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12. Why is measuring dissolved oxygen important in aquatic ecosystems?

a) It provides data on the water's salinity levels.
b) It indicates the presence of harmful chemicals in the water.
c) It helps assess the water's ability to support aquatic life.
d) It measures the water's temperature for environmental monitoring.

5 answers

c) It helps assess the water's ability to support aquatic life.

Measuring dissolved oxygen is crucial because it is essential for the survival of fish and other aquatic organisms. Adequate levels of dissolved oxygen indicate a healthy ecosystem capable of supporting diverse forms of life.

13. In freshwater ecosystems, what is the relationship between salinity and conductivity?
a) Salinity and conductivity are inversely related. As salinity increases, conductivity decreases.
b) Salinity and conductivity have no relationship; they are independent of each other.
c) Salinity and conductivity are directly proportional. As salinity increases, conductivity increases.
d) The relationship between salinity and conductivity varies depending on the ecosystem.

c) Salinity and conductivity are directly proportional. As salinity increases, conductivity increases.

In freshwater ecosystems, as the concentration of dissolved salts (salinity) increases, the electrical conductivity of the water also increases. This relationship occurs because dissolved salts enhance the water's ability to conduct electricity.

14. Bivalves, like mussels, have evolved to allow them to move from ocean waters to freshwater like rivers and bays. What is the significance of this evolutionary phenomenon?
a) It led to the extinction of bivalve freshwater mussel species.
b) It allowed bivalve freshwater mussels to access new food sources and habitats.
c) It prevented bivalve freshwater mussels from reproducing effectively.
d) It caused a decrease in the diversity of bivalve freshwater mussels.

b) It allowed bivalve freshwater mussels to access new food sources and habitats.

The ability of bivalves to thrive in both marine and freshwater environments enables them to exploit diverse resources and habitats, potentially leading to greater ecological opportunities and adaptive success.