One difference between dna and rna is that a) adenine is found only in rna. b) guanine is found only in dna. c) cytosine is found only in rna. d) thymine is found only in dna.

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.

correct answer: false

while planning water activities, it is very important to consider the weather, because if we do not plan and are going for a surf, then it might be that the hurricane came and drown us or may carry us to long distance from where we can not come back. there are many reasons to take information about the weather when we are planning any water activities.

hence, the correct answer would be false.