Page 46 - Biology Form Two

Biology for Secondary Schools

small intestine, large intestine and anus. Premolars
The first step before the beginning of the These are located just behind the
digestion process is called ingestion, canines. They have a broad shape
which is the process of taking in food and are specialised for crushing and
through the mouth. When food is in the grinding food. An adult person has eight
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mouth, digestion begins whereby food premolars, four in the lower jaw and four
is broken down into small particles
by the mechanical process known as in the upper jaw.
chewing or mastication. The process Molars

of chewing is done by the teeth. In They are located at the back of the
mammals, there are various types of mouth. They have a broader shape than
teeth which differ in shape, size, and premolars. They are specialised for
functions. This condition is known grinding and crushing food into small
as heterodonty, where different teeth particles that can be easily swallowed.
are specialised for various tasks like An adult person has twelve molars, six
biting, tearing, grinding, and crushing in the lower jaw and six in the upper
food. There are four different types of jaw.

teeth in human beings, namely incisors,
canines, premolars and molars (Figure
2.2).

Incisors
These are found in the front part of
the mouth. They have sharp chisel-like
shape specialised for biting and cutting
food or other substances. An adult has
eight incisors, four in the upper jaw Incisors Canines Premolars
and four in the lower jaw.

Canines
These are located next to the incisors.
They have a sharp pointed shape

specialised for holding and tearing
food. An adult person has four canines,
two in the upper jaw and two in the Molars

lower jaw. Figure 2.2: Types of human teeth

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