Lipids, proteins, polysaccharides, and nucleic acids are large polymers that make up the different components of our bodies. Which element can be found as the backbone of all of these macromolecules? Phosphorus
Oxygen
Nitrogen
Carbon

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.