问题 单项选择题

在“观察DNA和RNA在细胞中的分布”实验中,下列分析正确的是()

A.实验的操作步骤是:“制片→水解→冲洗→染色→酒精去浮色→晾干→观察”

B.染色时先用甲基绿染液染色,再滴加吡罗红染液

C.与甲基绿结合的核酸分子主要分布在细胞核中

D.将涂片用质量分数为8%的盐酸处理后,接着用染色剂染色

答案

参考答案:C

解析:

在“观察DNA和RNA在细胞中的分布”实验中,操作步骤是:制片→水解→冲洗涂片→染色→观察,故A错;甲基绿和吡罗红试剂需要混合使用,故B错;甲基绿与DNA结合,将DNA染成绿色,DNA主要存在于细胞核中,故C正确;在用盐酸水解后,需要冲洗涂片后再染色,故D错。

考点:本题主要考查教材中的实验,意在考查考生能独立完成“生物知识内容表”所列的生物实验,包括理解实验目的、原理、方法和操作步骤,掌握相关的操作技能,并能将这些实验涉及的方法和技能进行综合运用的能力。

单项选择题
单项选择题

Training as mental-health professionals is supposed to be "color blind". That sounds fine but in practice it means that people from black and ethnic groups get an unfair treatment because their particular problems are seldom acknowledged.

So a project was piloted involving Bangladeshi women in inner-city London, most of whom migrated to the UK in the 1960s and 1970s from a rural background. Many of these women turned to their doctors with common symptoms of anxiety, such as headaches, sleeping difficulties, loss of appetite and lack of energy. They were usually prescribed tranquillizers or even Vitamin C since the underlying causes remained, the women visited their doctors with increasing frequency and some were referred on to mental-health professionals.

The psychologists wanted to see how normal Western approaches to anxiety problems might work when applied across cultures. However, they found that many things in the standard approach had to be changed. They had to translate many of the usual examples—they would normally compare learning to relax with learning to drive, for instance, which would not have been culturally appropriate. At first they asked the women to rate, on a scale one to ten, the effect of relaxation on their level of anxiety. They found numbers an odd way of expressing how they were feeling. So psychologists shifted their focus to words and talked of five stages form "very good" to "very bad".

As it was a pilot project, there were shortcomings. Psychologists looked for too little back-up and did not collect as much objective data as they might have done with a white group. They fell into the white stereotype of assuming that Bangladeshi women would find the use of various checklists and written records foreign. Perhaps racism has conditioned the professionals to a greater extent than they expected. Psychologists found that using a Western model across cultures has potential. But it needs political, financial and personal commitment.

What is meant in Para. 1 by "color blind"().

A. Not liking people from ethnic groups.

B. Giving specialized treatment to ethnic groups.

C. Unable to distinguish certain colors.

D. Not treating ethnic groups differently.