Exponential growth of cells is a characteristic feature of tissue culture cells.

Explanation:
Exponential growth means the number of cells increases rapidly with time. Tissue culture refers to the growth of cells in vitro, i.e. outside the organism in a controlled environment. Tissue culture cells are isolated from the tissues of plants or animals and grown in laboratory conditions.

Some factors that contribute to the exponential growth of tissue culture cells are:

1. Optimal growth conditions: Tissue culture cells require specific nutrients, pH, temperature, and other environmental factors to grow and divide rapidly.

2. Absence of limiting factors: In vivo, cells may face competition for resources or space, which can limit their growth. In tissue culture, these limiting factors can be controlled or eliminated.

3. Continuous division: Some tissue culture cells, such as cancer cells, have lost the ability to stop dividing and can continue to grow indefinitely.

Applications of tissue culture cells:

1. Study of cell biology: Tissue culture cells are used to study the behavior of cells in a controlled environment, which can help in understanding cell biology and disease processes.

2. Drug discovery: Tissue culture cells can be used to test the efficacy and toxicity of drugs before they are tested in vivo.

3. Biotechnology: Tissue culture cells can be used to produce large quantities of proteins or other molecules for medical or industrial purposes.

Unicellular organisms grow by cell division it can be exponentional