Search results
Results From The WOW.Com Content Network
The first step in energetics is photosynthesis, where in water and carbon dioxide from the air are taken in with energy from the sun, and are converted into oxygen and glucose. [7] Cellular respiration is the reverse reaction, wherein oxygen and sugar are taken in and release energy as they are converted back into carbon dioxide and water.
By the middle of the 19th century, biogenesis was supported by so much evidence that spontaneous generation had been effectively disproven. Pasteur remarked, about an 1864 finding of his, "Never will the doctrine of spontaneous generation recover from the mortal blow struck by this simple experiment."
A biogeochemical cycle, or more generally a cycle of matter, [1] is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cycle , the nitrogen cycle and the water cycle .
The glyoxylate shunt pathway is an alternative to the tricarboxylic acid (TCA) cycle, for it redirects the pathway of TCA to prevent full oxidation of carbon compounds, and to preserve high energy carbon sources as future energy sources. This pathway occurs only in plants and bacteria and transpires in the absence of glucose molecules.
The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, producing large amounts of energy (ATP). Respiration is one of the key ways a cell releases chemical energy to fuel cellular activity. The overall reaction occurs in a series of biochemical steps, some of which are redox reactions.
Spontaneous generation is a superseded scientific theory that held that living creatures could arise from nonliving matter and that such processes were commonplace and regular. It was hypothesized that certain forms, such as fleas , could arise from inanimate matter such as dust, or that maggots could arise from dead flesh.
Several energy sources in planetary atmospheres can induce these dissociation reactions and subsequent hydrogen cyanide or aldehyde formation, including lightning, [32] ultraviolet light, [30] and galactic cosmic rays. [33] For example, here is a set photochemical reactions of species in the Miller-Urey atmosphere that can result in ...
A C3 plant uses the Calvin cycle for the initial steps that incorporate CO 2 into organic material. A C4 plant prefaces the Calvin cycle with reactions that incorporate CO 2 into four-carbon compounds. A CAM plant uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions. C4 and CAM plants have special adaptations ...