Question

A cell is a building unit of an organism. Select the correct statements.
A. In unicellular organisms, a single cell is capable of performing all the functions of life.
B. In multicellular organisms, a single cell is capable of performing all the functions of life.
C. Both A and B.
D. None of these.

Answer 1

Hint: A cell is defined as a structural and functional unit of life. Cell performs all the necessary life processes like nutrition, digestion, respiration, excretion, reproduction, etc.

Complete answer:
We know the typical and classical definition of the cell as ‘Cells are called the structural and functional unit of life’. This definition only tells us that a cell is the building unit of an organism.
If we take an example of the unicellular organism like Paramecium or amoeba that have an only single cell as a whole body. This single-cell only performs all the necessary life processes like nutrition, digestion, respiration, excretion, reproduction, etc. this indicates that in unicellular organisms, a single cell is capable of performing all the functions of life.

Hence, the statement in option (A) is correct.

Now, for multicellular organisms that are made up of multiple cells, it is true that a cell is a structural and functional unit of life. But in multicellular organisms, a single cell is not capable of performing all the functions of life. Multicellular organisms like hydra have cellular grade body organization, meaning they have different types of specialized cells to perform life processes. Then in birds, mammals or amphibians, organ system grade body organization can be seen, where special cells form tissues and then organs and organ systems. For example, the blood circulation system consists of blood tissue, veins, arteries, and heart. Digestion system requires the mouth, esophagus, stomach, intestine, etc. to carry out the process of digestion. So, in multicellular organisms, a single cell is not sufficient to carry out all the life processes.
Hence, the statement in option (B) is incorrect.

Therefore, we can say that option (A) In unicellular organisms, a single cell is capable of performing all the functions of life.

Note:
 We need to read the question very carefully. It has been asked whether a single cell is capable of performing all the functions of life in case of the unicellular and multicellular organism. So, for a unicellular organism, a single cell is capable of performing all the necessary life processes. But for a multicellular organism, a single cell is not capable of performing all life processes.