Immunity — Set 4

Correct Answer: D. Edward Jenner

Edward Jenner used cowpox material to create immunity against smallpox in 1796. His discovery laid the scientific foundation for modern immunology and vaccination. Smallpox was eventually eradicated globally due to vaccination efforts.

Correct Answer: B. Tonsils

Tonsils are clusters of lymphoid tissue located at the back of the throat. They act as the first line of defense against pathogens entering through the nose or mouth. They can sometimes become inflamed, a condition known as tonsillitis.

Correct Answer: D. A substance that triggers an immune response

Antigens are molecules, usually proteins, found on the surface of pathogens. The immune system identifies these as 'foreign' or 'non-self'. This recognition is what initiates the production of antibodies.

Correct Answer: C. IgA

IgA provides localized protection on mucosal surfaces of the body. It prevents pathogens from adhering to and colonizing the lining of tracts. It is the most common antibody found in the body's external secretions.

Correct Answer: B. General protection when most of a population is immune

Herd immunity occurs when a large percentage of a community is immune to a disease. This makes the spread of the pathogen unlikely, protecting those who cannot be vaccinated. It can be achieved through both natural infection and widespread vaccination.

Correct Answer: C. Eosinophils

Eosinophils release specialized enzymes to attack and destroy large parasites like worms. They also play a role in modulating allergic inflammatory responses. Their count in the blood is usually low unless such a condition exists.

Correct Answer: A. T-lymphocytes

The correct answer is 'T-lymphocytes'. Cell-mediated immunity does not involve antibodies but relies on the activation of T-cells. These cells directly attack infected cells or coordinate other immune responses. This system is particularly effective against intracellular viruses and cancers.

Correct Answer: B. To filter lymph and trap pathogens

Lymph nodes are small, bean-shaped structures found along the lymphatic vessels. They serve as checkpoints where immune cells monitor the lymph for any signs of infection. Swollen lymph nodes often indicate that the body is fighting an active infection.

Correct Answer: C. IgE

IgE binds to allergens and triggers mast cells to release histamine. This is the primary antibody responsible for the symptoms of hay fever and asthma. It is typically found in very small amounts in healthy individuals.

Correct Answer: B. Innate Immunity

Innate immunity is the basic resistance to disease that an individual is born with. It is immediate and does not require prior exposure to a pathogen. It includes barriers like the skin and generic responses like fever.