During exercise, why is the oxygen concentration in arterial blood different from the oxygen
concentration in venous blood?
asap ! : )

blood leaving the lungs normally has an oxygen content of 16 to 24 ml/100 ml blood and an oxygen saturation of approximately 95% to 98%. the arteriovenous oxygen difference is greater during exercise, normally resulting from lower venous oxygen content in the presence of stable arterial oxygen content.

explanation:

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.