Notes On Digestion in Amoeba - CBSE Class 7 Science

Amoeba

The amoeba is a microscopic unicellular, eukaryotic organism. It belongs to the group protozoa. The name comes from the Greek word ‘amoibe’ meaning ‘change’.


                                                       
General characteristics of amoeba

Amoebae are found at the bottom of fresh water bodies like ponds and lakes, even in a gutter or muddy water. Some of them are also found in damp soil and food.
  • An amoeba contains jelly-like cytoplasm. In the cytoplasm are present the cell organelles like nucleus, food vacuoles and contractile vacuole.
  • An amoeba takes in oxygen, gives off carbon dioxide through the cell membrane by the mechanism of diffusion. It takes in dissolved oxygen from water.
  • Amoeba possesses false feet called as pseudopodia. Pseudopodia are used to capture food as well as for locomotion.
  • An amoeba can move in all directions using temporary feet-like structures called pseudopodia. It can change its shape with the help of these pseudopodia to exhibit locomotion.  
  • Amoeba is a simple, unicellular organismwhich reproduces by binary fission. The division begins with the division of the nucleus.
  • Amoeba forms a cyst in unfavourable conditions.
  • Amoeba either lives as a free-living organism or as a parasite.  
  • Parasite causes a disease amoebiasis. This is the intestinal disease caused by the parasite Entamoeba histolytica. It is symptomatic during excess infection percentage. The patients experience blood motions with mucus. It is advised to wash hands with soap after using toilet.
  • Some species of amoeba living in the mouth and intestine are not dangerous to human beings.

Nutrition in amoeba
  • Amoeba is omnivorous organism. It feeds on plants, microorganisms, smaller organisms etc. Nutrition is holozoic. 
  • Amoeba does not possess any mouth. It can ingest through any place on the surface of cell membrane. 
  • Amoeba has a sense of ability to accept food molecules and reject non-food particles. 
  • Amoeba extends its pseudopodia when the food is found. 
  • Pseudopodium just wraps around the food molecule and forms a food vacuole around it. 
  • An amoeba engulfs its prey along with a droplet of water in the food vacuole inside the cytoplasm. 
  • Food vacuoles circulate in the cytoplasm by streaming movements. 
  • The prey can be killed and digested with the help of the digestive enzymes secreted by the food vacuole. 
  • Digestion is intracellular in amoeba. 
  • The diffusible substances resulting from the process of digestion are uilised in synthesisng more protoplasm. They are also stored as reserved food. They are also used to generate energy by the process of respiration.
  • The undigested food is sent out through an opening appearing on the vacuole by changing the shape of the body. This process is called as egestion.

  


Summary

Amoeba

The amoeba is a microscopic unicellular, eukaryotic organism. It belongs to the group protozoa. The name comes from the Greek word ‘amoibe’ meaning ‘change’.


                                                       
General characteristics of amoeba

Amoebae are found at the bottom of fresh water bodies like ponds and lakes, even in a gutter or muddy water. Some of them are also found in damp soil and food.
  • An amoeba contains jelly-like cytoplasm. In the cytoplasm are present the cell organelles like nucleus, food vacuoles and contractile vacuole.
  • An amoeba takes in oxygen, gives off carbon dioxide through the cell membrane by the mechanism of diffusion. It takes in dissolved oxygen from water.
  • Amoeba possesses false feet called as pseudopodia. Pseudopodia are used to capture food as well as for locomotion.
  • An amoeba can move in all directions using temporary feet-like structures called pseudopodia. It can change its shape with the help of these pseudopodia to exhibit locomotion.  
  • Amoeba is a simple, unicellular organismwhich reproduces by binary fission. The division begins with the division of the nucleus.
  • Amoeba forms a cyst in unfavourable conditions.
  • Amoeba either lives as a free-living organism or as a parasite.  
  • Parasite causes a disease amoebiasis. This is the intestinal disease caused by the parasite Entamoeba histolytica. It is symptomatic during excess infection percentage. The patients experience blood motions with mucus. It is advised to wash hands with soap after using toilet.
  • Some species of amoeba living in the mouth and intestine are not dangerous to human beings.

Nutrition in amoeba
  • Amoeba is omnivorous organism. It feeds on plants, microorganisms, smaller organisms etc. Nutrition is holozoic. 
  • Amoeba does not possess any mouth. It can ingest through any place on the surface of cell membrane. 
  • Amoeba has a sense of ability to accept food molecules and reject non-food particles. 
  • Amoeba extends its pseudopodia when the food is found. 
  • Pseudopodium just wraps around the food molecule and forms a food vacuole around it. 
  • An amoeba engulfs its prey along with a droplet of water in the food vacuole inside the cytoplasm. 
  • Food vacuoles circulate in the cytoplasm by streaming movements. 
  • The prey can be killed and digested with the help of the digestive enzymes secreted by the food vacuole. 
  • Digestion is intracellular in amoeba. 
  • The diffusible substances resulting from the process of digestion are uilised in synthesisng more protoplasm. They are also stored as reserved food. They are also used to generate energy by the process of respiration.
  • The undigested food is sent out through an opening appearing on the vacuole by changing the shape of the body. This process is called as egestion.

  


Videos

Activities

Activity 1
Stem.org.uk has designed a template with many activities. Click on 'Amoeba' button on the template. Inside this, students are provided with instructions. When the student selects the 'Play the movie' button, amoeba is displayed along with the formation of the food vacuole, pseudopodia, contractile vacuole etc. Depending on the selected option, animlation is shown. Hotspots are also highlighted to explain the paths. There is also another button 'Explore the science'. This is an additional information provided to the student about digestion in amoeba. There are some features provided on the template. These include Inform, Question, Challenge, Hypothesise. 
Go to Activity

Activity 2
lcmrschooldistrict.com has provided a clear animation about the 'Digestion in amoeba'.Student has to click on the different parts of amoeba to know the information about it. When the student clicks on the food vacuole, the digestion of food in it can be observed clearly. All the parts of amoeba are labelled and represented in a diagram. 
Go to Activity

References

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