Question

the graph shows one estimate for changes to the percent of oxygen in the atmosphere and major biological developments over time. the bands a, b, and c show information from the geologic record. which two statements explain the connection between the atmospheric, biological, and geological changes shown in the graph? a. oxidation of iron in rocks steadily added oxygen and other nutrients to the atmosphere. b. the development of an oxygen - based ozone layer made it possible for life to evolve out of the water. c. increased atmospheric oxygen levels enabled the development of modern plant and animal metabolic processes. d. early oxygen levels were low because the earliest cells produced and recycled oxygen more efficiently than later cells. e. oxygen levels first increased in the ocean because land organisms produced oxygen more slowly than marine organisms.

Explanation:

• Option B: The ozone - layer, formed from oxygen, protects life from harmful UV radiation, allowing life to move from water to land.
• Option C: Higher oxygen levels in the atmosphere enabled the development of aerobic metabolism in plants and animals, which are modern metabolic processes.

Answer:

B. The development of an oxygen - based ozone layer made it possible for life to evolve out of the water.
C. Increased atmospheric oxygen levels enabled the development of modern plant and animal metabolic processes.