What is the correct answer?
the weakness of hydrogen bonds between the bases of dna allows -

a: rearrangement of the sequence of bases to take place
b: base pairs to separate during transcription and replication
c: new bases to be incorporated into the dna molecule
d: conversion of bases to amino acids in the event of cell starvation

it's     c       this is a cell (b) with a nucleus (c) containing dna (a). the dna is organized into chromosomes (d). a section of the chromosome that codes for a trait is called a gene (e).

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.