Question

what can be achieved and prevented by proper checking of blood before blood donation

Answer 1

Proper checking of blood before blood donation prevents diseases that are spread by blood like diabaties, HIV, etc.

Answer 2

Blood tests help to determine any abnormalities or issues in the blood. This helps to keep our bodies fit.

If unchecked blood is donated which might be infected or has some disease , the same infection may go to the receiver. Hence we must check our blood before donating it..