枯草芽孢杆菌培养液中加入溶菌酶溶液37℃水浴作用1小时后，菌体由杆状变为球状，这是因为：
A. 枯草芽孢杆菌是革兰氏阳性菌，细胞壁的主要成分是肽聚糖和胞壁酸，细胞壁厚
B. 枯草芽孢杆菌是革兰氏阴性菌，细胞壁的主要成分是脂多糖，细胞壁薄
C. 溶菌酶能水解N–乙酰葡萄糖胺与N–乙酰胞壁酸之间的β–1，4–糖苷键连接起来的聚合物
D. 失去细胞壁支撑的杆菌因为表面张力的作用变成球形
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使用凝胶过滤法脱盐时，先洗脱下来的是硫酸铵。
A. 对
B. 错
双缩脲反应中产生的紫色络合物颜色的深浅与蛋白质浓度成正比，而与蛋白质分子量及氨基酸成分无关，故可用来测定蛋白质含量。
A. 对
B. 错
What are the services that a local guide should offer in food and beverage?
A. On the way to the restaurant, the local guide should introduce the local special culinary characteristics.
B. The local guide can tell all the process of cooking.
C. The local guide should know the famous restaurants.
D. On arrival, the local guide should lead the tour group to the seats.
E. The local guide should inform the waiters of the special requirements.
F. During the meal, the local guide should go to the tourists several times.
Chinese cuisine has changed in each region according to .
A. climate
B. imperial fashion
C. religion
D. local preferences
E. ethnic background
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