You are required to draw blood from a patient and to keep it in a test tube for analysis of blood corpuscles and plasma. You are also provided with the following four types of test tubes.
which of these you will not use for the purpose.

In the ABO system of blood groups, if both antigens are present but no antibody, the blood group of the individual would be

The cardiac pacemaker in a patient fails to function normally. The doctors find that an artificial pacemaker is to be grafted in him. It is likely that it will be grafted at the site of

Bundle of His is a network of