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2.2) Levels of organisation

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

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