Question

In Ulothrix/Spirogyra, reduction division (meiosis) occurs at the time of

• A. gamete formation
• B. zoospore formation
• C. zygospore germination
• D. vegetative reproduction.

Answer 1

The Correct Option is C

The question is asking about when meiosis (reduction division) occurs in Ulothrix or Spirogyra. Let's analyze each option to determine the correct answer.

Explanation:

• Gamete Formation: In many organisms, meiosis occurs during gamete formation. However, in algae like Ulothrix and Spirogyra, gametes are typically produced through mitosis, not meiosis. Therefore, this is not the correct phase for reduction division in these organisms.
• Zoospore Formation: Zoospores are generally formed through mitotic division. These structures allow asexual reproduction, and meiosis is not involved in their formation.
• Zygospore Germination: In Ulothrix and Spirogyra, meiosis occurs during the germination of the zygospore. After fertilization, the diploid zygote forms a zygospore. When this zygospore germinates, it undergoes meiosis to form haploid cells, which then develop into new filaments. Therefore, this is the correct answer.
• Vegetative Reproduction: This involves the formation of new individuals without meiosis, typically through processes like fragmentation or cell division. Since reduction division is not part of vegetative reproduction, this option is also incorrect.

Conclusion: The correct answer is "zygospore germination" because this is when meiosis occurs in the life cycle of Ulothrix or Spirogyra. During this stage, the zygospore undergoes reduction division to produce haploid cells.