(Uerj)  Os indivíduos de uma determinada espécie de peixe, bem adaptada a seu ambiente, podem ser classificados, quanto ao tamanho, em três grupos: pequenos, médios e grandes. O grupo mais numeroso corresponde ao que apresenta fenótipo médio.

Considere a introdução de um predador desses peixes no ambiente. Ao longo do tempo, os indivíduos do grupo médio passam a ser os menos numerosos, pois os peixes de tamanho menor conseguem defender-se do predador escondendo-se nas tocas, enquanto os de maior tamanho, mais fortes, não são atacados pela espécie predadora.

As alterações descritas exemplificam o tipo de seleção denominado 

(UFPA) The Impact of Media Violence on Children and Adolescents: Opportunities for Clinical Interventions

Over the past 30 years there has been extensive research on the relationship between televised violence and violent behavior among youth. Longitudinal, cross-sectional, and experimental studies have all confirmed this correlation. Televised violence and the presence of television in American households have increased steadily over the years. Studies reveal that children watch approximately 28 hours of television a week, more time than they spend in school. The typical American child will view more than 200,000 acts of violence, including more than 16,000 murders before age 18. Television programs display 812 violent acts per hour; children's programming, particularly cartoons, displays up to 20 violent acts hourly.

How does televised violence result in aggressive behavior? Some researchers have demonstrated that very young children will imitate aggressive acts on TV in their play with peers. Before age 4, children are unable to distinguish between fact and fantasy and may view violence as an ordinary occurrence. In general, violence on television and in movies often conveys a model of conflict resolution. It is efficient, frequent, and inconsequential. Heroes are violent, and, as such, are rewarded for their behavior. 1They become role models for youth. The typical scenario of using violence for a righteous cause may translate in daily life into a justification for using violence to retaliate against perceived victimizers. Hence, vulnerable youth who have been victimized may be tempted to use violent means to solve problems. Unfortunately, there are few, if any, models of nonviolent conflict resolution in the media. Additionally, children who watch televised violence are desensitized to it. They may come to see violence as a fact of life and, over time, lose their ability to empathize with both the victim and the victimizer.

Child and adolescent psychiatrists, pediatricians and other physicians can have a major impact on the effects of media violence. The American Academy of Pediatrics (AAP) has created a list of recommendations to address television violence. It suggests that physicians talk openly with parents about the nature and extent of viewing patterns in their homes. Parents should limit television to 1-2 hours daily and watch programs with their children, enabling them to address any objectionable material seen.

Physicians should make parents and schools "media literate," meaning they should understand the risks of exposure to violence and teach children how to interpret what they see on television and in the movies, including the intent and content of commercials. In doing so, children may be increasingly able to discern which media messages are suitable. Schools and homes should teach children conflict resolution.

Physicians, in their role as health promoters, should become more active in educating the media to become more sensitive to the impact of violence on youth. The arena of media violence is a new frontier where physicians can promote health through public education and advocacy.

(http://www.aacap.org/cs/root/developmentor/the_impact_of_media_violence_on_children_and_adolescents_opportunities_for_clinical_interventions)

No enunciado “They become role models for youth” (ref. 1), o vocábulo sublinhado se refere a:

Leia o fragmento a seguir.

“D. José, nobre espanhol e benfeitor da cidade.” O termo sublinhado classifica-se, sintaticamente, como um aposto explicativo , pois

Ácido muriático (ou ácido clorídrico comercial) é bastante utilizado na limpeza pesada de pisos para remoção de resíduos de cimento, por exemplo. Sua aplicação em resíduos contendo quantidades apreciáveis de CaCO₃ resulta na liberação de um gás. Considerando a ampla utilização desse ácido por profissionais da área de limpeza, torna-se importante conhecer os produtos formados durante seu uso.

A fórmula do gás citado no texto e um teste que pode ser realizado para confirmar sua presença são, respectivamente:

Arqueólogos e físicos cobiçam igualmente o chumbo romano antigo existente em antigas embarcações de naufrágios, estimado em 2 mil anos de idade. Para os físicos, como o chumbo antigo é puro, denso e muito menos reativo que o metal recém-minerado, ele será muito aplicado nos dias de hoje, entretanto, ele também tem significado histórico e muitos arqueólogos se opõem ao derretimento de lingotes. Considerando a importância desse metal, assinale a afirmação verdadeira.