It happened over 300 years in Holland

part of the body by 43 pairs of nerves. Twelve
pairs go to and from the brain, with 31 pairs going
from the spinal cord. There are nearly 63
kilometres of nerves running through our bodies.
Messages travel along the nerves as electrical
impulses. They travel at speeds up to
400kilometres per hour.
It takes about 20 seconds for a red blood cell to
circle the whole body.
(8) Except for red blood cells, all
other cells in our bodies have a
nucleus. Because it controls what
the cells does, the nucleus is often
called the brains of the cell. A
nucleus appears as a large dots in
the centre of a cell. The word nuclei
is used to refer to more than one
nucleus.
(9) Cells work to keep us healthy
and alive. As soon as they wear out,
they are replaced by new ones.
This is most noticeable with our skin.
Humans shed and regrow outer
skin cells about every 27 days; that
is almost 1,000 new skins in a
lifetime. But not all types of cells are
replaced. It is generally believed that
once brain cells die, new ones are
not created. This is often the
argument used in drug education
programs. Drugs and alcohol
destroy brain cells which can never
be replaced. Using and/or abusing
these substances can leave to permanent brain damage.

Whales and Fish: Creatures of the Deep

(1) Fish and whales are both
vertebrates, This means they both have
backbones. They also live in aquatic
environments. Except for a couple of species,
whales live only in the ocean water. Fish, however,
inhabit both fresh and salt waters. Whales are among the
largest animals on earth. Fish are among the smallest.
(2) Being mammals, whales are warm-blooded. This means they must maintain a