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subduction : movement of one tectonic plate beneath another | https://openstax.org/books/biology/pages/46-key-terms |
tertiary consumer : carnivore that eat other carnivores | https://openstax.org/books/biology/pages/46-key-terms |
trophic level : position of a species or group of species in a food chain or a food web | https://openstax.org/books/biology/pages/46-key-terms |
trophic level transfer efficiency (TLTE) : energy transfer efficiency between two successive trophic levels | https://openstax.org/books/biology/pages/46-key-terms |
Biodiversity exists at multiple levels of organization and is measured in different ways depending on the goals of those taking the measurements. These measurements include numbers of species, genetic diversity, chemical diversity, and ecosystem diversity. The number of described species is estimated to be 1.5 million ... | https://openstax.org/books/biology/pages/47-chapter-summary |
Five mass extinctions with losses of more than 50 percent of extant species are observable in the fossil record. Biodiversity recovery times after mass extinctions vary, but have been up to 30 million years. Recent extinctions are recorded in written history and are the basis for one method of estimating contemporary e... | https://openstax.org/books/biology/pages/47-chapter-summary |
Humans use many compounds that were first discovered or derived from living organisms as medicines: secondary plant compounds, animal toxins, and antibiotics produced by bacteria and fungi. More medicines are expected to be discovered in nature. Loss of biodiversity will impact the number of pharmaceuticals available t... | https://openstax.org/books/biology/pages/47-chapter-summary |
Crop diversity is a requirement for food security, and it is being lost. The loss of wild relatives to crops also threatens breedersâ abilities to create new varieties. Ecosystems provide ecosystem services that support human agriculture: pollination, nutrient cycling, pest control, and soil development and maintenan... | https://openstax.org/books/biology/pages/47-chapter-summary |
Biodiversity may provide important psychological benefits to humans. Additionally, there are moral arguments for the maintenance of biodiversity. | https://openstax.org/books/biology/pages/47-chapter-summary |
The core threats to biodiversity are human population growth and unsustainable resource use. To date, the most significant causes of extinctions are habitat loss, introduction of exotic species, and overharvesting. Climate change is predicted to be a significant cause of extinctions in the coming century. Habitat loss ... | https://openstax.org/books/biology/pages/47-chapter-summary |
New technological methods such as DNA barcoding and information processing and accessibility are facilitating the cataloging of the planetâs biodiversity. There is also a legislative framework for biodiversity protection. International treaties such as CITES regulate the transportation of endangered species across in... | https://openstax.org/books/biology/pages/47-chapter-summary |
Conservation preserves are a major tool in biodiversity protection. Presently, 11percent of Earthâs land surface is protected in some way. The science of island biogeography has informed the optimal design of preserves; however, preserves have limitations imposed by political and economic forces. In addition, climate... | https://openstax.org/books/biology/pages/47-chapter-summary |
Habitat restoration has the potential to restore ecosystems to previous biodiversity levels before species become extinct. Examples of restoration include reintroduction of keystone species and removal of dams on rivers. Zoos have attempted to take a more active role in conservation and can have a limited role in capti... | https://openstax.org/books/biology/pages/47-chapter-summary |
adaptive radiation : rapid branching through speciation of a phylogenetic tree into many closely related species | https://openstax.org/books/biology/pages/47-key-terms |
biodiversity : variety of a biological system, typically conceived as the number of species, but also applying to genes, biochemistry, and ecosystems | https://openstax.org/books/biology/pages/47-key-terms |
biodiversity hotspot : concept originated by Norman Myers to describe a geographical region with a large number of endemic species and a large percentage of degraded habitat | https://openstax.org/books/biology/pages/47-key-terms |
bush meat : wild-caught animal used as food (typically mammals, birds, and reptiles); usually referring to hunting in the tropics of sub-Saharan Africa, Asia, and the Americas | https://openstax.org/books/biology/pages/47-key-terms |
chemical diversity : variety of metabolic compounds in an ecosystem | https://openstax.org/books/biology/pages/47-key-terms |
chytridiomycosis : disease of amphibians caused by the fungusBatrachochytrium dendrobatidis;thought to be a major cause of the global amphibian decline | https://openstax.org/books/biology/pages/47-key-terms |
DNA barcoding : molecular genetic method for identifying a unique genetic sequence to associate with a species | https://openstax.org/books/biology/pages/47-key-terms |
ecosystem diversity : variety of ecosystems | https://openstax.org/books/biology/pages/47-key-terms |
endemic species : species native to one place | https://openstax.org/books/biology/pages/47-key-terms |
exotic species : (also, invasive species) species that has been introduced to an ecosystem in which it did not evolve | https://openstax.org/books/biology/pages/47-key-terms |
extinction : disappearance of a species from Earth; local extinction is the disappearance of a species from a region | https://openstax.org/books/biology/pages/47-key-terms |
extinction rate : number of species becoming extinct over time, sometimes defined as extinctions per million speciesâyears to make numbers manageable (E/MSY) | https://openstax.org/books/biology/pages/47-key-terms |
genetic diversity : variety of genes in a species or other taxonomic group or ecosystem, the term can refer to allelic diversity or genome-wide diversity | https://openstax.org/books/biology/pages/47-key-terms |
heterogeneity : number of ecological niches | https://openstax.org/books/biology/pages/47-key-terms |
megafauna : large animals | https://openstax.org/books/biology/pages/47-key-terms |
secondary plant compound : compound produced as byproducts of plant metabolic processes that is usually toxic, but is sequestered by the plant to defend against herbivores | https://openstax.org/books/biology/pages/47-key-terms |
species-area relationship : relationship between area surveyed and number of species encountered; typically measured by incrementally increasing the area of a survey and determining the cumulative numbers of species | https://openstax.org/books/biology/pages/47-key-terms |
tragedy of the commons : economic principle that resources held in common will inevitably be overexploited | https://openstax.org/books/biology/pages/47-key-terms |
white-nose syndrome : disease of cave-hibernating bats in the eastern United States and Canada associated with the fungusGeomyces destructans | https://openstax.org/books/biology/pages/47-key-terms |
Microorganisms(ormicrobes) are living organisms that are generally too small to be seen without a microscope. | https://openstax.org/books/microbiology/pages/1-summary |
Throughout history, humans have used microbes to make fermented foods such as beer, bread, cheese, and wine. | https://openstax.org/books/microbiology/pages/1-summary |
Long before the invention of the microscope, some people theorized that infection and disease were spread by living things that were too small to be seen. They also correctly intuited certain principles regarding the spread of disease and immunity. | https://openstax.org/books/microbiology/pages/1-summary |
Antonie van Leeuwenhoek, using a microscope, was the first to actually describe observations of bacteria, in 1675. | https://openstax.org/books/microbiology/pages/1-summary |
During the Golden Age of Microbiology (1857â1914), microbiologists, including Louis Pasteur and Robert Koch, discovered many new connections between the fields of microbiology and medicine. | https://openstax.org/books/microbiology/pages/1-summary |
Carolus Linnaeus developed a taxonomic system for categorizing organisms into related groups. | https://openstax.org/books/microbiology/pages/1-summary |
Binomial nomenclatureassigns organisms Latinized scientific names with a genus and species designation. | https://openstax.org/books/microbiology/pages/1-summary |
Aphylogenetic treeis a way of showing how different organisms are thought to be related to one another from an evolutionary standpoint. | https://openstax.org/books/microbiology/pages/1-summary |
The first phylogenetic tree contained kingdoms for plants and animals; Ernst Haeckel proposed adding kingdom for protists. | https://openstax.org/books/microbiology/pages/1-summary |
Robert Whittakerâs tree contained five kingdoms: Animalia, Plantae, Protista, Fungi, and Monera. | https://openstax.org/books/microbiology/pages/1-summary |
Carl Woese used small subunit ribosomal RNA to create a phylogenetic tree that groups organisms into three domains based on their genetic similarity. | https://openstax.org/books/microbiology/pages/1-summary |
Bergeyâs manuals of determinative and systemic bacteriology are the standard references for identifying and classifying bacteria, respectively. | https://openstax.org/books/microbiology/pages/1-summary |
Bacteria can be identified through biochemical tests, DNA/RNA analysis, and serological testing methods. | https://openstax.org/books/microbiology/pages/1-summary |
Microorganisms are very diverse and are found in all three domains of life: Archaea, Bacteria, and Eukarya. | https://openstax.org/books/microbiology/pages/1-summary |
Archaeaandbacteriaare classified as prokaryotes because they lack a cellular nucleus. Archaea differ from bacteria in evolutionary history, genetics, metabolic pathways, and cell wall and membrane composition. | https://openstax.org/books/microbiology/pages/1-summary |
Archaea inhabit nearly every environment on earth, but no archaea have been identified as human pathogens. | https://openstax.org/books/microbiology/pages/1-summary |
Eukaryotesstudied in microbiology include algae, protozoa, fungi, and helminths. | https://openstax.org/books/microbiology/pages/1-summary |
Algaeare plant-like organisms that can be either unicellular or multicellular, and derive energy via photosynthesis. | https://openstax.org/books/microbiology/pages/1-summary |
Protozoaare unicellular organisms with complex cell structures; most are motile. | https://openstax.org/books/microbiology/pages/1-summary |
Microscopicfungiincludemoldsandyeasts. | https://openstax.org/books/microbiology/pages/1-summary |
Helminthsare multicellular parasitic worms. They are included in the field of microbiology because their eggs and larvae are often microscopic. | https://openstax.org/books/microbiology/pages/1-summary |
Virusesare acellular microorganisms that require a host to reproduce. | https://openstax.org/books/microbiology/pages/1-summary |
The field of microbiology is extremely broad. Microbiologists typically specialize in one of many subfields, but all health professionals need a solid foundation in clinical microbiology. | https://openstax.org/books/microbiology/pages/1-summary |
Light waves interacting with materials may bereflected,absorbed, ortransmitted, depending on the properties of the material. | https://openstax.org/books/microbiology/pages/2-summary |
Light waves can interact with each other (interference) or be distorted by interactions with small objects or openings (diffraction). | https://openstax.org/books/microbiology/pages/2-summary |
Refractionoccurs when light waves change speed and direction as they pass from one medium to another. Differences in therefraction indicesof two materials determine the magnitude of directional changes when light passes from one to the other. | https://openstax.org/books/microbiology/pages/2-summary |
Alensis a medium with a curved surface that refracts and focuses light to produce an image. | https://openstax.org/books/microbiology/pages/2-summary |
Visible light is part of theelectromagnetic spectrum; light waves of different frequencies and wavelengths are distinguished as colors by the human eye. | https://openstax.org/books/microbiology/pages/2-summary |
A prism can separate the colors of white light (dispersion) because different frequencies of light have different refractive indices for a given material. | https://openstax.org/books/microbiology/pages/2-summary |
Fluorescent dyesandphosphorescentmaterials can effectively transform nonvisible electromagnetic radiation into visible light. | https://openstax.org/books/microbiology/pages/2-summary |
The power of a microscope can be described in terms of itsmagnificationandresolution. | https://openstax.org/books/microbiology/pages/2-summary |
Resolution can be increased by shortening wavelength, increasing thenumerical apertureof the lens, or using stains that enhance contrast. | https://openstax.org/books/microbiology/pages/2-summary |
Antonie van Leeuwenhoekis credited with the first observation of microbes, including protists and bacteria, with simple microscopes that he made. | https://openstax.org/books/microbiology/pages/2-summary |
Robert Hookewas the first to describe what we now call cells. | https://openstax.org/books/microbiology/pages/2-summary |
Simple microscopeshave a single lens, whilecompound microscopeshave multiple lenses. | https://openstax.org/books/microbiology/pages/2-summary |
Numerous types of microscopes use various technologies to generate micrographs. Most are useful for a particular type of specimen or application. | https://openstax.org/books/microbiology/pages/2-summary |
Light microscopyuses lenses to focus light on a specimen to produce an image. Commonly used light microscopes includebrightfield,darkfield,phase-contrast,differential interference contrast,fluorescence,confocal, andtwo-photonmicroscopes. | https://openstax.org/books/microbiology/pages/2-summary |
Electron microscopyfocuses electrons on the specimen using magnets, producing much greater magnification than light microscopy. Thetransmission electron microscope (TEM)andscanning electron microscope (SEM)are two common forms. | https://openstax.org/books/microbiology/pages/2-summary |
Scanning probe microscopyproduces images of even greater magnification by measuring feedback from sharp probes that interact with the specimen. Probe microscopes include thescanning tunneling microscope (STM)and theatomic force microscope (AFM). | https://openstax.org/books/microbiology/pages/2-summary |
Samples must be properly prepared for microscopy. This may involvestaining,fixation, and/or cuttingthin sections. | https://openstax.org/books/microbiology/pages/2-summary |
A variety of staining techniques can be used with light microscopy, includingGram staining, acid-fast staining,capsule staining,endospore staining,andflagella staining. | https://openstax.org/books/microbiology/pages/2-summary |
Samples for TEM require very thin sections, whereas samples for SEM require sputter-coating. | https://openstax.org/books/microbiology/pages/2-summary |
Preparation for fluorescence microscopy is similar to that for light microscopy, except that fluorochromes are used. | https://openstax.org/books/microbiology/pages/2-summary |
The theory ofspontaneous generationstates that life arose from nonliving matter. It was a long-held belief dating back to Aristotle and the ancient Greeks. | https://openstax.org/books/microbiology/pages/3-summary |
Experimentation by Francesco Redi in the 17th century presented the first significant evidence refuting spontaneous generation by showing that flies must have access to meat for maggots to develop on the meat. Prominent scientists designed experiments and argued both in support of (John Needham) and against (Lazzaro Sp... | https://openstax.org/books/microbiology/pages/3-summary |
Louis Pasteur is credited with conclusively disproving the theory of spontaneous generation with his famous swan-neck flask experiment. He subsequently proposed that âlife only comes from life.â | https://openstax.org/books/microbiology/pages/3-summary |
Although cells were first observed in the 1660s by Robert Hooke,cell theorywas not well accepted for another 200 years. The work of scientists such as Schleiden, Schwann, Remak, and Virchow contributed to its acceptance. | https://openstax.org/books/microbiology/pages/3-summary |
Endosymbiotic theorystates that mitochondria and chloroplasts, organelles found in many types of organisms, have their origins in bacteria. Significant structural and genetic information support this theory. | https://openstax.org/books/microbiology/pages/3-summary |
Themiasma theory of diseasewas widely accepted until the 19th century, when it was replaced by thegerm theory of diseasethanks to the work of Semmelweis, Snow, Pasteur, Lister, and Koch, and others. | https://openstax.org/books/microbiology/pages/3-summary |
Prokaryotic cells differ from eukaryotic cells in that their genetic material is contained in anucleoidrather than a membrane-bound nucleus. In addition, prokaryotic cells generally lack membrane-bound organelles. | https://openstax.org/books/microbiology/pages/3-summary |
Prokaryotic cells of the same species typically share a similarcell morphologyandcellular arrangement. | https://openstax.org/books/microbiology/pages/3-summary |
Most prokaryotic cells have acell wallthat helps the organism maintain cellular morphology and protects it against changes in osmotic pressure. | https://openstax.org/books/microbiology/pages/3-summary |
Outside of the nucleoid, prokaryotic cells may contain extrachromosomal DNA inplasmids. | https://openstax.org/books/microbiology/pages/3-summary |
Prokaryoticribosomesthat are found in the cytoplasm have a size of 70S. | https://openstax.org/books/microbiology/pages/3-summary |
Some prokaryotic cells haveinclusionsthat store nutrients or chemicals for other uses. | https://openstax.org/books/microbiology/pages/3-summary |
Some prokaryotic cells are able to formendosporesthroughsporulationto survive in a dormant state when conditions are unfavorable. Endospores cangerminate, transforming back intovegetative cellswhen conditions improve. | https://openstax.org/books/microbiology/pages/3-summary |
In prokaryotic cells, thecell envelopeincludes aplasma membraneand usually a cell wall. | https://openstax.org/books/microbiology/pages/3-summary |
Bacterial membranes are composed of phospholipids with integral or peripheral proteins. The fatty acid components of these phospholipids are ester-linked and are often used to identify specific types of bacteria. The proteins serve a variety of functions, including transport, cell-to-cell communication, and sensing env... | https://openstax.org/books/microbiology/pages/3-summary |
Some molecules can move across the bacterial membrane by simple diffusion, but most large molecules must be actively transported through membrane structures using cellular energy. | https://openstax.org/books/microbiology/pages/3-summary |
Prokaryotic cell walls may be composed ofpeptidoglycan(bacteria) orpseudopeptidoglycan(archaea). | https://openstax.org/books/microbiology/pages/3-summary |
Gram-positive bacterial cells are characterized by a thickpeptidoglycanlayer, whereas gram-negative bacterial cells are characterized by a thin peptidoglycan layer surrounded by an outer membrane. | https://openstax.org/books/microbiology/pages/3-summary |
Some prokaryotic cells produceglycocalyxcoatings, such ascapsulesandslime layers, that aid in attachment to surfaces and/or evasion of the host immune system. | https://openstax.org/books/microbiology/pages/3-summary |
Some prokaryotic cells havefimbriaeorpili, filamentous appendages that aid in attachment to surfaces. Pili are also used in the transfer of genetic material between cells. | https://openstax.org/books/microbiology/pages/3-summary |
Some prokaryotic cells use one or moreflagellato move through water.Peritrichousbacteria, which have numerous flagella, userunsandtumblesto move purposefully in the direction of a chemical attractant. | https://openstax.org/books/microbiology/pages/3-summary |
Eukaryotic cells are defined by the presence of anucleuscontaining the DNA genome and bound by anuclear membrane(ornuclear envelope) composed of two lipid bilayers that regulate transport of materials into and out of the nucleus through nuclear pores. | https://openstax.org/books/microbiology/pages/3-summary |
Eukaryotic cell morphologies vary greatly and may be maintained by various structures, including the cytoskeleton, the cell membrane, and/or the cell wall | https://openstax.org/books/microbiology/pages/3-summary |
Thenucleolus, located in the nucleus of eukaryotic cells, is the site of ribosomal synthesis and the first stages of ribosome assembly. | https://openstax.org/books/microbiology/pages/3-summary |
Eukaryotic cells contain80S ribosomesin the rough endoplasmic reticulum (membrane bound-ribosomes) and cytoplasm (free ribosomes). They contain 70s ribosomes in mitochondria and chloroplasts. | https://openstax.org/books/microbiology/pages/3-summary |
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