8th Class Science Cell - Structure and Functions Unicellular Organism

     Unicellular Organism

The organisms made up of single cell are called unicellular organisms. Most of the microorganisms, such as, bacteria is made up of single cell. The figure given below is of a cluster of Escherichia coli bacteria, which is magnified 10,000 times. Unicellular organisms are divided into two types:

(i) Prokaryotic

(ii) Eukaryotic cell  

             Unicellular Organism  

The prokaryotic cells are those cells, whose nucleus is not bounded by nuclear membrane. The nucleus and cytoplasm cannot be differentiated. For example, Bacteria, Archaea etc.

The Eukaryotic cells are those cell, whose nucleus is bounded by the nuclear membrane. These cells are very complex and nucleus can be easily differentiated from the rest of the cell.

        Drik went for a visit to a national park. He had not taken water bottle with him. Due to intense heat, he was feeling thirsty and could not resist himself from drinking water from the river. The very next day he was suffering from lose motion and vomiting. On consulting doctors, he was told that that, he was suffering from diarrhoea. Which organism was responsible for this?

(a) Virus

(b) Bacteria

(c) Plasmodium

(d) Flagella

(e) None of these

Answer: (b)

Explanation

Diarrhoea is caused due to the bacteria in the water and food.

We know that the milk can be changed into the curd. This conversion is done by the bacteria. Similarly, there are many such organisms, useful to us. The bacteria, which convert the milk into the curd is_______.

(a) Lactobacillus

(b) Salmonella

(c) E.coli

(d) L. monocytogenes

(e) None of these

Answer: (a)

Explanation

The bacteria which is found in milk is Lactobacillus.