These structures are best classified as

Answer: Homologous - common ancestry Despite different functions (grasping, swimming, flying), the bones share the same arrangement (humerus, radius/ulna, carpals, digits). This pattern indicates inheritance from a common ancestor - homology.

The near-universality of the genetic code is evidence for

Answer: A common ancestor of all life on Earth Sharing the same code is most parsimoniously explained by inheritance from LUCA (Last Universal Common Ancestor).

Bacteria can acquire genes (e.g., antibiotic resistance) from unrelated bacteria via

Answer: Horizontal gene transfer (transformation, transduction, conjugation) HGT helps bacteria adapt rapidly; complicates phylogenetic reconstruction.

AP Biology · Topic 7.7

Common Ancestry Practice

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

Practice questions

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Sample questions

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Sample 1difficulty 1/5
$The diagram compares forelimb skeletons across three mammals.$
$These structures are best classified as$
- A
  $Vestigial - non-functional remnants$
- B
  $Analogous - convergent evolution$
- C
  $Homologous - common ancestry$
  check_circle
- D
  $Atavistic - reappearance of ancestral trait$
Why
$Despite different functions (grasping, swimming, flying), the bones share the same arrangement (humerus, radius/ulna, carpals, digits). This pattern indicates inheritance from a common ancestor - homology.$
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Sample 2difficulty 2/5
$The near-universality of the genetic code is evidence for$
- A
  $Rapid horizontal gene transfer among lineages$
- B
  $Convergent biochemistry across all kingdoms$
- C
  $A common ancestor of all life on Earth$
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- D
  $Independent origins of life on Earth$
Why
$Sharing the same code is most parsimoniously explained by inheritance from LUCA (Last Universal Common Ancestor).$
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Sample 3difficulty 3/5
$Bacteria can acquire genes (e.g., antibiotic resistance) from unrelated bacteria via$
- A
  $Mendelian segregation (independent assortment of alleles into gametes)$
- B
  $Horizontal gene transfer (transformation, transduction, conjugation)$
  check_circle
- C
  $Meiotic recombination (crossover between homologous chromosomes in meiosis)$
- D
  $Vertical inheritance only (parent-to-daughter transmission via binary fission)$
Why
$HGT helps bacteria adapt rapidly; complicates phylogenetic reconstruction.$
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