Human Immunity and Blood

Blood is red in colour due to haemoglobin present in the red blood cells. Therefore, test tube A will show unusual colour of blood because of deficiency in red blood cells.

Heparin is a natural anticoagulant substance found in blood, produced by mast cells and basophils. It prevents blood clotting by inhibiting thrombin. Fibrinogen and thrombin are actually involved in blood clotting (coagulation), not preventing it. Globin is a protein component of hemoglobin and unrelated to clotting.

Fibrin is a fibrous protein involved in the clotting of blood and is non-globular. It is a fibrillar protein that is polymerised to form a mesh that forms a hemostatic plug or clot (in conjunction with platelets) over a wound site.

Blood group O lacks both A and B antigens on red blood cells. It is known as the 'universal donor' because the absence of antigens means it can be transfused to recipients with any blood type without causing an immune reaction.

Agglutination is the clumping of cells, most commonly observed in blood typing when antibodies react with antigens on red blood cells. It is a fundamental immunological reaction used in blood compatibility testing.

Alanine is necessary for the maintainance of proper blood glucose level from dietary protein. It stimulates lymphocyte production and may help people who have immune suppression. It also strengthens the immune system by producing antibodies.

Complements C1 to C5 are activated during endotoxin inactivation.

This is the correct option. Wandering macrophages are the macrophages that leave blood and migrate to an infected tissue. Peritoneal macrophages are wandering macrophages.

Regulatory T-cells also known as suppressor and helper T-cells call in phagocytes to destroy bacterial cells.

Monocytes are the precursors of macrophages. They differentiate into macrophages.

Antibodies are the regulatory proteins released by the activated T-cells.

Killer T-cells recognise the antigens coupled to class I MHC molecules.

Memory T-cells typically express the cell surface protein CD45RO. It is an essential regulator of T and B-cell antigen receptor signaling.

Inflammation of blood vessels throughout the body, swelling, redness, heat and pain takes place in Behcet's syndrome.

In X-linked agammaglobulinemia, B-cells are not generated. Due to this, antibodies are not formed and it manifests as a complete lack of antibodies in their bloodstream. It happens due to a mutation in X-chromosome.