Question

Female sex organ of algae is called as
A) Carpel
B) Oogonium
C) Archegonia
D) Oosphere

Answer 1

Algae are Autotrophic thalloid plants which don't have well-differentiated root, leaves, and stem. But they have specialized male and female sex organs in which male and female gametes are produced respectively.

Complete answer:
Generally, sex organs in the algae is unicellular and jacketless, Chara is an exception.
A) Carpel is known as a female reproductive part present in angiospermic plants. They are made up of style, stigma, and ovary which contain ovule.
B) Oogonium: It is the unicellular female sex organ in the algae which is a diploid structure and produces female gamete.
C) Archegonium: it is multicellular, jacketed, flask shaped female reproductive organs in bryophytes, pteridophytes and gymnosperms.
D) Oosphere is the female reproductive cell in some algae, fungi which is produced in the oogonium and fertilized to form oospore.
So the correct answer is option (B).

Additional information:
Sexual reproduction in algae occurs in three methods.

1. Isogamy: in this, gametes produced are similar in morphology and genetically. They may be either flagellated or non flagellated. Example: Chlamydomonas (motile), Spirogyra (non-motile).
2. Anisogamy: When both gametes are of different size, in most of the case female gametes are larger in shape. Example : in certain species of Chlamydomonas.
3. Oogamy: Female gametes are larger, non-motile while the male gamete is smaller and motile. And fertilisation takes place within the sex organ.
   Example: Volvx, Sargassum, Chlamydomaonas.

Note: 1) Chlamydomonas is the algae in which all three types of sexual reproduction occurs (Isogamy, Anisogamy, and oogamy).
2) Chara is the green algae in which sex organ is multicellular and jacketed. Male and female organs are found in the same plant. The female sex organ is called Nucule, found above the male sex organ while the male sex organ is called Globule.