A - Read below
Diffusion is simply particles spreading around. Think of it like spraying perfume in a room. Where the person sprayed the perfume would be a high concentration as there is a lot of that perfume there. However, on the other side of the room there would be little to no perfume. So the perfume spreads around until it is evenly distributed in the room.
They share some of the same matter.
The answer is foreign pathogens.
Crossing over is essential for the normal segregation of chromosomes during meiosis. Crossing over also accounts for genetic variation, because due to the swapping of genetic material during crossing over, the chromatids held together by the centromere are no longer identical.
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