(a) Wildlife sanctuary is a protected area of land where animals are protected in their natural habitat. Hunting is strictly prohibited and punishable by law in this area and tress cannot be cut down for any purpose. Example: Sanjay Gandhi Wildlife Sanctuary (Maharashtra), Bharatpur Bird Sanctuary (Rajasthan). 

A biosphere reserve is a large protected area meant for the conservation of biodiversity and the traditional lifestyle of the people living in the area. A biosphere reserve is a very large area that may contain other protected areas like a Wildlife sanctuary and National park in it. Example: Pachmarhi biosphere reserve in Madhya Pradesh consists of one National park (Satpura) and two Wildlife sanctuary (Bori and Pachmarhi).

(b) Wildlife sanctuary is a protected area of land where animals are protected in their natural habitat while Zoo is the place where the animals live in the artificial habitat. In the zoo, the animals are protected in a small area for a public view while in a wildlife sanctuary, the animals are conserved over a large area.

(c) The species which are at risk of extinction are called endangered species. Examples: Great Indian rhinoceros, tiger, snow leopard, Asiatic lion, lion-tailed macaque, etc. 

The species which no longer exist (which have died completely) on Earth are called extinct species. Ex: Dinosaur, dodo, cave lion, iris deer and caspian tiger. 

(d) The plants that grow naturally in a particular area are called flora and animals which live naturally in a particular area called fauna. So, the plants and animals of a particular area are called the flora and fauna of that area.