Nos mapas, está representada a região dos Bálcãs, em dois momentos do século XX. Uma causa para a mudança geopolítica representada foi a

(IFCE)

O esquema acima representa o aparelho projetado por Stanley Miller e Urey em meados do século passado. Por esse engenhoso sistema circulavam hidrogênio (H₂) vapor de água (H₂O) metano (CH₄) e amônia (NH₃) e, através de eletrodos, era fornecida energia na forma de descargas elétricas, simulando assim as condições da atmosfera primitiva do planeta Terra.

Após algum tempo, Miller e Urey observaram, como resultado de reações químicas, a formação de produtos como aminoácidos, carboidratos e ácidos graxos simples, que foram se acumulando.

Sobre a hipótese que este experimento corroborou sobre a origem da vida no planeta Terra, é correto afirmar que

(UDESC) 2012’s Second Sun 

Earth is believed to be getting a second sun burning in the sky near the end of 2012, as the second biggest star in the universe, Betelgeuse, is dying, which will lead to “multiple days of constant daylight.”

Many ancient cultures ⁴have speculated about the appearance of a second sun and this event appears to ¹tie in very closely with the December 21 2012 predictions.

Betelgeuse is the second ²biggest star in the universe and the eighth ³brightest in the night sky, Scientists ⁵have determined that the star is losing mass at a rapid rate, which indicates it will go supernova very soon.

The light emitted from this exploding star will be so bright that it will appear for a few weeks at the end of 2012 as a second sun in the sky. There may be little if no period of darkness or night according to senior lecturer of physics at the University of Southern Queensland, Brad Carter.

Earth will experience “brightness for a brief period of time for a couple of weeks and then over the coming months it begins to fade and then eventually it will be very hard to see at all,” explained the Australian scientist Brad Carter to news.com.au.

Scientist ⁶have known about this dying star which is 640 light years away from Earth, since 2005. It is believed that as Betelgeuse goes supernova it will not be harmful to Earth. “There will be neutrinos emitted during the supernova process, said University of Minnesota physics professor Priscilla Cushman, but neutrinos, even lots and lots of them, are only weakly interacting, so they won't affect life on earth,” but that is only speculation at this point.

The fact is, we as human beings have never experienced anything like this before so close to our home planet, and to be honest, we just don’t know for sure what this event could bring.

(www.december212012.com) on 30/08/11 

The verb tenses “have speculated” (ref. 4), “have determined” (ref. 5) and “have known” (ref. 6) are:

(FUVEST 2012 1ª FASE) O retículo endoplasmático e o complexo de Golgi são organelas celulares cujas funções estão relacionadas. O complexo de Golgi

(UNICENTRO) A crise na usina nuclear Daiichi, de Fukushima, despertou preocupações sobre os efeitos para a saúde da exposição à radiação.

(COMO..., 2011) (QUAIS SÃO..., 2011).

Com base nos conhecimentos sobre níveis de radiação e sobre as formas de como pode ameaçar a saúde, é correto afirmar: