题干

如图是某生物体内的细胞分裂图,图Ⅰ中的1、8上分别有基因M、m,根据有关信息,判断下列叙述正确的是

A:若图Ⅰ中的2和6表示两个Y染色体,则此图可以表示次级精母细胞

B:图Ⅱ中①上有基因B,如果②上相应位点的基因是b,则一定是基因突变造成的。

C:图Ⅱ可能是图Ⅰ的子细胞

D:图Ⅰ中有4个染色体组

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D

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    Several days ago, Brenda had a car accident that led to one of her legs being cut off. Since then she didn't talk to anyone."I wish I could bring her friends to visit her," said Brenda's mother. "But it's a long bus trip." The nurse smiled, "Don't worry. We have a plan."Later that day, the nurse had taken Brenda to another room. "Here's your new roommate, Annie Wiggle-Do," the nurse introduced a dark-hair teenager on the other bed.

    As soon as the nurse left, she jumped out of her bed with her only foot and sat at the other end of Brenda's bed, "I lost my leg from bone cancer," she said. "What happened to yours?" Brenda was so shocked that she couldn't say a word. "You're lucky." Annie continued. "You've still got your knee. They had to take mine."

    "I'd like to have a chat with you, but my friends are coming any time now, so I have to get ready." Annie said when she took off her hair! Her head was completely bald(秃头的).

    "Oh, I forgot to tell you, the medicine they gave me to kill the cancer also killed my hair." Annie looked out her wigs(假发), brown and yellow, short and long, straight and curly."That's why I thought up 'Annie Wiggle-Do'." Annie smiled. "Get it? Any wig will do? Annie Wiggle-Do?" "When Annie's friends came, she introduced Brenda to them all. Before long, Brenda started chatting with Annie and her friends. They didn't make her feel like a strange person at all!

    The girls shared their names with each other. When it was time to go to bed, Brenda said, "Good night, Annie-Wiggle-Do. Can't wait till morning."