Question

(a) What are unicellular organisms? Name two unicellular organisms.
(b) What are multicellular organisms? Name two multicellular organisms.

Answer 1

(a). Unicellular organisms:

1. When all the vital functions which are necessary for life are performed by a single cell then such cell is called the unicellular organism.
2. Some examples of unicellular organisms are Amoeba, Paramecium etc.​
3. Bacteria are also unicellular organisms.

(b). Multicellular organisms:

1. Multicellular organisms are the organisms which are made from a large number of cells or which are made from multiple numbers of cells.
2. Examples include human beings, complex plants and animals like dear, elephant, etc​.
3. Multicellular organisms show a level of organisation in which cells are organised into tissues, many tissue form organs, many organs form organ system, and finally the whole living organism.
4. It can be shown as follows:

Cell⟶Tissues⟶Organs⟶Organ system⟶Organism.