Answer: Thymus is a gland in the chest where T cells mature; it is large in childhood and involutes (shrinks) after puberty.
- A Thymus is mainly a lymph node located in the neck region of the body in standard practice under most conditions encountered
- B Thymus is a gland in the chest where T cells mature; it is large in childhood and involutes (shrinks) after puberty
- C Thymus remains fairly active and largely unchanged in overall size throughout most of a human lifetime as frequently observed in practice
- D Thymus is sometimes mistakenly described as the principal organ where B lymphocytes undergo maturation in many documented cases
Correct answer: B. Thymus is a gland in the chest where T cells mature; it is large in childhood and involutes (shrinks) after puberty
Explanation: The thymus is a bilobed gland in the chest (mediastinum) where T cells mature and undergo positive/negative selection. It is largest in childhood and starts involuting after puberty. By old age, it is mostly replaced by fat. Thymic involution contributes to decreased immune function with aging.
An antibody is Y-shaped, with two identical antigen-binding sites at the tips of the variable regions - each shaped to recognise one specific antigen - while the constant (Fc) region at the base is recognised by immune cells to trigger further responses.
Concept context
Innate and adaptive immunity, B cells, T cells, antibodies, vaccines, and immune disorders. Critical for NEET.