VSTEP Reading Mock Test 07

The evidence that humans are causing global warming is strong, but the question of what to do about it remains controversial. Economics, sociology, and politics are all important factors in planning for the future.

Even if we stopped emitting greenhouse gases (GHGs) today, the Earth would still warm by another degree Fahrenheit or so. But what we do from today forward makes a big difference. Depending on our choices, scientists predict that the Earth could eventually warm by as little as 2.5 degrees or as much as 10 degrees Fahrenheit.

A commonly cited goal is to stabilize GHG concentrations around 450-550 parts per million (ppm), or about twice pre-industrial levels. This is the point at which many believe the most damaging impacts of climate change can be avoided. Current concentrations are about 380 ppm, which means there isn’t much time to lose. According to the IPCC, we’d have to reduce GHG emissions by 50% to 80% of what they’re on track to be in the next century to reach this level.

Is this possible?

Many people and governments are already working hard to cut greenhouse gases, and everyone can help.

Researchers Stephen Pacala and Robert Socolow at Princeton University have suggested one approach that they call “stabilization wedges.” This means reducing GHG emissions from a variety of sources with technologies available in the next few decades, rather than relying on an enormous change in a single area. They suggest 7 wedges that could each reduce emissions, and all of them together could hold emissions at approximately current levels for the next 50 years, putting us on a potential path to stabilize around 500 ppm.

There are many possible wedges, including improvements to energy efficiency and vehicle fuel economy (so less energy has to be produced), and increases in wind and solar power, hydrogen produced from renewable sources, biofuels (produced from crops), natural gas, and nuclear power. There is also the potential to capture the carbon dioxide emitted from fossil fuels and store it underground - a process called “carbon sequestration”.

In addition to reducing the gases we emit to the atmosphere, we can also increase the amount of gases we take out of the atmosphere. Plants and trees absorb CO2 as they grow, “sequestering” carbon naturally. Increasing forestlands and making changes to the way we farm could increase the amount of carbon we’re storing.

Some of these technologies have drawbacks, and different communities will make different decisions about how to power their lives, but the good news is that there are a variety of options to put us on a path toward a stable climate.

Art communicates to us primarily through our eyes. We look at art, and we try to find some meaning in the experience. If we are to begin to think about art more seriously, we might do well to become more aware of the process of seeing itself.

Science tells us that seeing is a mode of perception, or the recognition and interpretation of sensory data - in other words, how information comes in our senses, and what we make of it. In visual perception, our eyes take in information in the form of light patterns; the brain processes these patterns to give them meaning. The mechanics of perception work much the same way for everyone, yet in a given situation we do not all see the same things.

We can take great pleasure in merely looking at art, just as we take pleasure in the view of a distant mountain range or watching the sun set over the ocean. But art, unlike nature, is a human creation. It is one of the many ways we express ourselves and attempt to communicate. A work of art is the product of human intelligence, and we can meet it with our own intelligence on equal footing. This is where study comes in.

The understanding of process - the how - often contributes quite a lot to our appreciation of art. If you understand why painting in watercolor may be different from painting in oil, why clay responds differently to the artist’s hands than does wood or glass - you will have a richer appreciation of the artist’s expression.

Knowing the place of a work of art in history - what went before and came after - can also deepen your understanding. Artists learn to make art by studying the achievements of the past and observing the efforts of their contemporaries. They adapt ideas to serve their own needs and then bequeath those ideas to future generations of artists. For example, Matisse assumed that his audience would know that Venus was the ancient Roman goddess of love. But he also hoped that they would be familiar with one Venus in particular, a famous Greek statue known as the Venus de Milo.

An artist may create a specific work for any of a thousand reasons. An awareness of the why may give some insight as well. Looking at Van Gogh’s “The Starry Night”, it might help you know that Van Gogh was intrigued by the belief that people journeyed to a star after their death, and that there they continued their lives. “Just as we take the train to get to Tarascon or Rouen”, he wrote in a letter, “we take death to reach a star.” This knowledge might help you understand why Van Gogh felt so strongly about the night sky, and what his painting might have meant to him.

But no matter how much you study, Van Gogh’s painting will never mean for you exactly what it meant for him, nor should it. Great works of art hold many meanings. The greatest of them seem to speak anew to each generation and to each attentive observer. The most important thing is that they mean something to you, that your own experiences, thoughts, and emotions find a place in them.

Antibiotics block the life cycle of bacteria that invade the human body. The first of these antibiotics, penicillin, works by blocking the molecules that construct the cell walls of particular bacteria. The bacteria, with incomplete cell walls, are not able to reproduce.

When penicillin was introduced during World War II, it was truly a “miracle drug”. Until that time, anyone who was cut or wounded stood a great risk of infection. Once penicillin became available, the situation changed. Wounded soldiers, children with ear infections, and many others began to benefit from the ability to block the growth of bacteria.

While humanity may have won that particular battle against bacteria, the war is far from over. The reason is that in any bacterial population, there are bound to be a few bacteria that, for one reason or another, are not affected by a particular antibiotic. For example, they may have a slightly differently shaped enzyme that builds cell walls, so that penicillin will not fit onto that particular shape of the enzyme. These bacteria will not be affected by that particular drug.

For that small group, the antibiotic is a real godsend. It doesn’t affect them, but it does wipe out all of their competition. They are thus free to multiply, and, over time, all of the bacteria will have whatever properties that made those individuals resistant.

Traditionally, medical scientists have dealt with this phenomenon by developing a large number of antibiotics, each of which intervenes in the bacterial life cycle in a slightly different way.

Consequently, if you happen to have a bacterium that is resistant to one antibiotic, probably it will succumb to the action of another. You may, in fact, have had the experience of going to a doctor with an infection, being given an antibiotic, and then finding that it didn’t work. In all likelihood, all your doctor had to do then was prescribe a different antibiotic and everything was fine.

The problem is that as time has passed, more and more bacteria have become resistant to antibiotics. In fact, currently, there is one strain of bacteria - Staphylococcus - that is resistant to every commercially available antibiotic except one, and in 1996, a bacterium with lowered resistance to that last antibiotic appeared in Japan.

The appearance of drug-resistant bacteria is not particularly surprising; in fact, it probably should have been anticipated. Nevertheless, in the late 1980s, there was a general sense of complacency among scientists on the antibiotic question. Little profit was to be made by developing the one-hundred-and-first antibiotic. Drug companies concentrated their efforts on other areas. Therefore, a gap developed between the production of new antibiotics and the development of resistance among bacteria.

By the early 1990s, this gap was recognized and highlighted in several national news magazines. More companies returned to develop new kinds of antibiotics, and currently, a number are undergoing clinical trials. By early in the twenty-first century, some of these new drugs will start to come on the market, and the problem will be “solved”, at least for the moment.

Additional research will focus on the processes by which cells repair the constant damage to DNA, but the computer design of new drugs, the development of new antibiotics, and techniques to combat bacteria should remain a top priority.