题干

下面是对高等动物通过减数分裂形成的♀、♂配子以及受精作用的描述,其中正确的是(  )

A:每个卵细胞继承了初级卵母细胞 14 的细胞质

B:等位基因进入卵的机会并不相等,因为一次减数分裂只形成一个卵

C:进入卵细胞并与之融合的精子几乎不携带细胞质

D:♀、♂配子彼此结合的机会相等,因为它们的数量相等

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答案(点此获取答案解析)

C

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    A man walked into a small Irish pub and ordered three beers. Bartender was surprised, but he served that man three beers. One hour later the man ordered three beers again. The very next day that man ordered three beers again and drank quietly at a table. This repeated several times and shortly after the people of the town were whispering about the man, who was ordering three beers at once.

    A couple of weeks later, the bartender decided to clear this out and inquired: “I do not want to pry, but could you explain, why do you order three beers all the time?” The man replied: “It seems strange, isn't it? You see, my two brothers live abroad at the moment, one – in France and another – in Italy. We have made an agreement, that every time we go to pub each of us will order extra two beers and it will help keeping up the family bond”.

    Soon all the town have heard about the man's answer and liked it a lot. The man became a local celebrity. Residents of the town were telling this story to newcomers or tourists and even invited them to that pub to look at Three Beer Man.

    However, one day the man came to pub and ordered only two beers, not three as usual. The bartender served him with bad feeling. All that evening the man ordered and drank only two beers. The very next day all the town was talking about this news, some people pray for the soul of one of the brothers, others quietly grieve.

    When the man came to pub the next time and ordered two beers again, the bartender asked him: “I would like to offer condolences to you, due to the death of your dear brother”. The man considered this for a moment and then replied: “Oh, you are probably surprised that I order only two beers now? Well, my two brothers are alive and well. It's just because of my decision. I promised myself to give up drinking.”