Earthworms: - live in soil - feed on dead and decaying plant matter - have soft, moist skin - exchange gases through their skin 02.1 Give two abiotic factors and two biotic factors that could affect the size of an earthworm population. Abiotic factors 1 _______________ 2 _______________ Biotic factors 1 _______________ 2 _______________ 02.2 Students investigated the populations of earthworms in the soil in two different areas: - Area A: a grass lawn - Area B: a farmer's field. Chemical X can be mixed with water and poured onto the soil. The mixture brings earthworms to the surface of the soil but does not harm the earthworms. Plan an investigation using chemical X to compare the number of earthworms per m² in areas A and B.

GCSE AQA Biology Adaptations, Interdependence & Competition: Earthworms: - live in soil

Earthworms: - live in soil - feed on dead and decaying plant matter - have soft, moist skin - exchange gases through their skin 02.1 Give two abiotic factors and two biotic factors that could affect the size of an earthworm population - AQA - GCSE Biology - Question 2 - 2022 - Paper 1

Question 2

Earthworms: - live in soil - feed on dead and decaying plant matter - have soft, moist skin - exchange gases through their skin 02.1 Give two abiotic factors and t... show full transcript

Worked Solution & Example Answer:Earthworms: - live in soil - feed on dead and decaying plant matter - have soft, moist skin - exchange gases through their skin 02.1 Give two abiotic factors and two biotic factors that could affect the size of an earthworm population - AQA - GCSE Biology - Question 2 - 2022 - Paper 1

Step 1

Abiotic factors

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Answer

Water: Essential for the survival of earthworms, as it maintains moisture in the soil and helps them with metabolic activities.
pH (of the soil): The acidity or alkalinity of the soil can significantly influence earthworm populations, affecting their habitat suitability.

Step 2

Biotic factors

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Answer

Food: The availability of decaying plant matter directly impacts earthworm populations, as they feed on this material.
Predators/consumers: The presence of predators, such as birds or other animals, can decrease the earthworm population.

Step 3

Plan an investigation using chemical X to compare the number of earthworms per m² in areas A and B.

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Answer

Preparation: Ensure that the same concentration and volume of chemical X is applied to both areas (A and B).
Sampling: Define the area to be sampled, e.g. using quadrats of 1 m².
Application: Apply the chemical X mixture evenly over each selected area, ensuring consistent application across both sites.
Collection: After a set time (e.g., 30 minutes), count the number of earthworms that surface in each quadrat in both areas A and B.
Repetition: Repeat this process at least five times in both areas to ensure reliability of results.
Analysis: Compare the average number of earthworms per m² between the two areas to assess the effect of the soil type on the population.

Earthworms: - live in soil - feed on dead and decaying plant matter - have soft, moist skin - exchange gases through their skin 02.1 Give two abiotic factors and two biotic factors that could affect the size of an earthworm population - AQA - GCSE Biology - Question 2 - 2022 - Paper 1

Abiotic factors

Biotic factors

Plan an investigation using chemical X to compare the number of earthworms per m² in areas A and B.

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