MOCK EXAM 1-BIO-ING1

Prévia do material em texto

Universidad Nacional de Moreno 
 	 Departamento Ciencias Aplicadas y Tecnología INGLÉS I 
 Licenciatura en Biotecnología. 
MOCK EXAM 1 
How are good bacteria helpful to the environment?
by MAJA FIKET Last Updated: Jan 28, 2015
We think about bacteria as harmful, disease-causing, invisible creatures. But actually, only a few species are dangerous. The majority of bacteria are good, and without them, life on Earth wouldn’t be possible. 
Bacteria help degrade dead animals and plants and bring valuable nutrients back to Earth. Some species also help clean harmful pollutants out of the environment in a process called bioremediation. By using bioremediation techniques, toxic substances such as heavy metals and petroleum are no longer harmful to the environment. Bacteria are also cheap and accurate sensors of toxic chemicals.
Significance
The most numerous organisms in the soil are bacteria. They are a necessary part of nutrient, or biogeochemical, cycles in which carbon, nitrogen, sulfur and phosphorus are recycled between living organisms and the environment. Without these cycles, there would be no exchange of elements that are the backbone of proteins, sugars and fats—there would be no life. 
Bacteria as Biosensors
According to the U.S. Environmental Protection Agency, U.S. industries generate 292 million tons of hazardous waste each year, with at least 40 million tons released into the environment. Traditional chemical analyses for determining and locating toxic waste are expensive and often not accurate. Therefore, scientists have designed biosensors, which are genetically modified bacteria that can locate pollutants.
Biosensors do not require costly chemicals or equipment, and they work within minutes. Some bacteria emit light when they encounter a certain toxic chemical. Others emit light as long as they are healthy but stop if they have been killed by toxins.
· 		
· 		


Bacteria as Pollution Fighters
Heavy metals from industry and toxic synthetic chemicals, including pesticides, petroleum products, explosives and flame retardants, pose serious environmental and health risks. They enter soil, air and water and are extremely resistant to natural breakdown processes. Bioremediation uses certain bacteria that digest toxic substances and convert them into less harmful substances. To some degree, bioremediation occurs naturally, but it is usually enhanced by adding bacterial “food,” such as phosphorus and nitrogen, which make bacteria grow better and clean chemicals more effectively. Bioremediation is usually less expensive and less labor-intensive than traditional technologies.
Specifically Selected Bacteria
Industrial pollution and oil spills are often of a magnitude that requires enhanced bioremediation, where researchers select bacteria that grow specifically on a certain pollutant or genetically modified bacteria that can metabolize a specific pollutant. The addition of such bacteria is called bioaugmentation, which is used to clean up oil spills in water. Also, researchers have genetically altered radiation-resistant bacteria to make them more useful in cleaning up sites contaminated with radioactive materials.
Good bacteria are necessary cleaners of toxic waste, and without them many accidents in the environment would turn into catastrophes. In 1989, the ship Exxon Valdez hit a reef near the shoreline of Prince William Sound, Alaska, causing one of the greatest oil spills in history. Researchers are still working on how to completely clean these pristine waters. In the first five years after the accident, the oil was disappearing at a rate of about 70 percent due to successful bioremediation.
Pre- reading.
1.- Look at the picture, read the title and the first paragraph, skim the text and state your reading hypothesis. 
………………………………………………………………………………………………………………………………………………………………
Language activities
 
2.- Identify and match the tenses of the verb phrases in bold type. 
	Bacteria help degrade dead animals and plants
	 Present simple 
	Scientist have designed biosensors
	Present continuous
	In 1989, the ship Exxon Valdez hit a reef
	Present perfect simple
	Researchers are still working on how to completely clean these pristine waters. 
	Past simple 
	In the first five years after the accident, the oil was disappearing at a rate of about 70 percent due to successful bioremediation
	Past continuous
 3. -Scan the “Bacteria as Pollution Fighters” section and find the following items: 
a. a noun
b. an adverb 
c. a verb
d. a preposition
e. a comparative adjective
f. a personal pronoun
g. a connector introducing an example
h. a connector that shows contrast or concession
i. a word with a prefix
 4.- Are these sentences in the active or passive voice? Justify your answer (in Spanish) 
a. Reasearchers have genetically altered radiation-resistant bacteria. 
b. Some bacteria have been genetically modified to locate pollutants.
Reading comprehension activities
5.- What do the highlighted words refer to in the text? 
		Some
	
	They
	
	which 
	
	them 
	
	
	
6.- Are these sentences true or false? Underline the evidence in the text. 
a. Most species of bacteria are dangerous
b. According to the Environmental Protection Agency, 292 million tons of hazardous waste is generated by industries each year. 
c. Bioaugmentation is used to clean up oil spills. 
7.- Answer these questions in Spanish. BASE YOUR ANSWERS ON THE TEXT. 
a. What are biosensors? 
……………………………………………………………………………………………………………………………………………………………….
b. When did the Exxon Valdez oil spill occur? 
………………………………………………………………………………………………………………………………………………………………
c. Why is bioremediation so convenient in comparison to traditional technologies? 
………………………………………………………………………………………………………………………………………………………………
After-reading activities
8. -Read these noun phrases taken from the text. Underline the head noun and attempt a translation
Example: heavy metals----- metales pesados 
a. toxic synthetic chemicals 
b. petroleum products 
c. serious environmental and health risks 
d. natural breakdown processes 
e. less harmful substances
9.- Translate the underlined sentences into Spanish
Heavy metals from industry and toxic synthetic chemicals, including pesticides, petroleum products, explosives and flame retardants, pose serious environmental and health risks. 
………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
They enter soil, air and water and are extremely resistant to natural breakdown processes. 
………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
Bioremediation uses certain bacteria that digest toxic substances and convert them into less harmful substances.
………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
10.- In Spanish, summarise the central ideas in the text in about 100 words. (Explain how “good bacteria” can help the environment). 
……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….........................5