题干

下列有关孟德尔一对相对性状杂交实验的说法中正确的是(  )。

①豌豆是自花传粉,实验过程免去了人工授粉的麻烦

②“豌豆在自然状态下一般是纯种”属于孟德尔假说的内容   

③解释性状分离现象的“演绎”过程是:若F1产生配子时,成对的遗传因子分离,则测交后代出现两种表现型,且比例接近1:1

④解释实验现象时提出的“假说”之一:F1产生配子时,成对的遗传因子分离

A:③④

B:①②③

C:②④

D:①②

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A

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    Something's happening at the lowest point on our planet.

    The Dead Sea, a salt lake bordered by Jordan to the east and Israel and Palestine to the west, is shrinking(缩小) at an alarming rate-----about 3.3 feet per year, according to the environmentalist group EcoPeace Middle East. And human actions are largely to blame.

    “It's not just like one country is punishing the Dead Sea; it's more like the whole area,” said photographer Mortize Kustner, who visited the area in February to work on his series “The Dying Dead Sea”.

    The Dead Sea needs water from the other natural sources surrounding it, such as the Jordan River basin. But around the 1960s, some of the water sources it relied on were diverted(使改道).Israel, for instance, built a pipeline during that time so it could supply water throughout the country.

    Mineral extraction(开采) industries are another main reason the water levels are falling, experts say. The Dead Sea's minerals have been used as medicine and can often be found in cosmetics(化妆品) and other consumer products.

    And then, of course, there's the Middle East's hot, dry climate, which makes it difficult for the lake to replenish itself.

    Last year, Israel and Jordan signed a $900 million deal in an effort to keep the Dead Sea's water levels stable(稳定). It includes building a canal from the Red Sea to the Dead Sea which would be able to not only supply water to Israel and Jordan but also to pump water into the Dead Sea.

    But for now, Kustner shows us that the Dead Sea remains very much a place of interest, with people from all over the world going there to swim in its salty waters.

    The Dead Sea, known as the Salt Sea in the language of Hebrew, is one of the saltiest bodies of water in the world. And because of what has been happening over the years, the salt is only getting saltier.