Tài liệu Cracking the Toefl IBT 2009 edition part 31 pdf

Okay, | know from having taught this class before that the topic I'm about to cover has the potential to get people's blood boiling, so I'd like to start off by making something clear: I

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adrenaline

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Female Professor: Okay, | know from having taught this class before that the topic I'm about to

cover has the potential to get people's blood boiling, so I'd like to start off by making something clear: I'm going to discuss the physical effects of tobacco on the body

This is not the place for a debate over social issues If you all want to get into it over lunch after class is over, you're welcome to Just don't expect me to join in

‘Anyway, what we want to talk about is what happens to your body when you smoke

or chew tobacco The primary active ingredient in tobacco is one you're probably all familiar with: nicotine Nicotine is a class of chemical called an alkaloid, meaning that its a close relative of the caffeine in coffee and the natural drugs found in some plants It generally has a stimulant effect—it gets your body systems going, makes them more active It actually makes up a very small percent of the tobacco plant— about 5 percent by mass—not much, right? Also, when you smoke tobacco, most of the nicotine burns away before you can even inhale it That means that most of the nicotine in your cigarettes never gets to your lungs It's not ingested So between those two things—the low proportion of nicotine in the tobacco plant, and the high proportion of the nicotine that's destroyed before you ingest it—you're not really getting a whole lot with each putt

Even so, the nicotine in cigarettes has a powerful effect on the body for a few reasons For one thing, while some drugs pass through the body largely without being absorbed, nicotine inhaled into the lungs is absorbed almost completely This

is because the lungs have a lot of surface area that's usually used to exchange oxygen and carbon dioxide when you breathe All that surface area provides lots

and lots of places for nicotine to pass into the bloodstream Then there's the fact that nicotine crosses the blood-brain barrier quickly The blood-brain barrier is a sort of gatekeeping system in the bloodstream It severely limits the ability of substances and organisms to pass from the blood into the brain This helps keep the chemical environment of the brain stable, which it needs to function properly, and it also keeps the brain clean you know, nasty infections can't get in, even if the rest of the body is sick fighting them off

Because nicotine is one of those chemicals that crosses the blood-brain barrier quickly, it affects the nervous system right from its command center, And it has two big effects One is that it stimulates the production of the hormone adrenaline More adrenaline means an increase in your heartbeat, your breathing, and possibly even cognition—that is, the thinking and perceiving nerves in your brain, That would help right? to explain why people report feeling energized and sharper, more aware, after smoking a cigarette Their breathing and heart rates are jazzed up, and their thinking nerves are too

You may be thinking at this point, Well, that's how people get addicted to smoking—it makes them feel more energetic and stuff, and you're partially right, but there's another physiological reason Scientists have evidence that nicotine stimulates the production of not only adrenaline but also another chemical: dopamine Levels of dopamine rise when you're doing something enjoyable, like eating your favorite food So what happens is some researchers refer to it as a reinforcement or reward mechanism Dopamine signals well-being, so when nicotine stimulates dopamine production, its kind of like exciting your pleasure center, That's probably the source

Now, those are the most obvious direct affects, but nicotine alters body functions in

other ways that are also significant For instance, it decreases the amount of oxygen that gets to the brain, which can make you feel more relaxed It also, at least in the short term, relaxes the stomach In fact—some of you may know this, but—nicotine used to be prescribed as medicine for these reasons Doctors would tell people

to use tobacco if they were nervous or anxious because the nicotine calmed them down Likewise, people with upset stomachs would be told to use nicotine because

the relaxing effect on the stomach helped digestion Now, the problem—the biggest

problem—is that these are short-term effects, but as you continue to use nicotine a lot over a period of time, it has bad effects that aren't immediately obvious Nicotine can cause stomach ulcers and make heart problems worse You may get short-term relief, but you'll eventually be worse off

Now, ask one of your friends to repeat the part of the lecture below, which is what you will hear on the actual TOEFL

Okay, | know from having taught this class before that the topic I'm about to cover has the potential to get people's blood boiling, so I'd like to start off by making something clear: I'm going to discuss the physical effects of tobacco on the body This is not the place for a debate over social issues

1 Listen again to part of the discussion Then answer the question

What can be inferred about the professor? €)

(A) She is not used to teaching students about the effects of tobacco

(B) She thinks the topic may be confusing

(C) She wants to avoid a controversial discussion

(D) She thinks the debate over tobacco is interesting

2 Why is only a small amount of nicotine ingested in smoking?

Click on 2 answers

(A) _ The processing of tobacco removes a lot of nicotine

(8) The body does not absorb nicotine easily (©) Most of the nicotine is destroyed by burning

{D) The tobacco plant contains little nicotine

3 Why does nicotine affect the nervous system powerfully?

(A) _ The brain has a large surface area

(B) Nicotine is similar in structure to some hormones

(C) Blood travels directly from the lungs to the brain

(D) Nicotine crosses the blood-brain barrier quickly

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4 What effect does adrenaline have on people's moods?

(A) They feel more alert

(B) They feel calmer

(C) They become more nervous

(D) They think more slowly and carefully

5 How does dopamine contribute to cigarette addiction?

(A) It makes people more energetic

(B) It sends signals associated with pleasure

(C) It decreases the amount of oxygen to the brain

(D) It lowers heart and breathing rates

6 What kinds of illnesses used to be treated with tobacco?

Click on 2 answers

(A) Heart disease

(B) Anxiety

{C) Poor digestion

(D) Breathing problems

DRILL #4: A LECTURE

Listen to Track 3 on the CD, ‘Then answer the following questions

Psychology

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ectomorphic mesomorphic endomorphic

Listening Practice Drils | 307

1, What is the lecture mainly about?

(A) The layers of the human body (B) Away of categorizing people's personalities (C)_ The best kind of exercise for different body types (D) How students can identify their own body types

2 What do biologists use to divide the body into layers?

(A) The amount of fat in each type of tissue (B) The origins of the different cells

(C)_ The type of personality in which each area is dominant (D) The kind of activity with which the tissues are associated

Now, ask one of your friends to repeat the part of the lecture below, which is what you will hear on the actual TOEFL

So when biologists talk about the layers of the body, that's

what they mean: The outermost is the skin and nervous system,

the middle is the muscles, and the innermost is the stomach, basically It’s important to get that straight right from the beginning because most people—well, isn’t it natural to think of the bones as the innermost layer?

3 Listen again to part of the lecture Then answer the question

What did the professor mean by this? €)

Well, isn't it natural to think of the bones as the innermost

layer?

(A) The layers of the body do not include the bones

(B) Most people are familiar with the categories

(C) Scientists have recently changed their thinking

(D) The mistake is understandable

4 Which of the following are characteristics of an ectomorphic

body?

Click on 2 answers

(A) Lack of fat (B) Strong bones (C)_ Low muscle development (D) Enlarged stomach

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5 What will the professor discuss next?

(A) Problems with Sheldon’s theory

(B) The questions Sheldon used in his interviews

(C) Anewer theory of personality types

(D) Studies that have tested Sheldon’s theory

6 Based on the information in the lecture, indicate whether the

following are characteristics of the mesomorphic or endomorphic

personality type

Seeks ways to fulfill

appetites

Friendly and outgoing

Reacts to situations

physically

Physically inactive

Atcacks problems

without planning

DRILL #5: A LECTURE

Ask a few friends to read aloud the following lecture and discussion from an anthropology class The discussion is be- tween a male professor (MP), a female student (FS), and a male student (MS) The lecture and discussion are similar to what you'll hear on the TOEFL Then answer the questions that follow

nny

Male Professor: Since yesterday's brief introduction on the origin of banking confused some of

you, today | would like to review it alittle bit Banking the way we know it today is a

convenience The money used in banking represents a certain amount of value, but

the money itself isn't valuable; it's just paper To see how we got here suppose we think about a society far, far back in history—what would it have used before the paper money we have today?

Female Student: Didn't they trade with the goods themselves?

MP: Sure The system of exchanging one good for another of equal value is called bartering Bartering was common in early societies, first with essential goods, then with nonessential goods By nonessential, | mean, for example, art or cultural objects You might trade a curtain that had been dyed in a decorative pattern for some wheat The curtain’s decorative value isn't essential to survival the way the food value of the grain is That's the first step toward a money economy: Recognizing trade-worthy value in something that isn't essential to survival

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Of course, you may see a hitch Different cultures don't value the same decorations,

‘so something could be worth a lot to one tribe and nothing to another With food,

that’s not a problem—everyone has to eat—but with nonessential items, you're going

to use something with cross-cultural value Can anyone think of anything that would

work?

Male Student: How about gold? I's durable easy to shape and it's beautiful Is that why

cultures started using it as money?

MP: Well, you can't refer to the earliest trade with gold as a money economy, but yes

Gold is a perfect example As societies grew more stable and trade flourished, gold, usually molded into small ingots, gradually replaced the system of bartering There were problems with gold, though

FS: Yeah, | was going to say, gold is heavy, isn't it? How did people carry enough of it around to buy things? And wasn't it dangerous—like, you'd get robbed if people knew you had money with you?

MP: Definitely Hauling all your gold around was a real risk in early societies, when

there were bandits roaming around and no police to help you And as you say, gold

is heavy and unwieldy One advantage it has, though, is that, unlike livestock or food,

it doesn't go bad, so you don't have to use it up immediately

That combination of characteristics gave people an idea They started leaving their gold ingots with gold specialists for safekeeping, The specialists stored the gold for a small fee, and they gave their customers receipts, the way you'd get today So you'd get something that said that, you know, you were the owner of such-and-such an amount of gold stored at this particular shop The quality of gold from different mines varies, so the purity and density of your gold ingots—you know, how heavy they were for their size—determined their value and would also be recorded

Then, when you wanted to use it, you just went back, gave the shopkeeper the receipt, and he gave you your gold

MS: So if you were storing 500 ounces of gold of whatever percent purity, you'd give

the receipt back, and get your 500 ounces of gold back? They kept it for you in your own little drawer or something?

MP: Whoops! | guess | did make it sound that way—thanks for catching that! No,

you'd get 500 ounces of gold of the same purity back They would have equal value, but would not necessarily be the exact same pile of ingots that you originally gave to the shopkeeper

FS: The shopkeeper would use the gold or lend it out while you were storing it?

MP: Sure, and you can see how that's another of the beginnings of banking as we

know it You wouldn't get back your very own pile of gold; you'd get back a pile of

equal value It was the value itself that was important

MS: So how did it become like money? | mean, we're stil talking about big, heavy

stacks of things, and—

MP: Well, that's the last point Eventually, people figured out that they could use their

receipts from storing gold to trade with one another If they wanted to buy something, instead of running to the gold shop, withdrawing gold, and bringing it to another shop