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The prepupa is a stage in the life cycle of certain insects, following the larva or nymph and preceding the pupa. It occurs in both holometabolous and hemimetabolous insects. Examples
The reflux system in a typical industrial distillation column. Reflux is a technique involving the condensation of vapors and the return of this condensate to the system from which it originated. It is used in industrial [1] and laboratory [2] distillations. It is also used in chemistry to supply energy to reactions over a long period of time.
This course is designed for students who wish to pursue an interest in the life sciences. The College Board recommends successful completion of high school biology and high school chemistry [2] before commencing AP Biology, although the actual prerequisites vary from school to school and from state to state.
The reaction mechanism of the Mitsunobu reaction is fairly complex. The identity of intermediates and the roles they play has been the subject of debate. Initially, the triphenyl phosphine (2) makes a nucleophilic attack upon diethyl azodicarboxylate (1) producing a betaine intermediate 3, which deprotonates the carboxylic acid (4) to form the ion pair 5.
In chemistry, a precursor is a compound that participates in a chemical reaction that produces another compound. In biochemistry , the term "precursor" often refers more specifically to a chemical compound preceding another in a metabolic pathway , such as a protein precursor .
[7] [8] Inorganic processes also help drive plate tectonics. [9] Carbon-based photosynthesis life caused a rise in oxygen on Earth. This increase of oxygen helped plate tectonics form the first continents. [10] It is frequently assumed in astrobiology that if life exists elsewhere in the Universe, it will also be carbon-based.
Dialysis is the process used to change the matrix of molecules in a sample by differentiating molecules by the classification of size. [6] [7] It relies on diffusion, which is the random, thermal movement of molecules in solution (Brownian motion) that leads to the net movement of molecules from an area of higher concentration to a lower concentration until equilibrium is reached.
A buffer solution is a solution where the pH does not change significantly on dilution or if an acid or base is added at constant temperature. [1] Its pH changes very little when a small amount of strong acid or base is added to it.