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Connection
HEALTH
Many of the medicines that are used today are derived from
plants or other organisms. You probably know that penicillin, a powerful antibiotic
discovered in 1928 by Alexander Fleming, is derived from bread mold. Ancient
Greeks, Native Americans, and others extracted salicin, a painkiller, from the willow
tree. Today, a version of this drug is synthesized in laboratories and is known as
aspirin.
Figure 6
shows a Madagascar periwinkle flower, which was found to yield an
extract that is useful in treating some forms of leukemia. This extract has been used to
develop drugs that have increased the survival rate for some leukemia patients from
20 percent to more than 95 percent.
Scientists continue to find new extracts from plants and other organisms that help in
the treatment of human diseases. However, many species of organisms are yet to be
identified, especially in remote regions of Earth, so their ability to provide extracts or
useful genes is unknown.
Indirect economic value
A healthy biosphere provides many services to humans and other organisms that live on
Earth. For example, green plants provide oxygen to the atmosphere and remove carbon
dioxide. Natural processes provide drinking water that is safe for human use. Sub-
stances are cycled through living organisms and nonliving processes, providing nutri-
ents for all living organisms. As you will soon learn, healthy ecosystems provide
protection against floods and drought, generate and preserve fertile soils, detoxify and
decompose wastes, and regulate local climates.
Figure 6
Medicines developed from an extract from
Madagascar periwinkle,
Catharanthus roseus
, are used
to treat forms of leukemia.
Summarize
Why is it important to maintain biodiversity
for medical reasons?
STEM CAREER Connection
Agronomist
How can we continue to feed Earth’s growing human
population? Do you want to help develop solutions to one
of humanity’s biggest challenges? Agronomists apply
what they know about soil and plant science to improve
crop production and increase the food supply.
CROSSCUTTING CONCEPTS
Cause and Effect
Choose a species that you’re familiar with
and think about how changing environmental conditions might
challenge its survival. Develop a model to illustrate how genetic
diversity within interbreeding populations of the species would
increase the chances that some individuals survive changing
environmental conditions. What evidence supports your model?
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Module 5 • Biodiversity and Conservation