You are a marine biologist who wants to study what type of zooplankton (microscopic animals that live in the ocean and feed larger organisms) inhabit a particular area of the Pacific Ocean. You have taken your samples, but now need to collect your data. What advantage would using a compound light microscope have over using a dissecting microscope?
The magnification of a compound light microscope is much greater than a dissecting microscope, the latter having a power of circa 50x; the former could magnify as much as 500x.
Dissecting (stereo) microscopes can use reflected or transmitted light and give adequate magnification for identifying zooplankton. I used to do this, trust me.
Buenchico, there are a lot of assumptions in the question, not least of which is he assumption that the person answering the question knows whether the samples are alive or have been killed and preserved and have been stained either before or after death. The morphological structures used for identification are usually external so a dissecting microscope of 50x would be suitable especially if it is necessary to count as well as identify the specimens in the sample. It might on occasion be necessary to use a higher power compound microscope to distinguish between closely related species (but not in the same sample) but if you had to choose only one I would go for a dissecting/stero microscope without question. Modern good quality microscopes are more than up to the job.
PP, It does have all the hallmarks of homework or coursework which is why my first answer was fairly minimal, my later reply was really to Buenchico. As you can see evolution is working well and every ecological niche is being filled. I wonder if there is a vegan submarine spiritualist available for the more esoteric questions.