FIND OUT MORE. Atoms 157 • Cells 73 • Chemistry 162 • Farming 66
Science and Technology^207
Plants need minerals from the soil to grow well. But repeated use
of soil drains the minerals from it and fewer crops are produced.
The farming industry uses agrochemicals to
help them improve the quality of the soil,
and also to fight off the insect pests,
diseases, and weeds that would
otherwise destroy their crops.WHAT IS ORGANIC FARMING?
Because of the effect of artificial sprays
and fertilizers on the environment, organic
farmers choose not to use them. Instead,
they use animal manure and compost, and
rotate their crops with beans and peas to
replace nitrogen in the soil. They also control
pests with natural methods, such as planting
onions between carrots to discourage carrot fly.A pharmaceutical is any substance used to treat or prevent
disease. Since ancient times, people have experimented with plants
as medicines, often poisoning themselves, but sometimes finding
substances with real benefits – aspirin, for example. Today, the
pharmaceutical industry is based on stricter scientific methods.
WHAT ARE SELECTIVE WEEDKILLERS?
In the past, farmers tried to kill weeds with sea salt
and other common chemicals. But these substances
killed crops as well. Modern herbicides (weedkillers)
are organic chemicals designed to limit weed growth.
Many are selective, which means that they kill the
weeds but do little harm to the crop.HOW ARE NEW DRUGS DEVELOPED?
Now that biochemists understand the chemicals in
living cells, they can design molecules to combat
illness. Molecules can be made in a laboratory and
tested on cells in a culture (in vitro). Successful
compounds are then tested on animals (in vivo).
HOW ARE NEW DRUGS TESTED?
When a drug has been tested in a laboratory it is
given to patients in tests called clinical trials. In these,
some patients are given the new drug while others
receive a placebo (a dummy medicine). Because the
patients do not know which drug they have received,
the test will show if the drug has a genuine effect.
DRUG MANUFACTURE 1
This mould is used for shaping
tablets (pills). Pills contain the
drugs prescribed for patients by
doctors. Each drug is made into a
pill with a different shape, colour,
size, or pattern. This makes it less
likely that the wrong pill will be
taken by mistake.4 TAKING DRUGS
Most types of drug are taken
orally (by mouth) in the form of
tablets or pills, or as powders.
Some drugs are swallowed in
liquid form, and some are
injected using a hypodermic
syringe. Some drugs can also be
absorbed through the skin.AGROCHEMICALS
PHARMACEUTICALS
1 CROP SPRAYING
Fruit trees in an orchard are
sprayed with pesticides to control
insects and other pests that
would damage the fruit or the
trees. At the same time, care
must be taken not to kill helpful
insects, such as bees.