题干

果蝇的两对相对性状灰身与黑身、小翅与长翅各由一对等位基因控制.有实验小组做了以下两组实验:

实验一

P

母本

纯合灰身小翅

F1

雌性:灰身长翅

F1个体间自由交配得到F2

父本

纯合黑身长翅

雄性:灰身小翅

实验二

P

母本

纯合黑身长翅

F1

雌性:灰身长翅

F1个体间自由交配得到F2

父本

纯合灰身小翅

雄性:灰身长翅

根据实验结果分析作答:

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    We get back on the road. Ed is driving now. When all the tabloids(小报)have been read, the travel has grown tedious and anyone under age 12 asks “Are we there yet?” at ever-shortening internals. Just outside Manteca, California, we stop for coffee. At a Starbucks checkout, Ed buys a CD of Joni Mitchell's favorite musical picks. The hope is that it will have a calming effect.

    As we pull back onto the highway, it starts to pour. Then something amazing happens. As we climb the mountain, the rain turns to snow. The pines are spotted with white. We're struck dumb(说不出话)by the scene outside. For a solid 15 minutes, everyone forgets about their bladder, their blood sugar and the temperature. Alisha has never seen snow, so we pull over to make snowmen and catch snowflakes on our tongues. Then Ed realizes we need tire chains, and we have to turn back and drive 30miles to Oakhurst. “Good,” says Doris. “There was a very nice restroom there.”