Some people consider glass to be a liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition range. The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. Nonetheless, the equilibrium theory of phase transformations does not entirely hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids.
What theory isn't completely valid for glass?
equilibrium theory of phase transformations

During the process of meiotic cell division, an event called genetic recombination or crossing-over can sometimes occur, in which a length of DNA on one chromatid is swapped with a length of DNA on the corresponding sister chromatid. This has no effect if the alleles on the chromatids are the same, but results in reassortment of otherwise linked alleles if they are different.:5.5 The Mendelian principle of independent assortment asserts that each of a parent's two genes for each trait will sort independently into gametes; which allele an organism inherits for one trait is unrelated to which allele it inherits for another trait. This is in fact only true for genes that do not reside on the same chromosome, or are located very far from one another on the same chromosome. The closer two genes lie on the same chromosome, the more closely they will be associated in gametes and the more often they will appear together; genes that are very close are essentially never separated because it is extremely unlikely that a crossover point will occur between them. This is known as genetic linkage.
When can an event called genetic recombination or crossing-over sometimes occur?
During the process of meiotic cell division

Over the course of thousands of years, American indigenous peoples domesticated, bred and cultivated a large array of plant species. These species now constitute 50–60% of all crops in cultivation worldwide. In certain cases, the indigenous peoples developed entirely new species and strains through artificial selection, as was the case in the domestication and breeding of maize from wild teosinte grasses in the valleys of southern Mexico. Numerous such agricultural products retain their native names in the English and Spanish lexicons.
What percent of worldwide crops in cultivation derive from the efforts of the America's indigenous people?
50–60%