Biological Concepts, Origin of Life, and Geologic Time Scale

Comprehensive vocabulary flashcards covering the definition of life, origin of life theories, the geologic time scale, and principles of biological evolution based on the lecture notes.

Life (Author's Definition)

A process taking place in highly organized organic structures, characterized by being preprogrammed, interactive, adaptive, and evolutionary.

NASA's Definition of Life

A self-sustaining chemical system of Darwinian evolution.

Living Organism

The system where the process of life occurs.

Organic Nature

A characteristic of life involving carbon-based chemistry where molecules obey the laws of chemistry.

Highly Organized Structure

A trait where living organisms maintain order ($\text{low entropy}$), cellular organization, and energy flow.

Pre-programmed

The characteristic of life where $DNA$ contains instructions for growth, morphology, physiology, and reproduction.

Adaptation

The process by which organisms adjust to changing environments through natural selection, such as hibernation or epigenetic changes.

Evolution (Population level)

A process acting on populations through variation, inheritance, and natural selection, allowing species to adapt over generations.

Neo-Darwinian Synthesis

Modern evolutionary theory that combines Darwin’s natural selection, Mendelian genetics, and population genetics.

Scientific Theory

A well-supported explanation backed by evidence that is testable and capable of being disproven.

Primitive Earth Age

Earth was created approximately $4.54 \times 10^9$ years ago, with the earliest microscopic life appearing roughly $3.7$ to $3.8 \times 10^9$ years ago.

Primordial Soup Hypothesis (Oparin-Haldane)

A theory suggesting life began in a body of water from a mixture of simple organic building blocks and an energy source like lightning.

Iron-sulfur World Hypothesis

The proposal that life began on iron sulfide mineral surfaces at deep-sea hydrothermal vents driven by metabolic cycles and volcanic gases.

Miller-Urey Experiment

A $1953$ experiment that simulated primordial Earth conditions to prove inorganic compounds could spontaneously form organic molecules like amino acids.

Dehydration Synthesis

A process of combining organic molecules into macromolecules by the removal of water.

Protobionts / Protocells

Non-living, membrane-closed spheres made of lipids that represent the evolutionary stepping stone between simple molecules and true living cells.

Chemoautotrophs

Anaerobic autotrophs that harvest energy from inorganic chemicals, reacting with gases like $H_2$ and $CO_2$ to produce methane and water.

Endosymbiosis

A process where one prokaryote consumes another but instead of digestion, they combine to form eukaryotes.

Ediacaran Period

A period from $600$ to $542$ million years ago ($mya$) marked by the formation of multicellular organisms.

Cambrian Radiation

A phenomenon beginning around $542$ $mya$ where animals evolved into many different forms, including all major animal phyla.

Anomalocaris

An abnormal shrimp-like creature identified as Earth’s first apex predator during the Cambrian period.

Ordovician Period

The geologic period where the first vertebrate, the jawless fish, appeared.

Devonian Period

Known as the "Age of fishes," it saw the appearance of the first tetrapods ($amphibians’ ancestors$) and gnathostomes ($jawed vertebrates$).

Placoderms

Prominent Devonian fish-like vertebrates with armor-like bodies and well-developed jaws.

Amniotes

A group of animals characterized by the amniotic egg, allowing them to colonize terrestrial land away from water.

Synapsida

A line of amniotes with one temporal fenestra (hole) in the skull, serving as the ancestors of mammals.

Saurapsids

A line of amniotes that diverges into Anapsida ($no holes in skull$) and Diapsida ($two holes in skull$).

Permian Extinction

A mass extinction at the end of the Paleozoic era that killed $90$% of marine species and $70$% of land-dwelling vertebrates.

Ornithischia

A group of dinosaurs characterized as being ‘bird-hipped’ where the pubis is parallel with the ischium.

Saurischia

A group of dinosaurs characterized as being ‘reptile-hipped’ where the pubis is protruding or forward.

Therapsids

Mammal-like reptiles that developed nocturnal behavior, high sense of smell, and endothermic properties.

Morganucodon

The ancestor of rats.

Cynodonts

Ancestors of true mammals that could breathe while eating and possessed powerful jaws for chewing.

K-T Extinction

An extinction event occurring approximately $66$ $mya$ that caused the extinction of the dinosaurs.

Cenozoic Era

The era from $66$ $mya$ to the present, featuring the diversification of plants, insects, and mammals.

Perpetual Change

The model stating the living world is always changing, with evidence found in fossil records.

Common Descent

The concept that all forms of life descended from a common ancestor through branching lineages.

Phylogeny

The line of descent of a species or a group of organisms.

Multiplication of Species

The evolutionary process that produces new species by splitting and transforming older ones based on genetic variation.