The human chromosome number (2n) is: MCQ with Answer and Explanation

Explanation:
The spleen is the largest organ in the lymphatic system. It plays a vital role in immune function by filtering blood, producing lymphocytes, and removing old or damaged red blood cells and platelets. The thymus is crucial for T-cell maturation but is largest in childhood and shrinks with age. Tonsils and Peyer's patches are smaller, localized lymphoid tissues. The spleen acts as a major blood filter and immune response center.

Explanation:
G.H.A. Hansen discovered Mycobacterium leprae in 1873, the first bacterium identified as causing a human disease. Koch later discovered TB.

Explanation:
The pituitary gland is termed the master gland because it secretes hormones that regulate other endocrine glands. The thyroid gland secretes thyroxine, triiodothyronine, and calcitonin, which regulates blood calcium. The adrenal cortex secretes cortisol (a glucocorticoid), while the adrenal medulla secretes adrenaline and noradrenaline. Thus, statements 1 and 2 are correct.