What is the correct sequential order of events during sexual reproduction (isogamy) in *Chlamydomonas*, starting from environmental induction to the production of new vegetative cells?
- 1Nitrogen starvation induces haploid vegetative cells to differentiate into flagellated gametes.
- 2Compatible gametes adhere by their flagellar tips and fuse their anterior cytoplasm.
- 3Karyogamy completes syngamy to form a mobile, quadriflagellate diploid zygote.
- 4The diploid zygote sheds its flagella and secretes a thick, resistant wall to become a dormant zygospore.
- 5The zygospore nucleus undergoes meiosis upon favorable conditions, releasing four haploid zoospores.
Answer
The correct sequence of sexual reproduction in *Chlamydomonas* is: differentiation of haploid vegetative cells into gametes due to nitrogen starvation -> flagellar pairing and anterior cytoplasm fusion -> nuclear fusion forming a quadriflagellate diploid zygote -> shedding of flagella and thick wall secretion to form a dormant zygospore -> meiotic division inside the zygospore releasing four haploid zoospores.
Sexual reproduction in *Chlamydomonas* follows a strict temporal sequence. First, environmental stress (such as nitrogen starvation) triggers haploid vegetative cells to act as gametes. Compatible gametes pair at their flagella and fuse cytoplasm (plasmogamy) followed by nuclei (karyogamy), generating a temporary quadriflagellate diploid zygote. This zygote then retracts/sheds its flagella and secretes a heavy protective wall to become a dormant zygospore. Finally, upon return of favorable conditions, the diploid nucleus inside the zygospore undergoes meiosis to produce four haploid vegetative zoospores.
Step-by-Step Solution
Key Concept
Isogamous Sexual Reproduction and Zygospore Life Cycle in Unicellular Chlorophyta
Estimated Time:2m 0s