Chapter 25 Flashcards
(35 cards)
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
