The correct answer for this question is "shaded square." The symbol that would the horse breeder use to show a male who is affected by a defective gene is the shaded square. <span>Pedigree charts use shaded symbols to show organisms that have a particular trait, such as a defective gene, being traced in the chart. </span>
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Quartzite is a metamorphic rock formed when quartz-rich sandstone or chert has been exposed to high temperatures and pressures. Such conditions fuse the quartz grains together forming a dense, hard, equigranular rock. The name quartzite implies not only a high degree of induration (hardness), but also a high quartz content. Quartzite generally comprises greater than 90% percent quartz, and some examples, containing up to 99% quartz, and are the largest and purest concentrations of silica in the Earth's crust. Although a quartz-rich sandstone can look similar to quartzite, a fresh broken surface of quartzite will show breakage across quartz grains, whereas the sandstone will break around quartz grains. Quartzite also tends to have a sugary appearance and glassy lustre. The variety of colours displayed by quartzite are a consequence of minor amounts of impurities being incorporated with the quartz during metamorphism. Although quartzite can sometimes appear superficially similar to marble, a piece of quartzite will not be able to be scratched by a metal blade, and quartzite will not fizz on contact with dilute hydrochloric acid.Explanation:
Answer:La transición de formas de vida unicelulares a multicelulares ha ocurrido en más de una ocasión a lo largo de la evolución. Las plantas, las algas marrones, los hongos y los animales han adquirido estilos de vida multicelulares de forma independiente y convergente.
La aparición de los animales representó un paso evolutivo clave en la historia de la vida. El desarrollo embrionario y todas las funciones que requiere la vida multicelular se hallan conservados en todos los animales, desde las esponjas a los humanos.
La secuenciación de los genomas de las especies unicelulares más cercanas a los animales ha revelado que estas ya contenían muchos de los genes necesarios para la multicelularidad. Estos habrían sido reutilizados para nuevas funciones multicelulares en el ancestro común de todos los animales.
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