! www.clutchprep.com

!

BIOLOGY - CLUTCH

CH.26 - HISTORY OF LIFE ON EARTH

CONCEPT: HISTORY OF LIFE ON EARTH ● Plate tectonics – theory that the Earth’s crust is made of large solid plates essentially floating on the hot inner mantle EXAMPLE:

● Continental drift – the movement of tectonic plates resulting in the shifting of the continents over time EXAMPLE:

BIOLOGY - CLUTCH

CH.26 - HISTORY OF LIFE ON EARTH

Page 2

CONCEPT: HISTORY OF LIFE ON EARTH ● Biogeography – study of distributions of species and ecosystems in geographic space and over geologic time EXAMPLE: ● Fossil record is limited and biased, age of fossils is determined by radiocarbon dating □ Stromatolite – structure created by photosynthetic cyanobacteria, and oldest fossil of a living organism ● Half-life – represents the time it takes for half a sample to decay, but the sample only decays by half each half-life period EXAMPLE:

BIOLOGY - CLUTCH

CH.26 - HISTORY OF LIFE ON EARTH

Page 3

CONCEPT: HISTORY OF LIFE ON EARTH ● Mass extinctions have occurred 5 times, when the majority of lineages died out resulting in dramatic reshaping of life EXAMPLE: ● Adaptive Radiation – the process by which organisms rapidly diversify into many new forms, often in response to changes in the environment that shift evolutionary pressures, and open niches EXAMPLE:

BIOLOGY - CLUTCH

CH.26 - HISTORY OF LIFE ON EARTH

Page 4

CONCEPT: HISTORY OF LIFE ON EARTH ● Precambrian – period between the formation of Earth and the appearance of most animal groups □ Life was unicellular during the majority of Earth’s history

□ Oxygen was absent for a long time until photosynthetic processes evolved □ First eukaryotes are formed through symbiogenesis, and multicellular organisms appear

● Phanerozoic era □ Paleozoic era – Cambrian explosion creates great diversity of life, terrestrialization of plants and animals □ Mesozoic era – dominance of gymnosperms and dinosaurs □ Cenozoic era – dominance of angiosperms and mammals EXAMPLE: ● Punctuated Equilibrium – theory that most evolutionary changes occur rapidly punctuating long periods of little change

BIOLOGY - CLUTCH

CH.26 - HISTORY OF LIFE ON EARTH

Page 5