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In accounting, adjusting entries are journal entries usually made at the end of an accounting period to allocate income and expenditure to the period in which they actually occurred. The revenue recognition principle is the basis of making adjusting entries that pertain to unearned and accrued revenues under accrual-basis accounting .
The cortical reaction is a process initiated during fertilization that prevents polyspermy, the fusion of multiple sperm with one egg.In contrast to the fast block of polyspermy which immediately but temporarily blocks additional sperm from fertilizing the egg, the cortical reaction gradually establishes a permanent barrier to sperm entry and functions as the main part of the slow block of ...
Living organisms are complex adaptive systems. Although complexity is hard to quantify in biology, evolution has produced some remarkably complex organisms. [38] This observation has led to the common misconception of evolution being progressive and leading towards what are viewed as "higher organisms". [39]
Adaptation is a major topic in the philosophy of biology, as it concerns function and purpose . Some biologists try to avoid terms which imply purpose in adaptation, not least because they suggest a deity's intentions, but others note that adaptation is necessarily purposeful.
In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane-impermeable solutes across a cell membrane which determine the direction and extent of osmotic flux.
In biology, a substitution model, also called models of sequence evolution, are Markov models that describe changes over evolutionary time. These models describe evolutionary changes in macromolecules, such as DNA sequences or protein sequences, that can be represented as sequence of symbols (e.g., A, C, G, and T in the case of DNA or the 20 "standard" proteinogenic amino acids in the case of ...
An example of this in cell biology is that activated CDK1 (Cyclin Dependent Kinase 1) activates its activator Cdc25 while at the same time inactivating its inactivator, Wee1, thus allowing for progression of a cell into mitosis. Without this double feedback, the system would still be bistable, but would not be able to tolerate such a wide range ...
The same set of equations was published in 1926 by Vito Volterra, a mathematician and physicist, who had become interested in mathematical biology. [13] [18] [19] Volterra's enquiry was inspired through his interactions with the marine biologist Umberto D'Ancona, who was courting his daughter at the time and later was to become his son-in-law.