2. how does water form during cellular respiration?
a oxygen is oxidized, losing electrons and gaining hydrogen ions.
b oxygen is reduced, gaining electrons and hydrogen ions.
c oxygen is reduced, losing electrons and gaining hydrogen ions,
d oxygen is oxidized, gaining electrons and hydrogen ions.

B

Explanation:

During the Krebs cycle in the matrix of the mitochondria, H+ ions are usually pumped to the intermembrane space creating a proton-motive force. This potential difference is harness by ATP synthase to make ATPs as the H+ ions 'drain' back to the matrix of the mitochondria. As these H+ get to the matrix, they ultimately reduce oxygen to water. In this reaction, oxygen also acts as the ultimate electron acceptor in the Krebs cycle accepting 4 electrons from NADPH/ NADH (so these molecules can be recycled back as NAD+ and NADP+).

4H⁺ + O₂ + 4 ⁻e → 2H₂O

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.