What serious condition can happen to someone with a vitamin B12 deficiency?

Why does the initial rate of an enzymatic reaction eventually plateau at a maximal velocity even though the concentration of the substrate continues to be increased?

A) Enzymes are denatured following action on a substrate. B) High concentrations of substrate inhibit movement of the substrate to available enzymes. C) The enzyme available in the solution has been consumed. D) The enzyme is saturated and unable to bind substrate at a higher rate.

When treating an injured geriatric patient, it is very important to:

A) always use high-concentration oxygen. B) work to achieve an oxygen saturation of at least 94%. C) place the patient in a sitting position to promote adequate breathing. D) avoid use of a nonrebreather and high-concentration oxygen unless apneic.