Unit 2_Biodiversity and Evolution Flashcards

Comprehensive vocabulary flashcards covering the origins of DNA and RNA, patterns of evolution, and the various lines of evidence for evolutionary theory including fossil records, biogeography, anatomy, and biochemistry.

RNA World Hypothesis

The most widely accepted scientific hypothesis proposing that RNA came first and DNA evolved from it.

Primordial soup

The theory that Earth’s early atmosphere contained the necessary building blocks to construct RNA, with lightning triggering the necessary reactions.

Miller-Urey Experiment

A laboratory study that recreated Earth’s early atmospheric conditions and demonstrated that molecules for life could be created in that environment.

Coevolution of DNA and RNA Hypothesis

The hypothesis that DNA and RNA evolved at the same time in hydrothermal vents or the primordial soup, each serving unique roles from the beginning.

Ancestral Hybrid Nucleic Acid Hypothesis

The idea that early life contained a molecule with characteristics of both DNA and RNA, which later evolved into two separate specialized molecules.

Evolution

Cumulative change in a group of organisms through time.

L.U.C.A

The acronym for the last Universal Common Ancestor, the organism from which all life forms are theorized to have originated.

Fossil Record

The collection of all fossils discovered on Earth, which provides a history of life and shows changes in species over time.

Law of Superposition

The principle that bottom rock layers are the oldest and higher layers are younger, used by scientists to date fossils.

Stasis

A period in a species' history characterized by little or no evolutionary change.

Punctuated Equilibrium

An evolutionary model where species go through long periods of stasis followed by short periods of rapid change caused by favored mutations.

Gradualism

An evolutionary model where species undergo slow and continuous changes leading to speciation over a long period of time.

Transitional fossils

Fossils that show the small, incremental changes that occur as one species turns into another during gradualism.

Biogeography

Also known as geographic distribution, it is the study of species locations showing that closely related species are usually found near each other geographically.

Geographic Isolation

The separation of two populations by physical barriers like rivers, mountains, or bodies of water, which can lead to speciation.

Homologous structures

Anatomically similar structures inherited from a common ancestor that may have different functions.

Analogous Structure

Structures that serve the same function but are built differently and do not indicate common ancestry, such as bat wings versus insect wings.

Vestigial Structure

Structures that are reduced in size and no longer serve a purpose, but can be used to determine evolutionary ancestry.

Comparative Embryology

The study of physical similarities in organisms before they are born, where more closely related organisms look more similar in later stages of development.

Comparative Biochemistry

The comparison of nitrogen bases and amino acid sequences in species, where greater similarity indicates a more recent common ancestor.

Cladogram

A chart that depicts the relationship between organisms and successive points of species divergence from common ancestral lines.

Dendrogram

A branching diagram representing a hierarchy of categories based on the degree of similarity or number of shared characteristics.

Timeline

A chronological arrangement of events in the order of their occurrence.

Spindle Diagram

A diagram used to illustrate taxonomic diversity within geologic time.