How can a single-celled organism carry out all its life processes when billions of cells. Class 9

How can a single-celled organism carry out all its life processes when billions of cells. Class 9

(Page 236)

Question 1.

How can a single-celled organism carry out all its life processes when billions of cells are required to perform similar functions in multicellular organisms like us? Class 9

Answer:

A single-celled organism carries out all its life processes within that single cell itself. The one cell performs all functions such as nutrition, respiration, excretion, reproduction, and movement. In multicellular organisms like humans, the body is so large and complex that billions of specialised cells are needed, with each group of cells performing specific functions (for example, muscle cells for movement, nerve cells for coordination, etc.).

In contrast, a single cell in unicellular organisms is self-sufficient - it does not need to depend on other cells. All the necessary organelles and structures within that one cell work together to keep the organism alive. For example, Amoeba uses pseudopodia for movement and engulfing food, a cell membrane for gas exchange, and the nucleus for reproduction, all within a single cell.