If oxygen is unavailable, what happens to the citric acid cycle?A. It stops because the supplies of NAD+ and FAD become depleted.B. It continues because none of the reactions in the citric acid cycle require oxygen.C. It continues because ATP levels are low, and low ATP activates enzymes of the cycle.D. It stops because ADP levels increase in the absence of oxygen.----------------------------------------------------------------------------------------------In eukaryotic cells, the oxidation of pyruvate occurs in:A. the cytoplasm.B. the endoplasmic reticulum.C. the nucleus.D. the matrix of the mitochondria.E. vacuoles.------------------------------------------------------------------------------------------------The citric acid cycle begins when acetyl-CoA combines with ____________ to form ____________.A. pyruvate; citrateB. oxaloacetate; citrateC. malate; oxaloacetateD. oxaloacetate; malateE. citrate; cis-aconitate-------------------------------------------------------------------------------------------------Consulting Figure 7.1 if necessary, during which stage(s) of cellular respiration is(are) carbon dioxide released?A. stages 1 and 2B. stages 2 and 3C. stage 1 onlyD. stage 3 onlyE. stages 3 and 4-------------------------------------------------------------------------------------------------In human cells such as muscle tissue, the product of anaerobic respiration is:A. ethanol.B. acetic acid.C. lactic acid.D. FADH2.E. pyruvate.