题干

某学者欲研究被石油污染过的土壤中细菌数量,并从中筛选出能分解石油的细菌.下列操作错误的是(    )

A:利用平板划线法对细菌进行计数

B:以石油为唯一碳源的培养基筛选

C:采用稀释涂布平板法分离菌种

D:称取和稀释土壤样品时应在火焰旁

上一题 下一题 0.0难度 选择题 更新时间:2019-10-05 10:09:33

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A

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    The Women's Institute is urging supermarkets to do more to help consumers reduce their home food waste, after a survey of its own membership showed widespread confusion about “best before” and “use by” labeling(标签) on packaging.

    Its new analysis of products on supermarket shelves found that “once-opened” instructions were often contradictory and often failed to make clear whether they were a guide to food safety or quality. Only 45% of 5,000 WI members surveyed understood that best-before dates were a sign of food quality, while 26% did not understand that the more important use-by dates were a decisive guide to food safety.

    In its report on food waste, the WI said supermarkets were “potentially contributing to home food waste by leading customers to buy more food than they need, and giving conflicting and confusing on-pack information that leaves customers unsure about how long a product remains safe to eat in the home setting”. The 42-page report is part of the WI's ongoing campaign to reduce food waste. To underline the point about conflicting information, it cites(引用) a can of Sainsbury's own-brand sweetcorn advising consumers to eat it within one day of opening, while a similar tin from Waitrose gave consumers two days to finish it. Green Giant sweetcorn, however, has no specified date for eating once opened.

    Marylyn Haines Evans, chair of the Women's Institute's public affairs said: “WI members are some of the more informed members of society about food and cookery, but they are still confused about food labelling and 'once-opened' information. So we would like supermarkets to extend the amount of time that consumers have to use a product in their homes by making all of their once-opened instructions on product packaging consistent, and completely remove once-opened instructions on products where food safety is not an issue.”