Page 56 - Biology Form Two

Biology for Secondary Schools

Absorption in the large intestine Procedure
The large intestine is part of the 1. Observe the parts of the digestive

alimentary canal that joins with the system of a mouse.
ileum. It has larger width than the 2. Identify the oesophagus, stomach,
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ileum. Most water carried in the liver, pancreas, duodenum, small
digestive system is absorbed in the intestine, and the large intestine.
colon. Its inner wall is folded to allow
the maximum absorption of water. 3. Describe what you have observed.

The colon also has some bacteria that
synthesise vitamins B , B , B and The digestive system of ruminants
1 2 12
K, although these vitamins are also Task 2.5
obtained from the foods we eat. Searchfrom the library and internet

There are no digestive enzymes in the sources for animations about digestion
colon. The undigested and indigestible process in ruminant animals. Observe
food materials are passed into the the animation. Then,
colon from the ileum by the process of (a) Describe the structures of the rumen,

peristalsis. Then, these materials are reticulum, omasum and abomasum.
transported into the rectum and finally (b) Explain the digestive processes that
eliminated from the body as waste occur in the four chambers in (a).
materials in the form of faeces. This is
the last step which is called egestion. Ruminants are herbivorous mammals
When there is enough accumulation that obtain food from plant sources.
of waste materials in the rectum, the The term ruminant comes from the
sphincter muscles at the anus relax and Latin word "ruminare" which means

allow faeces to pass out. This is called “to chew over again”. Therefore,
defecation or egestion. ruminants are animals that chew

food, swallow it, and later return it
Activity 2.1: Observe of the digestive to the mouth for further chewing. The
system of a mouse or rat returning of food to the mouth is called
regurgitation. The food returned to the
Material
Dissected mouse, forceps, and petri mouth is known as cud. Ruminants
dish have a rumen that is an extended
portion of the oesophagus where food
is temporarily stored and periodically

50 Student’s Book - Form Two

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