Chapter 15 Flashcards
Earth’s environments are in a state of ___ – ever changing, but balanced and resilient – so conditions don’t swing too wildly, and the planet continues to be habitable
Dynamic Equilibrium
The envelope of gas that surrounded early Earth
Primary Atmosphere
Earth generated a ___ by volcanic outgassing of volatile materials from its interior
Secondary Atmosphere
Traces of oxygen were probably generated in the early atmosphere through the breakdown of water molecules into oxygen and hydrogen by ultraviolet light
Photodissociation
A chemical reaction whereby plants use light energy to induce carbon dioxide to react with water, producing carbohydrates and oxygen
Photosynthesis
The period from 2.4 to 2.0 billion years ago, during which free oxygen began to build up in the ocean and atmosphere, is known as the ___
Great Oxygenation Event
Photosynthesis in the oxygen cycle is balanced by ___, in which organic carbon combines with oxygen to form carbon dioxide
Decomposition
Around 3.55 billion years ago, entire colonies of bacterial life forms have developed and can be found in fossils of layered structures of bacterial origin
Stromatolites
Extracting energy and material sustenance from its environment
Metabolism
Set of 20 carbon-based molecules
Amino Acids
The basic structure and functional unit of life; a complex grouping of chemical compounds enclosed in a porous membrane
Cell
Maintaining a relatively constant chemical environment
Homeostasis
Carbon is essential to life on Earth because carbon atoms can ___ to form very long chains and complex molecules which enable cells to function
Polymerize
Every cell nucleus contains a molecule called ___
DNA (Deoxyribonucleic Acid)
A double-chain biopolymer that contains all the genetic information needed for an organism to grow and reproduce
DNA
DNA is like a good ole’ twisted ladder, in each run consists of two complementary organic molecules called ___, which fit together like a lock and key
Nucleotides
Most experts believe that a simpler, single-stranded molecule called ___ must have appeared first
RNA (Ribonucleic Acid)
___ is when animals obtain energy from the food they eat, and oxygen is needed to release the energy
Aerobic Metabolism
Many kinds of bacteria have ___, obtaining energy through the nonoxygenated breakdown of food by the process of fermentation
Anaerobic Metabolisms
___ is when an organism can extract energy directly from hydrogen, sulfur or salt
Chemosynthesis
Organisms that live in the extreme end of the chemical and thermal circumstances in which organic molecules can remain chemically stable are called ___
Extremophiles
Chemical residues that signal the former presence of life
Biosignatures
A single-celled organism with no distinct nucleus - that is, no membrane separates its DNA from the rest of the cell
Prokaryote
The broadest taxonomic category of living organisms; biologists today recognize three domains: Bacteria, Archaea, and Eukarya
Domain
___ are mound-like structures that consist of many thin layers of calcium carbonate
Stromatolites
Similar structures to stromatolites can be found today and are formed in seawater by the action of photosynthetic organisms called ___
Cyanobacteria
An organism composed of cells - that is, cells that have a well-defined nucleus and organelles
Eukaryote
Eukaryotes appeared at least ___ billion years ago
1.4
The earliest fossils of multicellular eukaryotic organisms appeared at the end of the Proterozoic Era, preserved in rock about ___ million years old. These organisms were called ___
630, Ediacara Fauna
The theory that life on Earth has developed gradually, from simple organism to more complex organisms
Evolution
The process by which individuals that are well adapted to their environment have a survival advantage and pass on their favorable characteristics to their offspring
Natural Selection
A ___ trait is one that is transmissible from parent to offspring
Heritable
Heritable traits are encoded in ___ on an organisms DNA
Genes
A population of genetically and/or morphologically similar individuals that can interbreed and produce fertile offspring
Species
Darwin favored extremely slow, ___ change
Gradual
Called Gradualism
Stephen Jay Gould, and some other folks, argued for ___, in which species persist for a very long time with few changes and undergo occasional periods of very rapid change
Punctuated Equilibrium
Remains of an organism from a past age, embedded and preserved in rock
Fossil
___ is when bones and shells are often replaced, molecule by molecule, by minerals carried in solution by groundwater
Mineralization
Mineralization creates ___
Wood
___ can preserve even delicate leaf structures; it occurs when volatile material in the plant evaporates, leaving behind a thin film of carbon
Carbonization
Organelles that are responsible for producing colour
Melanosomes
Fossilized evidence of an organism’s life processes, such as tracks, footprints, and burrows
Trace Fossil
Prehistoric animals also left behind fecal droppings (shit.) called ___ when preserved and fossilized
Coprolites
The Paleozoic Era started ___ million years ago, with the Cambrian period
541
The Cambrian period ushered in the development of ___
Skeletons, internal and external
Hard shell organisms are called ___
Trilobites
The second-broadest taxonomic category. The six recognized kingdoms are Bacteria, Archaea, and Protista, Plantae, Fungi, and Animalia. The hierarchical subdivisions of this are phylum, class, order, family, genus, and species
Kingdom
Plants evolved from green algae more than ___ million years ago
600
During the Silurian period, ___ evolved. These plants have structural support from stems and limbs, and they have a set of vessels through which water and dissolved elements are transferred from the roots to the leaves
Vascular Plants
Gas exchange occurs by diffusion through adjustable openings in the leaves called ___
Stomata
A naked-seed plant
Gymnosperm
First creature to make transition from sea to land. Crabs, spiders, centipedes, and insects. Named for their jointed legs.
Arthropods
The phylum that humans belong to. These animals have the least primitive version of a spinal cord.
Chordates
Permanent disappearance of a species
Extinction
__% of all living species disappeared at the end of the Permian period, in the greatest mass extinction in history
96
A flowering, or seed-enclosed, plant
Angiosperm
During the Pleistocene epoch, giant sloths, tapirs, saber-toothed cats, dire wolves, bison, mammoths, and mastodons roamed through Europe, North America, and South America, constituting what is know as the ___
Pleistocene Megafauna
Human-like organisms
Hominids
Routinely walking upright
Bipedal
Scientists refer to the fact that the majority of species that have ever lived are now extinct as ___
Background Extinction
A catastrophic episode in which a large fraction of living species become extinct within a geologically short time
Mass Extinction
The most famous mass extinction occurred __ million years ago and is sometimes called the __ extinction
65 and K-T
