2.2) Levels of organisation
Most cells, when they have finished dividing and growing, become specialised.
- They do one particular job
- They develop a distinct shape
- Special kinds of chemical change take place in their cytoplasm.
‘Division of labour’- the specialisation of cells to carry out particular functions in an organism.
Palisade mesophyll cells – photosynthesis
Nerve cells – conduction of impulses
Sperm and egg cells – reproduction
Tissue is a group of cells with similar structures, working together to perform a shared function.
Eg. Bone, nerve, muscle, epidermis, xylem
Organ is a structure made up of a group of tissues, working together to perform a specific function.
Eg. Stomach, heart, lungs, intestines, brain, eyes
Organ system is a group of organs with related functions, working together to perform a body function.
Eg. Nervous and circulatory system