Defence against infectious disease Quiz

HIV infects and destroys helper T cells (Th cells), which play a central role in coordinating the immune response. The loss of these cells severely weakens the immune system, making the body highly susceptible to opportunistic infections that a healthy immune system would easily fight off.

HIV specifically targets and infects helper T cells (Th cells, or CD4+ T cells) by binding to the CD4 receptor on their surface. This targeted destruction leads to the progressive failure of the immune system.

Florey and Chain conducted experiments where they infected mice with lethal doses of Streptococcus bacteria and treated some of them with penicillin. The treated mice survived while the untreated ones died, demonstrating that penicillin has powerful antibiotic properties against bacterial infections.

Antibiotics target specific metabolic processes and structures unique to prokaryotic cells, such as cell wall synthesis or bacterial protein translation. Because viruses lack their own metabolism and instead rely entirely on the host cell's metabolic machinery, antibiotics have no target structures to act upon in a virus.

Antibiotics act on prokaryotic cells by targeting and blocking essential cellular processes, such as cell wall synthesis (e.g., penicillin) and DNA replication or protein synthesis. This selectively kills or inhibits the growth of the bacteria without harming eukaryotic host cells.

Antibiotics are designed to selectively target metabolic pathways and structures that occur only in prokaryotic cells, such as peptidoglycan cell walls or 70S ribosomes. This allows them to destroy bacterial pathogens without damaging the eukaryotic cells of the host organism.

Antibiotics are only effective against bacteria; they do not work against viruses. Viral infections cannot be treated with antibiotics because viruses lack the specific metabolic pathways and cell structures that antibiotics target.

Phagocytic white blood cells provide non-specific immunity by engulfing and digesting any foreign pathogens they encounter, regardless of the pathogen's specific identity. In contrast, the production of antibodies by lymphocytes is a highly specific immune response tailored to target specific antigens.

Thrombin is an active enzyme that catalyzes the conversion of the soluble plasma protein fibrinogen into insoluble fibrin strands. These fibrin strands form a mesh that traps blood cells to form a clot.

Platelets (thrombocytes) adhere to damaged blood vessel walls and release clotting factors that initiate the coagulation cascade. While damaged tissues also release clotting factors, among the blood cells listed, platelets are the primary source.