When one plant's pollen fertilizes the egg of another plant it is called cross pollination.
Umm...
biology is the study of life
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Well, when chromosomes cross over during prophase 1 of meiosis, the homologous pair of chromosomes exchange segments of DNA which happen to be the genes. So the significance of crossing-over during prophase 1 is that it adds genetic variation to sexually reproducing organisms.
Answer:
The correct answer is CHLOROPHYLL