问题 填空题 案例分析题

研究人员发现,当以弱强度的刺激施加于海兔的喷水管时,海兔的鳃很快缩入外套腔内,这是海兔的缩鳃反射。若每隔1min重复此种轻刺激,海兔的缩鳃反射将逐渐减弱甚至消失,这种现象称为习惯化。下图1表示海兔缩鳃反射习惯化的神经环路示意图,图2表示习惯化前后轴突末梢模型。请回答:

若在图1中b处给予有效刺激,还可在图中()点检测到电位变化,原因是()。

答案

参考答案:d;突触间兴奋的传递是单向的(或递质只能由突触前膜释放作用于突触后膜)

解析:

神经递质只存在于突触前膜,只能由突触前膜释放作用于突触后膜,所以若在图1中b处给予有效刺激,只能在图中d点检测到电位变化。

单项选择题
翻译题

完成句子

1. I had already heard that George didn't like________,so I got there a few minutes earlier.(keep)

我早就听说乔治不喜欢等待,所以我提早几分钟到了那里.

2. ________the importance of protecting the environment accounts for their polluting the river.(aware)

他们污染了河流是因为他们没有意识到保护环境的重要性.

3. ________,the old man was so excited that he could hardly say a word.(help)

摆脱困境后,这个老人是如此激动以至于一句话也说不出来.

4. I________the moment when he jumped into the water to save the drowning boy without hesitation.(reflect)

我一直都在思考他毫不犹豫跳下水去救那个溺水小男孩的时刻.

5. Everyone present at the meeting urged that new measures________the house prices by the government.(take)

与会的每个人都要求政府应该采取新措施来控制房价.

6. After Sam got divorced with his wife,he quit his job and________every day.(abandon)

山姆和她妻子离婚以后,他就辞去了工作而且每天沉迷于饮酒.

7. Jim was said to have been killed in an accident,so when I saw him last night,nearly________.(scare)

基姆据说已经在一次事故中丧生,所以当我昨晚见到他时,差点吓死.

8. The old man________is a professor in chemistry and has been teaching in the university for twenty years.(opposite)

坐在我对面的那位老人是一位化学教授,而且已经在这所大学教了二十年了.

9. You can not eat anything before________.(operate)

做手术之前你什么都不能吃.

10. Over the past 10 years________in the small town.(witness)

在过去的十年里,这个小镇见证了巨大变化.