Gross photosynthesis versus scalar irradiance curves (P vs
Rate of Photosynthesis over one hour (= Gross Photosynthesis · 10 minutes x 60 minutes)
Carbon Cycle Processes - Pennsylvania State University
Above all else, life is an energy acquisition process. All life exploits the potential energy in various atomic and molecular arrangements, or captures energy directly, as in photosynthesis. Early life exploited the . The chemosynthetic ideal is capturing chemicals fresh to new environments that have yet to react with other chemicals. The currently most-accepted hypothesis has life first appearing on Earth about 3.5-3.8 bya, probably in volcanic vents on the ocean floor. The earliest life forms took advantage of fresh chemicals introduced to the oceans. Life had to be opportunistic and quick in order to capture that energy before other molecules did.
I woke up one morning a few months ago and realised that assumptions about CO2 and global warming could not be right. I reasoned that CO2 makes up a tiny fraction of the atmosphere and that the atmosphere is dwarfed by the oceans, so it is not possible for CO2 to have such an enormous effect. Imagine a gas mixture 80%N2, 20% O2 and 0.02%CO2. This would represent preindustrial levels of CO2. An increase in CO2 levels to 0.04%, still represents a very low concentration, particularly in comparison to water vapour which is estimated to be present at a concentration of about 2%. Finding objective information about climate and atmospheric heat has proved difficult, so I am grateful to everyone in this forum for contributions. The principles of physics hold, so now I can the science my students.
Climate Change Catastrophes in Critical Thinking
Building on the RNA World in 2009, researchers led by John Sutherland of the University of Cambridge reported that reactions of relatively simple compounds (acetylene and formaldehyde) could produce two of the four nucleotides needed to build RNA. Six years later, Sutherland's team found that RNA could be created by a sequence of reactions of even simpler precursors: hydrogen cyanide, hydrogen sulfide and ultraviolet light. Even better, the same sequence of reactions could make the precursors of amino acids and lipids. The research helped resolve a conundrum that long vexed biologists: The genetic materials needed to make proteins also depended on those proteins, and everything needed lipids. This research indicated that all three components could have been created in a relatively short time. Sutherland's team argued that our planet's nascent environment would have provided the hydrogen cyanide, hydrogen sulfide and ultraviolet light necessary to start the process, but cautioned that the reactions would require different catalysts and probably wouldn't happen in the same place. They might, however, have been washed into a warm Darwinian pool by rainwater.
In the earliest days of life on Earth, it had to solve the problems of how to reproduce, how to separate itself from its environment, how to acquire raw materials, and how to make the chemical reactions that it needed. But it was confined to those areas where it could take advantage of briefly available potential energy as . The earliest process of skimming energy from energy gradients to power life is called respiration. That earliest respiration is today called because there was virtually no free oxygen in the atmosphere or ocean in those early days. Respiration was life’s first energy cycle. A biological energy cycle begins by harvesting an energy gradient (usually by a proton crossing a membrane or, in photosynthesis, directly capturing photon energy), and the acquired energy powered chemical reactions. The cycle then proceeds in steps, and the reaction products of each step sequentially use a little more energy from the initial capture until the initial energy has been depleted and the cycle’s molecules are returned to their starting point and ready for a fresh influx of energy to repeat the cycle.
Energy and the Human Journey: Where We Have Been; …
used the energy of captured photons to strip electrons from various chemicals. Hydrogen sulfide was an early electron donor. In the early days of photosynthetic life, there was no atmospheric oxygen. Oxygen, as reactive as it is, was deadly to those early bacteria and archaea, damaging their molecules through oxidization. , or the stripping of electrons from life’s molecules, has been a problem since the early days of life on Earth. Oxidative stress is partly responsible for how organisms age, but it can also be beneficial, as organisms use oxidative stress in various ways.
When the Earth was forming, harsh conditions were probably the norm on our planet, although when those conditions eased is a matter of ongoing study and debate. About 4 billion years ago, the solar system was young and conditions were violent, with giant chunks of rock careening into planets regularly. Our own moon may have been formed by one such impact. In 2014, a team of Czech scientists conducted an experiment to replicate the pressure-cooker conditions created by an asteroid slamming into the Earth. The researchers used a high-powered laser to blast a solution of formamide — a chemical that forms from the reaction of hydrogen cyanide and water, and was likely abundant in the early days of our planet. The experiment produced adenine, guanine, cytosine and uracil: the nucleobases of RNA. The experiment suggested that, rather than impeding the development of life, the violent impacts of our early solar system might have contributed to its formation. On the other hand, some studies indicate that our planet might have cooled relatively early on, and hosted some forms of simple life. Zircon crystals from western Australia, dated at over 4 billion years old, have been found to contain oxygen isotopes suggesting that the crystals formed under cool, moist conditions. A 2015 paper by UCLA geologists focused on a Western Australia zircon crystal containing graphite. The authors argued that the carbon isotopes in that crystal constituted "probable" evidence of the occurrence of photosynthesis on Earth as long as 4.1 billion years ago. Vigorous debate about this finding, though, would be more than probable.
Overwhelmingly, this occurs through photosynthesis
Strange Science: What is Evolution?
Net and gross rates of oxygen flux were plotted against irradiance to generate photosynthesis versus ..
Poales - Missouri Botanical Garden
Ecosystem - Wikipedia
Spaceship Earth - Science NetLinks
Primary production is the production of organic matter from inorganic carbon sources
Physiology of citrus fruiting - SciELO
About the time that the continents began to grow and began, Earth produced its first known glaciers, between 3.0 and 2.9 bya, although the full extent is unknown. It might have been an ice age or merely some mountain glaciation. The , and numerous competing hypotheses try to explain what produced them. Because the evidence is relatively thin, there is also controversy about the extent of Earth's ice ages. About 2.5 bya, the Sun was probably a little smaller and only about as bright as it is today, and Earth would have been a block of ice if not for the atmosphere’s carbon dioxide and methane that absorbed electromagnetic radiation, particularly in the . But life may well have been involved, particularly oxygenic photosynthesis, and it was almost certainly involved in Earth's first great ice age, which may have been a episode, and some pertinent dynamics follow.
Functional Ecology - Wiley Online Library
As oxygenic photosynthesis spread through the oceans, everything that could be oxidized by oxygen was, during what is called the (“GOE”), although there may have been multiple dramatic events. The event began as long as three bya and is . The ancient carbon cycle included volcanoes spewing a number of gases into the atmosphere, including hydrogen sulfide, sulfur dioxide, and hydrogen, but carbon dioxide was particularly important. When the continents began forming, carbon dioxide was removed from the atmosphere via water capturing it, , the carbon became combined into calcium carbonate, and plate tectonics subducted the calcium carbonate in the ocean sediments into the crust, which was again released as carbon dioxide in volcanoes.
C3: Climate Change Models, Computer Simulations, …
In reality, it is the litterfall that is actually measured instudies of carbon flow through ecosystems; that, combined with ameasure of the gross primary productivity (the total amount of carbonused in photosynthesis) gives an estimate of the plant respirationflow according to the following equation:
Weird Life: Must Life Be Based on Carbon and Water?
Around when Harland first proposed a global ice age, a climate model developed by Russian climatologist concluded that if a Snowball Earth really happened, the runaway positive feedbacks would ensure that the planet would never thaw and become a permanent block of ice. For the next generation, that climate model made a Snowball Earth scenario seem impossible. In 1992, a professor, , that coined the term Snowball Earth. Kirschvink sketched a scenario in which the supercontinent near the equator reflected sunlight, as compared to tropical oceans that absorb it. Once the global temperature decline due to reflected sunlight began to grow polar ice, the ice would reflect even more sunlight and Earth’s surface would become even cooler. This could produce a runaway effect in which the ice sheets grew into the tropics and buried the supercontinent in ice. Kirschvink also proposed that the situation could become unstable. As the sea ice crept toward the equator, it would kill off all photosynthetic life and a buried supercontinent would no longer engage in . Those were two key ways that carbon was removed from the atmosphere in the day's , especially before the rise of land plants. Volcanism would have been the main way that carbon dioxide was introduced to the atmosphere (animal respiration also releases carbon dioxide, but this was before the eon of animals), and with two key dynamics for removing it suppressed by the ice, carbon dioxide would have increased in the atmosphere. The resultant greenhouse effect would have eventually melted the ice and runaway effects would have quickly turned Earth from an icehouse into a greenhouse. Kirschvink proposed the idea that Earth could vacillate between states.
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