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

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Biology & Environmental Systems and Societies

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

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

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

the (exam) results speak for themselves:

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