Cell Specialization Quiz: Multicellular Organisms and Cell Hierarchy

Study Notes

Levels of Organisation in Multicellular Organisms

Multicellular organisms are composed of many cells, which are the building blocks of life and the first level of organisation.
The second level of organisation is a tissue, which is a group of similar cells that work together to perform a specific function.
Examples of animal tissues include muscle tissue, which enables movement, and nervous tissue, which facilitates message transmission.
Examples of plant tissues include xylem, which transports water around the plant.
The third level of organisation is an organ, which is made up of different tissues that work together to perform a specific function.
Main organs in animals and plants include:
- Brain: controls the body
- Lungs: exchange oxygen and carbon dioxide
- Heart: pumps blood
- Liver: removes toxins and produces bile
- Intestine: absorbs nutrients
- Stomach: digests food
- Kidney: filters blood and produces urine
- Bladder: stores urine
- Stem: supports the plant
- Leaf: absorbs sunlight for photosynthesis
- Root: anchors the plant and absorbs water and minerals
The fourth level of organisation is an organ system, which is a group of organs that work together to perform a specific function.
Examples of organ systems include:
- Circulatory system: transports materials in the blood
- Respiratory system: exchanges oxygen and carbon dioxide
- Reproductive system: produces new organisms
Plant structure is primarily organised into organs or tissues, with flowers being an exception as they contain both male and female sex organs, forming the reproductive system.
The fifth level of organisation is a multicellular organism, which is made up of multiple organ systems working together to perform all necessary life processes.