1 An organ is a collection of different tissues that carries out a particular function (e.g. liver). 2  An organ system is a collection of organs that functions to carry out a specific task in the organism (e.g. digestive system).  At each level of organization, the structure helps determine the function.
Shivalik Express: Toy Train to Shimla. The best way to reach Shimla is to travel by Toy train from Kalka. The railway track is small in width between Kalka and Shimla and is known as meter gauge track opened by British Government in the year 1903. The distance of 96 KM between Shimla and Kalka passes through 102 tunnels and 87 bridges. There are more than 20 stations in this railway system which still uses the old Neales Token Instrument system for track interlocking. It connects Kalka at a height of 656 meter to Shimla at 2076 meter from mean sea level.
Buses are frequently available from Chandigarh to Shimla at a gap of half an hour. Delux Buses and Ordinary Buses are also available from all the places. By Air: Shimla Airport is at Jubbarhatti, 23 kms from city and is connected to Chandigarh, Kullu, Delhi. It has daily flights from Delhi and Kullu.