62 Sentences With "respiring" | Random Sentence Generator

As I showed you [through] the little hole in the bag, this produce is alive so it's respiring — it's releasing CO2 and it's consuming oxygen.

Roberts's abdominal cavity looked like the inside of a mossy, yellow cave lit up by miners' headlamps; vasculature appeared like streaks of mineral ore, the liver like a respiring troglobite.

Just 22 days in, an injured crew member was evacuated, dispelling any pretense of a "closed," Mars-ready system, and thanks to respiring soil bacteria, a glut of carbon dioxide threw the atmosphere out of whack.

The human resources department — what used to be called "personnel" until people come to be considered as a metabolising, respiring form of mineral ore — will probably tell you that men usually work harder, get sick less frequently and seldom get pregnant.

Ideonella dechloratans is a chlorate-respiring bacterium from the genus Ideonella and family Comamonadaceae.

Reductive dehaholagenses (EC 1.97.1.8) are a group of enzymes utilized in organohalide respiring bacteria. These enzymes are mostly attached to the periplasmic side of the cytoplasmic membrane and play a central role in energy-conserving respiratory process for organohalide respiring bacteria by reducing organohalides. During such reductive dehalogenation reaction, organohalides are used as terminal electron acceptors.

Desulfurococcaceae are anaerobic, sulfur respiring, extreme thermophiles. Desulfurococcaceae share the same family as Desulfurococcus. Two species of Staphylothermus have been identified: S. marinus and S. hellenicus. They are both heterotrophic, anaerobic members of the domain Archea.

Thauera selenatis is a gram-negative rod-shaped motile bacterium from the genus of Thauera with a single polar flagellum.UniProt Thauera selenatis has the ability to generate energy by respiring anaerobically with the enzyme selenate reductase.

This will amount in significant reduction of manufacturing and transportation costs. When selecting packaging films for MAP of fruits and vegetables the main characteristics to consider are gas permeability, water vapour transmission rate, mechanical properties, transparency, type of package and sealing reliability. Traditionally used packaging films like LDPE (low-density polyethylene), PVC (polyvinyl chloride), EVA (ethylene-vinyl acetate) and OPP (oriented polypropylene) are not permeable enough for highly respiring products like fresh-cut produce, mushrooms and broccoli. As fruits and vegetables are respiring products, there is a need to transmit gases through the film.

Chrysiogenes arsenatis is a species of bacterium in the family Chrysiogenaceae. It has a unique biochemistry. Instead of respiring with oxygen, it respires using the most oxidized form of arsenic, arsenate. It uses arsenate as its terminal electron acceptor.

The genus Thiomargarita. Heide Schulz. The Prokaryotes 2006, part 3, section 3.3, 1156–1163 Recent research has also indicated that the bacterium may be facultatively anaerobic rather than obligately anaerobic, and thus capable of respiring with oxygen if it is plentiful.

Some species of bacteria catalyze redox transformations of arsenic. Dissimilatory arsenate-respiring prokaryotes (DARP) speed up the reduction of As(V) to As(III). DARP use As(V) as the electron acceptor of anaerobic respiration and obtain energy to survive. Other organic and inorganic substances can be oxidized in this process.

However, this line of inquiry was ended when Albrich et al. found that cellular inactivation precedes loss of respiration by using a flow mixing system that allowed evaluation of viability on much smaller time scales. This group found that cells capable of respiring could not divide after exposure to HOCl.

The apparent function of Lbs in nodules is to facilitate the diffusion of O2 to the respiring bacteroids for nitrogen-fixation. At the same time, Lb contributes to maintain low O2-levels (~10 nM) to avoid inactivation of the O2-sensitive nitrogenase that fixes the atmospheric nitrogen.Appleby C. A., Leghemoglobin and Rhizobium respiration.

If both tubes are yellow then the organism is capable of fermentation ("F"). If there is, however, growth evident on the aerobic tube yet the medium has not turned yellow, either (a) glucose has been respired and evolved CO2 without significant production of acid, or (b) the organism is respiring the peptone.

Organohalides in general contribute to a large proportion of environmental pollutants and the enzyme reductive dehalogenase is responsible for the biological dehalogenation in organohalide respiring bacteria. However, some of these enzymes are usually membrane associated and oxygen sensitive and therefore inhibits the process of dehalogenation, which the enzyme published upon was able to overcome.

Dissimilatory As(+5)-respiring prokaryotes consist of a diverse phylogenetic group, including Chrysiogenes, Bacillus, Desulfomicrobium, Sulfurospirillum, Shewanella, Citrobacter, and Sulfurihydrogenibium species. Some specific species include Klebsiella oxytoca, Citrobacter freundii, and Bacillus anthracis. Although the ability to respire As(+5) is spread across several phylogenetic groups, the As(+5) reduction mechanism in these organisms seems to be conserved.

Ubiquinone-1 is a naturally occurring 1,4-benzoquinone that is involved in respiration apparatus. Ubiquinones, as their name implies, are ubiquitous in living creatures, being components of respiratory apparatus. right They are conjectured to occur in all respiring organisms. Some serve as electron acceptors in electron transport chains such as those in photosynthesis (plastoquinone, phylloquinone), and aerobic respiration (ubiquinone).

The female deposits her eggs inside freshwater mussels. The male sheds his sperm into the inhalent current of the respiring mussel and thereby fertilizes the eggs. The young hatch and remain protected within the mussel for about a month, eventually leaving the mussel as actively swimming larvae. Both sexes reach sexual maturity in 1 year, at a length of .

The partial pressure of the system also affects O2 affinity where, at high partial pressures of oxygen (such as those present in the alveoli), the relaxed (high affinity, R) state is favoured. Inversely, at low partial pressures (such as those present in respiring tissues), the (low affinity, T) tense state is favoured.Voet, D. (2008) Fundamentals of Biochemistry, 3rd. ed., Fig.

Phytoplankton have been shown to be able to take up nutrients from small local concentrations of organic material (e.g. fecal matter from an individual zooplankton cell, regenerated nutrients from organic decomposition by bacteria). As the aggregates slowly sink to the bottom of the ocean, the many microorganisms residing on them are constantly respiring and contribute greatly to the microbial loop.

A fluorescent compound is embedded in silicone on the bottom of 16 × 100 mm round bottom tubes. The fluorescent compound is sensitive to the presence of oxygen dissolved in the broth. Initially, the large amount of dissolved oxygen quenches emissions from the compound and little fluorescence can be detected. Later, actively respiring microorganisms consume the oxygen and allow the fluorescence to be detected.

The highly aquatic nature of the group is typified by the presence of cloacal breathing in some species of the genera Elseya and Rheodytes.Gordos, M. A.; Franklin, C. E. & Limpus, C. J. (2004). "Effect of water depth and water velocity upon the surfacing frequency of the bimodally respiring freshwater turtle, Rheodytes leukops". The Journal of Experimental Biology. 207: 3099-3107.

The microbial nif genes required for nitrogen fixation are widely distributed in diverse environments. Nitrogenases are rapidly degraded by oxygen. For this reason, many bacteria cease production of the enzyme in the presence of oxygen. Many nitrogen-fixing organisms exist only in anaerobic conditions, respiring to draw down oxygen levels, or binding the oxygen with a protein such as leghemoglobin.

An exoelectrogen normally refers to a microorganism that has the ability to transfer electrons extracellularly. While exoelectrogen is the predominant name, other terms have been used: electrochemically active bacteria, anode respiring bacteria, and electricigens. Electrons exocytosed in this fashion are produced following ATP production using an electron transport chain (ETC) during oxidative phosphorylation. Conventional cellular respiration requires a final electron acceptor to receive these electrons.

In natural ubiquinones, the number can be anywhere from 6 to 10. This family of fat-soluble substances, which resemble vitamins, is present in all respiring eukaryotic cells, primarily in the mitochondria. It is a component of the electron transport chain and participates in aerobic cellular respiration, which generates energy in the form of ATP. Ninety-five percent of the human body's energy is generated this way.

This nickname is derived from their unusual ability to absorb oxygen whilst submerged through highly vascularized bursae located in the cloaca. Rheodytes leukops is a bimodally respiring turtle that extracts oxygen from the water chiefly via two enlarged cloacal bursae that are lined with multi-branching papillae (Priest and Franklin, 2002). Therefore, reductions in aquatic oxygen levels, particularly by agriculture and dams,Aust Gov. SPRaT Database Rheodytes leukopsQueensland Government Dept.

The process of halorespiration, or dehalorespiration, uses reductive dehalogenation to produce energy that can be used by the respiring microorganism to carry out its growth and metabolism. Halogenated organic compounds are used as the terminal electron acceptor, which results in their dehalogenation. Reductive dehalogenation is the process by which this occurs. It involves the reduction of halogenated compounds by removing the halogen substituents, while simultaneously adding electrons to the compound.

Under eutrophic conditions, dissolved oxygen greatly increases during the day, but is greatly reduced after dark by the respiring algae and by microorganisms that feed on the increasing mass of dead algae. When dissolved oxygen levels decline to hypoxic levels, fish and other marine animals suffocate. As a result, creatures such as fish, shrimp, and especially immobile bottom dwellers die off. In extreme cases, anaerobic conditions ensue, promoting growth of bacteria.

When an ecosystem experiences an increase in nutrients, primary producers reap the benefits first. In aquatic ecosystems, species such as algae experience a population increase (called an algal bloom). Algal blooms limit the sunlight available to bottom-dwelling organisms and cause wide swings in the amount of dissolved oxygen in the water. Oxygen is required by all aerobically respiring plants and animals and it is replenished in daylight by photosynthesizing plants and algae.

Peter D. Mitchell proposed the chemiosmotic hypothesis in 1961 . The theory suggests essentially that most adenosine triphosphate (ATP) synthesis in respiring cells comes from the electrochemical gradient across the inner membranes of mitochondria by using the energy of NADH and FADH2 formed from the breaking down of energy-rich molecules such as glucose. Chemiosmosis in a mitochondrion. Molecules such as glucose are metabolized to produce acetyl CoA as an energy-rich intermediate.

While aerobic organisms during respiration use oxygen as a terminal electron acceptor, anaerobic organisms use other electron acceptors. These inorganic compounds have a lower reduction potential than oxygen, meaning that respiration is less efficient in these organisms and leads to slower growth rates than aerobes. Many facultative anaerobes can use either oxygen or alternative terminal electron acceptors for respiration depending on the environmental conditions. Most respiring anaerobes are heterotrophs, although some do live autotrophically.

One of the most distinguished features of bacteria is their biochemical versatility. A bacterial genus called Pseudomonas can metabolize a wide range of chemicals and fertilizers. In contrast, another genus known as Nitrobacter can only derive its energy by turning nitrite into nitrate, which is also known as oxidation. The genus Clostridium is an example of bacterial versatility because it, unlike most species, can grow in the absence of oxygen, respiring anaerobically.

2,3-Bisphosphoglyceric acid (conjugate base 2,3-bisphosphoglycerate) (2,3-BPG), also known as 2,3-diphosphoglyceric acid (conjugate base 2,3-diphosphoglycerate) (2,3-DPG), is a three-carbon isomer of the glycolytic intermediate 1,3-bisphosphoglyceric acid (1,3-BPG). 2,3-BPG is present in human red blood cells (RBC; erythrocyte) at approximately 5 mmol/L. It binds with greater affinity to deoxygenated hemoglobin (e.g. when the red blood cell is near respiring tissue) than it does to oxygenated hemoglobin (e.g.

This may occur with or without the presence of oxygen. Many chemosynthetic microorganisms are consumed by other organisms in the ocean, and symbiotic associations between chemosynthesizers and respiring heterotrophs are quite common. Large populations of animals can be supported by chemosynthetic secondary production at hydrothermal vents, methane clathrates, cold seeps, whale falls, and isolated cave water. It has been hypothesized that anaerobic chemosynthesis may support life below the surface of Mars, Jupiter's moon Europa, and other planets.

Atmosphere within the package can be modified passively or actively. In passive modified atmosphere packaging (MAP), the high concentration of CO2 and low O2 levels in the package is achieved over time as a result of respiration of the product and gas transmission rates of the packaging film. This method is commonly used for fresh respiring fruits and vegetables. Reducing O2 and increasing CO2 slows down respiration rate, conserves stored energy, and therefore extended shelf life.

In vertebrates, hemoglobin is found in the cytosol of red blood cells. Hemoglobin is sometimes referred to as the oxygen transport protein, in order to contrast it with myoglobin, which is stationary. In vertebrates, oxygen is taken into the body by the tissues of the lungs, and passed to the red blood cells in the bloodstream. Oxygen is then distributed to all of the tissues in the body and offloaded from the red blood cells to respiring cells.

Primarily by grazing on phytoplankton, zooplankton provide carbon to the planktic foodweb, either respiring it to provide metabolic energy, or upon death as biomass or detritus. Organic material tends to be denser than seawater, so it sinks into open ocean ecosystems away from the coastlines, transporting carbon along with it. This process, called the biological pump, is one reason that oceans constitute the largest carbon sink on Earth. However, it has been shown to be influenced by increments of temperature.

Early tetrapods probably had a three-chambered heart, as do modern amphibians and reptiles, in which oxygenated blood from the lungs and de-oxygenated blood from the respiring tissues enters by separate atria, and is directed via a spiral valve to the appropriate vessel — aorta for oxygenated blood and pulmonary vein for deoxygenated blood. The spiral valve is essential to keeping the mixing of the two types of blood to a minimum, enabling the animal to have higher metabolic rates, and be more active than otherwise.

Films designed with these properties are called permeable films. Other films, called barrier films, are designed to prevent the exchange of gases and are mainly used with non- respiring products like meat and fish. MAP films developed to control the humidity level as well as the gas composition in the sealed package are beneficial for the prolonged storage of fresh fruits, vegetables and herbs that are sensitive to moisture. These films are commonly referred to as modified atmosphere/modified humidity packaging (MA/MH)films.

The soil contains microbial organisms such as bacteria, which break down leaf litter and other organic matter into inorganic forms of carbon usable by plants through a process called decomposition. During the decomposition process the microbial community is respiring, taking up oxygen and releasing carbon dioxide. The decomposition rate can be evaluated by measuring the uptake of oxygen. High temperatures and precipitation increase decomposition rate, which allows plant litter to rapidly decay in tropical regions, releasing nutrients that are immediately taken up by plants through surface or ground waters.

Phylogenetic analysis shows that microbial arsenic metabolism probably extends back to the anoxic primordial Earth. As(+5) produced by anoxygenic photosynthesis might have created niches for primordial Earth's first As(+5)-respiring prokaryotes. In microbial biofilms growing on the rock surfaces of anoxic brine pools fed by hot springs containing arsenite and sulfide at high concentrations, light-dependent oxidation of arsenite (+3) to arsenate (+5) was discovered occurring under anoxic conditions. A pure culture of a photosynthetic bacterium grew as a photoautotroph when As(+3) was used as the sole photosynthetic electron donor.

Otto Warburg, whose research activities led to the formulation of the Warburg hypothesis for explaining the root cause of cancer. The Warburg hypothesis (), sometimes known as the Warburg theory of cancer, postulates that the driver of tumorigenesis is an insufficient cellular respiration caused by insult to mitochondria. The term Warburg effect in oncology describes the observation that cancer cells, and many cells grown in vitro, exhibit glucose fermentation even when enough oxygen is present to properly respire. In other words, instead of fully respiring in the presence of adequate oxygen, cancer cells ferment.

Brine pools are sometimes called sea floor "lakes" because the dense brine does not easily mix with overlying seawater creating a distinct interface between water masses. The pools range in size from less than 1 m2 to as large as the 120 km2 and 200 m deep Orca Basin. The high salinity raises the density of the brine, which creates a surface and shoreline for the pool. Because of the brine's high density and lack of mixing currents in the deep ocean, brine pools often become anoxic and deadly to respiring organisms.

These fishes exhibit a number of adaptations for feeding on large prey. The "open" structure of its jaws reduces water resistance, allowing them to be snapped shut more quickly, while large recurved teeth and powerful jaw closing muscles assure a secure hold on prey items. The connection between the head and the body is reduced, with unossified vertebrae, allowing the cranium to be tilted back and the jaws thrust forward for a wider gape. Finally, the gills are exposed to the outside, allowing the fish to continue respiring while slowly swallowing large prey.

This unique feature allows them to remain in places without access to the air, respiring through their skins. Ribs are generally absent, so the lungs are filled by buccal pumping and a frog deprived of its lungs can maintain its body functions without them. For the skin to serve as a respiratory organ, it must remain moist. This makes frogs susceptible to various substances they may encounter in the environment, some of which may be toxic and can dissolve in the water film and be passed into their bloodstream.

Oxygenated blood from the lungs and de-oxygenated blood from the respiring tissues enter the heart through separate atria. When these chambers contract, the two blood streams pass into a common ventricle before being pumped via a spiral valve to the appropriate vessel, the aorta for oxygenated blood and pulmonary artery for deoxygenated blood. The ventricle is partially divided into narrow cavities which minimizes the mixing of the two types of blood. These features enable frogs to have a higher metabolic rate and be more active than would otherwise be possible.

Dehalococcoides are obligately organohalide-respiring bacteria, meaning that they can only grow by using halogenated compounds as electron acceptors. Currently, hydrogen (H2) is often regarded as the only known electron donor to support growth of dehalococcoides bacteria. However, studies have shown that utilizing various electron donors such as formate, and methyl viologen, have also been effective in promoting growth for various species of dehalococcoides. In order to perform reductive dehalogenation processes, electrons are transferred from electron donors through dehydrogenases, and ultimately utilized to reduce halogenated compounds, many of which are human- synthesized chemicals acting as pollutants.

His results now showed that this air was not just an especially pure form of common air but was "five or six times better than common air, for the purpose of respiration, inflammation, and ... every other use of common air". He called the air dephlogisticated air, as he thought it was common air deprived of its phlogiston. Since it was therefore in a state to absorb a much greater quantity of phlogiston given off by burning bodies and respiring animals, the greatly enhanced combustion of substances and the greater ease of breathing in this air were explained.

Chlorite dismutase, also known as Chlorite O2-lyase (), is an enzyme that catalyzes the chemical reaction : ClO → Cl− \+ O2 Reactions that generate oxygen molecules are exceedingly rare in biology and difficult to mimic synthetically. Perchlorate - respiring bacteria enzymatically detoxify chlorite, ClO, the end product of the perchlorate, ClO respiratory pathway, by converting it to dioxygen, O2 and chloride, Cl−. Chlorite dismutase is a heme- containing protein, but it bears no structural or sequence relationships with known peroxidases or other heme proteins and is part of a large family of proteins with more than one biochemical function.

This species may be preyed upon by larger sharks. Known parasites include the tapeworms Paraorygmatobothrium arnoldi, Pseudogrillotia spratti, Phoreiobothrium perilocrocodilus, and Platybothrium jondoeorum. Sicklefin lemon sharks have been documented resting on the bottom and eliciting cleanings by bluestreak cleaner wrasses (Labroides dimidiatus), during which they may open their mouths and stop respiring for as long as 150 seconds to give the wrasses access to their mouths and gills. As with other members of its family, the sicklefin lemon shark is viviparous; the developing embryos are sustained by a placental connection formed from their depleted yolk sacs.

Acidophiles display a great range of adaptations to not just tolerating, but thriving in an extreme pH environment (the definition of an acidophile being an organism that has a pH optimum below pH 3). Principal in these is the necessity of maintaining a large pH gradient, to ensure a circumneutral cytoplasm (normally, however not in Picrophilus species). The archaeans have already been discussed above, and further information on their and bacterial adaptations are in basic form in the Figure. To elaborate upon the figure, the bacteria also use membrane proton blocking to maintain a high cytoplasmic pH, which is a passive system as even non-respiring A.ferrooxidans exhibit it.

Microbial electrochemistry utilizes bacteria that are able to transfer electrons to the anode of an electrochemical cell. Called “anode-respiring bacteria,” they are able to oxidize organic molecules and create an electrical current that can be used to generate electrical power, hydrogen gas, hydrogen peroxide, or other reduced materials, depending on conditions at the cathode of the electrochemical cell. Working with Center colleagues Dr. César Torres and Dr. Sudeep Popat, Rittmann is advancing the fundamental science and technology bases for microbial electrochemistry, with the ultimate goal of using the technology to capture the energy in organic waste streams as valuable energy or chemical outputs.

Adult Siamese fighting fish (Betta splendens) with velvet disease Initially, infected fish are known to "flash", or sporadically dart from one end of an aquarium to another, scratching against objects in order to relieve their discomfort. They will also "clamp" their fins very close to their body, and exhibit lethargy. If untreated, a 'dusting' of particles (which are in fact the parasites) will be seen all over the infected fish, ranging in color from brown to gold to green. In the most advanced stages, fish will have difficulty respiring, will often refuse food, and will eventually die of hypoxia due to necrosis of their gill tissue.

When alkaliphiles lose these acidic residues in the form of induced mutations, it has been shown that their ability to grow in alkaline conditions is severely hindered. However, it is generally agreed upon that passive methods of cytosolic acidification are not sufficient to maintain an internal pH 2-2.3 levels below that of external pH; there must also be active forms of acidification. The most characterized method of active acidification is in the form of Na+/H+ antiporters. In this model, H+ ions are first extruded through the electron transport chain in respiring cells and to some extent through an ATPase in fermentative cells.

Like other enzymes, the activity of F1FO ATP synthase is reversible. Large- enough quantities of ATP cause it to create a transmembrane proton gradient, this is used by fermenting bacteria that do not have an electron transport chain, but rather hydrolyze ATP to make a proton gradient, which they use to drive flagella and the transport of nutrients into the cell. In respiring bacteria under physiological conditions, ATP synthase, in general, runs in the opposite direction, creating ATP while using the proton motive force created by the electron transport chain as a source of energy. The overall process of creating energy in this fashion is termed oxidative phosphorylation.

At night respiring aquatic organisms can deplete the oxygen to the point where sensitive species, such as certain fish, die. This is more likely to happen near the sea floor or a thermocline. Water acidity also cycles daily during a bloom, with the pH reaching 9 or more during the day and dropping to low values at night, further stressing the ecosystem. In addition, many cyanobacteria species produce potent cyanotoxins which concentrate during a bloom to the point where they become lethal to nearby aquatic organisms and any other animals in direct contact with the bloom, including birds, livestock, domestic animals and sometimes humans.

The novel is set in 1943 in the fictional town of Thames Lockdon (based on Henley- on-Thames), and largely follows the experiences of Miss Roach who lives in the Rosamund Tea Rooms, a guest house, having left London during the Blitz. Also residing at the guest house are Mr Thwaites (described as the 'President in Hell'), Miss Steele, Miss Barrett (both aging spinsters) and Mr Prest (a retired comedian). Miss Roach works at a publishing firm, 'as a secretary and in other capacities' in London. The opening sequence describes London as a great monster respiring, drawing workers into the city through its lungs in the morning and expelling them in the evening.

Plants on Earth's surface capture energy from sunlight to photosynthesize sugars from carbon dioxide and water, releasing oxygen in the process that is then consumed by oxygen- respiring organisms, passing their energy up the food chain. Even life in the ocean depths, where sunlight cannot reach, was thought to obtain its nourishment either from consuming organic detritus rained down from the surface waters or from eating animals that did. The world's ability to support life was thought to depend on its access to sunlight. However, in 1977, during an exploratory dive to the Galapagos Rift in the deep-sea exploration submersible Alvin, scientists discovered colonies of giant tube worms, clams, crustaceans, mussels, and other assorted creatures clustered around undersea volcanic features known as black smokers.

Arsenate is the major arsenic form in oxidizing environments; however, in one study, bacteria from arsenic-contaminated soil at a smelter site was able to reduce As(+5) to As(+3) under anaerobic conditions at arsenic concentration as high as 75 mg/L. Arsenate-respiring bacteria and Archaea have also recently been isolated from a diversity of natural environments, including freshwater streams and sediments, alkaline and saline lakes, and hot springs. However, arsenate-reducing bacteria may exist in low numbers until provided with new sources of carbon especially and possibly the selective pressure of higher concentrations of arsenic. Some common locations with arsenate reducing bacteria that is causing major contamination problems by releasing arsenic into drinking water in shallow wells include Bangladesh, the American Midwest, and the Canadian Maritime Provinces.

Sir Hans Adolf Krebs (; 25 August 1900 – 22 November 1981) was a German-born British biologist, physician and biochemist. He was a pioneer scientist in the study of cellular respiration, a biochemical process in living cells that extracts energy from food and oxygen and makes it available to drive the processes of life. He is best known for his discoveries of two important sequences of chemical reactions that take place in the cells of humans and many other organisms, namely the citric acid cycle and the urea cycle. The former, often eponymously known as the "Krebs cycle", is the key sequence of metabolic reactions that provides energy in the cells of humans and other oxygen-respiring organisms; and its discovery earned Krebs a Nobel Prize in Physiology or Medicine in 1953.

A heterotrophic ecosystem often means that allochthonous (coming from outside the ecosystem) inputs of organic matter, such as leaves or debris fuel ecosystem respiration rates, resulting in respiration greater than production within the ecosystem. However, autochthonous (coming from within the ecosystem) pathways also remain important to metabolism in heterotrophic ecosystems. In an autotrophic ecosystem, conversely, primary production (by algae, macrophytes) exceeds respiration, meaning that ecosystem is producing more organic carbon than it is respiring. Stream metabolism can be influenced by a variety of factors, including physical characteristics of the stream (slope, width, depth, and speed/volume of flow), biotic characteristics of the stream (abundance and diversity of organisms ranging from bacteria to fish), light and nutrient availability to fuel primary production, organic matter to fuel respiration, water chemistry and temperature, and natural or human-caused disturbance, such as dams, removal of riparian vegetation, nutrient pollution, wildfire or flooding.