The functional unit of the human lung is: MCQ with Answer and Explanation

Explanation:
FSH, released from the anterior pituitary, stimulates Sertoli cells in the seminiferous tubules to support spermatogenesis (production of sperm). Luteinizing hormone (LH) stimulates Leydig cells to produce testosterone, which is also necessary for spermatogenesis. Estrogen is female hormone, prolactin for milk, oxytocin for uterine contraction.

Explanation:
Innate immunity is the non-specific, inborn defense mechanism present from birth. It includes physical barriers (skin, mucous membranes), physiological barriers (stomach acid, tears), cellular barriers (neutrophils, macrophages), and cytokine barriers (interferons). Antibodies and memory cells are part of acquired (adaptive) immunity.

Explanation:
The root is divided into zones. The root hair zone contains epidermal extensions (root hairs) that vastly increase surface area, making it the primary region for water and mineral absorption. The zone of cell division (meristematic zone) is at the very tip, where active mitosis occurs; the zone of elongation is where cells expand in length, pushing the root tip forward. The root cap is a thimble-like structure protecting the delicate apical meristem as it pushes through soil. Thus, statements 1 and 3 are correct.