AP BIOLOGY

Detailed explanation-1: -The prothallus develops from a germinating spore. It is a short-lived and inconspicuous heart-shaped structure typically 2–5 millimeters wide, with a number of rhizoids (root-like hairs) growing underneath, and the sex organs: archegonium (female) and antheridium (male).

Detailed explanation-2: –The antheridia are located in the posterior margin, above the rhizoids, while the archegonia are located in the lower side of the anterior margin, below the apical notch. Hence, both of these organs are located on the lower surface of the prothallus.

Detailed explanation-3: -Function of Prothallus The prothallus is a sexually reproductive structure and is the only part of the fern that contains both male and female reproductive organs. The male organs, the antheridia, produce sperm, and the female organs, the archegonia, produce eggs.

Detailed explanation-4: -The common example is fern prothallus. The prothallium essentially contains the gametophyte. The gametophyte produces the sex cell, also known as gametes. They produce both the male and female gametes.