Name the 4C compound which gains 2C from acetyl CoA and the 6C compound which results

Oxaloacetate (4 carbon) joins with Acetyl CoA to yield Citrate (6 carbon)

Explanation:

Citrate synthase is an enzyme required during the first step of the citric acid cycle. This enzyme catalyzes the condensation of Acetate from Acetyl Coenzyme A (Acetyl CoA) and Oxaloacetate to yield Citrate, a six-carbon molecule, and Coenzyme A (CoA). Oxaloacetate is first condensed with acetyl CoA to produce citryl CoA which is subsequently hydrolyzed to CoA and citrate.

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.