Did the first living cell evolve suddenly in a single step or gradually as the result of many intermediate steps?

Gradually as the result of many intermediate steps is my answer because as life on Earth for example started off with simple atoms making molecules, and as the time went past more complex compounds were be produced. And from there later on unicellular organisms started appearing. Nothing in evolution that I know of happens in a short time, at least from the human perspective.

golgi body just took the test on edge

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.