Avery and his colleagues extract material from a killed sample of lethal bacteria. They eliminated carbohydrates, proteins, fats, RNA, and DNA from the extract and showed that exposure to the DNA alone could make non-lethal bacteria become deadly. What does this observation demonstrate about DNA

That the DNA is a transforming molecule

Explanation:

DNA molecule could make non-lethal bacteria become deadly and as such, it is said to be the molecule responsible for transformation.

The observation effectively demonstrated that DNA is the molecule that is responsible for inheritance of traits from one generation to another.

The DNA contains information about traits and these information are some ways passed on from one generation to another in a process known as gene expression.

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.