The layer that protects living organisms from UV radiation is the ozone layer. Located in the Earth's stratosphere, this layer absorbs the majority of the sun's harmful ultraviolet radiation, preventing it from reaching the surface. Without the ozone layer, increased exposure to UV radiation can lead to health issues like skin cancer and cataracts, as well as detrimental effects on ecosystems. Protecting and preserving the ozone layer is crucial for maintaining biodiversity and overall environmental health.