AT skills covered by this practical activity: AT 1, 3, 4, 6 and 8.

The idea

This activity develops key apparatus and techniques (AT). AT 1 involves using apparatus to make accurate measurements, such as measuring a transect line. AT 3 requires observing and measuring biological changes in the field. AT 4 covers the safe and ethical use of living organisms, ensuring minimal disruption to habitats. AT 6 involves applying sampling techniques, such as using random quadrats or systematic transects to investigate organism distribution. AT 8 (using qualitative reagents to test for biological molecules) is a distinct skill. While not part of standard ecological sampling, synoptic questions may link it to ecology by asking how to test sampled plants for starch using iodine to assess photosynthesis.

What earns the marks

• Selects and uses appropriate apparatus to make accurate measurements, such as using a tape measure to lay out a transect line (AT 1).
• Uses appropriate apparatus and techniques for the observation and measurement of biological processes in the field (AT 3).
• Safely and ethically uses living organisms to measure responses to the environment, ensuring organisms and habitats are not harmed (AT 4).
• Applies appropriate sampling techniques, such as random quadrats or systematic transects, to investigate organism distribution (AT 6).
• Identifies that using qualitative reagents to test for biological molecules (AT 8), such as iodine for starch, is a distinct procedure that can be synoptically linked to ecological studies.

Common mistakes and how to put them right

• Placing quadrats only where organisms are obvious, which biases results.

  Put it right: Use a random number generator to determine coordinates for quadrat placement to ensure valid data (AT 6).

• Misunderstanding AT 4 as only applying to laboratory animals.

  Put it right: AT 4 includes the ethical handling of plants and animals in their natural habitat, such as avoiding trampling.

• Assuming chemical tests for biological molecules (AT 8) are conducted directly in the field as part of standard population sampling.

  Put it right: Recognise that AT 8 is a separate laboratory procedure, even if the plants were collected during fieldwork.

Exam tips

• When describing sampling (AT 6), explicitly state how you achieved randomness (e.g., using a random number generator) and explain why this improves the validity of the data.
• In synoptic questions, be prepared to link ecological sampling (AT 6) with plant metabolism, such as explaining how to test leaves collected from different light intensities for starch (AT 8).