Nutrition: Energy is required for physiological function. Food is the source ofthis
energy. Nutrition is a process, By this process Amoeba performs its food
ingestion, digestion, absorption, assimilation and excretion of faecal
materials Body reorganization and growth also occur through this process.
Food: Amoeba takes small algae, bacteria, diatom and various microorganisms as
its food.
Process of intake of food: Amoeba has no digestive system. For the intake offood there is no mouth
or any other fixed organ. At the time of food intake Amoeba becomes attached to
a surface and with the help of pseudopodia ingest food by various methods. It
can select organic and inorganic foods. It takes about 2 to 3 minutes to ingest
the food. Amoeba intakes food mainly by the following five processes:
1. Circumvallation
2. Circumfluence
3. Import
4. Invagination
5. Pinocytosis
1. Circumvallation: In this process Amoeba takes mobile and solid foodsubstances. With the
help of pseudopodia it surrounds the food material. Without touching the food
material, the edges of the pseudopodia come close together and with the
ectoplasmic membrane form the food vacuole along with water. When the
pseudopodia surround the food material it looks like a cup. It is called
"Food cup". The ectoplasm transforms into endoplasm and protects
2. Circumfluence: In this process Amoeba takes immobile food materials.Immediately after
coming in contact with the food material, amoeba forms a "food cup"
and by stretching the pseudopodia it brings the enclosed food in direct contact
with the body. In this way, Amoeba takes the food material inside the body.
3. Import: If any food material comes on its body, by being
motionless andwithout stretching any pseudopodia, Amoeba makes the food
inactive. Then the inactive food material is taken inside the body. This is
called import process.
4. Invagination: When the body of amoeba comes in contact with any
foodparticle it secretes
sticky substance and fixes it with the body surface. Besides Amoeba
secretes a kind of toxic juice from the body which kills the living food
material. The ectoplasm along with the food enters the endoplasm in the form of
a tube. Then the plasma membrane disappears and forms a food vacuole. In this
process no pseudopodium is required to receive the food material.
5. Pinocytosis: In this process Amoeba takes liquid food materials. At manytimes in
different parts of the body surface of Amoeba the plasmalema gets folded and
enters into the endoplasm,"as a result of which a tube like structure is
formed. This tube is called pinocytic tube. With liquid food materials the tube
forms pinosome or small cavities, which later on is taken within the endoplasm.
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