You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. you have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. i. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectiousii. filtering the substance to remove all elements smaller than what can be easily seen under a light microscopeiii. culturing the substance by itself on nutritive medium, away from any plant cellsiv. treating the sample with proteases that digest all proteins and then determining whether it is still infectiouswhich treatment could definitively determine whether or not the component is a viroid? a) ib) iic) iiid) ive) first ii and then iii

47

explanation:

ok

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.

wegner's theory did not explain how the continents could move

explanation: