BIO 181 EXAM 3 GENERAL BIOLOGY 1
PRACTICE QUESTIONS AND RATIONALE GUIDE
2026
◉ phylogeny. Answer: Evolutionary history of species or group
◉ Clade. Answer: group of evolutionary ancestors & descendants of
common ancestor
◉ Sister clades. Answer: share an immediate common ancestors;
each other's closest relatives
◉ cladogram. Answer: diagram showing evolutionary relationships
among organisms
◉ phylogenetic trees. Answer: based on homology (similar in
features due to common environmental pressures)
◉ ancestral trait. Answer: in ancestor of group; may be retained or
changed in descendants
◉ derived trait. Answer: differs from ancestral form; evolutionary
novelty
, ◉ synapomorphy. Answer: derived traits
◉ plesiomorphies. Answer: ancestral trait state
◉ symplesiomorphies. Answer: shared ancestral trait states
◉ Michael Urey. Answer: spark-> reduced atm->condenser->liquid
with amino acids
◉ first cells formed. Answer: 3.5 BYA and resemble prokaryotes
◉ stromatolite. Answer: mats of cynabacterial cells that trap mineral
deposits
◉ Great Oxygen Event. Answer: 2.3 BYA; cyanobacteria; began
producing oxygen by photosynthesis and it began to accumulate in
the atm. The O2 reacted with the UV radiation to form O3 (Ozone)
◉ Three monophyletic domains. Answer: BAE
◉ Eukaryotes formed. Answer: 1.5 BYA > 2BY after bacteria
PRACTICE QUESTIONS AND RATIONALE GUIDE
2026
◉ phylogeny. Answer: Evolutionary history of species or group
◉ Clade. Answer: group of evolutionary ancestors & descendants of
common ancestor
◉ Sister clades. Answer: share an immediate common ancestors;
each other's closest relatives
◉ cladogram. Answer: diagram showing evolutionary relationships
among organisms
◉ phylogenetic trees. Answer: based on homology (similar in
features due to common environmental pressures)
◉ ancestral trait. Answer: in ancestor of group; may be retained or
changed in descendants
◉ derived trait. Answer: differs from ancestral form; evolutionary
novelty
, ◉ synapomorphy. Answer: derived traits
◉ plesiomorphies. Answer: ancestral trait state
◉ symplesiomorphies. Answer: shared ancestral trait states
◉ Michael Urey. Answer: spark-> reduced atm->condenser->liquid
with amino acids
◉ first cells formed. Answer: 3.5 BYA and resemble prokaryotes
◉ stromatolite. Answer: mats of cynabacterial cells that trap mineral
deposits
◉ Great Oxygen Event. Answer: 2.3 BYA; cyanobacteria; began
producing oxygen by photosynthesis and it began to accumulate in
the atm. The O2 reacted with the UV radiation to form O3 (Ozone)
◉ Three monophyletic domains. Answer: BAE
◉ Eukaryotes formed. Answer: 1.5 BYA > 2BY after bacteria
