Questions

The OSI Model is used as a reference model.

The primary reason the OSI model was created was so that different networks could inter-operate. Hence, different networks could communicate.

Strait is nothing but a narrow passage of water which connects two seas or other large areas of water. Here Palk strait is the strait that separates India from Sri Lanka.

1. Lichens are plants that grow in exposed places such as rocks or tree bark.

2.  Lichens are widely used as environmental indicators or bio-indicators. They can be used as air pollution indicators, especially of the concentration of sulfur-di-oxide in the atmosphere.  

3. They need to be very good at absorbing water and nutrients to grow there.