A coral reef is home to a species of sea anemone. The sea anemone absorbs dissolved nutrients from the surrounding water, responds to touch by retracting its tentacles, produces waste ammonia that passes out of its body, and reproduces by splitting into two identical individuals. Explain how each of these four observations demonstrates a different characteristic of living organisms.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A coral reef is home to a species of sea anemone. The sea anemone absorbs dissolved nutrients from the surrounding water, responds to touch by retracting its tentacles, produces waste ammonia that passes out of its body, and reproduces by splitting into two identical individuals.
Model answer (4 marks)
Absorbing dissolved nutrients demonstrates nutrition – the sea anemone takes in materials from its environment to provide energy and raw materials for growth and other life processes.
Retracting its tentacles in response to touch demonstrates sensitivity – the sea anemone detects and responds to a change in its environment (a stimulus).
Producing waste ammonia that passes out of its body demonstrates excretion – the removal of waste products of metabolism from the organism.
Splitting into two identical individuals demonstrates reproduction – the sea anemone produces new organisms of the same species, ensuring the continuation of the species.
Retracting its tentacles in response to touch demonstrates sensitivity – the sea anemone detects and responds to a change in its environment (a stimulus).
Producing waste ammonia that passes out of its body demonstrates excretion – the removal of waste products of metabolism from the organism.
Splitting into two identical individuals demonstrates reproduction – the sea anemone produces new organisms of the same species, ensuring the continuation of the species.
Examiner tips
- Use the exact terminology: nutrition, sensitivity, excretion, reproduction. Give one sentence for each observation. Show the link between observation and characteristic clearly.
Common mistakes
- Confusing nutrition with feeding. Using vague terms like ‘growth’ instead of ‘nutrition’. Failing to match each observation to a distinct characteristic.
Mark scheme (4 marks)
- Absorbing dissolved nutrients demonstrates nutrition — the sea anemone takes in materials from its environment to provide energy and raw materials for growth and other life processes.
- Retracting its tentacles in response to touch demonstrates sensitivity — the sea anemone detects and responds to a change in its environment (a stimulus).
- Producing waste ammonia that passes out of its body demonstrates excretion — the removal of waste products of metabolism from the organism.
- Splitting into two identical individuals demonstrates reproduction — the sea anemone produces new organisms of the same species, ensuring the continuation of the species.
Related
- All Pearson Edexcel International GCSE Biology (4BI1) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →