Questions

In a computer, the area where the data is stored for the quick access by the computer's processor is called Main storage or Primary storage or Memory or RAM.

Hence, main storage is also called Memory.

During vigorous exercise capillaries of the active muscles will be engorged with blood.

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.

It is Blackboard or Chalkboard which is Black when clean, and as you write on it with white chalk it becomes dirty in White color.

The path that data takes from source to destination is called a Channel. A channel is a communication medium. A channel has a certain capacity for transmitting information. 

The "capacity" of a channel is the theoretical upper-limit to the bit rate over a given channel that will result in negligible errors. Channel capacity is often measured by its Bandwidth in Hz or its data rate in bits per second.