Origin and Evolutionary History of Life Vocabulary

Flashcards for reviewing vocabulary related to the origin and evolutionary history of life.

Early Earth Atmosphere

The atmosphere of early Earth included CO2, H2O, CO, N2, NH3, H2S, CH4, and little to no O2

Prebiotic soup hypothesis

Organic molecules formed near Earth’s surface

Iron-sulfur world hypothesis

Organic precursors formed at cracks in the ocean’s floor

Protobionts

Vesicle-like assemblages of abiotically produced organic polymers

Microspheres

Type of protobiont formed by adding water to abiotically formed polypeptides

Microfossils

Ancient remains of microscopic life; earliest cells were prokaryotes

Stromatolites

Rocklike columns composed of many minute layers of prokaryotic cells (microbial biofilms)

Primitive heterotrophs

Consumed many types of organic molecules that had formed spontaneously

Anaerobes

First cells to use fermentation as an anaerobic process

Chemoautotrophs

Organisms that have genes required to fix CO2 and obtain energy from H2

Photosynthesis

Requires both light energy and a source of electrons, which are used to reduce CO2 to form organic molecules

Photoheterotrophs

Organisms unable to carry out carbon fixation

Photoautotrophs

Use the energy of sunlight to obtain electrons by splitting hydrogen-rich molecules such as H2S, releasing elemental sulfur

Cyanobacteria

The first photosynthetic autotroph to obtain hydrogen electrons by splitting water

Obligate anaerobes

Organisms that cannot use oxygen for cellular respiration

Aerobes

Use a respiratory pathway to extract more energy from food

Carbon cycling

Moving from nonliving physical environment to photosynthetic organisms to heterotrophs that feed on the photosynthetic organisms

Formation of Ozone

Molecular oxygen reacted to form ozone (O3)

Serial endosymbiosis

Organelles such as mitochondria and chloroplasts may have originated from mutually advantageous symbiotic relationships between two prokaryotic organisms

Endosymbionts

Organisms that live symbiotically inside a host cell

Sediments of Earth’s crust

Consist of 5 major rock strata (layers), each subdivided into minor strata

Eons

Largest divisions of the geologic time scale

Eons

Divided into eras that are based primarily on organisms that characterized each era

Ediacaran Period

The last period of the Proterozoic eon

Cambrian Period

Also called Cambrian radiation or Cambrian explosion

Silurian Period

Two life-forms of great biological significance appeared: terrestrial plants and air-breathing animals

Devonian Period

Called the Age of Fishes

Tiktaalik

A transitional form between fishes and tetrapods

Carboniferous Period

Great swamp forests whose remains persist today as major coal deposits

Therapsids

Mammal-like reptiles originated in the Permian and extended into the Mesozoic era

Mass Extinction at the end of the Paleozoic era

More than 90% of all existing marine species became extinct

Mesozoic Era

Called the Age of Reptiles

Thecodonts

Early ruling reptiles which were primarily carnivores

Pterosaurs

First flying reptiles

Mosasaurs

Large voracious marine predators during the Late Cretaceous period

Cenozoic Era

Called the Age of Mammals, the Age of Birds, the Age of Insects, or the Age of Flowering Plants

Paleocene Epoch

Marked the explosive radiation of primitive mammals

Eocene Epoch

Marked the explosive radiation of birds

Oligocene Epoch

Many modern families of mammals evolved, including the first apes in Africa

Homo

The genus to which humans belong