A
Because the cells and somethings forms into something new
They only have one X chromosome so if the get a recessive gene then there's no chance for a dominant gene to out way the recessive
Why should we think that a mitochondrion used to be a free-living organism ... Based on decades of accumulated evidence, the scientific community ... The evidence suggests that these chloroplast organelles were also once free-living bacteria. ... to be the irreversible step at which the two independent organisms
Answer:
Wind and water
Explanation:
For plants, Darwin came to the conclusion that spores, seeds, pollen, etc were blown over from the mainland.
For animals, Darwin theorized that the ancestors of the Galapagos animals were carried over on storm debris during a hurricane or something of the like.
(birds simply just flew over)