Chapter 25: The History of Life on Earth

A collection of vocabulary flashcards covering key concepts from Chapter 25 on the history of life on Earth.

Abiotic Synthesis

The formation of organic molecules from inorganic precursors, believed to have occurred on early Earth.

Protobionts

Aggregates of abiotically produced molecules that exhibit some properties of life, such as simple reproduction and metabolism.

Endosymbiosis

The hypothesis that mitochondria and plastids originated from prokaryotes living within larger host cells.

Radiometric Dating

A method used to determine the age of rocks and fossils by measuring the decay of radioactive isotopes.

Cambrian Explosion

A period approximately 535 to 525 million years ago marked by the rapid appearance of diverse multicellular organisms.

Pangaea

The supercontinent that existed during the late Paleozoic and early Mesozoic eras, which subsequently broke apart due to continental drift.

Hox Genes

A group of genes that determine the basic structure and arrangement of body parts during development.

Adaptive Radiation

The diversification of a group of organisms into forms filling different ecological niches.

Mass Extinction

A significant and rapid decrease in biodiversity on Earth, where more than 50% of species become extinct in a relatively short time.

Heterochrony

Evolutionary change in the timing or rate of developmental events affecting the shape and size of an organism.

Exaptation

A structure that evolves for one function but is later adapted for a different use.

Snowball Earth

A hypothesis suggesting that Earth underwent severe glaciation events confining life to specific regions.