Common ancestry Knowledge-Based Download PDF

Questions

1. 1.

   Which statement best explains why the presence of identical endogenous retrovirus (ERV) sequences at orthologous genomic loci in humans and chimpanzees provides robust evidence of common ancestry?

   • A) Both species independently evolved molecular mechanisms that direct retroviruses to insert at identical chromosomal coordinates.
   • B) The retroviral insertion occurred in the germline of a shared ancestral population and was inherited by both descendant lineages.
   • C) Retroviral insertions consistently alter non-coding regions to confer adaptive benefits that were independently selected in both species.
   • D) Frequent horizontal gene transfer between modern primate species continually exchanges retroviral sequences across populations.
2. 2.

   During early embryonic development, all vertebrate embryos temporarily exhibit pharyngeal pouches and a post-anal tail, even though their adult anatomies and ecological niches differ drastically. Which evolutionary explanation accounts for the presence of these shared developmental structures across diverse vertebrate classes?

   • A) Convergent evolution independently shaping embryonic morphology to withstand common mechanical stresses within amniotic or egg environments.
   • B) Directional natural selection repeatedly favoring identical physiological specializations that functional adult vertebrates require to survive.
   • C) Genetic drift randomly fixing identical complex gene-regulatory networks across completely unrelated evolutionary lineages.
   • D) Descent with modification preserving conserved developmental regulatory pathways inherited from a shared ancestral vertebrate.
3. 3.

   Which observation provides the strongest evidence that all extant organisms on Earth descend from a single universal common ancestor?

   • A) All organisms inhabit overlapping ecological niches and undergo natural selection.
   • B) Organisms across different domains utilize identical respiratory organs for gas exchange.
   • C) Different species possess analogous structures that perform equivalent physical functions.
   • D) All living cells share the same basic genetic code and core biochemical pathways.
4. 4.

   Which of the following biological explanations best accounts for why the forelimbs of humans, bats, and whales exhibit a strikingly similar arrangement of bones despite serving vastly different functions?

   • A) They arose independently through convergent evolution in response to comparable environmental demands.
   • B) They perform identical mechanical actions that necessitate an unvarying skeletal framework across all vertebrates.
   • C) They develop from fundamentally distinct embryonic tissue layers via separate developmental pathways.
   • D) They were inherited from a shared tetrapod ancestor and subsequently modified through divergent evolution.
5. 5.

   In phylogenetic analysis, what does an internal node (branching point) on an evolutionary tree directly represent?

   • A) A common ancestor shared by two or more descendant lineages
   • B) An extinction event that abruptly terminated an entire ancestral lineage
   • C) A point of convergent evolution where two distinct taxa merge into one
   • D) The independent development of analogous structures under similar selective pressures