Photosynthesis Takes on World Hunger Enrichment LESSON 4

Name
Date
Class
Chapter 2 Lesson 4
Enrichment
LESSON 4
Photosynthesis Takes on World Hunger
Hunger affects millions of people
worldwide. Scientists are working hard
to find solutions to this problem. A promising
solution might be found in one of the most
common processes on Earth—photosynthesis.
During photosynthesis, plants and
certain algae use sunlight, carbon dioxide,
and water to make sugar-rich food.
Photosynthesis releases oxygen into the
atmosphere; the oxygen is used by living
things during cellular respiration.
Photosynthesis is clearly crucial to life
functions. However, it is not an efficient
process. At best, plants store only about 1
percent of the energy they receive from the
Sun. By improving the efficiency of
photosynthesis, scientists hope to increase
crop yields.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Switching Enzymes
Enzymes are proteins that break larger
molecules into smaller molecules. The
rubisco enzyme is the most abundant
protein on Earth. In photosynthesizing
organisms, the rubisco enzyme helps take
in carbon dioxide and convert it into
sugars and other compounds. It is also slow
and inefficient.
Red algae, however, contain a more
efficient form of rubisco. Scientists theorize
that they can increase crop yields by
replacing the enzyme currently found in
grains and other crops with the more efficient
form of rubisco. Or they might be able to
alter the rubisco in crops so it resembles the
more efficient form of the enzyme.
Mixed Reviews
Scientists are divided about whether
these theories hold true promise. Some
scientists state that studies thus far have not
proved the connection between increasing
the efficiency of photosynthesis and
increasing crop yields. Other scientists insist
that making photosynthesis more efficient
leads to marked increases in crop yields—as
much as 12 percent in a two-year period.
As the debate over rubisco continues,
scientists are exploring other methods of
improving the efficiency of photosynthesis.
For example, photosynthetic efficiency
might be increased by forcing large
amounts of carbon dioxide into a plant’s
cells, a process know as supercharging.
Using these and other techniques, scientists
hope to substantially reduce world hunger.
Applying Critical-Thinking Skills
Directions: Answer each question.
1. Apply Assume that scientists are successful in putting the more efficient form of
rubisco into common crops. Could you assume that such crops would produce higher
yields when they are grown in fields? Why or why not?
2. Judge Some scientists do not see any promise in increasing the efficiency of
photosynthesis, but other scientists do. How could you decide which argument to support?
3. Weigh What possible disadvantages might be associated with increasing the efficiency
of photosynthesis?
Cell Structure and Function
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