Content Curator
Amoeba is a unicellular organism that engulfs tiny particles of food with the help of pseudopodia also known as the “false feet”. It has the capability to change its shape. They are typically found near water bodies such as lakes, ponds, rivers and other fresh water surfaces. The amoeba has a scientific and genus name called the “Amoeba Proteus”. It belongs to the family amoebidae that replicates itself through a process of asexual reproduction called binary fission.
| Table of Content |
Keyterms: unicellular organism, pseudopodia, asexual reproduction, binary fission, amoebidae, protozoa
What is Amoeba?
[Click Here for Sample Questions]
Amoeba is a protozoa consisting of a single cell that uses its false feet pseudopodia to capture and engulf its food. It is often found in fresh water surfaces like lakes, ponds, rivers and other wet regions. It was first discovered in the year 1755 by a German naturalist August Johann Rösel Von Rosenhof.
Check out:
Structure of Amoeba
[Click Here for Sample Questions]
As the amoeba is a unicellular organism it consists of a simple body design. Some of the features characterized by all the amoebas are as follows:
They move via pseudopodia. The cytoplasm pushes the plasma membrane either inward or outward creating projections similar to fingers. Amoebas may have multiple pseudopodia and result in drastic change of its shape.
The three parts of amoeba’s structure are cytoplasm, plasma membrane and nucleus. Cytoplasm consists of two layers that are outer ectoplasm and inner endoplasm. Plasma membrane embodies proteins and lipid molecules within the thin and double layer membrane. Nucleus is the central part that controls reproduction and other important functions. It is large and shaped like a disk.
An amoeba consists of other cellular organelles that are contractile vacuole, Golgi apparatus, mitochondria and fat globules. Amoeba reproduces through the biological process called binary fission. It is a asexual reproduction. Lifespan of an amoeba is two days. But as they replicate through the binary fission, amoebas can be considered immortal.
In unfavorable living conditions, the amoeba transforms itself into a protective ball called microbial cyst. It changes back once the living conditions become better. The full body of amoeba stays in direct contact with the environment. There are no specific organs for gas exchange or food intake.
Classification of Amoeba
[Click Here for Sample Questions]
The amoeboid cells only consist of a true single nucleus. So, it is neither classified as a plant or an animal and is generally mentioned among the Protista kingdom. Amoeba classification in the scientific representations are as follows:
Domain: Eukaryota
Kingdom: Amoebozoa
Phylum: Tubulinea
Order: Tubulinida
Family: Amoebidae
Genus: Amoeba
Species: Proteus, animalcule, dubia, animalcule
Nutrition in Amoeba
[Click Here for Sample Questions]
The amoeba eats tiny plants and animals as food that are available in the water. The mode of nutrition is Holozoic. It spreads its pseudopodia and engulfs the food nearby.
Steps Involved in Amoeba Nutrition:
Food particle is near the amoeba body
Step 1: Amoeba takes in food by making temporary finger-like projections of its body surface called pseudopodia.
Step 2: When the pseudopodium fuses with the food particle, it forms a food vacuole.
Step 3: Complex substances are broken down into simpler substances inside the food vacuole.
Step 4: These simple substances are then diffused into the cytoplasm.
Step 5: The remaining unwanted material is taken to the surface of the body and thrown out. The cell membrane is ruptured In amoeba to remove undigested food materials from its body.
Read More:
Things to Remember
- Amoeba is a protozoa consisting of a single cell that uses ‘false feet’ pseudopodia to capture and engulf its food.
- It is generally found in lakes, ponds, rivers and other fresh water surfaces.
- It was first discovered in the year 1755 by a German naturalist August Johann Rösel Von Rosenhof.
- The three parts of amoeba’s structure are cytoplasm, plasma membrane and nucleus.
- Amoeba follows Holozoic nutrition.
- The steps involved in the nutrition of Amoeba are Ingestion, Digestion, Absorption, Assimilation and Egestion.
Sample Questions
Ques. How many parts of Amoeba are there? (3 marks)
Ans. The amoeba consists of three parts: Cytoplasm, plasma membrane and nucleus.
Cytoplasm consists of two layers that are outer ectoplasm and inner endoplasm.
Plasma membrane embodies proteins and lipid molecules within the thin and double layer membrane.
Nucleus is the major part that controls reproduction and other functions within the body. It is large and is in disk shape.
Ques. Describe the nutrition in Amoeba? (3 marks)
Ans. Amoeba follows Holozoic nutrition. It engulfs the solid food particles that are digested after being acted upon by the enzymes. The steps involved in the nutrition of Amoeba are as follows:
By spreading it’s projection, it engulfs the food nearby. The pseudopodia capture the food particles and push them into the plasma membrane. A food vacuole is formed when pseudopodia fuses acts upon the food. Later, the complex and larger food particles are broken down to simple substances. These are then diffused into the cytoplasm.
To remove the undigested waste material, the cell membrane is ruptured and the food particles are ejected out.
Ques. How does Amoeba affect Humans? (3 marks)
Ans. When an individual unknowingly drinks water containing Amoeba, it enters the body through the nose and infects people. From the nose it travels to the brain and causes severe damage to the nervous system. This is often observed in the people going for fishing or swimming in the fresh water surfaces.
In case an individual gets infected, he may possibly die within a week showing symptoms such as fever, headache, nausea, vomiting, lack of sense and taste, stiff neck, confusion, loss of balance and others.
Ques. Why is amoeba considered immortal? (2 marks)
Ans. Amoeba undergoes natural death. Though it has a lifespan of only two days, it replicates and reproduces at a rapid rate within these days. Each daughter cell is a replica of the parent cell. They consistently reproduce asexually by the process of binary fission.
They live faster than it occurs and eventually repair the normal wear and tear. Only during unfavorable living conditions, the amoeba finds it difficult to live. But the organism does not die based on age. So, they are called immortal.
Ques. Can amoeba regenerate if cut? (2 marks)
Ans. Amoeba cannot reproduce if it is cut. The unicellular organism doesn’t follow the regeneration process. In regeneration, one cell of the organism can reproduce another whole organism. While, the amoeba is only single celled. It cannot reproduce a whole new cell.
If any of the cells is cut, the amoeba cannot reproduce or replicate.
Ques. How many nuclei can an amoeba have? (2 marks)
Ans. The unicellular amoeba consists of cytoplasm, stiff cell membrane and a nucleus. The nucleus is found to be floating in the cytoplasm. Some of the species may have one nucleus, while some others may have hundreds of nuclei. Generally, the amoeba consists of only one nucleus.
Ques. How does amoeba reproduce? (2 marks)
Ans. Asexual reproduction can be observed in amoeba. The biological process is called binary fission. In this process, a single cell is split into two. First, the genetic material (DNA) of the cell replicates and divides the amoeba into two daughter cells. This process is called Karyokinesis. It is during this process that the DNA turns into condensed chromosomes to ease the separation.
Later, the cytoplasm is also divided into the two daughter cells. So, two daughter cells with a nucleus and Cytoplasm are formed. The entire process may take 30 minutes to one hour.
Also Read:
Comments