Chapter 25 Flashcards
Macroevolution
Changes over large time scales (emergence of terrestrial vertebrates, origin of flight in birds)
Chemical and physical processes on early Earth may have produced very simple cells through a sequence of stages:
1) Abiotic synthesis of small organic molecules
2) Joining of these small molecules into macromolecules
3) Packaging of molecules into protocells
4) Origin of self-replication molecules
T/F: Earth formed about 4.6 billion years ago, along with the rest of the solar system
True
T/F: Bombardment of Earth by rocks and ice likely vaporized water and prevented landmasses from forming before about 4 billion years ago
False, prevented seas from forming
T/F: Early Earth’s atmosphere likely contained water vapor and chemicals released by volcanic eruptions
True
Protocells
1) Replication and metabolism likely appeared together in protocells
2) May have formed from fluid-filled vesicles with a membrane-like structure
3) In water, lipids and other organic molecules can spontaneously form vesicles with a lipid bilayer
T/F: DNA was the first genetic material
False, RNA
Ribozymes
RNA molecules that can catalyze many different reactions (example: can make complementary copies of short stretches of RNA)
Natural selection has produced __________ RNA molecules
self-replicating
The fossil record is biased in favor of species that…
1) Existed for a long time
2) were abundant and widespread
3) Had hard parts
Stromatolites
The oldest known fossils; rocks formed by the accumulation of sedimentary layers on bacterial mats; date back 3.5 billion years
T/F: Prokaryotes were Earth’s sole inhabitants for more than 1.5 billion years
True
The endosymbiont theory
Proposes that mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells
The oldest fossils of eukaryotic cells date back __________ years
1.8 billion
The oldest known fossils of multicellular eukaryotes that can be resolved taxonomically are of __________ that lived about 1.2 billion years ago
small algae
Cambrian explosion
refers to the sudden appearance of fossils resembling modern animal phyla in the Cambrian period (535-525 MYA)
Plate tectonics
Earth’s crust is composed of plates floating on Earth’s mantle
Pangaea
The supercontinent that formed about 250 million years ago
Effects of Pangaea
1) A deepening of ocean basins
2) A reduction in shallow water habitat
3) A colder and drier climate inland
Effects of Continental drift on living organisms
1) the climate changes as it moves north or south
2) separation of land masses can lead to allopatric speciation
When was the Origin of the solar system and Earth
About 4.75 bullion years ago
When did prokaryotes first appear
About 3.75 BYA during the Archaean period
When did atmospheric oxygen first originate
About 2.7 billion years ago near the end of the Archaean period
When did Single-cell eukaryotes appear
Over 2 BYA during the Proterozoic period
When did the first Multicellular eukaryotes appear
about 1.5 billion years ago during the Proterozoic period
When did animals first appear
About 600 MYA near the end of the Proterozoic period
When did the colonization of land occur
About 500 million years ago near the beginning of the Paleozoic period
When did humans fist appear
About 2 MYA during the Cenozoic period
The big five mass extinction events
1) Ordovician extinction: Approximately 443 million years ago.
2) Devonian extinction: Around 359 million years ago.
3) Permian extinction: Approximately 251 million years ago.
4) Triassic-Jurassic extinction: Around 201 million years ago.
5) Cretaceous extinction: Roughly 65 million years ago.
Permian Extinction
Caused by intense volcanism, global warming and ocean acidification, and anoxic conditions from nutrient enrichment of ecosystems; about 251 MYA
The presence of iridium in sedimentary rocks suggests a __________ about 65 million years ago
meteorite impact
Heterochrony
an evolutionary change in the rate or timing of developmental events
T/F: The contrasting shapes of human and chimpanzee skulls are the result of the number of chromosomes in the cells
False; result of small changes in relative growth rates
Paedomorphosis
the rate of reproductive development accelerates compared with somatic development; An evolutionary process in which adults retain juvenile traits
T/F: The sexually mature species may retain body features that were juvenile structures in an ancestral species
True
