According to the principle of superposition, which group of fossils is the OLDEST?

Answer: Trilobites (Layer 5) In an undisturbed sequence of sedimentary rock, lower layers were deposited first. Therefore the deepest layer (Layer 5, trilobites) contains the oldest fossils.

Why do related finch species on different Galapagos islands show different beak shapes?

Answer: Adaptive radiation following geographic isolation and divergent selection Galapagos finches descended from a common ancestor and diversified across islands. Different food resources on each island created divergent selection, producing distinct beak morphologies (adaptive radiation).

Why does a whale possess vestigial pelvic bones?

Answer: Whales evolved from terrestrial tetrapod ancestors that had functional pelvises Vestigial structures are remnants of features that were functional in ancestors. Cetacean ancestors were terrestrial mammals with hind limbs and pelvises; whales today retain reduced, non-functional pelvic bones as evidence of that ancestry.

AP Biology · Topic 7.6

Evidence of Evolution Practice

Part of Natural Selection.(EVO-1.F)

Practice questions

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Sample questions

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Sample 1difficulty 1/5
$According to the principle of superposition, which group of fossils is the OLDEST?$
- A
  $Dinosaurs (Layer 2)$
- B
  $Mammals (Layer 1)$
- C
  $Amphibians (Layer 3)$
- D
  $Trilobites (Layer 5)$
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Why
$In an undisturbed sequence of sedimentary rock, lower layers were deposited first. Therefore the deepest layer (Layer 5, trilobites) contains the oldest fossils.$
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Sample 2difficulty 1/5
$Different finch species inhabit different Galapagos islands; each has a beak adapted to a different food source.$
$Why do related finch species on different Galapagos islands show different beak shapes?$
- A
  $Adaptive radiation following geographic isolation and divergent selection$
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- B
  $Genetic drift unaffected by environment$
- C
  $Lamarckian inheritance of feeding behavior$
- D
  $Convergent evolution from unrelated mainland ancestors$
Why
$Galapagos finches descended from a common ancestor and diversified across islands. Different food resources on each island created divergent selection, producing distinct beak morphologies (adaptive radiation).$
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Sample 3difficulty 1/5
$Why does a whale possess vestigial pelvic bones?$
- A
  $Vestigial bones are evidence against common ancestry$
- B
  $Whales evolved from terrestrial tetrapod ancestors that had functional pelvises$
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- C
  $Whales developed pelvic bones de novo from selection pressure$
- D
  $The bones serve a primary structural role in swimming$
Why
$Vestigial structures are remnants of features that were functional in ancestors. Cetacean ancestors were terrestrial mammals with hind limbs and pelvises; whales today retain reduced, non-functional pelvic bones as evidence of that ancestry.$
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Sample 4difficulty 1/5
$Each circle represents a Hawaiian island, with geological ages noted; molecular dating shows that endemic Drosophila species on each island are youngest on the youngest islands.$
$Hawaiian Drosophila species on each island are most closely related to species on the next-older island. This pattern reflects$
- A
  $Convergent evolution from soil bacteria$
- B
  $Progression rule via colonization of new islands and adaptive radiation$
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- C
  $Independent origin on each island from the mainland$
- D
  $Hybridization across the entire archipelago$
Why
$The progression rule describes a stepping-stone colonization pattern in island chains: new species form by colonizing newly emerged islands and radiating, mirroring the geological age progression.$
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Sample 5difficulty 1/5
$Pharyngeal slits appear in early embryos of fish, chickens, and humans. This is best evidence for$
- A
  $Vestigial structures in adults$
- B
  $Adaptive radiation$
- C
  $Convergent evolution in adults$
- D
  $Common ancestry among vertebrates$
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Why
$Shared embryonic structures across diverse vertebrates indicate inheritance of developmental programs from a common ancestor, supporting common descent.$
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