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Vírus (do latim virus, "veneno" ou "toxina") são pequenos agentes infecciosos (20-300 ηm de diâmetro) que apresentam genoma constituído de uma ou várias moléculas de ácido nucleico (DNA ou RNA), as quais possuem a forma de fita simples ou dupla. Os ácidos nucleicos dos vírus geralmente apresentam-se revestidos por um envoltório proteico formado por uma ou várias proteínas, o qual pode ainda ser revestido por um complexo envelope formado por uma bicamada lipídica.
Alguns vírus atacam e destroem bactérias e por isso receberam o nome de bacteriófagos ou simplesmente fagos.
Com relação a esses vírus, afirma-se que
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Os animais, em geral, são divididos em invertebrados e vertebrados. O que os difere é a presença ou a ausência de espinha dorsal e caixa craniana. A divisão é feita apenas para facilitar o estudo dos animais. Compreendendo 97% de todas as espécies de animais de todo o mundo – 1,5 milhão de espécies diferentes, os invertebrados são considerados os animais mais antigos do reino animal, uma vez que foi a partir deles que surgiram os vertebrados.
Analise a seguinte caracterização: “Animal com cnidócito em grande quantidade nos tentáculos; quando é tocado, lança fora o nematocisto, liberando líquido urticante, que pode provocar sérias queimaduras no homem.”
Esse animal pertence aos
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Observe a tabela abaixo, que relaciona diversos códons do RNA mensageiro aos aminoácidos codificados por eles.
Códons do RNAm Aminoácidos Códons do RNAm Aminoácidos
AAA Lisina AUG Metionina
AAG Lisina CCA Prolina
AGG Arginina CCG Prolina
AUA Isoleucina
Sabe-se que um dos modos de atuação do ácido nitroso como agente mutagênico é a transformação da base nitrogenada citosina em uracila, nas moléculas de DNA. A uracila assim formada conserva as mesmas propriedades de formação de ponte de hidrogênio da uracila encontrada em RNA.
Suponha que o segmento de DNA: … TTC TCC GGC TAC … tenha sofrido a ação do ácido nitroso e tenha tido todas as moléculas de citosina transformadas em uracila.
Pode-se concluir que a cadeia polipeptídica codificada pelo segmento de DNA original será diferente da cadeia polipeptídica codificada pelo segmento transformado em
Provas
No processo evolutivo foram selecionados os seres de fecundação externa que liberam uma grande quantidade de gametas para o meio ambiente. As hidras, no entanto, reproduzem-se rapidamente, embora lancem um pequeno número de gametas na água.
A explicação para esse fato é que as hidras apresentam um acelerado processo de reprodução
Provas
Sabe-se que a maioria das plantas terrestres retira a água do solo através do seu sistema radicular (pelos absorventes), principalmente, embora existam casos em que outras partes da planta possam se adaptar a essa função.
Dentre os vários fenômenos relacionados à absorção de água pela planta existe a exsudação. Assim, se cortarmos o caule de uma planta, esta começa a eliminar a seiva bruta na região do corte, assim como, cortando-se a extremidade do caule de uma planta cultivada em solo que havia sido bem irrigado, nota-se a saída de quantidade significativa de água líquida através da superfície cortada. Essa exsudação deve-se
Provas
Endemia é uma doença localizada em um espaço limitado denominado “faixa endêmica”. Isso quer dizer que endemia é uma doença que se manifesta apenas numa determinada região, de causa local. Para entender melhor: endemia é qualquer doença que ocorre apenas em um determinado local ou região, não atingindo nem se espalhando para outras comunidades.
Sabe-se que a maioria das endemias brasileiras poderia ser controlada com algumas intervenções nas áreas de ocorrência.
No caso da esquistossomose o procedimento mais eficaz para a queda de sua incidência seria
Provas
A água que banha o nosso litoral é bastante fria, devido, principalmente, à influência das correntes marítimas que vêm do sul. Essas correntes trazem consigo uma enorme quantidade de plâncton. Em biologia marinha e limnologia chama-se fitoplâncton ao conjunto dos organismos aquáticos microscópicos que têm capacidade fotossintética e que vivem dispersos flutuando na coluna de água, muitas vezes, representado por aquela "nata" que sobrenada na zona continental e que está constituída, principalmente, por algas marrons.
Estas algas são, taxonomicamente, classificadas como
Provas
Saint Patrick's Day, also known as The Feast of Saint Patrick, is a traditional holiday celebrated every year on March 17th, the day the patron saint of Ireland, Saint Patrick, died.
Patrick, who was born in the fourth century, lived in the British Isles, a land that had been invaded and conquered first by the Romans and then by Germanic tribes. At the age of 16, Patrick was captured and taken as a slave from the British Isles to what is now Ireland. He lived there for several years herding sheep. He was a religious boy, and he prayed that he would someday return to his homeland.
Legend has it that one night while he was praying, a voice told him to escape from the farm, and find a ship that was waiting for him in a harbor two hundred miles aways. Patrick got to the ship, sailed to Europe, and disembarked in what is now probably France. He ---1--- several of the ship's crew through a dangerous forest, praying all the time. Neither Patrick nor any member of his crew was captured. When some of the men were about to die of starvation, wild animals appeared to them to eat. Events such as these appeared to be miracles and gave rise to later legends surrounding Patrick.
Finally finding his way home, Patrick felt that he was called by God to perform an important mission. He believed it was his duty to go back to Ireland and convert the Celtic people to the Christian Religion.
Patrick arrived in England and became a missionary, traveling from village to village and talking about his faith. Once, several members of a tribe approached Patrick and told him that they found it difficult to understand and believe in the Holy Trinity. Patrick thought a moment, then stooped down and picked one of the plentiful shamrocks growing wild around Ireland. “Here are three leaves", he said, “yet it is one plant. Imagine the Father, Son and the Holy Spirit as each of these leaves. Here they are, yet they are one plant." The tribesmen understood, because Patrick had used a familiar object to explain. From that time on, the shamrock has been a revered symbol of Ireland.
There are lots of stories about Patrick. One of them is about him forcing snakes out of the entire country of Ireland. Even though there are many different stories about how he accomplished such a task, it is probably not true. Patrick died on March 17th, and the Irish people set aside the day to mourn. He became the patron saint of Ireland. Mourning turned to commemorating him and celebrating his life.
Because of Saint Patrick, lots of cities around the world with a large population of Irish have parades. Green is one of the national colors of Ireland. Green stripes are painted on the streets where the parade will travel. People wear green shirts, ties, hair ribbons, and hats. There are even pubs which serve green beer on that day.
Saint Patrick's Day was made an official Christian holiday in the early seventeenth century. It is now observed by the Catholic Church, the Anglican Communion, the Eastern Orthodox Church and Lutheran Church. The day commemorates Saint Patrick and the arrival of Christianity in Ireland. Not only that, but it also celebrates the heritage and culture of the Irish in general.
Source: adapted from http://www.inglesnapontadalingua.com.br/2014/03
Provas
- Gramática - Língua InglesaSubstantivos e compostos | Nouns and compoundsPlural dos substantivos | Plural of nouns
Saint Patrick's Day, also known as The Feast of Saint Patrick, is a traditional holiday celebrated every year on March 17th, the day the patron saint of Ireland, Saint Patrick, died.
Patrick, who was born in the fourth century, lived in the British Isles, a land that had been invaded and conquered first by the Romans and then by Germanic tribes. At the age of 16, Patrick was captured and taken as a slave from the British Isles to what is now Ireland. He lived there for several years herding sheep. He was a religious boy, and he prayed that he would someday return to his homeland.
Legend has it that one night while he was praying, a voice told him to escape from the farm, and find a ship that was waiting for him in a harbor two hundred miles aways. Patrick got to the ship, sailed to Europe, and disembarked in what is now probably France. He ---1--- several of the ship's crew through a dangerous forest, praying all the time. Neither Patrick nor any member of his crew was captured. When some of the men were about to die of starvation, wild animals appeared to them to eat. Events such as these appeared to be miracles and gave rise to later legends surrounding Patrick.
Finally finding his way home, Patrick felt that he was called by God to perform an important mission. He believed it was his duty to go back to Ireland and convert the Celtic people to the Christian Religion.
Patrick arrived in England and became a missionary, traveling from village to village and talking about his faith. Once, several members of a tribe approached Patrick and told him that they found it difficult to understand and believe in the Holy Trinity. Patrick thought a moment, then stooped down and picked one of the plentiful shamrocks growing wild around Ireland. “Here are three leaves", he said, “yet it is one plant. Imagine the Father, Son and the Holy Spirit as each of these leaves. Here they are, yet they are one plant." The tribesmen understood, because Patrick had used a familiar object to explain. From that time on, the shamrock has been a revered symbol of Ireland.
There are lots of stories about Patrick. One of them is about him forcing snakes out of the entire country of Ireland. Even though there are many different stories about how he accomplished such a task, it is probably not true. Patrick died on March 17th, and the Irish people set aside the day to mourn. He became the patron saint of Ireland. Mourning turned to commemorating him and celebrating his life.
Because of Saint Patrick, lots of cities around the world with a large population of Irish have parades. Green is one of the national colors of Ireland. Green stripes are painted on the streets where the parade will travel. People wear green shirts, ties, hair ribbons, and hats. There are even pubs which serve green beer on that day.
Saint Patrick's Day was made an official Christian holiday in the early seventeenth century. It is now observed by the Catholic Church, the Anglican Communion, the Eastern Orthodox Church and Lutheran Church. The day commemorates Saint Patrick and the arrival of Christianity in Ireland. Not only that, but it also celebrates the heritage and culture of the Irish in general.
Source: adapted from http://www.inglesnapontadalingua.com.br/2014/03
Provas
Saint Patrick's Day, also known as The Feast of Saint Patrick, is a traditional holiday celebrated every year on March 17th, the day the patron saint of Ireland, Saint Patrick, died.
Patrick, who was born in the fourth century, lived in the British Isles, a land that had been invaded and conquered first by the Romans and then by Germanic tribes. At the age of 16, Patrick was captured and taken as a slave from the British Isles to what is now Ireland. He lived there for several years herding sheep. He was a religious boy, and he prayed that he would someday return to his homeland.
Legend has it that one night while he was praying, a voice told him to escape from the farm, and find a ship that was waiting for him in a harbor two hundred miles aways. Patrick got to the ship, sailed to Europe, and disembarked in what is now probably France. He ---1--- several of the ship's crew through a dangerous forest, praying all the time. Neither Patrick nor any member of his crew was captured. When some of the men were about to die of starvation, wild animals appeared to them to eat. Events such as these appeared to be miracles and gave rise to later legends surrounding Patrick.
Finally finding his way home, Patrick felt that he was called by God to perform an important mission. He believed it was his duty to go back to Ireland and convert the Celtic people to the Christian Religion.
Patrick arrived in England and became a missionary, traveling from village to village and talking about his faith. Once, several members of a tribe approached Patrick and told him that they found it difficult to understand and believe in the Holy Trinity. Patrick thought a moment, then stooped down and picked one of the plentiful shamrocks growing wild around Ireland. “Here are three leaves", he said, “yet it is one plant. Imagine the Father, Son and the Holy Spirit as each of these leaves. Here they are, yet they are one plant." The tribesmen understood, because Patrick had used a familiar object to explain. From that time on, the shamrock has been a revered symbol of Ireland.
There are lots of stories about Patrick. One of them is about him forcing snakes out of the entire country of Ireland. Even though there are many different stories about how he accomplished such a task, it is probably not true. Patrick died on March 17th, and the Irish people set aside the day to mourn. He became the patron saint of Ireland. Mourning turned to commemorating him and celebrating his life.
Because of Saint Patrick, lots of cities around the world with a large population of Irish have parades. Green is one of the national colors of Ireland. Green stripes are painted on the streets where the parade will travel. People wear green shirts, ties, hair ribbons, and hats. There are even pubs which serve green beer on that day.
Saint Patrick's Day was made an official Christian holiday in the early seventeenth century. It is now observed by the Catholic Church, the Anglican Communion, the Eastern Orthodox Church and Lutheran Church. The day commemorates Saint Patrick and the arrival of Christianity in Ireland. Not only that, but it also celebrates the heritage and culture of the Irish in general.
Source: adapted from http://www.inglesnapontadalingua.com.br/2014/03
Provas
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