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问题 单项选择题 A1/A2型题

关于梅毒螺旋体的生物学特性，下述哪项不正确（）

A.菌体有致密而规则的螺旋

B.两端尖直

C.有鞭毛

D.不能在人工培养基上生长

E.抵抗力弱，加热至50℃，5分钟内死亡

答案

参考答案：C

解析：梅毒螺旋体有8～14个致密而规则的小螺旋，两端尖直，运动活泼，革兰染色阴性，电镜下可见胞壁和胞膜，原生质圆柱体上紧绕3～4根周浆鞭毛，与运动有关。梅毒螺旋体不能在无活细胞的人工培养基上生长繁殖，抵抗力弱，在50℃，5分钟内死亡；血液中的苍白螺旋体在4℃置3天死亡。

选择题

已知醋酸、醋酸根离子在溶液中存在下列平衡：

CH3COOH+H2OCH3COO-+H3O+  K1=1.75×10-5

CH3COO-+H2OCH3COOH+OH-  K2 =5.71×10-10

现将50 mL 0.2 mol/L醋酸与50 mL 0.2 mol/L醋酸钠溶液混合制得溶液甲，下列叙述正确的是 [ ]

A．溶液甲的pH >7

B．对溶液甲进行微热，K1、K2同时增大

C．若在溶液甲中加入少量的NaOH溶液，溶液的pH明显增大

D．若在溶液甲中加入5 mL 0.1 mol/L的盐酸，则溶液中醋酸的K1会变大

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单项选择题 案例分析题

People born in autumn live longer than those born in spring and are less likely to fall chronically ill when they are older, according to an Austrian scientist, Using census (人口普查) data for more than one million people in Austrian. Denmark and Australia, scientists at the Max Plank Institute for Demographic (人口统计的) Research found the month of birth was related to life expectancy over the age of 50. Seasonal differences in what mothers ate during pregnancy, and infections occurring at different times of the year could both have an impact on the health of a new - born baby and could influence its life expectancy in old age. "A mother giving birth in spring spends the last stage of her pregnancy in winter, when she will eat fewer vitamins than in summer. " said one of the scientists. "When she stops breast - feeding and starts giving her baby normal food, it’s in the hot weeks of summer when babies are inclined to infections of the digestive system. " In Austria, adults born in autumn lived about seven months longer than those born in spring, and in Denmark adults with birthdays in autumn outlived those born in spring by about four months. In the southern hemisphere, the picture is similar. Adults born in the Australian autumn lived about four months longer than those born in the Australian spring. The study focused on people born at the beginning of the 20th century, using death certificates and census data. Although nutrition at all times of the year has improved since then, the seasonal pattern persists.

The term "life expectancy" (Line7) refers to（）。

A. the average period that a person may expect to live

B. the length of time for each person

C. the expectations of a person’s life

D. the seasonal changes in a person’s life
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