Principles of organisation — AQA GCSE Biology
Test yourself on Principles of organisation with AQA GCSE practice questions.
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Principles of organisation explained
In multicellular organisms, cells that share a similar structure and carry out the same job are grouped together to form a tissue.
Read the full explanation
Working as a tissue allows a job to be done more effectively than a single cell could manage alone. For example, muscular tissue contains muscle cells that contract to move parts of the body, glandular tissue contains secretory cells that release substances such as enzymes, and epithelial tissue covers and protects surfaces. In plants, palisade mesophyll tissue contains many chloroplasts for photosynthesis, while xylem tissue transports water and mineral ions. Recognising tissues as the level between cells and organs helps you explain how the organ systems of a plant or animal are built up and how each level contributes to the functioning of the whole organism.
Your focus
- Define a tissue as a group of cells with a similar structure and function.
- Identify named examples of tissues in plants and animals and state their functions.
- Explain how tissues contribute to the structure and function of organs and organ systems.
Principles of organisation exam tips
Marking Points
- Define a tissue as a group of cells with a similar structure and function.
- Give named examples of tissues, such as muscular, glandular, epithelial, xylem or palisade mesophyll tissue.
- Explain that cells in a tissue work together to carry out a shared function more efficiently.
- Relate the structure of the tissue to its function, for example muscle tissue contains contractile cells that shorten to produce movement.
- Place tissue correctly in the hierarchy: cells form tissues, tissues form organs, organs form organ systems.
- Distinguish tissue from organ by noting that an organ contains several different tissues working together.
Examiner Tips
- 💡Learn at least two animal and two plant tissue examples with their functions so you can answer both context and definition questions.
- 💡When defining a tissue, include both parts of the definition: similar structure and shared function.
- 💡Use the hierarchy cell, tissue, organ, organ system, organism to structure answers about levels of organisation.
Common Mistakes
- Calling a single cell a tissue; the correction is that a tissue is a group of similar cells working together.
- Describing an organ as a tissue; the correction is that an organ is made of several tissues and performs a specific function.
- Assuming all cells in a tissue are identical in every way; the correction is that they share a similar structure and function, which may still vary in detail.