Answer
Ozone loss and more UV exposure would decrease numbers of nitrogen-fixing bacteria, in turn reducing availability of N in the environment. This would limit the growth of plants by limiting the amount of N-containing molecules, such as proteins, which they could make, in turn limiting animal life.
Work Step by Step
Consider what would be changed by ozone loss (UV exposure, and this nitrogen fixation), and the effects of this in ecosystems. As a cautionary note, given that land plants usually fix nitrogen underground, much of the fixation might be safe from UV as being shielded by the soil.
