AQA · A-Level · Biology
Course version: 7402 · Version from Sept 2016
Required practical 5: Dissection of animal or plant gas exchange system or…
Full specification wording
Mass transport in animals: Required practical 5: Dissection of animal or plant gas exchange system or mass transport system or of organ within such a system.
Dissection techniques and biological drawing conventions are assessable.
Checked against the AQA 7402 specification (opens in a new tab) on .
- Point 14 of 14
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Dissection techniques and biological drawing conventions are assessable. When dissecting an organ like a heart or fish gills, safety is paramount. Use a scalpel or scissors on a dissecting board, cutting away from your body. Disinfect surfaces and wash hands afterwards to minimise infection risk. Before cutting a heart, orientate it by locating the thicker left ventricle wall. Record observations using biological drawings. These must feature continuous, unbroken lines with no shading or sketchy strokes. Draw structures in proportion, include a title, and use straight, ruled label lines that do not cross or have arrowheads. Include a magnification or scale bar where appropriate to indicate size.
What earns the marks
- State a named safety or hygiene precaution with a valid reason, such as cutting away from the body to prevent injury.
- Identify the left side of a mammalian heart by locating the thicker muscular wall of the left ventricle.
- Produce a biological drawing using continuous, unshaded lines with structures drawn in correct proportion.
- Draw straight, non-crossing label lines without arrowheads.
- Calculate actual size using the formula: actual size = image size / magnification, providing appropriate units.
Common mistakes and how to put them right
Shading or using short sketchy strokes.
Put it right: Use single, continuous, unbroken lines for biological drawings.
Assuming actual size must always be converted to micrometres.
Put it right: Retain the unit you measured in (e.g., millimetres) unless the question specifically requests a conversion.
Drawing label lines that cross each other or end in arrowheads.
Put it right: Use a ruler to draw straight label lines that stop exactly at the structure without crossing or using arrows.
Stating a safety precaution without a justification.
Put it right: Pair a precaution with its specific biological or safety reason (e.g., wash hands to remove pathogens).
Exam tips
- Always link a safety precaution to its specific reason when describing dissection methods.
- Practise rearranging the magnification equation and ensure you state the units clearly in your final answer.
Try the lesson
The start of the Mass transport in animals: Required practical 5: Dissection of animal or plant gas exchange system or mass transport system or of organ within such a system. lesson, made from checked teaching notes for this specification point.
Have a go first
A student dissects a mammalian heart to examine the internal structures. After cutting open the ventricles, the student observes that one ventricular wall is much thicker than the other. Which conclusion about the heart's function is best supported by this observation?
Listen
Dissection techniques and biological drawing conventions are assessable. When dissecting an organ like a heart or fish gills, safety is paramount. Use a scalpel or scissors on a dissecting board, cutting away from your body. Disinfect surfaces and wash hands afterwards to minimise infection risk. Before cutting a heart, orientate it by locating the thicker left ventricle wall. Record observations using biological drawings. These must feature continuous, unbroken lines with no shading or sketchy strokes. Draw structures in proportion, include a title, and use straight, ruled label lines that do not cross or have arrowheads. Include a magnification or scale bar where appropriate to indicate size. A strong answer earns marks for these points. State a named safety or hygiene precaution with a valid reason, such as cutting away from the body to prevent injury. Identify the left side of a mammalian heart by locating the thicker muscular wall of the left ventricle. Produce a biological drawing using continuous, unshaded lines with structures drawn in correct proportion. Draw straight, non-crossing label lines without arrowheads. A common slip: Shading or using short sketchy strokes. Instead, use single, continuous, unbroken lines for biological drawings. Exam tip: Always link a safety precaution to its specific reason when describing dissection methods.
Key words
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Dissection technique and safety
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Biological drawing conventions
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Magnification and scale
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See every definition
- Dissection technique and safety
- Use a scalpel or scissors on a dissecting board, cutting away from your body, and disinfect surfaces and wash hands afterwards to minimise infection risk.
- Biological drawing conventions
- Feature continuous, unbroken lines with no shading or sketchy strokes, draw structures in proportion, include a title, and use straight, ruled label lines that do not cross or have arrowheads.
- Magnification and scale
- Include a magnification or scale bar where appropriate to indicate size.
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