Human body, blood groups and common diseases MCQ - Practice Questions with Answers

ABO groups depend on which antigens are present on red blood cells and which antibodies are present in plasma. If incompatible blood is given, these antibodies can react with unmatched red-cell antigens and cause agglutination, meaning red cells clump together. That clumping may produce a dangerous transfusion reaction. Therefore the assertion about unsafe clumping is true, and the antigen-antibody basis of ABO grouping gives the direct reason for it.

The communicable-disease section treats tuberculosis as a disease where the prevention and control logic includes early diagnosis and complete treatment. It then gives the reason: in TB, completing the full treatment course is essential because irregular treatment can lead to drug resistance. The assertion that the full course matters is therefore true, and the reason is also true. More importantly, the reason directly explains the assertion by linking incomplete or irregular treatment with the danger of drug resistance.

The immunisation section defines a vaccine as exposure to a safe form, part or instruction related to a pathogen. The purpose is to train the immune system so that the body can respond faster during a later infection. This is different from saying that a vaccine directly kills a current infection like an antibiotic. Vaccination also sits alongside hygiene, safe water, sanitation, surveillance and treatment, so it does not replace those measures. The correct description is preventive immune preparation.

Learning communicable diseases by pathogen type and route of spread. Dengue is described as a viral disease spread by Aedes mosquitoes, which often breed in clean stagnant water near homes. Malaria is different: it is caused by Plasmodium parasites and spreads through infected female Anopheles mosquitoes. Cholera is a bacterial water-borne disease linked with unsafe water and sanitation, while tuberculosis is linked with airborne or droplet spread. The dengue-Aedes-clean-stagnant-water pairing is therefore the correctly stated route.

The two layers separately. In the ABO system, group A has A antigen, group B has B antigen, group AB has both, and group O has neither A nor B antigen on red cells. The Rh system is another layer: when the Rh antigen is present, the blood group is positive; when it is absent, the group is negative. Since both statements reproduce these rules, the correct response accepts both. This is the reason blood banks record combinations such as A positive or O negative.