Biological samples should be extracted under acidic conditions to reduce the interference of endogenous substances (mostly acidic) in the biological matrix.

Proteins can be separated electrophoretically on the basis of their relative contents of acidic and basic residues.（）

Which of the following compounds is the most acidic？ A: phenol B: p-cresol C: p-nitrophenol D: benzyl alcohol

Apoptotic<br/>cells can be stained positively when subjected to acidic lysosomal<br/>SA-β-GAL staining. (<br/>)

Factors that contribute to calcium absorption, except(<br/>) A: Lactose B: 1,25 -(OH)2VD3 C: Acidic conditions D: Fatty acids

The<br/>most acidic of the following flavonoids is __. A: 3-OH-Flavones B: 5-OH-Flavones C: 5,7-di-OH-Flavones D: 7,4'-di-OH-Flavones E: 3’,4’-di-OH-Flavones

Hypokalemia can result in following conditions except for () A: Arrhythmia B: Flaccid paralysis C: Metabolic acidosis D: Acidic urine E: Flat and low T wave

Hyperkalemia can cause the following results except for () A: Ventricular fibrillation B: Paralysis of skeletal muscle C: Metabolic acidosis D: Acidic urine E: Tall and peaked T wave in ECG

Paradoxical acidic urine in metabolic alkalosis always indicates () A: Severe<br/>hyponatremia. B: Severe<br/>hypernatremia. C: Severe<br/>hypokalemia. D: Severe<br/>hyperkalemia. E: Severe<br/>dehydration

12.At 25°C, Kw=Kc= &#91;H+&#93; &#91;OH–&#93; = 1.0 ×10–14, pH + pOH =14.(3) ( ) solutions: &#91;H+&#93; = 1.0×10–7 M, pH=7.00 A: acidic B: basic C: neutral