General Biology 2 - History of Life on Earth and Geologic Time Scale

Vocabulary practice flashcards covering genetic engineering terms and key concepts, divisions, and periods of the Geologic Time Scale from General Biology 2.

Plasmid

A small, circular DNA molecule found in bacteria that is separate from chromosomal DNA and used as a vector in genetic engineering.

Gene of Interest

A specific gene cut from a donor organism's genome to be isolated and inserted into a target organism.

Recombinant DNA

A DNA molecule formed in the laboratory by combining genetic material from different sources.

Geologic Time Scale

A system of chronological dating that records life forms and geological events throughout Earth's history.

Strata

Layers of sedimentary rock deposited over time that contain clues about Earth's geological and biological history.

Fossils

The remnant, impression, or trace of an animal or plant from a past geologic age preserved in Earth's crust.

Fossil Record

The total collection of data recorded in fossils worldwide, serving as the primary source of information about the history of life on Earth.

Law of Superposition

A rule of relative dating stating that in undisturbed sedimentary rock layers, the youngest rocks are at the top and the oldest rocks are at the bottom.

Law of Original Horizontality

A rule of relative dating stating that layers of sediment are originally deposited horizontally, meaning any tilting, folding, or faulting happened after deposition.

Law of Cross-Cutting Relationships

A rule of relative dating stating that if an igneous intrusion or fault cuts through existing rock, the intrusion or fault is younger than the rock it cuts through.

Index Fossils

Fossils from short-lived, widely distributed organisms used to define, identify, and date specific geologic periods.

Absolute Dating

A technique that determines the actual numeric age of a fossil or rock through radiometric dating of radioactive isotopes.

Half-life

The time required for half of the atoms of a radioactive element to decay into stable daughter atoms.

Carbon-14 (C-14)

An unstable radioactive isotope that decays into stable Nitrogen-14, used in absolute dating for relatively recent organic remains up to approximately 50,000 years old.

Potassium-40 (K-40)

An unstable radioactive isotope that decays into stable Argon-40, used in absolute dating for older rocks spanning millions to billions of years.

Eon

The largest division of the geologic time scale, spanning half a billion to nearly 2 billion years.

Precambrian

A major span of geologic time lasting 4.5 billion years—about 88% of Earth's history—comprising the Hadean, Archean, and Proterozoic eons.

Era

A major division of the geologic time scale that spans time periods of tens to hundreds of millions of years.

Period

A division of geologic time within an era spanning time intervals of no more than 100 million years.

Epoch

The smallest unit and division of the geologic time scale.

Paleozoic Era

Meaning 'ancient or old life,' an era that started more than 540 million years ago and was dominated by marine invertebrates.

Cambrian Explosion

A spectacular burst of rapid evolutionary diversification and new life forms at the start of the Paleozoic Era.

Ordovician Period

A geologic period (505–440 million years ago) marked by abundant ocean invertebrates, the evolution of the first jawless armored fish, and the initial colonization of land by plants.

Devonian Period

A geologic period (410–360 million years ago) during which the first seed plants evolved and air-breathing lobe-finned fish emerged.

Carboniferous Period

A geologic period (360–290 million years ago) featuring massive forests that formed coal deposits, along with the evolution of the first land-colonizing amphibians and early reptiles.

Pangaea

A supercontinent formed during the Permian Period when all major global land masses collided.

Permian Period

A geologic period (290–245 million years ago) characterized by extreme dry climates, the formation of Pangaea, and ending with a major mass extinction.

Mesozoic Era

Meaning 'Middle Life,' an era starting more than 280 million years ago commonly referred to as the 'Age of Reptiles' or 'Era of Dinosaurs.'

Triassic Period

The first period of the Mesozoic Era when dinosaurs first branched off from reptiles, and forests were dominated by seed ferns and conifers.

Jurassic Period

A Mesozoic period known as 'The Golden Age of Dinosaurs,' during which the earliest birds evolved from reptile ancestors, small mammals diversified, and flowering plants appeared.

Cretaceous Period

A Mesozoic period during which dinosaurs reached peak size and distribution in an ice-free global climate, ending with their mass extinction.

Cenozoic Era

Meaning 'Recent Life,' an era starting 65 million years ago and extending to the present, known as the 'Age of Mammals.'

Tertiary Period

A Cenozoic period (65–1.8 million years ago) with a warm and humid climate where mammals expanded into vacated dinosaur niches and primates evolved.

Quaternary Period

A Cenozoic period (1.8 million years ago to present) characterized by ice ages, lowered sea levels creating land bridges, and large cold-adapted mammals like wooly mammoths.

Geologist

A scientist who studies Earth's solid material, rock layers, strata, and geological processes.

Paleontologist

A scientist who studies fossils to understand the evolution, environments, and history of past life on Earth.