Question

Biological importance of ozone layer is

• A. it stops ultraviolet rays
• B. ozone layer reduces green house effect
• C. ozone layer reflects radio waves
• D. ozone layer controls $ O_2 /H_2 $ ratio in atmosphere

Answer 1

The Correct Option is A

The ozone layer, situated in the Earth's stratosphere, plays a crucial role in protecting all forms of life on Earth. The biological importance of the ozone layer can be understood by examining its function in stopping ultraviolet (UV) rays.

1. Protection from Ultraviolet Rays: The ozone layer absorbs the majority of the Sun's harmful ultraviolet radiation, primarily UV-B and UV-C rays.
   • UV-B rays can cause skin cancer in humans, cataracts in the eyes, and also affect the photosynthesis process in plants and phytoplankton.
   • By blocking these rays, the ozone layer prevents potential health hazards to humans, animals, and plants, safeguarding ecosystems.
2. Explanation of Incorrect Options:
   • Ozone layer reduces green house effect: The greenhouse effect is not directly controlled by the ozone layer. It is primarily influenced by greenhouse gases such as carbon dioxide, methane, and water vapor.
   • Ozone layer reflects radio waves: Radio waves are reflected by the ionosphere, not the ozone layer.
   • Ozone layer controls O_2 /H_2 ratio in the atmosphere: The ozone layer does not regulate the ratio of oxygen to hydrogen in the atmosphere.

Conclusively, the primary biological importance of the ozone layer is its ability to stop ultraviolet rays, thus protecting life on Earth from their harmful effects. Therefore, the correct answer is: it stops ultraviolet rays.