Annelids have neither an external or an internal shell. Examples of annelids are
earthworms and leeches.
Part 1;
Because there is only limited amounts of fresh water on the Earth the rest is salt water; which humans can not survive on as the salt dehydrates our bodies instead of hydrates.
1) The more we try to get the the fresh water the more we will likely make more pollution.
2) The more we use the less there is.
3) Everything needs water.
Part 2; no idea I believe it is the ice caps, as it is fresh water in the ice caps and not a lot of humans up there to pollute the runoff.
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!
