 and S4 share the most recent common ancestor because both have trait B
3. S3 and S4 share a more recent common ancestor than either does with S2 (correct answer)
4. S1 is most closely related to S4 because S4 has all derived traits
5. S2 is more closely related to S1 than to S3 because S2 has fewer traits

Explanation: This question tests the skill of inferring phylogenetic relationships from nested derived characters in fungi. The traits form a clear nested hierarchy where trait C is shared only by S3 and S4, making them sister taxa that share a more recent common ancestor than either shares with S2. This pattern follows cladistic principles where the most exclusive shared derived trait identifies the most recently diverged species pair. A common misconception is grouping species by shared absence of traits (like S1 and S2 both lacking trait C) rather than by shared presence of derived traits. When analyzing trait hierarchies, identify the most restricted trait distribution to find sister taxa relationships.

Question 12

1. M and N
2. N and P
3. P and Q (correct answer)
4. M and Q
5. N and Q

Explanation: This question tests the skill of inferring phylogenetic relationships using nested sets of shared derived characters. The traits form a nested hierarchy: vertebral column (all species), hinged jaw (N, P, Q), bony skeleton (P, Q), and amniotic egg (Q only). Species P and Q share the most derived traits (vertebral column, hinged jaw, and bony skeleton), indicating they share the most recent common ancestor that possessed all three traits. A common misconception is to pair species based on total trait count similarity rather than identifying which species share the most recently evolved traits. When analyzing nested character sets, identify the most derived trait shared by exactly two species, as this indicates their exclusive common ancestry.

Question 13

1. C is more closely related to B than to D
2. E and F share a more recent common ancestor than E and D (correct answer)
3. B and F share the most recent common ancestor because both have trait X
4. A is most closely related to F because A lacks derived traits
5. D and E are equally related to F because all have trait Y

Explanation: This question assesses the skill of inferring phylogenetic relatedness from shared derived traits and specified splits. The derived traits nest as follows: trait X groups B-C-D-E-F, Y groups C-D-E-F, Z groups E-F, and the most recent split is within Z between E and F, meaning E and F share the most recent common ancestor. This follows AP Biology cladistics, where synapomorphies define clades, and the stated split confirms E and F as sister taxa. No reversals occur, and A lacks derived traits, positioning it outside. A tempting distractor is choice A (C is more closely related to B than to D), but this ignores the nesting of Y grouping C with D but not B, a misconception of teleology where traits are seen as goals rather than clade definers. For these questions, build the clade hierarchy from shared traits and identify pairs with the innermost shared ancestor.

Question 14

1. P and Q
2. Q and R
3. R and S (correct answer)
4. P and S
5. P and R

Explanation: This question assesses the skill of inferring phylogenetic relatedness from a described cladogram's branching order. The cladogram indicates that R and S are separated by the final split, meaning they share the most recent common ancestor compared to other pairs. Earlier splits separate P first, then Q from the (R,S) lineage, establishing a nested hierarchy where (R,S) is the innermost clade. No branch lengths are provided, so relatedness is based solely on branching topology. A tempting distractor is B (Q and R), which might arise from a misconception of counting splits incorrectly, a level-of-organization error confusing clade nesting with recency of ancestry. A transferable strategy for this question type is to trace back from tips to find the nearest node connecting each pair, selecting the pair with the shallowest shared node as most closely related.

Question 15

1. W and X (correct answer)
2. X and Z
3. Y and Z
4. W and Z
5. W and Y

Explanation: This question assesses the skill of inferring phylogenetic relatedness from molecular sequence data. The pair W and X differ at only one position in the 12-amino acid segment, indicating they have accumulated the fewest substitutions since diverging from a common ancestor, which aligns with the AP Biology concept that fewer molecular differences suggest a more recent common ancestor under the assumption of a molecular clock. In contrast, other pairs like X and Y differ at two positions, Y and Z at two, and X and Z at three, showing greater divergence times. The sequences provided confirm these differences, with W and X varying only at what appears to be position 11 (R vs. K), supporting their close relatedness. A tempting distractor is choice C (Y and Z), which differ at two positions, but this is incorrect due to a misconception of minimal difference overlooking that one is still fewer than two, confusing relative divergence scales. To approach similar questions, systematically compare all pairwise differences and select the pair with the smallest number to identify the most closely related taxa.

Question 16

1. Species 1 and 4 are sister taxa because their difference is largest
2. Species 2 and 3 are most closely related to each other (correct answer)
3. Species 1 is equally closely related to species 2, 3, and 4
4. Species 4 is most closely related to species 2 because both differ from 3
5. Species 1 and 2 share a more recent common ancestor than species 2 and 3

Explanation: This question assesses the skill of inferring phylogenetic relatedness from protein sequence differences. Species 2 and 3 differ by only 1 amino acid in cytochrome c, the fewest among pairs, indicating they share the most recent common ancestor under the AP Biology molecular clock assumption where fewer differences reflect less divergence time. Comparisons from species 1 show 2 and 3 both differ by 4, while 4 differs by 9, and cross-pairs like 2-4=10, 3-4=10, confirm 2 and 3 are closest. This protein is conserved, making differences reliable for phylogeny. A tempting distractor is choice E (1 and 2 share more recent ancestor than 2 and 3), but 1-2=4 vs 2-3=1 shows otherwise, due to a structure-function confusion mistaking reference species differences for overall relatedness. Always compute all pairwise differences and select the minimal for the closest pair in such analyses.

Question 17

1. C and D share a more recent common ancestor than either shares with A (correct answer)
2. A and D share a more recent common ancestor than A shares with B
3. B and C share a more recent common ancestor than C shares with D
4. A is equally related to B, C, and D because all share character 1
5. D is most closely related to the outgroup because it has character 3

Explanation: This question assesses the skill of inferring phylogenetic relatedness using shared derived characters in cladistic analysis. The presence of character 2 only in C and D indicates they share a more recent common ancestor than either does with A, as this synapomorphy defines their clade relative to the outgroup. Character 1 is shared by all, representing an ancestral trait for the ingroup, while character 3 is unique to D and character 4 groups A and B separately. These patterns support a tree where C and D form a subclade branching after the split from A and B. A tempting distractor is D, suggesting equal relatedness due to shared character 1, which reflects a misconception of treating plesiomorphies as evidence of close relatedness, a teleological error assuming shared ancestry implies equal divergence. A transferable strategy for this question type is to identify the most exclusive shared derived characters to determine the most recent common ancestors, assuming parsimony in trait evolution.

Question 18

1. V and W
2. W and X
3. X and Y (correct answer)
4. V and Y
5. V and X

Explanation: This question assesses the skill of inferring phylogenetic relatedness using derived traits in insects. Taxa X and Y both possess trait 3, in addition to traits 1 and 2 shared with W, indicating X and Y share the most recent common ancestor defined by this exclusive synapomorphy. All taxa share trait 1 basally, W, X, Y share trait 2, and Y has unique trait 4, supporting a nested tree with (X,Y) as sisters. Assumptions of single evolution and no loss promote parsimony in this inference. A tempting distractor is B (W and X), which might tempt because they share trait 2, but ignores the more nested trait 3, a structure-function confusion equating broader traits with tighter clades. A transferable strategy for this question type is to prioritize the most restrictive shared traits to group taxa progressively, building the tree from the most recent divergences outward.

Question 19

1. G and H share the most recent common ancestor with each other (correct answer)
2. G and J share the most recent common ancestor with each other
3. H and J share the most recent common ancestor with each other
4. G is ancestral to H because they differ at 2 sites
5. All island populations are equally related because all live on islands

Explanation: This question assesses the skill of inferring phylogenetic relatedness from mitochondrial gene substitution data. The island populations G and H differ by only 2 substitutions, the smallest among island pairs, and both differ from the mainland K by 5, supporting they share a more recent common ancestor with each other than with J or K. J differs from K by only 1 but from G and H by 6, suggesting J diverged earlier or separately. This pattern implies G and H form a clade post-dating their split from the mainland lineage. A tempting distractor is C (H and J), which might arise from miscalculating differences, reflecting a teleological misconception that geographic proximity on islands implies closer ancestry without sequence evidence. A transferable strategy for this question type is to use an outgroup like the mainland to root the tree and identify island clades with minimal internal divergences.

Question 20

1. T and U are most closely related because their difference is 6
2. R and S are most closely related because their difference is 0 (correct answer)
3. R and U are most closely related because U has the most differences
4. S is ancestral to R because their sequences are identical
5. R is equally related to T and U because both differ from R

Explanation: This question assesses the skill of inferring phylogenetic relatedness from protein sequence differences. R and S show 0 amino acid differences, indicating they are most closely related and share the most recent common ancestor, assuming orthology and that minimal differences reflect recent divergence. Comparatively, T differs from R and S by 3, U by 7 from R and S, and T-U by 6, suggesting (R,S) as a tight clade separate from others. This supports R and S as essentially identical or very recently diverged lineages. A tempting distractor is A (T and U), which might appeal due to their 6-difference being smaller than some but not the minimal, reflecting a teleological error of assuming larger differences imply closer ties through adaptation. A transferable strategy for this question type is to scan for the absolute minimal pairwise difference as evidence of closest relatedness, then contextualize with other pairs for tree structure.