BIOL 1P92 Introduction to Biology II Lecture Notes FINAL
EXAM 2025 Brock University
Chapter 20
-universe began 13.7 billion years ago; solar system began 4.6 billion years ago; earth is 4.55 byo
-4 billion years ago the earth cooled enough for outer layers to solidify and oceans to form
-4 bya to 3.5 bya.. first life on earth
Bio-: life or relating living
organisms end(o)-: within; inside
evolution: change
micro-: small; too small to be seen by naked eye
macro: large
paleo: early; dealing with ancient times
pre: earlier than
symbiosis: close association between 2 organisms
-zoic: animal life
History of life on earth
-Geological time scale Beginning
of the earth 4.55 bya to present
-4 Eons
Phanerozoic, {Proterozoic, Archean, Hadean (oldest) } =Precambrian
-Changes in living organisms are the result of genetic changes, environmental changes (can allow for
new types of organisms; responsible for many extinctions)
Major Environmental Changes
-Climate/temperature, atmosphere, land masses, floods, glaciation, volcanic eruptions &plate
tectonics, meteorite impacts
Mass Extinctions
-5 large mass extinctions near the end of Ordovician, Devonian, Permian, Triassic, and Cretaceous
periods
,-Geologic time periods are often based on these events
Fossils
-recognizable remains of past life on earth; Paleontologists study fossils
-many rocks with fossils are sedimentary
sediments pile up and become rock; Organisms buried quickly and hard parts replaced
by minerals
-older rock is deeper and older organisms are deeper in the rock bed
,Radioisotope dating
-Fossils can be dated using elemental isotopes in
accompanying rock
-Half life is the length of time required for exactly
one half of original isotope to decay
-Measure amount of a given isotope as well as the
amount of isotope produced when the isotope
decays
-Usually igneous rock dated
-expect fossil record to underestimate actual date
species came into existence
Biases in the fossil record
Anatomy: organisms with hard parts are more likely to be preserved than those with soft tissues
Size: remains of larger organisms are more likely to be found as fossils than those of smaller organisms
Number: abundant species more likely to be preserved than rare species
Environment: inland species more likely to be fossilized than those living in/near water
Geological processes: may have mixing of different species in a fossil bed
Time: organisms living recently are more likely to be found as fossils than those that lived long ago
Paleontological interests- more interesting types of fossils may influence what gets studied
Prokaryotic cells arose during Archean Eon
-Archean Eon when diverse microbial life flourished in primordial oceans; First known fossils 3.5bya
-First cells were prokaryotic Bacteria and Archaea (similar but different)
-all life forms were prokaryotic during Archean Eon; Hardly any free oxygen so organisms were
anaerobic
-First cells were heterotrophs.
-Autotrophs evolved as supply of organic molecules dwindled
Stromatolites
-Autotrophic cyanobacteria were preserved but heterotrophic ancestors were not
-Formed stromatolites- layered structure of calcium carbonate
-Cyanobacteria produce oxygen as a waste product of photosynthesis.
-Spelled doom for many prokaryotic groups that were anaerobic
-Allowed the evolution of aerobic species
, Proterozoic Eon
-Multicellular eukaryotes arise 1.5 bya
-2 possible origins: individuals form a colony; Single cell divides and stays stuck together
-Volvocine green algae display variations in the degree of multicellularity
-Multicellular animals emerge toward the end of the eon
-First animals: invertebrates.
Bilateral symmetry facilitates locomotion
Phanerozoic Eon
-Proliferation of multicellular eukaryotic life extensive during Phanerozoic Eon (543 mya to today)
-Cenozoic Era, Mesozoic Era, Paleozoic Era (oldest)
Paleozoic Era
-543-248 mya
-Permian period, Carboniferous period, Devonian period, Silurian period, Ordovician period,
Cambrian period (oldest)
Cambrian Period
-543-490 mya; Warm and wet with no ice at poles
-Cambrian explosion- abrupt increase in diversity of animal species= cause unknown-
shell evolution, atmospheric oxygen?
-all existing major types of marine invertebrates plus many other that no longer exist
-Although new species have arisen since, no major reorganizations of body plans
-First vertebrates 520 mya
Burgess Shale Significance
-World’s most significant fossil discovery, mainly because of their great age (505 mya), their diversity
and the incredible detail of their preservation
-Remarkable because soft parts of bodies were also preserved
-Unique geological events led to fossil formation
Phanerozoic Eon, Paleozoic Era, Ordovician Period
-490-443 mya; Warm temperatures and atmosphere very moist
-Diverse group of marine invertebrates including triobites and brachiopods
-Primitive land plants and arthropods first invade land
-Toward end, abrupt climate change (large glaciers) resulting in mass extinction
-Over 60% of existing marine invertebrates became extinct
Phanerozoic Eon, Paleozoic Era, Silurian Period
-443-417 mya
-Relatively stable climate; Glaciers largely melted; No new major invertebrates
-Significant new vertebrates and plants; Many new fish; Coral reefs appeared
EXAM 2025 Brock University
Chapter 20
-universe began 13.7 billion years ago; solar system began 4.6 billion years ago; earth is 4.55 byo
-4 billion years ago the earth cooled enough for outer layers to solidify and oceans to form
-4 bya to 3.5 bya.. first life on earth
Bio-: life or relating living
organisms end(o)-: within; inside
evolution: change
micro-: small; too small to be seen by naked eye
macro: large
paleo: early; dealing with ancient times
pre: earlier than
symbiosis: close association between 2 organisms
-zoic: animal life
History of life on earth
-Geological time scale Beginning
of the earth 4.55 bya to present
-4 Eons
Phanerozoic, {Proterozoic, Archean, Hadean (oldest) } =Precambrian
-Changes in living organisms are the result of genetic changes, environmental changes (can allow for
new types of organisms; responsible for many extinctions)
Major Environmental Changes
-Climate/temperature, atmosphere, land masses, floods, glaciation, volcanic eruptions &plate
tectonics, meteorite impacts
Mass Extinctions
-5 large mass extinctions near the end of Ordovician, Devonian, Permian, Triassic, and Cretaceous
periods
,-Geologic time periods are often based on these events
Fossils
-recognizable remains of past life on earth; Paleontologists study fossils
-many rocks with fossils are sedimentary
sediments pile up and become rock; Organisms buried quickly and hard parts replaced
by minerals
-older rock is deeper and older organisms are deeper in the rock bed
,Radioisotope dating
-Fossils can be dated using elemental isotopes in
accompanying rock
-Half life is the length of time required for exactly
one half of original isotope to decay
-Measure amount of a given isotope as well as the
amount of isotope produced when the isotope
decays
-Usually igneous rock dated
-expect fossil record to underestimate actual date
species came into existence
Biases in the fossil record
Anatomy: organisms with hard parts are more likely to be preserved than those with soft tissues
Size: remains of larger organisms are more likely to be found as fossils than those of smaller organisms
Number: abundant species more likely to be preserved than rare species
Environment: inland species more likely to be fossilized than those living in/near water
Geological processes: may have mixing of different species in a fossil bed
Time: organisms living recently are more likely to be found as fossils than those that lived long ago
Paleontological interests- more interesting types of fossils may influence what gets studied
Prokaryotic cells arose during Archean Eon
-Archean Eon when diverse microbial life flourished in primordial oceans; First known fossils 3.5bya
-First cells were prokaryotic Bacteria and Archaea (similar but different)
-all life forms were prokaryotic during Archean Eon; Hardly any free oxygen so organisms were
anaerobic
-First cells were heterotrophs.
-Autotrophs evolved as supply of organic molecules dwindled
Stromatolites
-Autotrophic cyanobacteria were preserved but heterotrophic ancestors were not
-Formed stromatolites- layered structure of calcium carbonate
-Cyanobacteria produce oxygen as a waste product of photosynthesis.
-Spelled doom for many prokaryotic groups that were anaerobic
-Allowed the evolution of aerobic species
, Proterozoic Eon
-Multicellular eukaryotes arise 1.5 bya
-2 possible origins: individuals form a colony; Single cell divides and stays stuck together
-Volvocine green algae display variations in the degree of multicellularity
-Multicellular animals emerge toward the end of the eon
-First animals: invertebrates.
Bilateral symmetry facilitates locomotion
Phanerozoic Eon
-Proliferation of multicellular eukaryotic life extensive during Phanerozoic Eon (543 mya to today)
-Cenozoic Era, Mesozoic Era, Paleozoic Era (oldest)
Paleozoic Era
-543-248 mya
-Permian period, Carboniferous period, Devonian period, Silurian period, Ordovician period,
Cambrian period (oldest)
Cambrian Period
-543-490 mya; Warm and wet with no ice at poles
-Cambrian explosion- abrupt increase in diversity of animal species= cause unknown-
shell evolution, atmospheric oxygen?
-all existing major types of marine invertebrates plus many other that no longer exist
-Although new species have arisen since, no major reorganizations of body plans
-First vertebrates 520 mya
Burgess Shale Significance
-World’s most significant fossil discovery, mainly because of their great age (505 mya), their diversity
and the incredible detail of their preservation
-Remarkable because soft parts of bodies were also preserved
-Unique geological events led to fossil formation
Phanerozoic Eon, Paleozoic Era, Ordovician Period
-490-443 mya; Warm temperatures and atmosphere very moist
-Diverse group of marine invertebrates including triobites and brachiopods
-Primitive land plants and arthropods first invade land
-Toward end, abrupt climate change (large glaciers) resulting in mass extinction
-Over 60% of existing marine invertebrates became extinct
Phanerozoic Eon, Paleozoic Era, Silurian Period
-443-417 mya
-Relatively stable climate; Glaciers largely melted; No new major invertebrates
-Significant new vertebrates and plants; Many new fish; Coral reefs appeared
