Final answer:
Chlamydomonas, a single-celled green alga, can reproduce asexually through mitotic cell division or sexually by gametes fusing to form a zygote, which develops into a zygospore. This sexual reproduction is important for genetic variation and surviving harsh conditions.
Step-by-step explanation:
Reproduction in Chlamydomonas
Chlamydomonas is a single-celled green alga from the Chlorophyta group that has the ability to reproduce both sexually and asexually. The sexual type of reproduction in Chlamydomonas starts when specific cells, which function as gametes, gain the ability to attach to one another, first by their flagella and then by their anterior ends. This leads to protoplast fusion and the formation of a zygote, which subsequently develops into a thick-walled dormant cell known as a zygospore. This zygospore can withstand adverse environmental conditions and will undergo meiosis before germinating and releasing haploid cells.
Asexual reproduction occurs when haploid cells divide, often multiple times, and create new daughter cells. This process involves mitosis but does not involve the fusing of gametes. Although sexual reproduction contributes less to the population growth compared to asexual reproduction, it is significant as it introduces genetic variation and produces individuals that can survive difficult conditions.
The ability of Chlamydomonas to reproduce asexually is significant for their survival and propagation, while the occasional sexual reproduction ensures genetic diversity and adaptation to changing environments.