Final answer:
The statement regarding the majority of the ocean's biomass being planktonic is true. Plankton, particularly phytoplankton, are key contributors to the ocean's biomass and essential primary producers in the marine food web.
Step-by-step explanation:
The question "The majority of the biomass in the ocean is planktonic" can be affirmed as true. The term 'planktonic' refers to plankton, which is a diverse group of photosynthetic microorganisms that drift in ocean currents. Among these photosynthetic organisms, phytoplankton are particularly significant as they contribute massively to the ocean's biomass and are the foundation of the aquatic food web. Phytoplankton perform photosynthesis and capture a substantial amount of the Earth’s biosphere energy, in fact, approximately half of it.
Moreover, phytoplankton growth is a determinant of the productivity of the oceans. Factors like the availability of nitrogen or iron can limit their growth in different oceans, such as the Atlantic and Pacific respectively. In trophic levels, these organisms generally occupy the lowest level and serve as primary producers. The vastness of the oceans and the proliferation of phytoplankton indicate that their combined biomass exceeds that of any other individual marine organisms, making them the majority biomass.