Evidence of Common Ancestry - Middle School Life Science
- What is a phylogenetic tree (cladogram) used to show?
- Hypothesized evolutionary relationships and common ancestors. Visual diagram mapping evolutionary relationships.
- What is common ancestry in evolutionary biology?
- Shared descent from the same ancestral species. All organisms evolved from earlier life forms through branching lineages.
- What does it mean when two species are "sister taxa" on a cladogram?
- They share an immediate common ancestor not shared by others shown. Closest relatives that split from same recent ancestor.
- What is comparative anatomy used for when inferring common ancestry?
- Comparing body structures to identify shared evolutionary origins. Reveals homologous structures that indicate common descent.
- Which type of evidence is being used when comparing amino acid sequences in proteins?
- Molecular (biochemical) evidence. Proteins are molecular evidence like DNA sequences.
- What does comparative embryology study to infer relatedness?
- Similarities in early developmental stages. Related species show similar patterns during embryonic development.
- What is the fossil record?
- Preserved remains or traces showing life over time. Fossils document evolutionary changes through geological time.
- What does a fossil record provide as evidence for common ancestry?
- Shows changes over time and transitional forms linking groups. Preserves evidence of evolutionary transitions between groups.
- What is molecular evidence for common ancestry?
- Similar DNA or protein sequences indicate relatedness. Genetic similarities reflect shared evolutionary history.
- Which evidence best supports common ancestry: same bone pattern in forelimbs or same habitat use?
- Same bone pattern in forelimbs (homologous structure). Structural similarity shows shared ancestry, not ecology.
- What is molecular evidence of common ancestry based on?
- Similarities in DNA or amino acid sequences. Genetic code similarities reflect shared evolutionary history.
- What does it mean if two species share many DNA sequence similarities?
- They likely share a more recent common ancestor. Less time since divergence means fewer genetic differences.
- What is a vestigial structure, and what does it suggest about evolution?
- Reduced or unused trait; inherited from ancestors where it was useful. Evidence of evolutionary history when structures lose function.
- On a cladogram, which organisms are most closely related: the two sharing the most recent node or the root?
- The two sharing the most recent node. Recent nodes show more recent divergence from common ancestor.
- Identify the best evidence type for common ancestry: same bone pattern in forelimbs across mammals.
- Homologous structures. Same skeletal pattern inherited from common mammalian ancestor.
- Which observation most strongly indicates convergent evolution: homologous bones or analogous wings?
- Analogous wings. Similar function without shared structure shows convergence.
- Which option best indicates closer relatedness: more DNA differences or fewer DNA differences?
- Fewer DNA differences. Less evolutionary time means fewer accumulated genetic changes.
- Identify the correct conclusion: Species A and B have fewer DNA differences than A and C.
- Species A and B are more closely related than A and C. Fewer differences mean more recent common ancestor.
- Which type of structure is stronger evidence of common ancestry: homologous or analogous?
- Homologous structures. Same structure from inheritance shows direct evolutionary connection.
- What is a homologous structure, and what does it indicate about ancestry?
- Similar structure from common ancestor; may have different functions. Same basic structure evolved once in shared ancestor.
- Which part of a cladogram represents the most recent common ancestor of two species?
- The node (branch point) where their lineages meet. Nodes show where one ancestral species split into two.
- What is comparative embryology evidence for in evolutionary biology?
- Similar early development patterns suggest common ancestry. Shared developmental stages reveal evolutionary relationships.
- What is a phylogenetic tree (cladogram) used to show?
- Hypothesized evolutionary relationships and common ancestors. Diagrams branching patterns of evolution from shared ancestors.
- Identify the evidence type: whale pelvis bones that no longer support walking.
- Vestigial structures. Remnants from land-dwelling ancestors that walked on legs.
- Identify the evidence type: wings of bats and insects share function but different structure.
- Analogous structures. Independent evolution created similar solutions for flight.
- What is an analogous structure, and what does it indicate about ancestry?
- Similar function, different origin; indicates convergent evolution. Different ancestors evolved similar solutions independently.
- Identify the stronger evidence for common ancestry: homologous structures or analogous structures?
- Homologous structures. Shared structure indicates common descent, not convergence.
- Which pair is more closely related if pair 1 differs by 2 DNA bases and pair 2 differs by 12?
- Pair 1 (2 base differences). Fewer mutations indicate less time since divergence.
- Choose the correct inference: two species have very similar embryos early in development.
- They likely share a common ancestor. Similar embryos indicate shared developmental programs.
- Identify the best overall conclusion if fossils, DNA, and homologous structures all agree.
- The organisms share a common ancestor. Multiple independent evidence types confirm evolutionary relationship.