Question

In Chlamydomonas, the meiosis occurs in

• A. Gamete
• B. Zygote
• C. Sporogonium
• D. Zoospore

Answer 1

Answer: (B)

Zygote

In Chlamydomonas, zygotes undergo a resting stage prior to meiosis, during which a multi-layered zygote wall is deposited. Basal bodies reappear at interphase. Heterochromatin is not visible in the interphase nucleus. Leptotene is characterized by the appearance of axial cores and the condensation of chromenemata. By early zygotene, axial elements associated with the condensing chromatin associate with the nuclear envelope. Tubular elements appear in the perinuclear space adjacent to the associated chromosomes. Bivalents begin to associate with the nucleolus. By pachytene, typical synaptinemal complexes have formed. The synaptinemal complexes possess two lateral elements associated with the chromosomes and separated by a central space of about 130 nm. A central element may form midway between the lateral elements and be joined to them via transverse elements. Separated synaptonemal complexes appear in the cytoplasm by diplotene-diakinesis. At this stage the chromosomes become most condensed and chiasmata occur. The nucleolus disappears.