Question

Which of the following is an example of a single cell that does not function as a full-fledged organism?
A. White blood cell
B. Amoeba
C. Paramecium
D. Both A and B

Answer 1

Hint: Cells are the basic, functional and smallest unit of life. All organisms are made up of cells, and depending on the number of cells they can be either unicellular (single cell) or multicellular (more than one cell).

Complete answer:
Let us analyse the options and find the correct answer.

Option A: White blood cells or leukocytes are a component of blood. They are white in colour as they do not have haemoglobin and they help in providing defense against foreign bodies and microorganisms. Though they are single celled, they are not an example of a single cell which functions as a full-fledged organism. Therefore, this is the correct option.

Option B: Amoeba is an example of a unicellular organism which is generally found in water bodies like ponds, lakes, etc. Therefore, this is the incorrect option.

Option C: Paramecium is a genus of single celled protozoa and they are found in freshwater, brackish and marine water. Therefore, this is the incorrect option.

Option D: Option A is correct, but option B is incorrect, therefore, this is the incorrect option.

Thus, the correct option is A) White blood cells.

Note: On the basis of the number of cells, organisms are classified into two - single cell or unicellular and multicellular. The advantage of multicellular organism over unicellular organism are,
- Division of labour is seen at cellular, tissue, organ and organ system level.
- Injury to a cell does not cause death of the organism as it is seen in unicellular organisms.
- They have a longer life span than unicellular organisms.