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Different colors of bromothymol blue at marked pH conditions. Bromothymol blue may be used for observing photosynthetic activities, or as a respiratory indicator (turns yellow as CO 2 is added). [7] [8] A common demonstration of BTB's pH indicator properties involves exhaling through a tube into a neutral solution of BTB.
The following is a breakdown of the energetics of the photosynthesis process from Photosynthesis by Hall and Rao: [6]. Starting with the solar spectrum falling on a leaf, 47% lost due to photons outside the 400–700 nm active range (chlorophyll uses photons between 400 and 700 nm, extracting the energy of one 700 nm photon from each one)
Elodea is a genus of eight species of aquatic plants often called the waterweeds described as a genus in 1803. Classified in the frog's-bit family ( Hydrocharitaceae ), Elodea is native to the Americas [ 1 ] and is also widely used as aquarium vegetation and laboratory demonstrations of cellular activities.
If the test solution is of a dark colour, it is preferable to use a paper universal indicator, such as Hydrion paper. Solution: The main components of a universal indicator, in the form of a solution, are thymol blue , methyl red , bromothymol blue , and phenolphthalein .
Bromothymol blue is the indicator used in the agar, it changes to yellow in case of acid production during fermentation of lactose or changes to deep blue in case of alkalinization. Lactose-positive bacteria build yellow colonies. Bacteria which decarboxylate L-cystine cause an alkaline reaction and build deep blue colonies. [1]
The standards used include potassium dichromate (isosbestic points at 339 and 445 nm), bromothymol blue (325 and 498 nm) and congo red (541 nm). The wavelength of the isosbestic point determined does not depend on the concentration of the substance used, and so it becomes a very reliable reference.
The increase in pH then causes color change in the bromothymol blue indicator, turning it blue. Under neutral conditions the medium remains a green color. The color change to blue is useful because growth on Simmons' citrate agar is often limited and would be hard to observe if it were not for the color change.
The evolution of oxygen during the light-dependent steps in photosynthesis (Hill reaction) was proposed and proven by British biochemist Robin Hill. He demonstrated that isolated chloroplasts would make oxygen (O 2) but not fix carbon dioxide (CO 2). This is evidence that the light and dark reactions occur at different sites within the cell. [1 ...