True or False: Vaccines can cause autism in children.

Explanation: The secondary immune response provides long-lasting immunity because of the presence of memory B cells and memory T cells. These memory cells "remember" the specific antigen and can quickly mount a strong and effective immune response upon re-exposure to the same antigen, providing long-term protection.

Incorrect choices:

a. The primary immune response is primarily mediated by IgM antibodies, while the secondary immune response involves the predominance of IgG antibodies, which are more effective and provide long-lasting immunity.

b. The secondary immune response occurs after the primary immune response and is faster, not slower, due to the presence of memory cells.

c. Memory cells are a key component of the secondary immune response, playing a central role in providing rapid and robust immunity.

VI. Immune Disorders and Clinical Considerations:

Explanation: B cells are a type of lymphocyte that plays a central role in the adaptive immune response. When activated by the presence of specific antigens, B cells differentiate into plasma cells, which are responsible for producing large quantities of antibodies that can target and neutralize the invading pathogen.

Incorrect choices:

a. T cells are another type of lymphocyte that is involved in cell-mediated immunity, where they directly attack infected or abnormal cells. They do not produce antibodies.

b. Natural killer cells are part of the innate immune system and are responsible for killing infected or cancerous cells. They are not involved in antibody production.

d. Macrophages are phagocytic cells that engulf and destroy pathogens and debris in the body. While they play a crucial role in immune responses, they do not produce antibodies.