Syllabus Edition

First teaching 2024

First exams 2026

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UV Radiation (DP IB Environmental Systems & Societies (ESS))

Revision Note

UV Radiation Effects

  • The Sun emits electromagnetic radiation in a range of wavelengths, from low-frequency radio waves to high-frequency gamma radiation

  • Shorter wavelengths of radiation have higher frequencies

    • More energy damages living organisms

    • E.g. ultraviolet (UV) radiation

Effects on human health

  • Ultraviolet radiation from the Sun can have damaging effects on human living tissues

    • When excessive UV radiation reaches the surface of the Earth, it can lead to various health issues by damaging cells and tissues

UV Radiation Effects on Humans

Health issues caused by UV radiation

Explanation

Cataracts

Prolonged exposure to UV radiation can contribute to the development of cataracts

Cataracts cause clouding of the lens in the eye, leading to blurry vision and eventual vision loss if left untreated

UV radiation affects cells

UV radiation has the potential to induce mutations in DNA during cell division

When cells are exposed to UV radiation, it can lead to genetic alterations and mutations

This can disrupt normal cell growth and increase the risk of developing cancer

Skin cancer

UV radiation is a major risk factor for the development of skin cancer

UV rays can damage the DNA in skin cells, leading to uncontrolled cell growth and the formation of cancerous tumours

Prolonged or intense exposure to UV radiation, especially without proper protection, increases the risk of developing skin cancer

Sunburn

When the skin is exposed to excessive UV rays, it triggers an inflammatory response as a defence mechanism

Sunburned skin becomes red, painful and may blister, indicating damage to the skin cells

Premature skin ageing

Chronic exposure to UV radiation accelerates the ageing process of the skin

It can cause the breakdown of collagen and elastin fibres, leading to wrinkles, sagging skin and the development of age spots

Photo of sunscreen
Measures such as wearing sunscreen with a high sun protection factor (SPF), using sunglasses that block certain UV rays, seeking shade during peak sun hours and wearing protective clothing can help reduce the risk of UV-related health issues (Photo by Dimitris Chapsoulas on Unsplash )

Effects on biological productivity

  • Harmful UV radiation reaching the Earth's surface affects plant growth and productivity

  • Increased UV exposure can lead to:

    • Reduced photosynthesis rates

    • Altered plant metabolism

    • Decreased crop yields

  • Exposure to increased UV radiation can affect other photosynthetic organisms, such as phytoplankton

    • Phytoplankton play a crucial role in aquatic food webs

    • They convert sunlight, carbon dioxide and nutrients into organic matter through photosynthesis

    • UV radiation damages phytoplankton by:

      • Causing DNA damage

      • Reducing photosynthetic activity and growth

    • This leads to a decrease in primary productivity in aquatic ecosystems

  • Reduced phytoplankton productivity can have cascading effects on higher trophic levels in aquatic ecosystems

    • Zooplankton, which feed on phytoplankton, have less food available

      • This affects their growth and reproduction

    • This, in turn, can impact higher-level consumers, such as fish and marine mammals

      • Organisms in these higher trophic levels rely on phytoplankton and zooplankton as food source

      • This can significantly reduce the biodiversity of aquatic ecosystems

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Alistair Marjot

Author: Alistair Marjot

Expertise: Biology & Environmental Systems and Societies

Alistair graduated from Oxford University with a degree in Biological Sciences. He has taught GCSE/IGCSE Biology, as well as Biology and Environmental Systems & Societies for the International Baccalaureate Diploma Programme. While teaching in Oxford, Alistair completed his MA Education as Head of Department for Environmental Systems & Societies. Alistair has continued to pursue his interests in ecology and environmental science, recently gaining an MSc in Wildlife Biology & Conservation with Edinburgh Napier University.

Bridgette Barrett

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After graduating with a degree in Geography, Bridgette completed a PGCE over 25 years ago. She later gained an MA Learning, Technology and Education from the University of Nottingham focussing on online learning. At a time when the study of geography has never been more important, Bridgette is passionate about creating content which supports students in achieving their potential in geography and builds their confidence.