Role of Chlorophyll in Photosynthesis.
“The role of chlorophyll b in photosynthesis: Hypothesis.” BMC Plant Biology 1.1 (2001): 2.
LabBench Activity Plant Pigments and Photosynthesis
There is also evidence that life itself can contribute to mass extinctions. When the eventually , organisms that could not survive or thrive around oxygen (called ) . When anoxic conditions appeared, particularly when existed, the anaerobes could abound once again, and when thrived, usually arising from ocean sediments, they . Since the ocean floor had already become anoxic, the seafloor was already a dead zone, so little harm was done there. The hydrogen sulfide became lethal when it rose in the and killed off surface life and then wafted into the air and near shore. But the greatest harm to life may have been inflicted when hydrogen sulfide eventually , which could have been the final blow to an already stressed ecosphere. That may seem a fanciful scenario, but there is evidence for it. There is fossil evidence of during the Permian extinction, as well as photosynthesizing anaerobic bacteria ( and ), which could have only thrived in sulfide-rich anoxic surface waters. Peter Ward made this key evidence for his , and he has implicated hydrogen sulfide events in most major mass extinctions. An important aspect of Ward’s Medea hypothesis work is that about 1,000 PPM of carbon dioxide in the atmosphere, which might be reached in this century if we keep burning fossil fuels, may artificially induce Canfield Oceans and result in . Those are not wild-eyed doomsday speculations, but logical outcomes of current trends and , proposed by leading scientists. Hundreds of already exist on Earth, which are primarily manmade. Even if those events are “only” 10% likely to happen in the next century, that we are flirting with them at all should make us shudder, for a few reasons, one of which is the awesome damage that it would inflict on the biosphere, including humanity, and another is that it is entirely preventable with the use of technologies .
A) sunlight concentration B) temperature C) chlorophyll concentration D) carbon dioxide availability Effects of the variables and there concentrations: The amount of sunlight will decide the rate of photosynthesis as there will be a an increased rate of photosynthesis due to the increased availability of photons of light....
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Current understanding is that the earliest photosynthetic organisms were aquatic bacteria, some of which are still around today. One of these, halobacterium halobium, grows in extremely salty water. It makes use of the bacteriorhodopsin pigment. The chlorophyll system developed to use the available light, as if it developed in strata below the purple bacteria and had to use what it could get.
During the process of photosynthesis, carbon dioxide plus water in the presence of sunlight, enzymes and chlorophyll produce glucose and oxygen as waste product.
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After as little as a half-million years of bedraggled survivors adapting to ice age seas, the ice sheets retreated and the oceans rose. The of the time may have also changed, and upwelling, anoxia, and other dramatic chemistry and nutrient changes happened. Those dynamics are suspected to be responsible for the second wave of extinctions. There also seem to have been .Atmospheric oxygen levels may have fallen from around 20% to 15% during the Ordovician, which would have contributed to the mass death. Seafloor anoxia seems to have been particularly lethal to continental-shelf biomes, possibly all the way to shore. It took the ecosystems millions of years to recover from the Ordovician-Silurian mass extinction, but basic ecosystem functioning was not significantly altered in the aftermath, which is why a has been proposed as a more significant extinction event. The were laid down by the . Most oil deposits were formed in the era of dinosaurs and the processes of oil deposit formation were similar; they were related to oceanic currents. When currents came to shore via the bottom and the prevailing winds blew the top waters offshore, it became a and anoxic sediments could form. When the winds blew onshore and left via the bottom, the waters became clear and are known as nutrient deserts. The oscillation between nutrient traps and nutrient deserts can be seen in oil deposit sediments. In the mid-20th century, Soviet scientists revived an old hypothesis that oil was , a variation of which was also championed by , but improving tools and investigation invalidated those hypotheses. No petroleum geologists today seriously consider the abiogenic origin of hydrocarbons. Oil sediment formation events seem related to mantle and crust processes that created high sea levels and anoxic events, and the last great one was in the , which formed more than 10% of the world's oil deposits.
Recent environmental studies show that disturbed ecosystems can have cascading failures, as the removal of one part of a food chain can in , and entire ecosystems can go extinct. Cascades in today's world usually begin when the apex predator is removed (by humans, and called a ), but not always. Those cascading events can happen in aquatic and environments. Food chains are essentially energy chains , and the more complex they are, the more energy is required to sustain them. The leading hypothesis for why is also an energy-scarcity dynamic. Also, the most compelling findings that I have encountered regarding degenerative disease in humans shows that if individual cells no longer have their nutritional needs met by the organism, they stop acting out their role as specialized cells and “.” It may be difficult-to-impossible for scientists to reconstruct and test cascading failure hypotheses in ancient mass extinction events, but they may have played a major role in them, if not the dominant role.
Plant Energy Transformations-Photosynthesis - …
Cytochrome b6f complex - Wikipedia
, Fall 1981 Melvin Calvin shown with some of the apparatus he used to study the role of carbon in photosynthesis."
Energy and the Human Journey: Where We Have Been; …
DSpace @ MIT The role of chlorophyll b in photosynthesis: Hypothesis Research and Teaching Output of the MIT Community
Unit 8A Plants I - Biology Junction
Photosynthesis - Wikipedia
Physiology of citrus fruiting - SciELO
Our hypothesis states that the stronger coordination bonds between the Mg atom in chlorophyll b and chlorophyll c and amino acid sidechain ligands in chlorophyll a/b- and a/c-binding apoproteins, respectively, enhance their import into the chloroplast and assembly of light-harvesting complexes.
hydrocarbons: alkanes, alkenes, carotenoids - Lipid
A direct test of the hypothesis – with positive selection – is expression, in mutant plants that synthesize only chlorophyll a, of forms of Lhcb1 in which weak ligands are replaced with stronger Lewis bases.
Is the Sun driving ozone and changing the climate? « …
Presentation Biosynthetic modifications that introduce electronegative groups on the periphery of the chlorophyll molecule withdraw electrons from the pyrrole nitrogens and thus reduce their basicity.
Intelligent races who are not EARTH HUMANS
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.
His hypothesis was partially ..
As with other early life processes, the first photosynthetic process was different from today’s, but the important result – capturing sunlight to power biological processes – was the same. The scientific consensus today is that a respiration cycle was modified, and a in a was used for capturing sunlight. Intermediate stages have been hypothesized, including the cytochrome using a pigment to create a shield to absorb ultraviolet light, or that the pigment was part of an infrared sensor (for locating volcanic vents). But whatever the case was, the conversion of a respiration system into a photosynthetic system is considered to have only happened , and all photosynthesizers descended from that original innovation.
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