S4 Biology UNIT 2: Multicellular organisms Cells, tissues and organs

Cells, tissues and organs

Cells, tissues and organs Learning intention: Describe the levels of organisation found in multicellular organisms. Why? Cell must be organised within organisms or they would not function properly.

Cells Cells show specialisation. This means they have a special shape or structure which allows them to carry out a specific function.

Organisation Animals have levels of organisation which allow their bodies to function efficiently.

Cells Animal have different levels of organisation. This is a smooth muscle cell, it can contract to bring about movement.

Tissues Specialised cells which perform a specific function group together to form a tissue. For example smooth muscle cells group together to form smooth muscle tissue.

Organs Tissues work together to form an organ with a specific function. For example the stomach contains smooth muscle and nervous tissue. The smooth muscle cells in the stomach can contract which allow the stomach to mix food with digestive juices.

Organs

Systems Organs work together forming a system. For example the stomach is part of the digestive system which includes the oesophagus and small intestine etc.

Cells Like animals, plants have different levels of organisation. For example phloem cells transport sugar around a plant.

Tissues Phloem cells join together and work with companion cells to form phloem tissue.

Organs Phloem tissue works alongside xylem tissue in an organ called the vascular bundle. The cells in plant organs are specialised to carry out a specific function. For example the phloem cells in the vascular bundle have holes in their end walls which allow sugar to pass easily from one cell to the next.

Organs

Systems The vascular bundle is part of the transport system found in plants. Which also includes the roots, leaves etc.

Cells, tissues and organs Collect a copy of the booklet. Complete the cells, tissues and organs section.