NEET BIOLOGY

Detailed explanation-1: -Photosynthetic organisms are found mainly in shallow water due to the availability of sunlight. Without the energy from the sun, organisms cannot carry out photosynthesis in spite of the availability of oxygen, nutrient, and salt.

Detailed explanation-2: -Photosynthesis requires sunlight and therefore phytoplankton are restricted to the upper 50-100 m of oceanic water bodies because this is the maximum depth to which sunlight penetrates the water environment. Growth also depends upon mineral nutrients with the greatest supply coming from land.

Detailed explanation-3: -They live in various habitats including salt and freshwater aquatic environments, wet soil, or on moist rocks. Photosynthetic algae known as phytoplankton are found in both marine and freshwater environments. Most marine phytoplankton are composed of diatoms and dinoflagellates.

Detailed explanation-4: -Algae and vascular plants that live in the water must live close enough to the surface to receive sunlight. The euphotic zone is the layer of water in which there is enough light for net photosynthesis.

Detailed explanation-5: -Phytoplankton comprise two main groups: photosynthetic cyanobacteria and the single-celled algae that drift in the sunlit top layers of oceans. They provide food, directly or indirectly, for virtually every other marine creature. They emit much of the oxygen that permeates our atmosphere.