Question

E. Read the following passage, PHOTOSYNTHETIC

BIOHYBRID SYSTEM and write the paraphrase of each

paragraph after identifying the topic sentences of each one
of them

In the early 1900s, the Italian chemist Giacomo Ciamician

recognized that fossil fuel use was unsustainable. And like many

of today’s environmentalists, he turned to nature for clues on

developing renewable energy solutions, studying the chemistry of

plants and their use of solar energy. He admired their

unparalleled mastery of photochemical synthesis—the way they

use light to synthesize energy from the most fundamental of

substances—and how “they reverse the ordinary process of

combustion.” In photosynthesis, Ciamician realized, lay an

entirely renewable process of energy creation. When sunlight

reaches the surface of a green leaf, it sets off a reaction inside

the leaf. Chloroplasts, energized by the light, trigger the

production of chemical products—essentially sugars—which store

the energy such that the plant can later access it for its biological

needs. It is an entirely renewable process; the plant harvests the

immense and constant supply of solar energy, absorbs carbon

dioxide and water, and releases oxygen. There is no other waste.

If scientists could learn to imitate photosynthesis by providing

concentrated carbon dioxide and suitable catalyzers, they could

create fuels from solar energy. Ciamician was taken by the

seeming simplicity of this solution. Inspired by small successes in

chemical manipulation of plants, he wondered, “does it not seem

that, with well-adapted systems of cultivation and timely

intervention, we may succeed in causing plants to produce, in

quantities much larger than the normal ones, the substances

which are useful to our modern life?”

In 1912, Ciamician sounded the alarm about the unsustainable

use of fossil fuels, and he exhorted the scientific community to

explore artificially recreating photosynthesis. But little was done.

A century later, however, in the midst of a climate crisis, and​ armed with improved technology and growing scientific
knowledge, his vision reached a major breakthrough.
After more than ten years of research and experimentation,
Peidong Yang, a chemist at UC Berkeley, successfully created the
first photosynthetic biohybrid system (PBS) in April 2015. This
first-generation PBS uses semiconductors and live bacteria to do
the photosynthetic work that real leaves do—absorb solar energy
and create a chemical product using water and carbon dioxide,
while releasing oxygen—but it creates liquid fuels. The process is
called artificial photosynthesis, and if the technology continues to
improve, it may become the future of energy.
How Does This System Work?
Yang’s PBS can be thought of as a synthetic leaf. It is a
one-square-inch tray that contains silicon semiconductors and
living bacteria; what Yang calls a semiconductor-bacteria
interface.
In order to initiate the process of artificial photosynthesis, Yang
dips the tray of materials into water, pumps carbon dioxide into
the water, and shines a solar light on it. As the semiconductors
harvest solar energy, they generate charges to carry out
reactions within the solution. The bacteria take electrons from the
semiconductors and use them to transform, or reduce, carbon
dioxide molecules and create liquid fuels. In the meantime, water
is oxidized on the surface of another semiconductor to release
oxygen. After several hours or several days of this process, the
chemists can collect the product.
With this first-generation system, Yang successfully produced
butanol, acetate, polymers, and pharmaceutical precursors,
fulfilling Ciamician’s once-far-fetched vision of imitating plants to
create the fuels that we need. This PBS achieved a
solar-to-chemical conversion efficiency of 0.38%, which is
comparable to the conversion efficiency in a natural, green leaf.​

Answer 1

Answer:

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