Question

The female sex organ in red algae is flask shaped and is known as
A. Trichogyne
B. Carpogonium
C. Spermatium
D. Archegonium

Answer 1

In red algae the female sex organ remains attached to the plant even after formation of zygote and forms a new structure called as a cystocarp or carposporophyte.

Complete Answer:
- In Rhodophyta (red algae) the plants are usually dioecious (male and female sex organs are present on two separate plants) and rarely monoecious. Advanced oogamous type of sexual reproduction is present. The male sex organ is called as spermatangium that gives rise to spermatium, the male gamete. Male gametes are flagellated and thus, non-motile. The female sex organ is called carpogonium.
- Carpogonia are formed singly at the apex of short lateral branches called procarps or carpogonial filaments. A carpogonium filament consists of 3 – 5 cells and it arises from the fertile female trichoblast (short branch or branch of limited growth). Mature carpogonium is a flask shaped structure. It consists of a swollen basal portion known as carpogyne which is prolonged into an apical tubular neck like structure, trichogyne. Carphone contains a single uninucleated egg cell.
- The male and female gametes are non-motile in red algae. So, water plays an essential role in fertilization. The liberated spermatia or male gametes are carried passively by water currents and when they come in contact with carpogonium one of the spermatium becomes attached with the trichogyne.
- The wall at the point of attachment dissolves and a passage is formed through which the content of the spermatium along with male nucleus migrates into the carpogyne where the act of fertilization (fusion of male and female nuclei) takes place. The manner in which the male gametes come closer to the female sex organ and process of fertilization occurs is remarkably uniform in all the members of Rhodophyceae.

Thus, the correct answer is ‘B’, i.e., Carpogonium.

Note: Rhodophyta is one of the largest groups of algae as well as one of the oldest groups of eukaryotic algae. They consist of phycoerythrins as accessory pigments that are responsible for their red colour. They do not possess any flagellated stage in their life cycle.