Biosphere II is a self-contained ecological system that was sealed with researchers inside. Unfortunately, the microbes in the soil consumed rich organic matter and produced carbon dioxide. Oxygen levels plummeted and, subsequently, the mission failed. This depletion of oxygen was caused by small microorganisms carrying out the process of

cellular respiration

Explanation:

Cellular respiration is the metabolic reactions and processes of a cell, which involve the conversation of biochemical energy in food molecules into energy in the form of ATP and also release waste products. The cells of these small microorganisms that carry out cellular respiration as they consume rich organic matter, use up a lot of oxygen as they produce a lot of carbondioxide in this process as waste.

the answer is: the „power stroke“ step.

muscle contraction can be divided into a few steps:

1. the release of ach (acetylcholine) in the synaptic cleft, binding of ach for its receptor and consequently opening of the ca channels.

2. the release of ca, binding of ca for the troponin

3. troponin shifting the tropomyosin, which was blocking the active site on the actin

4. myosin heads attaching to actin by breaking down atp to adp+ pi

5.   formation of the ‘cross-bridge’ on the active site of the actin filament by myosin head

6. “power stroke” -the cross bridge pulls actin, which slides over the myosin

9.     7. the release of adp completes the cross-bridge movement and atp attaches to myosin, breaking the actin-myosin cross bridge.