单项选择题

A female-male mosaic fruit fly may be formed, if there is chromosome loss or ______.

A．equal division during sperm generation
B．abnormal mitosis during merogenesis (fertilized egg cleavage)
C．meiosis in embryo
D．meiosis when sperm is tailed

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热门试题

单项选择题

The cultured E. coli system was infected by two types of bacteriophages. One type is a-b-, another is a+b+. Then the lysate was sampled and smeared on medium. The data of the bacteriophage growth by counting plaques is as follows: a+b+=4750, a+b-=370, a-b+=330, a-b-=4550. How much is the recombination rate between a and b ______

A．70%
B．12.8%
C．7%
D．15%

单项选择题

Base-pair substitutions in point mutation include: ______.

A．transvertion and transformation
B．transition and transvertion
C．conversion and transition
D．transposition and transvertion