Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

What is the primary function of the ozone layer located in the stratosphere?

1. To regulate air pressure

2. To increase temperature

3. To absorb harmful UV radiation

4. To facilitate convection currents

The correct answer is: To absorb harmful UV radiation

The primary function of the ozone layer located in the stratosphere is to absorb harmful ultraviolet (UV) radiation from the sun. This layer contains a high concentration of ozone (O3) molecules that effectively filter out the majority of the sun's harmful UV rays, particularly UV-B and UV-C types, which can cause skin cancer and cataracts in humans and have damaging effects on wildlife, plants, and marine ecosystems. The ability of the ozone layer to absorb these harmful rays is crucial for maintaining life on Earth. By filtering a significant portion of UV radiation, the ozone layer helps to protect living organisms from the adverse effects that come with excessive exposure to sunlight. The other options provided relate to different atmospheric processes. While air pressure is influenced by a variety of factors including temperature and altitude, it is not a function of the ozone layer. The stratosphere does experience temperature increases with altitude due to the absorption of UV radiation by ozone; however, this is a secondary effect rather than the primary role of the layer. Convection currents, which are vital for weather patterns and atmospheric circulation, are driven by temperature differences and humidity, not by the presence of ozone.