Principles of Organisation
Revise Principles of Organisation for GCSE Biology with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Learn the hierarchy of organisation: cells build tissues, tissues build organs, organs build organ systems, and organ systems build the whole organism.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
Living organisms are organised in a hierarchy, from the smallest unit upwards. Cells are the basic building blocks of all living things.
Similar cells working together form a tissue. Different tissues working together form an organ, and organs working together form an organ system, which carries out a particular function within the whole organism.
The order runs cells, tissues, organs, organ systems, organism. The stomach is a useful example: it contains muscular tissue to churn food, glandular tissue to produce digestive juices, and epithelial tissue covering the inside and outside — three tissues cooperating in one organ.
Revision notes
The hierarchy
Cells → tissues → organs → organ systems → organism.
A tissue is a group of similar cells with a similar function. An organ is an aggregation of different tissues performing a specific function. An organ system is a group of organs working together.
The stomach as an example
Muscular tissue churns the food. Glandular tissue produces digestive juices containing enzymes. Epithelial tissue covers the inside and outside of the organ.
Three different tissues therefore cooperate within a single organ, which is exactly what the definition of an organ describes.
Organ systems
The digestive system is a group of organs — including the stomach, small intestine, liver and pancreas — working together to digest and absorb food.
Several organ systems together make up the whole organism.
Key points
- Cells are the basic building blocks of all living organisms.
- A tissue is a group of similar cells with a similar function.
- An organ is made of several different tissues.
- An organ system is a group of organs working together.
- The order is cells, tissues, organs, organ systems, organism.
- The stomach contains muscular, glandular and epithelial tissue.
Worked examples
Example 1
Put the following in order of increasing size: organ, cell, organ system, tissue. [1 mark]
Model answer
Cell, tissue, organ, organ system (1 mark).
Example 2
Name three tissues found in the stomach and give the function of each. [3 marks]
Model answer
Muscular tissue, which churns the food (1 mark). Glandular tissue, which produces digestive juices containing enzymes (1 mark). Epithelial tissue, which covers the inside and outside of the stomach (1 mark).
Example 3
Explain the difference between a tissue and an organ. [2 marks]
Model answer
A tissue is a group of similar cells working together to perform a particular function (1 mark), whereas an organ is made of several different tissues working together to perform a specific function (1 mark).
Common mistakes
Confusing a tissue with an organ.
A tissue is one cell type; an organ contains several different tissues.
Getting the hierarchy order wrong.
It runs from smallest to largest: cells, tissues, organs, organ systems, organism.
Naming only one stomach tissue.
Three are required: muscular, glandular and epithelial.
Calling the digestive system an organ.
It is an organ system — a group of organs working together.
Exam tips
- Learn the hierarchy as a single sequence you can recite.
- Use the stomach as your worked example of an organ.
- Give the function alongside each tissue you name.
- Say different tissues when defining an organ.
Key terms
- Tissue
- A group of similar cells working together.
- Organ
- A structure made of several different tissues.
- Organ system
- A group of organs working together.
- Epithelial tissue
- Tissue covering the inside or outside of an organ.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.