Levels of Organisation 2.

the levels in order (from small to large)

1. organelle

2. cell

3. tissue

4. organ

5. organ system

6. organism

Organelle

A component inside a cell that carries out a particular task (e.g. cell walls, cell membranes, mitochondrion…) NB. it is not the basic unit of living organisms, and cytoplasm is not considered an organelle.

Cell

Cells are the basic functional units of living organisms, all living organisms are made of cells. All cells come from pre-existing cells (e.g. guard cells, epithelial cells, red blood cells…)

Tissue

A tissue is a group of similar cells work together to carry out a specific function. (e.g. epithelial tissue, connective tissue, muscle tissue, meristematic tissues…)

Organ

An organ is a group of specific tissue that work together to carry out a specific function. (e.g. heart, liver, skin…)

Organ system

An organ system is made of a group of organs (respiratory system, digestive system, circulatory system…)

Why organelles are not the basic unit of living organisms?

Because organelles cannot live independently