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Gas exchange in Insects
There are tiny holes
called spiracles along
the side of insects.
The spiracles are
openings of small tubes
running into the insect's body; the larger ones are called tracheae
and the smaller ones being called tracheoles.
The ends of these tubes, which are in contact with individual cells,
contain a small amount of fluid in which the gases are dissolved. The
fluid is drawn into the muscle tissue during exercise. This increases
the surface area of air in contact with the cells. Gases diffuse in
through the spiracles and down the tracheae and tracheoles.
Ventilation movements of the body during exercise may help this
The spiracles can be closed by valves and may be surrounded by
tiny hairs. These help keep humidity around the opening, ensure
there is a lower concentration gradient of water vapour, and so less
is lost from the insect by evaporation.
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Gas Exchange in Plants
Plants obtain the gases they need through their leaves. They
require oxygen for respiration and carbon dioxide for
The gases diffuse into the intercellular spaces of the leaf through
pores, which are normally on the underside of the leaf - stomata.
From these spaces they will diffuse into the cells that require them.…read more