Chapter 29, Problem 5RAT

To determine

The correct option for the statement “The buildup of free oxygen was crucial to the emergence of life on Earth because it led to the formation of ”.

Answer to Problem 5RAT

The correct option for the statement “The buildup of free oxygen was crucial to the emergence of life on Earth because it led to the formation of ” is option (b).

Explanation of Solution

Oxygen is mostly present in the atmosphere as well as in the universe. Oxygen present in the atmosphere can easily react with other elements present near it. Free oxygen is the oxygen that does not react with other elements such as carbon, nitrogen, and sulfur.

The free oxygen atom can quickly join with the oxygen atom and formed ozone in the presence of ultraviolet light. These ozone atoms collect and form the ozone layer as a shield of Earth. Ultraviolet rays are harmful rays which can cause serious health issues for humans as well as other organisms also. Ozone layer consumes most of the ultraviolet light that falls on Earth.

Conclusion:

Therefore, the correct option for the statement “The buildup of free oxygen was crucial to the emergence of life on Earth because it led to the formation of ” is option (b).