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Water has a much lower condensation temperature than other materials that compose the terrestrial planets in the Solar System, such as iron and silicates. The region of the protoplanetary disk closest to the Sun was very hot early in the history of the Solar System, and it is not feasible that oceans of water condensed with the Earth as it formed.
These form where hydrogen-rich fluids emerge from below the sea floor, as a result of serpentinization of ultra-mafic olivine with seawater and a pH interface with carbon dioxide-rich ocean water. The vents form a sustained chemical energy source derived from redox reactions, in which electron donors (molecular hydrogen) react with electron ...
Photons trapped by photosystem II move the system from state S 0 to S 1 to S 2 to S 3 and finally to S 4. S 4 reacts with water producing free oxygen: 2 H 2 O → O 2 + 4 H + + 4 e −. This conversion resets the catalyst to the S 0 state. The active site of the OEC consists of a cluster of manganese and calcium with the formula Mn 4 Ca 1 O x ...
Around 2010, scholars at the University of Colorado revived the idea, arguing that the ammonia hypothesis is a viable contributor if the haze formed a fractal pattern. [12] [13] It is now thought that carbon dioxide was present in higher concentrations during this period of lower solar radiation. It was first proposed and tested as part of ...
Such archaeal photosynthesis might have been the earliest form of photosynthesis that evolved on Earth, as far back as the Paleoarchean, preceding that of cyanobacteria (see Purple Earth hypothesis). While the details may differ between species , the process always begins when light energy is absorbed by the reaction centers , proteins that ...
Both types of organisms use such compounds via cellular respiration to both generate ATP and again form CO 2 and water (two red arrows). A heterotroph ( / ˈ h ɛ t ər ə ˌ t r oʊ f , - ˌ t r ɒ f / ; [ 1 ] [ 2 ] from Ancient Greek ἕτερος ( héteros ) 'other' and τροφή ( trophḗ ) 'nutrition') is an organism that cannot produce ...
Water: properties of water – solvent – cohesion – adhesion – surface tension – pH; Organic compounds: carbon – carbon-carbon bonds – hydrocarbon – monosaccharide – amino acids – nucleotide – functional group – monomer – adenosine triphosphate (ATP) – lipids – oil – sugar – vitamins – neurotransmitter – wax ...
Endocrinology (from endocrine + -ology) is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions known as hormones.It is also concerned with the integration of developmental events proliferation, growth, and differentiation, and the psychological or behavioral activities of metabolism, growth and development, tissue function, sleep ...