Questions

 It is a strange sequence. Each number describes the resemblance of the previous one, except the first one.

11 describes the previous '1' which contains one '1'

21 describes the previous '11' which contains two '1'

1211 describes the previous '21' which contains one '2' and one '1'

111221 describes the previous '1211' which contains one '1', one '2' and two '1'.

So the next sequence will be 312211, that is the previous '111221' contains three '1', two '2' and one '1'.

The red blood corpuscles or Erythrocytes usually carry antigens and there are two types of antigens. The A group persons have antigen A in their red corpuscles and the B group have antigen A in their red corpuscles.The AB group persons have both antigen A and antigen B in their erythrocytes.The 'O'group persons have no antigens in their red corpuscles.

Most operating systems store files on a hard disk.

Data flow analysis studies the use of data on paths through the code.

Sir Sandford Fleming, (January 7, 1827 – July 22, 1915) was a Scottish Canadian engineer and inventor. Born and raised in Scotland, he emigrated to colonial Canada at the age of 18. He proposed worldwide standard time zones, designed Canada's first postage stamp.