# Explain how abiotic factors can determine the boundaries of a species' fundamental niche, using temperature as an example.

> IB DP Biology Higher Level (2023 syllabus) — B4.2 Ecological niches · Explain · 4 marks

## Mark scheme (4 marks)

1. The fundamental niche is the full range of abiotic and biotic conditions under which a species could theoretically survive and reproduce.
2. Each species has a range of temperatures (thermal tolerance range) within which enzymes function effectively, allowing metabolism, growth, and reproduction to occur.
3. The upper and lower lethal/tolerance limits of temperature define the boundaries of the niche along the temperature axis, so temperatures outside this range exclude the species from those areas.
4. The niche can be visualised as a multidimensional hypervolume, with temperature as one axis; other abiotic factors (e.g. pH, salinity, light intensity) each add further axes that together define the full fundamental niche.

## Key terms

- [fundamental niche](https://www.gradenine.co.uk/glossary/fundamental-niche)
- [abiotic factor](https://www.gradenine.co.uk/glossary/abiotic-factor)

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-abiotic-factors-can-determine-d95dc251) · Published by Druglandscape Ltd.