Cells and Organisation
Cells and organisation is the study of the basic unit of life, the cell, and how cells combine to form tissues, organs, organ systems and whole organisms. It covers the structures found in animal and plant cells, how specialised cells are adapted to their function, and using a microscope to observe and measure cells, including magnification calculations.
Before you start
No specific prerequisites - this is a good place to start.
Method
- Learn the names and functions of the structures found in animal cells and in plant cells.
- Compare animal cell diagrams with plant cell diagrams and list the extra structures plant cells have.
- Learn the levels of organisation in order: cell, tissue, organ, organ system, organism.
- Learn how specialised cells, such as sperm cells and root hair cells, are adapted to their function.
- Practise magnification calculations using magnification = image size / actual size, converting units carefully.
- Learn the correct order of steps for preparing and viewing a microscope slide.
Worked example
A student draws a plant cell as seen under a microscope. The actual width of the cell is 25 micrometres. The width of the student's drawing is 30mm. Calculate the magnification of the drawing.
- Write down the magnification equation: magnification = image size / actual size.
- Convert both measurements to the same unit: 25 micrometres = 0.025mm (the drawing is already in mm).
- Substitute the values into the equation: magnification = 30 / 0.025.
- Calculate: 30 / 0.025 = 1200.
- State the final answer: magnification = x1200.
Practice questions
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Q1Which part of a cell controls what substances enter and leave it?Show answer
Answer: Cell membrane
Q2Name the jelly-like substance inside a cell where most chemical reactions take place.Show answer
Answer: Cytoplasm
Q3State one function of the chloroplast in a plant cell.Show answer
Answer: It absorbs light energy for photosynthesis.
Q4Put these in order of increasing size: organ, cell, tissue.Show answer
Answer: cell, tissue, organ
Q5A drawing of a cell has an image width of 40mm and a magnification of x800. Calculate the actual width of the cell in micrometres.Show answer
Answer: 50 micrometres (40/800 = 0.05mm = 50 micrometres)
Q6A root hair cell has an actual diameter of 15 micrometres. Calculate the width of a scale drawing of the cell magnified x2000, giving your answer in millimetres.Show answer
Answer: 30mm (15 micrometres = 0.015mm; 0.015 x 2000 = 30mm)
Exam-style questions
Written in the style of a KS3 Science exam paper, with a full mark scheme.
State two differences between a plant cell and an animal cell.
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A student's drawing of a nerve cell is 84mm long. The drawing has been magnified x600. Calculate the actual length of the cell, giving your answer in micrometres.
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Muscle cells, xylem cells and egg cells (ova) are all specialised for their function. Explain how the structure of each of these three cell types is adapted to help it carry out its function.
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Free printable worksheet
Want more practice on paper? Download the cells and organisation worksheet pack - 11 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.
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