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All but one describes an effect of aging on the digestive system. a) decreased acid secretion b) decreased elasticity of stomach c) capacity to resist damage decreases d) food remains in stomach for less time

The breakdown of food is accomplished by enzymes. a. physical b. chemical c. mechanical d. none of the above

The current thought on the structure of the cell membrane is: a. a static phosphate sandwich of lipids b. a fluid-mosaic of phospholipids and proteins c. a bilayer of proteins with static lipid molecules d. an impermeable bilayer of protein molecules e. a static and permeable phospholipid single layer