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1. Ecosystem is the groups of organisms from all biological domains in conjunction with the physical (abiotic) environment. Biome is the continental scale (climatically and geographically contiguous areas with similar climatic conditions) grouping of ecosystems. Biosphere or Ecosphere is all life plus the physical (abiotic) environment. NOTE: Community < Ecosystem < Biome < Biosphere

2. Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as “nutrient-induced increase in phytoplankton productivity“. Water bodies with very low nutrient levels are termed oligotrophic and those with moderate nutrient levels are termed mesotrophic. NOTE: Oligotrophic <Mesotrophic <Eutrophication

3. Mangrove is a shrub or small tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are a variety of species of broad-leaved trees (10–40 feet high) lying in muddy creeks and tidal estuaries. They are located on the intermediate zone between the land and the sea and represent one of the best examples of ecotone.

  4. Environmental conditions required for the formation of coral reefs: • A hard-underwater surface like continental shelf or mid-oceanic ridges, is required for the compaction and solidification of coral polyps’ skeletons. • Coral polyps thrive in warm water with temperatures around 20 degrees Celsius. • Coral reefs prefer relatively sediment-free water, as excessive sediment can impede respiration and cause early death of coral polyps. • Adequate nutrient supply is essential for the healthy development of coral polyps.  

5. The Wildlife (Protection) Act, 1972 provides for the establishment of Protected Areas in India. There are different categories of protected areas which are managed with different objectives for the larger motive of conservation. National Parks provide protection to the entire ecosystem that is, flora, fauna, landscape, etc. of that region. The national parks not only conserve wildlife but also provide a diversion of environmental and landscape heritage in a manner that does not harm it, in order to provide enjoyment to future generations. National parks are given a greater degree of protection, with human activity greatly restricted. Only certain areas can be visited and only activities permitted by the chief wildlife warden of the state are allowed in the park. Wildlife Sanctuaries: Wildlife Sanctuary, as the name implies, is the place that is reserved exclusively for wildlife use, which includes animals, reptiles, insects, birds, etc. wild animals, especially those in danger of extinction and the rare ones, so that they can live in peace for a lifetime and keep their population viable. Restrictions are less and open to general public. Wildlife sanctuaries refer to an area that provides protection and living conditions favourable to wild animals.