Biosphere II Is a Huge, Dome-Covered, Self-Contained Structure Located Outside

Multiple Choice

Biosphere II is a huge, dome-covered, self-contained structure located outside Tucson, Arizona. It was built to try to duplicate Earth's biosphere and ecosystems in miniature and to use the information gained from this experiment to help design similar habitats on the Moon and Mars. Biosphere II contained small versions of many of Earth's ecosystems, including an ocean with a coral reef, mangrove wetlands, a grassland, a desert, an agricultural system, and a house for humans. Eight men and women were sealed inside the habitat for a proposed 2-year stay. The air, water, and food for these "biospherians" all came from inside the sealed habitat, and their only contact with the outside world was through computers and telephones.
Before the 2 years were up, however, the experiment failed. Supplemental oxygen was pumped into the facility, and food supplies were provided through the airlocks. What caused the failure of the experiment? It was traced to nutrient pollution. The soil in some of the biosphere ecosystems was unusually rich in nutrients. These excess nutrients caused a huge population explosion in decomposer bacteria, which led to oxygen depletion.
-How could a population explosion of bacteria lead to oxygen depletion?

A) The excess consumers used the oxygen for cellular respiration.
B) The excess producers used the oxygen to complete photosynthesis.
C) The excess decomposers removed all the nutrients from the habitat.
D) The excess decomposers prevented plants from performing photosynthesis.