PCR can be used to selectively duplicate one single gene out of thousands because the only primers available to start replication are the one unique pair that are complementary to the regions on both sides of the gene. Which of these primers (one for each strand) could you use to copy just the stretch (enlarged) of the amelogenin gene that differs between the X and Y chromosomes

100 dollars because yeah

estuaries are the partially enclosed coastal bodies of brackish water formed at the mouth of sea where river meets an ocean. it is a transition zone between river and sea water so estuaries are influenced to both marine environment such as tides, waves and to riverine such as flow of fresh water and sediments. the mixing of sea and fresh water provide high level of nutrients, making estuaries a high product habitats.

many estuaries suffers degradation from a variety of human activities like erosion from deforestation, overgrazing, overfishing, drainage and eutrophication.

so from the above statement answers will be

1. false as estuaries are formed due to both brackish and freshwater.

2.true, due to high productivity estuaries are breeding ground for many marine species.

3. direct and indirect activities of man that contribute to pollution and deposition of sediments.