The paleozoic era is the longest time period in the history of earth.

FALSE

Explanation:

The Paleozoic era is not the longest of all the era. It started from the Cambrian that was about 545 million years ago and ended in the Permian that was about 250 million years back.

The longest of all the era is the Precambrian era that started right from the time of formation of the earth that was the Hadean time and ended by the Proterozoic. The time range of this era was from 4.6 billion years to about 545 million years back.

Thus, the above given statement is false.

the answer is sex-linked recessive.

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.