Changes in the dna are called mutations. They can occur spontaneously. Mutations can only be passed down in gametes--sperm and egg cells. with Darwins theory at mind a mutation needs to pass the test of natural selection to remain in the gene pool. So purposly making mutation or altercations may end in diseases/illnesses or in some cases death because they body can not take it.....hope this helps if it doesnt im sorry!
C.Plant cells have a large central vacuole that takes up most of the cell's space, and animal cells have many smaller vacuoles.
Hope it helps : )
Explanation:
because at is formed,the lighter part floats on the surface and the really heavy part (like iron and nickel in the core)sank to the middle
