All MCQs

Bloodstream infections can rapidly spread microbes or toxins systemically, leading to severe inflammation, shock, and organ dysfunction.

Blood and lymph carry leukocytes, antibodies, complement, and signaling molecules. This allows defense responses to reach damaged or infected tissues.

Lacteals are lymphatic vessels in intestinal villi that absorb dietary fats and transport them as chyle into lymphatic circulation.

Dehydration lowers plasma volume, which can reduce venous return and blood pressure. Circulatory regulation attempts to compensate.

Hemoglobin binding is crucial for oxygen transport. Impaired binding reduces oxygen delivery, causing tissue hypoxia.

Earthworms have a closed circulatory system with major vessels that direct blood flow. This supports exchange and transport through the segmented body.

Melanization is an invertebrate immune reaction that encapsulates or kills invaders. It is common in arthropod defense.

Insects rely on innate immune mechanisms such as phagocytic hemocytes, melanization, clotting, and antimicrobial peptides.

Cytotoxic T cells recognize infected cells and kill them, limiting viral replication. This is a key cell-mediated immune response.

Activated B lymphocytes can differentiate into plasma cells that secrete antibodies specific to an antigen.

Memory B and T cells persist after first exposure. On re-exposure, they mount faster and stronger responses.

Innate immune cells detect broad pathogen-associated patterns using pattern-recognition mechanisms. This differs from highly specific adaptive antigen receptors.