For example, root exudates from legume ... can lead to severe alterations of the nitrogen cycle in both aquatic and terrestrial ecosystems. Industrial nitrogen fixation has increased exponentially ...

For example, if two significant figures are used in the question, then usually your answer would also be to two significant figures. Don't forget to check your rounding. Edexcel questions courtesy ...

A primary example of this involves the energy currency ... carbon, and energy that cycles through ecosystems (Figure 1). Using maps like these, we can compare different places, or measure primary ...