co-operative learning English

Hola ! Debido a la situación que se presento hoy por el trafico,  favor de enviar a mi correo la  actividad programada lo mas pronto posible..  Rebeca, Aaron, Bianca, Edgar,Noelia, Aristides.(the other students please check your e-mail)

 

 

 

 

 

 

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BIOOGICAL BARIIERS AND PATHWAYS.

 

1      Virtually all living things have some way of getting from here to there. Animals may walk, swim or fly. Plants and their seeds drift on wind or water or are carried by animals. There fore, it is reasonable to expect that, in time, all species might spread to every place on Earth where favorable conditions occur. Indeed, there are some cosmopolitan species. A good example is the housefly, found almost everywhere on Earth. ´however, such broad distribution is the rare exception. Just as barbed wire fences prevent cattle from leaving their pasture, biological barriers prevent the dispersal of many species.

 

2                   What constitutes barriers depends on the species and its method of dispersal. Some are physical barriers. For land animals, bodies of water, chain of mountains, or deserts are effective. For example, the American bison spread throughout the open grasslands of North America, but in the southern part of the continent there are deserts, so the bison could not spread there. For aquatic creatures, strong currents, differences in salinity, or land areas may serve as barriers.

 

3                   Some barriers involve competition with other species. A dandelion seed may be carried by the wind to bare ground, and, if environmental factors are right, it may germinate. There is not much chance, however, that any individual seedling will survive. Most places that are suitable for growth of dandelions are already occupied by other types of plants that are well adapted to the area. The dandelion seedling must compete with these plants for space, water, light, and nutrients. Facing such stiff competition, the chances of survival are slim.

 

4                   For animals, some barriers are behavioral. The blue spotted salamander lives only on mountain slopes in the southern Appalachian Highlands. Although these creatures could survive in the river valleys, they never venture there. Birds that fly lo9ng distances often remain in very limited areas. Kirkland8s warblers are found only in a few places in Michigan in the summer and fly to the Bahamas in winter. No physical barriers restrict the warblers to these two locations, yet they never spread beyond theses boundaries. Brazil’s Amazon River serves as a northern or southern boundary for many species of birds. They could freely fly over the river, but they seldom do.

 

5                   There are three types of natural pathways through which organisms can overcome barriers. One type is called a corridor. A corridor consists of a single type of habitat that passes through various other types of habitat. North America’s Rocky Mountains, which stretch from Alaska to northern Mexico, is an example. Various types of trees, such as the Engelmann spruce, can be found not only at the northern end of the corridor in Alaska but also at higher elevations along the entire length of this corridor.

 

6                   A second type of natural pathway is known as a filter route. A filter route consists of a series of habitats that are different from one another but are similar enough to permit organisms to gradually adapt to new conditions as they spread from habitat to habitat. The greatest difference between a corridor and a filter route is that a corridor consists of one type of habitat, while a filter consists of several similar types.


7                   The third type of natural pathway is called a sweepstakes route. This is dispersal caused by the chance combination of favorable conditions. Bird watchers are familiar with “accidentals,” which are birds that appear in places far from their native areas. Sometimes they may find ka habitat with favorable conditions and “colonize” it. Gardeners are familiar with “volunteers,” cultivated plants that grow in their gardens although they never planted the seeds for these plants. Besides birds and plants, insects, fish, and mammals also colonize new areas. Sweepstakes routes are unlike either corridors or filter routes in that organisms that travel these routes would not be able to spend their entire lives in the habitats that they pass through.

 

8                   Some organisms cross barriers with the intentional or unintentional help of humans, a process called invasion. An example is the New Zealand mud snail, which was accidentally brought to North America when trout from New Zealand were imported to a fish hatchery in the United States. It has caused extensive environmental damage in streams and rivers. In the invasive species’ native environments, there are typically predators, parasites, and competitors that keep their numbers down, but in their new habitat, natural checks are left behind, giving the invaders and advantage over native species. Invasive species may spread so quickly that they threaten commercial, agricultural, or recreational activities.

 

 

1.- Read the passage and according to the context write the meaning of the following words.

 

Pasture……in paragraph 1 _______________________

dispersal……in paragraph 1 _______________________

Salinity …..in paragraph 2 _______________________

Suitable……in paragraph 3 _______________________

behavioral……in paragraph 4 _______________________

Pathway….in paragraph 5 _______________________

Spruce …...in paragraph 5 _______________________

Colonize……in paragraph 7 _______________________

Predators …in paragraph 8_______________________

threaten……in paragraph 1 _______________________

 

2.- Read paragraph 5, tick the patter of organization

Listing _____             Time order _____       Comparison ____       Cause/Effect ___

 

3.- Read the text and answer the following:

 

  

1.- The word cosmopolitan in the passage is closest in meaning to

 

a) worldwide              b) useful          c) well-known            d) ancient

 

2.- How does the author explain the concept of biological barriers in paragraph 1

 

a) By providing several examples of biological barriers

b) By describing the process by which barriers are formed

c) By comparing biological barriers with a familiar  man-made barrier

d) By explaining how houseflies have been affected by biological barriers

 

3.-What does the author suggest about American bison in paragraph 2?

 

a) They spread to North America from South America

b) A body of  water stopped them from spreading south

c) They require open grasslands to survive

d They originally lived in deserts.

 

4.- According to the passage, very few dandelion seedlings survive because of

 

a). the danger of strong winds           b). competition from other dandelions

c). the lack of a suitable habitat         d. competition  from other species   

 

 

 

5.- The word slim in this passage is closets in meaning to (synonym)

a) unknown    

b) impossible

c) remarkable             

d) unlikely

 

Read this short text and write a short summary about it.

Corrosion (QUIMICA)

Today water is in the industry still mostly transported in metallic pipes or systems. The simpler the iron the greater is the risk of corrosion. The definition of corrosion is an (unwanted) reaction of materials with substances present in their environment. In the case of iron this reaction becomes visible for instance when rust forms. The reasons for this corrosion are diverse and are covered very extensively in the pertinent literature; we won't go into that any further in this place.

Merus yields safe and reproducible results where the less complicated reasons for corrosion between water and iron are on hand. These simple reasons are either stagnating water or water which is poor in minerals or unsaturated. Corrosion due to galvanic couples, alkaline or acescent fluids is at least moderated by Merus in most cases and it can even be stopped completely when certain favorable combinations are on hand. But such complicated applications require thorough technical scrutiny, we are glad to answer your questions via email. Merus perceives corrosion in pipes and machines as the most pressing problem of our customers worldwide. Damages caused by corrosion are the main reason for expensive emergency shut downs or replacement investments.
Latest results from the field show for instance a reduction of the corrosion rates, even in oil pipe lines,
by more then 10 times.

 

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Read this short text and write a short summary about it. (BIOQUIMICA)

Rise in livestock anthrax deaths is linked to drought

THIS STORY APPEARED IN.

DES MOINES — Anthrax has killed more than 100 animals on ranches in Colorado and Texas within the past two weeks, and specialists say the risk of infection may be greater with drought covering much of the United States.

Anthrax outbreaks happen occasionally in livestock herds and wild animals in the United States, usually west of the Mississippi River. Animals typically get the disease by ingesting or inhaling spores that survive in soil for decades. Once infected, livestock can die within hours. Anthrax bacteria react to drought and other harsh conditions by making more spores, and scientists said conditions are ripe for disease this year. A drought stretches from Ohio to California and from Texas to the Dakotas. Many places also have been burned by unusually long stretches of triple-digit temperatures.

‘‘My concern is that if we have more and more drought, if drought frequencies go up, we will see greater frequencies of these outbreaks,’’ said Mary Stromberger, associate professor of soil microbiology at Colorado State University.

More than 60 cows on three Colorado ranches and nearly 50 sheep in a Texas herd have died. Anthrax specialists and veterinarians warned ranchers to watch for sudden deaths, the usual sign of an anthrax infection. Herds can be decimated by an outbreak if animals are not quickly vaccinated. Anthrax cases have frequently been documented along the route of cattle drives common in the 1800s during the westward migration of pioneers and their livestock. The bacteria’s spores seem to survive better in alkaline soil with high levels of calcium, a type abundant in the West. In general, however, the spores are extremely durable and can lie dormant for years. Once ingested, they reconstitute and spread rapidly through the body of warm-blooded animals. Humans can get anthrax through direct contact with infected livestock, often when spores get into a cut on the skin. Without treatment, anthrax can be fatal, but early treatment with antibiotics is very effective……..

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